tag:theconversation.com,2011:/ca/topics/brain-waves-27265/articlesBrain waves – The Conversation2023-12-22T02:25:14Ztag:theconversation.com,2011:article/2192362023-12-22T02:25:14Z2023-12-22T02:25:14ZAlpha, beta, theta: what are brain states and brain waves? And can we control them?<figure><img src="https://images.theconversation.com/files/567204/original/file-20231222-17-kl638p.jpg?ixlib=rb-1.1.0&rect=69%2C77%2C5106%2C3368&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>There’s no shortage of apps and technology that claim to shift the brain into a “theta” state – said to help with relaxation, inward focus and sleep. </p>
<p>But what exactly does it mean to change one’s “mental state”? And is that even possible? For now, the evidence remains murky. But our understanding of the brain is growing exponentially as our methods of investigation improve.</p>
<h2>Brain-measuring tech is evolving</h2>
<p>Currently, no single approach to imaging or measuring brain activity gives us the whole picture. What we “see” in the brain depends on which tool we use to “look”. There are myriad ways to do this, but each one comes with trade-offs. </p>
<p>We learnt a lot about brain activity in the 1980s thanks <a href="https://www.aps.org/publications/apsnews/200607/history.cfm">to the advent</a> of magnetic resonance imaging (MRI).</p>
<p>Eventually we invented “functional MRI”, which allows us to link brain activity with certain functions or behaviours in real time by measuring the brain’s use of oxygenated blood during a task. </p>
<p>We can also measure electrical activity using EEG (electroencephalography). This can accurately measure the timing of brain waves as they occur, but isn’t very accurate at identifying which specific areas of the brain they occur in.</p>
<p>Alternatively, we can measure the brain’s response to magnetic stimulation. This is very accurate in terms of area and timing, but only as long as it’s close to the surface.</p>
<h2>What are brain states?</h2>
<p>All of our simple and complex behaviours, as well as our cognition (thoughts) have a foundation in brain activity, or “neural activity”. Neurons – the brain’s nerve cells – communicate by a sequence of electrical impulses and chemical signals called “neurotransmitters”. </p>
<p>Neurons are very greedy for fuel from the blood and require a lot of support from companion cells. Hence, a lot of measurement of the site, amount and timing of brain activity is done via measuring electrical activity, neurotransmitter levels or blood flow.</p>
<p>We can consider this activity at three levels. The first is a single-cell level, wherein individual neurons communicate. But measurement at this level is difficult (laboratory-based) and provides a limited picture.</p>
<p>As such, we rely more on measurements done on a network level, where a series of neurons or networks are activated. Or, we measure whole-of-brain activity patterns which can incorporate one or more so-called “brain states”. </p>
<p>According to <a href="https://doi.org/10.1016/j.tins.2023.04.001">a recent definition</a>, brain states are “recurring activity patterns distributed across the brain that emerge from physiological or cognitive processes”. These states are functionally relevant, which means they are related to behaviour.</p>
<p>Brain states involve the synchronisation of different brain regions, something that’s been most readily observed in animal models, usually rodents. Only now are we starting to see some evidence in human studies.</p>
<h2>Various kinds of states</h2>
<p>The most commonly-studied brain states in both rodents and humans are states of “arousal” and “resting”. You can picture these as various levels of alertness.</p>
<p>Studies show environmental factors and activity influence our brain states. Activities or environments with high cognitive demands drive “attentional” brain states (so-called task-induced brain states) with increased connectivity. Examples of task-induced brain states include <a href="https://www.cell.com/trends/neurosciences/fulltext/S0166-2236(23)00101-7#%20">complex behaviours</a> such as reward anticipation, mood, hunger and so on.</p>
<p>In contrast, a brain state such as “mind-wandering” seems to be divorced from one’s environment and tasks. Dropping into daydreaming is, by definition, without connection to the real world. </p>
<p>We can’t currently disentangle multiple “states” that exist in the brain at any given time and place. As mentioned earlier, this is because of the trade-offs that come with recording spatial (brain region) versus temporal (timing) brain activity.</p>
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<h2>Brain states vs brain waves</h2>
<p>Brain state work can be couched in terms such as alpha, delta and so forth. However, this is actually referring to brain <em>waves</em> which specifically come from measuring brain activity using EEG. </p>
<p>EEG picks up on changing electrical activity in the brain, which can be sorted into different frequencies (based on wavelength). Classically, these frequencies have had specific associations:</p>
<ul>
<li>gamma is linked with states or tasks that require more focused concentration</li>
<li>beta is linked with higher anxiety and more active states, with attention often directed externally</li>
<li>alpha is linked with being very relaxed, and passive attention (such as listening quietly but not engaging)</li>
<li>theta is linked with deep relaxation and inward focus</li>
<li>and delta is linked with deep sleep. </li>
</ul>
<p>Brain wave patterns are used a lot to monitor sleep stages. When we fall asleep we go from drowsy, light attention that’s easily roused (alpha), to being relaxed and no longer alert (theta), to being deeply asleep (delta).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=471&fit=crop&dpr=1 754w, https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=471&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/567205/original/file-20231222-16-r93ni6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=471&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Brainwaves are grouped into five different wavelength categories.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
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</figure>
<h2>Can we control our brain states?</h2>
<p>The question on many people’s minds is: can we judiciously and intentionally influence our brain states? </p>
<p>For now, it’s likely too simplistic to suggest we can do this, as the actual mechanisms that influence brain states remain hard to detangle. Nonetheless, researchers are investigating everything from the use of drugs, to environmental cues, to practising mindfulness, meditation and sensory manipulation.</p>
<p>Controversially, brain wave patterns are used in something called “neurofeedback” therapy. In these treatments, people are given feedback (such as visual or auditory) based on their brain wave activity and are then tasked with trying to maintain or change it. To <a href="https://pubmed.ncbi.nlm.nih.gov/36416067/">stay in a required state</a> they may be encouraged to control their thoughts, relax, or breathe in certain ways. </p>
<p>The applications of this work are predominantly around mental health, including for individuals who have experienced trauma, or who have difficulty self-regulating – which may manifest as poor attention or emotional turbulence.</p>
<p>However, although these techniques have intuitive appeal, they don’t account for the issue of multiple brain states being present at any given time. Overall, clinical studies have been <a href="https://pubmed.ncbi.nlm.nih.gov/33370575/">largely inconclusive</a>, and proponents of neurofeedback therapy remain frustrated by a lack of orthodox support.</p>
<p>Other forms of neurofeedback are delivered by MRI-generated data. Participants engaging in mental tasks are given signals based on their neural activity, which they use to try and “up-regulate” (activate) regions of the brain involved in positive emotions. This could, for instance, be useful for helping <a href="https://pubmed.ncbi.nlm.nih.gov/33370575/">people with depression</a>.</p>
<p>Another potential method claimed to purportedly change brain states involves different sensory inputs. Binaural beats are perhaps the most popular example, wherein two different wavelengths of sound are played in each ear. But the evidence for such techniques <a href="https://pubmed.ncbi.nlm.nih.gov/37205669/">is similarly mixed</a>.</p>
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<p>Treatments such as neurofeedback therapy are often very costly, and their success likely relies as much on the therapeutic relationship than the actual therapy.</p>
<p>On the bright side, there’s no evidence these treatment do any harm – other than potentially delaying treatments which have been proven to be beneficial.</p><img src="https://counter.theconversation.com/content/219236/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Susan Hillier receives funding from Medical Research Future Fund/NHMRC. </span></em></p>What we ‘see’ in the brain depends on which tool we use to ‘look’ – but each one comes with trade-offs.Susan Hillier, Professor: Neuroscience and Rehabilitation, University of South AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2178892023-12-06T13:27:31Z2023-12-06T13:27:31ZHow electroconvulsive therapy heals the brain − new insights into ECT, a stigmatized yet highly effective treatment for depression<figure><img src="https://images.theconversation.com/files/563043/original/file-20231201-17-j1qrjt.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2059%2C1454&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Electroconvulsive therapy involves inducing a controlled seizure under anesthesia.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/human-brain-impulse-concept-futuristic-royalty-free-illustration/1177917141">Inkoly/iStock via Getty Images Plus</a></span></figcaption></figure><p>When most people hear about <a href="https://theconversation.com/electroconvulsive-therapy-a-history-of-controversy-but-also-of-help-70938">electroconvulsive therapy, or ECT</a>, it typically conjures terrifying images of cruel, outdated and pseudo-medical procedures. Formerly known as electroshock therapy, this perception of ECT as dangerous and ineffective has been reinforced in pop culture for decades – think the 1962 novel-turned-Oscar-winning film “<a href="https://www.britannica.com/topic/One-Flew-over-the-Cuckoos-Nest-film-by-Forman">One Flew Over the Cuckoo’s Nest</a>,” where an unruly patient is subjected to ECT as punishment by a tyrannical nurse.</p>
<p>Despite this stigma, ECT is a <a href="https://doi.org/10.1056/nejmra2034954">highly effective treatment for depression</a> – up to 80% of patients experience at least a 50% reduction in symptom severity. For one of the <a href="https://doi.org/10.1016/S0140-6736(20)30925-9">most disabling illnesses</a> around the world, I think it’s surprising that ECT is <a href="https://doi.org/10.1097/yct.0000000000000320">rarely used</a> to treat depression.</p>
<p>Contributing to the stigma around ECT, psychiatrists still don’t know exactly how it heals a depressed person’s brain. ECT involves using <a href="https://www.ncbi.nlm.nih.gov/books/NBK538266/">highly controlled doses of electricity</a> to induce a brief seizure under anesthesia. Often, the best description you’ll hear from a physician on why that brief seizure can alleviate depression symptoms is that ECT <a href="https://www.uhhospitals.org/services/adult-psychiatry-psychology/ect-suite/about-ect-procedure">“resets” the brain</a> – an answer that can be fuzzy and unsettling to some.</p>
<p>As a <a href="https://scholar.google.com/citations?hl=en&user=tDUCQ3UAAAAJ">data-obsessed neuroscientist</a>, I was also dissatisfied with this explanation. In <a href="https://doi.org/10.1038/s41398-023-02631-y">our newly</a> <a href="https://doi.org/10.1038/s41398-023-02634-9">published research</a>, my colleagues and I in <a href="https://voyteklab.com">the lab of</a> <a href="https://scholar.google.com/citations?user=ydFvGx0AAAAJ&hl=en">Bradley Voytek</a> at UC San Diego discovered that ECT might work by resetting the brain’s electrical background noise.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/AcmarVpo2xE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Despite its high effectiveness in alleviating depression symptoms, misperceptions about ECT made it unpopular.</span></figcaption>
</figure>
<h2>Listening to brain waves</h2>
<p>To study how ECT treats depression, my team and I used a device called an <a href="https://www.ncbi.nlm.nih.gov/books/NBK563295/">electroencephalogram, or EEG</a>. It measures the brain’s electrical activity – or brain waves – via electrodes placed on the scalp. You can think of brain waves as music played by an orchestra. Orchestral music is the sum of many instruments together, much like EEG readings are the sum of the electrical activity of millions of brain cells.</p>
<p>Two <a href="https://doi.org/10.1038/s41593-020-00744-x">types of electrical activity</a> make up brain waves. The first, oscillations, are like the highly synchronized, melodic music you might hear in a symphony. The second, aperiodic activity, is more like the asynchronous noise you hear as musicians tune their instruments. These two types of activities coexist in the brain, together creating the electrical waves an EEG records.</p>
<p>Importantly, tuning noises and symphonic music shouldn’t be mistaken for one another. They clearly come from different processes and serve different purposes. The brain is similar in this way – aperiodic activity and oscillations are different because the biology driving them is distinct.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Diagram showing EEG reading of neural oscillations and aperiodic activity" src="https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=134&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=134&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=134&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=169&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=169&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563769/original/file-20231205-27-cj7f46.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=169&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This diagram shows two EEG readings: One signal contains slow neural oscillations and the other contains only aperiodic activity. Although these signals can be tricky to visually distinguish, certain data analysis methods can help tease them apart.</span>
<span class="attribution"><span class="source">Sydney Smith</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>However, the methods neuroscientists have traditionally used to analyze these signals are <a href="https://doi.org/10.1038/s41593-020-00744-x">unable to differentiate</a> between the oscillations (symphony) and the aperiodic activity (tuning). Both are critical for the orchestra, but so far neuroscientists have mostly ignored – or entirely missed – aperiodic signals because they were thought to be just the brain’s background noise.</p>
<p>In our new research, my team and I show that ignoring aperiodic brain activity <a href="https://doi.org/10.1038/s41398-023-02631-y">likely explains</a> <a href="https://doi.org/10.1038/s41398-023-02634-9">the confusion</a> behind about how ECT treats depression. It turns out we’ve been missing this signal all along.</p>
<h2>Connecting aperiodic activity and ECT</h2>
<p>Since the 1940s, ECT has been associated with <a href="https://doi.org/10.1176/ajp.99.4.525">increases in slow oscillations</a> in the brain waves of patients. However, those slow oscillations have never been linked to how ECT works. The degree to which slow oscillations appear is not consistently related to how much symptoms improve following ECT. Nor have ideas about how the brain produces slow oscillations connected those processes to the pathology underlying depression. </p>
<p>Because these two types of brain waves are <a href="https://doi.org/10.1007/s12021-022-09581-8">difficult to separate in measurements</a>, I wondered if these slow oscillations were in fact incorrectly measured aperiodic activity. Returning to our orchestra analogy, I believed that scientists had misidentified the tuning sounds as symphony music.</p>
<p>To investigate this, my team and I gathered three EEG datasets: one from nine patients with depression undergoing ECT in San Diego, another from 22 patients in Toronto receiving ECT and a third from 22 patients in Toronto participating in a clinical trial of <a href="https://doi.org/10.1001/archpsyc.58.3.303">magnetic seizure therapy, or MST</a>, a newer alternative to ECT that starts a seizure with magnets instead of electricity.</p>
<p>We found that aperiodic activity increases by <a href="https://doi.org/10.1038/s41398-023-02634-9">more than 40% on average</a> following ECT. In patients who received MST treatment, aperiodic activity increases more modestly, <a href="https://doi.org/10.1038/s41398-023-02631-y">by about 16%</a>. After accounting for changes in aperiodic activity, we found that slow oscillations do not change much at all. In fact, slow oscillations were not even detected in some patients, and aperiodic activity dominated their EEG recordings instead.</p>
<h2>How ECT treats depression</h2>
<p>But what does aperiodic activity have to do with depression?</p>
<p>A long-standing <a href="https://doi.org/10.1038/mp.2010.120">theory of depression</a> states that severely depressed patients have too few of a type of brain cell called inhibitory cells. These cells can turn other brain cells on and off, and maintaining the balance of these on and off states is critical for healthy brain function. This balance is particularly relevant for depression because the brain’s ability to turn cells off plays an important role in <a href="https://doi.org/10.2174%2F1570159X1304150831150507">how it responds to stress</a>, a function that, when not working properly, makes people particularly vulnerable to depression.</p>
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<a href="https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of a long green neuron touching a red neuron" src="https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=596&fit=crop&dpr=1 600w, https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=596&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=596&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=749&fit=crop&dpr=1 754w, https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=749&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/563047/original/file-20231201-21-7jfwil.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=749&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This microscopy image shows a mouse inhibitory neuron (red) contacting a pyramidal neuron (green).</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/J8HizN">McBain Laboratory, NICHD/NIH via Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Using a <a href="https://doi.org/10.1016/j.neuroimage.2017.06.078">mathematical model</a> of cell type-based electrical activity, I linked increases in aperiodic activity, like those seen in the ECT patients, to a huge <a href="https://doi.org/10.1038/s41398-023-02634-9">change in the activity</a> of these inhibitory cells. This change in aperiodic activity may be restoring the crucial on and off balance in the brain to a healthy level. </p>
<p>Even though scientists have been recording EEGs from ECT patients for decades, this is the first time that brain waves have been connected to this particular brain malfunction.</p>
<p>Altogether, though our sample size is relatively small, our findings indicate that ECT and MST likely treat depression by resetting aperiodic activity and restoring the function of inhibitory brain cells. Further study can help destigmatize ECT and highlight new directions for the research and development of depression treatments. Listening to the nonmusical background noise of the brain could help solve other mysteries, like how the brain changes in aging and in illnesses like schizophrenia and epilepsy.</p><img src="https://counter.theconversation.com/content/217889/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sydney E. Smith does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Electroconvulsive therapy often evokes inaccurate images of seizing bodies and smoking ears. Better understanding of how it reduces depression symptoms can illuminate new ways to treat mental illness.Sydney E. Smith, Ph.D. Candidate in Computational Neuroscience, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2065732023-05-31T20:07:02Z2023-05-31T20:07:02ZHave we got the brain all wrong? A new study shows its shape is more important than its wiring<figure><img src="https://images.theconversation.com/files/529233/original/file-20230531-29-nf3bmd.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3600%2C2700&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>The human brain is made up of around 86 billion neurons, linked by trillions of connections. For decades, scientists have believed that we need to map this intricate connectivity in detail to understand how the structured patterns of activity defining our thoughts, feelings and behaviour emerge. </p>
<p>Our new study, published in <a href="https://doi.org/10.1038/s41586-023-06098-1">Nature</a>, challenges this view. We have discovered that patterns of activity in our neurons are more influenced by the shape of the brain – its grooves, contours, and folds – than by its complex interconnections.</p>
<p>The conventional view is that specific thoughts or sensations elicit activity in specific parts of the brain. However, our study reveals structured patterns of activity across nearly the entire brain, relating to thoughts and sensations in much the same way that a musical note arises from vibrations occurring along the entire length of a violin string, not just an isolated segment.</p>
<h2>Function follows form</h2>
<p>We uncovered this close relationship between shape and function by examining the natural patterns of excitation that can be supported by the anatomy of the brain. In these patterns, called “eigenmodes”, different parts of the brain are all excited at the same frequency. </p>
<p>Consider the musical notes played by a violin string. The notes arise from preferred vibrational patterns of the string that occur at specific, resonant frequencies. These preferred patterns are the eigenmodes of the string. They are determined by the string’s physical properties, such as its length, density, and tension.</p>
<p>In a similar way, the brain has its own preferred patterns of excitation, which are determined by its anatomical and physical properties. We set out to identify which specific anatomical properties of the brain most strongly affect these patterns.</p>
<h2>A tale of two brains</h2>
<p>According to conventional wisdom, the brain’s complex web of connections <a href="https://www.pnas.org/doi/abs/10.1073/pnas.0811168106">fundamentally sculpts its activity</a>.</p>
<p>This perspective views the brain as a collection of <a href="https://www.nature.com/articles/nature18933">discrete regions</a>, each specialised for a specific function, such as vision or speech. These regions <a href="https://www.nature.com/articles/nrn2575">communicate</a> via interconnecting fibres called axons.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of a brain, showing one half as a web of dots and lines, and the other as a convoluted surface with wave patterns regions shaded red and blue." src="https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=771&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=771&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=771&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=969&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=969&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529081/original/file-20230530-23-x8028u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=969&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Conventional models divide the brain into a web of discrete nodes. Our analysis suggests large-scale brain activity is instead dominated by waves of excitation.</span>
<span class="attribution"><span class="source">James Pang</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>An alternative view, embodied by an approach to modelling brain activity called <a href="https://mna.episciences.org/9228">neural field theory</a>, eschews this division of the brain into discrete areas. </p>
<p>This view focuses on how <a href="https://www.nature.com/articles/nrn.2018.20">waves of cellular excitation</a> move continuously through brain tissue, like the ripples formed by raindrops falling into a pond. Just as the shape of the pond constrains the possible patterns formed by the ripples, wavelike patterns of activity are <a href="https://www.sciencedirect.com/science/article/pii/S1053811916300908">influenced by the three-dimensional shape</a> of the brain.</p>
<h2>Comparing the two views</h2>
<p>To compare the two views of the brain, we tested how easily the conventional, discrete view and the continuous, wave-based view can explain more than <a href="https://neurovault.org/">10,000 different maps of brain activity</a>. The activity maps were obtained from thousands of functional magnetic resonance imaging (fMRI) experiments as people performed a wide array of cognitive, emotional, sensory, and motor tasks.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/electricity-flow-in-the-human-brain-can-be-predicted-using-the-simple-maths-of-networks-new-study-reveals-200831">Electricity flow in the human brain can be predicted using the simple maths of networks, new study reveals</a>
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<p>We attempted to describe each activity map using eigenmodes based on the brain’s connectivity and eigenmodes based on the brain’s shape. We found that eigenmodes of brain shape – not connectivity – offer the most accurate account of these different activation patterns.</p>
<h2>Brain waves and icebergs</h2>
<p>We used computer simulations to confirm that the close link between brain
shape and function is driven by wavelike activity propagating throughout the brain. </p>
<p>The simulations relied on a simple wave model that is widely used to study other physical phenomena, such as earthquakes and ocean currents. The model only uses the shape of the brain to constrain how the waves evolve through time and space.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An animation showing multicoloured waves of activity propagating around the brain." src="https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529215/original/file-20230531-23-380kl.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Simulations of waves in the brain resemble real activity.</span>
<span class="attribution"><span class="source">James Pang</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Despite its simplicity, this model explained brain activity better than a more sophisticated, <a href="https://www.jneurosci.org/content/34/23/7886">state-of-the-art model</a> that tries to capture key physiological details of neuronal activity and the intricate pattern of connectivity between different brain regions.</p>
<p>We also found that most of the 10,000 different brain maps that we studied were associated with activity patterns spanning nearly the entire brain. This result again challenges conventional wisdom that activity during tasks occurs in discrete, isolated regions of the brain. In fact, it indicates that <a href="https://www.sciencedirect.com/science/article/pii/S1364661397010012">traditional approaches to brain mapping</a> may only reveal the tip of the iceberg when it comes to understanding how the brain works.</p>
<p>Together, our findings suggest that current models of brain function need to be updated. Rather than focusing solely on how signals pass between discrete regions, we should also investigate how waves of excitation travel through the brain. </p>
<p>In other words, ripples in a pond may be a more appropriate analogy for large-scale brain function than a telecommunication network.</p>
<h2>A new approach to brain mapping</h2>
<p>Our approach draws on centuries of work in physics and engineering. In these fields, the function of a system is understood with respect to the constraints imposed by its structure, as embodied by the system’s eigenmodes. </p>
<p>This approach has not been traditionally used in neuroscience. Instead, typical brain mapping methods rely on <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/hbm.460020402">complex statistics to quantify brain activity</a> without any reference to the underlying physical and anatomical basis of those patterns.</p>
<p>The use of eigenmodes offers a way to use physical principles to understand how diverse patterns of activity arise from brain anatomy. </p>
<p>Our discovery also offers immediate practical benefits, since eigenmodes of brain shape are much simpler to quantify than those of brain connectivity.</p>
<p>This new approach opens possibilities for studying how brain shape affects function through evolution, development and ageing, and in brain disease.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/illuminating-the-brain-one-neuron-and-synapse-at-a-time-5-essential-reads-about-how-researchers-are-using-new-tools-to-map-its-structure-and-function-187607">Illuminating the brain one neuron and synapse at a time – 5 essential reads about how researchers are using new tools to map its structure and function</a>
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</em>
</p>
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<img src="https://counter.theconversation.com/content/206573/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alex Fornito receives funding from the National Health and Medical Research Council of Australia, the Australian Research Council, and the Sylvia and Charles Viertel Charitable Foundation.. </span></em></p><p class="fine-print"><em><span>James Pang does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research may upend our understanding of the brain, showing that travelling waves of neuronal excitation dominate the activity associated with our thoughts and feelings.James Pang, Research Fellow in Psychology, Monash UniversityAlex Fornito, Professor of Psychology, Turner Institute for Brain & Mental Health, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2061692023-05-24T18:07:45Z2023-05-24T18:07:45ZRhythmically stimulating the brain with electrical currents could boost cognitive function, according to analysis of over 100 studies<figure><img src="https://images.theconversation.com/files/527837/original/file-20230523-25-ialkgs.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1999%2C1499&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A meta-analysis helps resolve conflicting evidence on the benefits of tACS.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/brain-stimulation-conceptual-image-royalty-free-image/1178748384">Science Photo Library via Getty Images</a></span></figcaption></figure><p>Figuring out how to enhance a person’s mental capabilities has been of considerable interest to psychology and neuroscience researchers <a href="https://scholar.google.com/citations?user=x40PdqgAAAAJ&hl=en">like me</a> <a href="https://doi.org/10.1007/s11948-009-9142-5">for decades</a>. From improving attention in high-stakes environments, like air traffic management, to reviving memory in people with dementia, the ability to improve cognitive function can have far-reaching consequences. New research suggests that <a href="https://theconversation.com/brain-stimulation-can-rewire-and-heal-damaged-neural-connections-but-it-isnt-clear-how-research-suggests-personalization-may-be-key-to-more-effective-therapies-182491">brain stimulation</a> could help achieve the goal of boosting mental function.</p>
<p>In the <a href="https://reinhartlab.org/">Reinhart Lab</a> at Boston University, my colleagues and I have been examining the effects of an emerging brain stimulation technology – <a href="https://www.science.org/doi/10.1126/scitranslmed.abo2044">transcranial alternating current stimulation, or tACS</a> – on different mental functions in patients and healthy people.</p>
<p>During this procedure, people wear an elastic cap embedded with electrodes that deliver weak electrical currents oscillating at specific frequencies to their scalp. By applying these controlled currents to specific brain regions, it is possible to alter brain activity by <a href="https://doi.org/10.1073/pnas.1815958116">nudging neurons to fire rhythmically</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/yoEu2mEdLjw?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Another type of transcranial electric stimulation, tDCS, applies a direct electrical current to the brain.</span></figcaption>
</figure>
<p>Why would rhythmically firing neurons be beneficial? Research suggests that brain cells <a href="https://doi.org/10.1016/j.cub.2012.06.061">communicate effectively</a> when they coordinate the rhythm of their firing. Critically, these rhythmic patterns of brain activity show <a href="https://doi.org/10.1001/jamapsychiatry.2015.0483">marked abnormalities</a> during neuropsychiatric illnesses. The purpose of tACS is to externally induce rhythmic brain activity that promotes healthy mental function, particularly when the brain might not be able to produce these rhythms on its own.</p>
<p>However, tACS is a relatively new technology, and how it works is still unclear. Whether it can strengthen or revive brain rhythms to change mental function has been a topic of considerable debate in the field of brain stimulation. While some studies <a href="https://doi.org/10.1038/s41467-019-13417-6">find evidence</a> of changes in brain activity and mental function with tACS, others suggest that the currents typically used in people <a href="https://doi.org/10.1038/s41467-018-02928-3">might be too weak</a> to have a direct effect.</p>
<p>When faced with conflicting data in the scientific literature, it can be helpful to conduct a type of study <a href="https://training.cochrane.org/handbook/current/chapter-10">called a meta-analysis</a> that quantifies how consistent the evidence is across several studies. A previous meta-analysis conducted in 2016 <a href="https://doi.org/10.1016/j.neuropsychologia.2016.04.011">found promising evidence</a> for the use of tACS in changing mental function. However, the number of studies has more than doubled since then. The design of tACS technologies has also become <a href="https://doi.org/10.1016/j.cub.2016.04.035">increasingly sophisticated</a>.</p>
<p>We set out to perform a new meta-analysis of studies using tACS to change mental function. To our knowledge, this work is the <a href="https://www.science.org/doi/10.1126/scitranslmed.abo2044">largest and most comprehensive meta-analysis</a> yet on this topic, consisting of over 100 published studies with a combined total of more than 2,800 human participants. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Electrodes being placed on a person's head" src="https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=377&fit=crop&dpr=1 600w, https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=377&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=377&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=474&fit=crop&dpr=1 754w, https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=474&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/527841/original/file-20230523-27-bw5s8e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=474&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Transcranial alternating current stimulation involves placing an electrode on a person’s scalp.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/SRnZ5m">J.M. Eddins Jr/U.S. Air Force via Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<p>After compiling over 300 measures of mental function across all the studies, we observed <a href="https://www.science.org/doi/10.1126/scitranslmed.abo2044">consistent and immediate improvement</a> in mental function with tACS. When we examined specific cognitive functions, such as memory and attention, we observed that tACS produced the strongest improvements in <a href="https://theconversation.com/cognitive-flexibility-is-essential-to-navigating-a-changing-world-new-research-in-mice-shows-how-your-brain-learns-new-rules-204259">executive function</a>, or the ability to adapt in the face of new, surprising or conflicting information. </p>
<p>We also observed improvements in the ability to pay attention and to memorize information for both short and long periods of time. Together, these results suggest that tACS could particularly improve specific kinds of mental function, at least in the short term.</p>
<p>To examine the effectiveness of tACS for those particularly vulnerable to changes in mental function, we examined the data from studies that included older adults and people with neuropsychiatric conditions. In both populations, we observed reliable evidence for <a href="https://www.science.org/doi/10.1126/scitranslmed.abo2044">improvements in cognitive function</a> with tACS. </p>
<p>Interestingly, we also found that a specialized type of tACS that can target two brain regions at the same time and manipulate how they communicate with each other can both <a href="https://www.science.org/doi/10.1126/scitranslmed.abo2044">enhance or reduce cognitive function</a>. This bidirectional effect on mental function could be particularly useful in the clinic. For example, some psychiatric conditions like depression may involve a reduced ability to process rewards, while others like bipolar disorder may involve a highly active <a href="https://doi.org/10.1097%2FYCO.0000000000000122">reward processing system</a>. If tACS can change mental function in either direction, researchers may be able to develop flexible and targeted designs that cater to specific clinical needs. </p>
<p>Developments in the field of tACS are bringing researchers closer to being able to safely enhance mental function in a noninvasive way that doesn’t require medication. Current statistical evidence across the literature suggests that tACS holds promise, and improving its design could help it produce stronger, long-lasting changes in mental function.</p><img src="https://counter.theconversation.com/content/206169/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>This work was supported by grants from the National Institutes of Health (R01-MH114877; R01-AG063775) and a gift from an individual philanthropist, all to Robert M. G. Reinhart, Ph.D., Associate Professor at the Department of Psychological and Brain Sciences, Boston University.</span></em></p>Transcranial alternating current stimulation, or tACS, is a type of brain stimulation that can change neural activity and improve memory, attention and executive function.Shrey Grover, Ph.D. Candidate in Psychological and Brain Sciences, Boston UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2042592023-04-26T15:12:44Z2023-04-26T15:12:44ZCognitive flexibility is essential to navigating a changing world – new research in mice shows how your brain learns new rules<figure><img src="https://images.theconversation.com/files/522864/original/file-20230425-26-ozwsdf.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2121%2C1412&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A class of inhibitory neurons can make long-distance connections across both hemispheres of the brain.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/brain-shape-labyrinth-with-staircase-royalty-free-image/1384468191">akinbostanci/iStock via Getty Images Plus</a></span></figcaption></figure><p>Being flexible and learning to adapt when the world changes is something you practice every day. Whether you run into a new construction site and have to reroute your commute or download a new streaming app and have to relearn how to find your favorite show, changing familiar behaviors in response to new situations is an essential skill.</p>
<p>To make these adaptations, your brain changes its activity patterns within a structure called the <a href="https://doi.org/10.1146/annurev.neuro.24.1.167">prefrontal cortex</a> – an area of the brain critical for cognitive functions such as attention, planning and decision-making. But which specific circuits “tell” the prefrontal cortex to update its activity patterns in order to change behavior have been unknown. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/i47_jiCsBMs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The prefrontal cortex of the brain is involved in executive functions like self-control and decision-making.</span></figcaption>
</figure>
<p>We are a <a href="https://scholar.google.com/citations?user=a-dRpwgAAAAJ&hl=en">team of</a> <a href="https://scholar.google.com/citations?user=EYE8lYIAAAAJ&hl=en">neuroscientists</a> who study how the brain processes information and what happens when this function is impaired. In our newly published research, we discovered a <a href="https://www.nature.com/articles/s41586-023-06012-9">special class of neurons</a> in the prefrontal cortex that may enable flexible behavior and, when they malfunction, may lead to conditions such as schizophrenia and bipolar disorder.</p>
<h2>Inhibitory neurons and learning new rules</h2>
<p><a href="https://www.brainfacts.org/brain-anatomy-and-function/cells-and-circuits/2021/how-inhibitory-neurons-shape-the-brains-code-100621">Inhibitory neurons</a> dampen the activity of other neurons in the brain. Researchers have traditionally assumed they send their electrical and chemical outputs only to nearby neurons. However, we found a particular class of inhibitory neurons in the prefrontal cortex that communicate across long distances to neurons in the opposite hemisphere of the brain.</p>
<p>We wondered whether these long-range inhibitory connections are involved in coordinating changes in activity patterns across the left and right prefrontal cortex. By doing so, they might provide the critical signals that help you change your behavior at the right moment.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Microscopy image of an interneuron" src="https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=923&fit=crop&dpr=1 600w, https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=923&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=923&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1160&fit=crop&dpr=1 754w, https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1160&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/522868/original/file-20230425-22-cg77ik.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1160&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Interneurons connect other neurons together.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/G2ScFK">NICHD/McBain Laboratory via Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>To test the function of these long-range inhibitory connections, we observed mice performing a task that required them to learn a rule to receive a reward and then later adapt to a new rule in order to continue receiving the reward. In this task, mice dug in bowls to find hidden food. Initially, the smell of garlic or the presence of sand within a bowl might indicate the location of the hidden food. The specific cue associated with the reward would later change, forcing the mice to learn a new rule. </p>
<p>We found that silencing the long-range inhibitory connections between the left and right prefrontal cortex <a href="https://www.nature.com/articles/s41586-023-06012-9">caused the mice to get stuck</a>, or perseverate, on one rule and prevented them from learning new ones. They were unable to change gears and learn that the old cue was now meaningless and the new cue signaled food.</p>
<h2>Brain waves and flexible behavior</h2>
<p>We also made surprising discoveries about how these long-range inhibitory connections create behavioral flexibility. Specifically, they synchronize a set of “brain waves” called <a href="https://doi.org/10.1523/jneurosci.0990-16.2016">gamma oscillations</a> across the two hemispheres. Gamma oscillations are rhythmic fluctuations in brain activity that occur roughly 40 times per second. These fluctuations can be detected during many cognitive functions, such as when performing a task that requires holding information in your memory or making different movements based on what you see on a computer screen. </p>
<p>Though scientists have observed the presence of gamma oscillations for many decades, their function has been controversial. Many researchers think that the synchronization of these rhythmic fluctuations across different brain regions doesn’t serve any useful purpose. Others have speculated that synchronization across different brain regions enhances communication between those regions.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/gvpuOBezW0w?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Fluctuations in neural activity manifest as brain waves, or neural oscillations.</span></figcaption>
</figure>
<p>We found a completely different potential role for gamma synchrony. When long-range inhibitory connections synchronize gamma oscillations across the left and right prefrontal cortex, they seem to also <a href="https://www.nature.com/articles/s41586-023-06012-9">gate communication between them</a>. When mice learn to disregard a previously established rule that no longer leads to a reward, these connections synchronize gamma oscillations and seem to stop one hemisphere from maintaining unneeded activity patterns in the other. In other words, long-range inhibitory connections seem to stop input from one hemisphere from “getting in the way” of the other when it is trying to learn something new. </p>
<p>For example, the left prefrontal cortex can “remind” the right prefrontal cortex about your usual route to work. But when long-range inhibitory connections synchronize these two areas, they also seem to shut off these reminders and enable new patterns of brain activity corresponding to your new commute to take hold.</p>
<p>Finally, these long-range inhibitory connections also <a href="https://www.nature.com/articles/s41586-023-06012-9">trigger long-lasting effects</a>. Shutting off these connections just once caused mice to have trouble learning new rules several days later. Conversely, rhythmically stimulating these connections to artificially synchronize gamma oscillations can reverse these deficits and restore normal learning.</p>
<h2>Cognitive flexibility and schizophrenia</h2>
<p>Long-range inhibitory connections play an important role in cognitive flexibility. The inability to appropriately update previously learned rules is one <a href="https://pubmed.ncbi.nlm.nih.gov/16965182/">hallmark form of cognitive impairment</a> in psychiatric conditions such as schizophrenia and bipolar disorder. </p>
<p>Research has also seen <a href="https://doi.org/10.1523/jneurosci.0990-16.2016">deficiencies in gamma synchronization</a> and abnormalities in a class of prefrontal inhibitory neurons, which includes the ones we studied, in people with schizophrenia. In this context, our study suggests that treatments that target these long-range inhibitory connections may help improve cognition in people with schizophrenia by synchronizing gamma oscillations.</p>
<p>Many details of how these connections affect brain circuits remain unknown. For example, we do not know exactly which cells within the prefrontal cortex receive input from these long-range inhibitory connections and change their activity patterns to learn new rules. We also do not know whether there are specific molecular pathways that produce the long-lasting changes in neural activity. Answering these questions could reveal how the brain flexibly switches between maintaining and updating old information and potentially lead to new treatments for schizophrenia and other psychiatric conditions.</p><img src="https://counter.theconversation.com/content/204259/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vikaas Sohal receives funding from the National Institutes of Health, the Simons Foundation Autism Research Initiative, the UCSF Dolby Family Center for Mood Disorders, and the Bay Area Psychedelic Research consortium.</span></em></p><p class="fine-print"><em><span>Kathleen Cho receives funding from the Institut national de la santé et de la recherche médicale (Inserm) and the Marie Skłodowska-Curie Individual Fellowship (MSCA-IF). </span></em></p>Learning new rules requires the suppression of old ones. A better understanding of the brain circuits involved in behavioral adaptation could lead to new ways to treat schizophrenia and bipolar disorder.Vikaas Sohal, Professor of Psychiatry, University of California, San FranciscoKathleen Cho, Principal Investigator in Neuroscience, InsermLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1829702022-06-30T14:45:23Z2022-06-30T14:45:23ZHow your brainwaves could be used in criminal trials<figure><img src="https://images.theconversation.com/files/469794/original/file-20220620-14-ypj54o.jpg?ixlib=rb-1.1.0&rect=80%2C8%2C5896%2C3975&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/patient-brain-testing-using-encephalography-medical-2005932185">Roman Zaiets/Shutterstock</a></span></figcaption></figure><p>American Kevin Strickland was <a href="https://www.bbc.co.uk/news/world-us-canada-59396598">exonerated</a> after spending 42 years in prison for being wrongfully convicted of a triple murder in November 2021. His 1978 conviction was based on mistaken identification of an eyewitness. The eyewitness later said that police pressured her into identifying Strickland, and attempted to have her testimony recanted but failed. She died in 2015.</p>
<p>Law enforcement agencies worldwide struggle with the unreliability of eyewitness identification and scarcity of physical clues at crime scenes. There is a <a href="https://www.proquest.com/openview/0238181ccc2a07f238634115e62cf511/1?pq-origsite=gscholar&cbl=28146">wealth of evidence</a> showing that mistaken eyewitness identification is a <a href="https://www.science.org/doi/full/10.1126/science.1111565">contributing factor</a> in wrongful convictions. Police <a href="https://www.astm.org/jfs14032j.html">only collect physical evidence</a> in approximately 15% or <a href="https://www.ojp.gov/ncjrs/virtual-library/abstracts/confessions-crown-court-trials">less</a> of crime scenes. This makes non-physical evidence like eyewitness testimony extremely important.</p>
<p>Strickland and other victims of wrongful identification, including <a href="https://www.cbsnews.com/news/thomas-raynard-james-florida-man-wrongfully-convicted-released/">Thomas Raynard James</a> – exonerated in April 2022 after spending 32 years in prison – might have been saved from lengthy prison sentences with innovative technology. </p>
<p>Developed by the <a href="https://groups.psych.northwestern.edu/rosenfeld/documents/MemoryDetection69-90.pdf">late Peter Rosenfeld</a>, a professor at Northwestern University, the Complex Trial Protocol (CTP) is considered a reliable and sound method for analysing a specific brainwave, known as the P300. This relatively inexpensive and non-invasive technique could be used to determine if a witness or a suspect recognises crucial pieces of information related to a crime, only known to that person and the authorities.</p>
<h2>How it works</h2>
<p>We have all been in situations where our attention was gripped by hearing our name mentioned in a social setting. This reflex has been a feature of survival since the beginning of humanity to enable us to detect whether a particular sound or sight was a threat. This <a href="https://www.oxfordhandbooks.com/view/10.1093/oxfordhb/9780195374148.001.0001/oxfordhb-9780195374148-e-007">involuntary reaction</a> is one of the leading theories underpinning this phenomenon.</p>
<p>The P300 is an electrical brainwave detectable by placing electrodes on a person’s scalp. It appears on an electroencephalogram (EEG) as a positive or negative deflection (a downward or upward looking curve) about 300 to 600 milliseconds after a person is presented with a novel and meaningful stimulus. This reaction is considered a <a href="https://groups.psych.northwestern.edu/rosenfeld/documents/MemoryDetection69-90.pdf">reliable index of memory recognition</a>. It can show when a person recognises an individual’s name, the sweet taste of chocolate, or the sound of an artist’s voice.</p>
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<img alt="Two charts showing how the P300 brainwave appears on an EEG." src="https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=299&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=299&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=299&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=376&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=376&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471167/original/file-20220627-12-b8n0bn.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=376&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">The baseline appearance of a P300 wave for an ‘innocent’ test subject (left), compared to how it appears in a ‘guilty’ subject (right) who recognises the probe information. Pz refers to the location of the electrode – over the hemispheric midline of the Parietal cortex.</span>
<span class="attribution"><a class="source" href="https://research.tees.ac.uk/en/publications/an-independent-validation-of-the-eeg-based-complex-trial-protocol">Funicelli, et al, 2021</a>, <span class="license">Author provided</span></span>
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<p>The CTP is a particular method for applying a concealed information test, a technique already used regularly in forensic investigations, such as in identity parades. The logic behind this is easy to understand. A witness or a suspect is presented with a crucial piece of information (the “probe”), mixed in with a series of neutral alternatives (“irrelevants”).</p>
<p>In this test, investigators analyse the interviewee’s brain activity via electrodes attached to their scalp. They then use a statistical calculation to determine if they recognise the probe – the face of an attacker or a weapon – in comparison to the irrelevants.</p>
<h2>Using it in the field</h2>
<p>So far, the CTP has primarily been tested in a <a href="https://pubmed.ncbi.nlm.nih.gov/33655464/">laboratory setting</a>, usually with young, healthy, university-educated adults under controlled conditions. The CTP has been the subject of dozens of <a href="https://www.sciencedirect.com/science/article/abs/pii/S0167876016307309">experiments</a> across four independent laboratories spanning at least four countries so far. Experiments have used different scenarios such as <a href="https://pubmed.ncbi.nlm.nih.gov/29083483/">mock theft</a> and <a href="https://pubmed.ncbi.nlm.nih.gov/20579312/">mock terrorism</a>. I am planning more field experiments to compare the success of the CTP with conventional photo parades and their subjective “I’m sure it’s him” responses from eyewitnesses. </p>
<p>Other methods similar to the CTP have been used in India, the US and New Zealand, in the context of a concealed information test. More independent studies with these methodologies are necessary before it becomes mainstream. With more research on the CTP, I hope that this memory detection technique could be admissible in UK courts in a matter of years. </p>
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Read more:
<a href="https://theconversation.com/if-a-brain-can-be-caught-lying-should-we-admit-that-evidence-to-court-heres-what-legal-experts-think-80263">If a brain can be caught lying, should we admit that evidence to court? Here's what legal experts think</a>
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<p>Performing the test on a suspect or eyewitness prior to formal interview could confirm whether or not they recognise a murder weapon or the offender’s face. The results of the test would then be used to assess their credibility – for example, if they contradict the test’s findings in an interview.</p>
<p>It’s impossible to know if photo identification using brainwave analysis with the CTP would have prevented the miscarriages of justice mentioned above. But preliminary findings from my ongoing research suggest the CTP could be an asset for law enforcement, enabling investigators to draw out evidence from the brain of suspects and eyewitnesses.</p>
<p>The potential for this technology is not without its pitfalls. <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3462434/">A major threat</a> to its usefulness is when relevant information is accidentally released in the public domain. For example, someone accused of a crime based on evidence from a brainwave analysis could claim that the witness recognised their face from the press, thus skewing the results of the test. This would be difficult to navigate in some situations, but could be mitigated by law enforcement keeping their cards closer to their chest.</p><img src="https://counter.theconversation.com/content/182970/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michel Funicelli is a member of the International Investigative Interviewing Research Group and of the Society for Police and Criminal Psychology.</span></em></p>An expert explains the technology behind a brainwave test that could change the way crimes are investigated.Michel Funicelli, Lecturer in Policing, Teesside UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1723802021-12-10T13:37:33Z2021-12-10T13:37:33ZGot Zoom fatigue? Out-of-sync brainwaves could be another reason videoconferencing is such a drag<figure><img src="https://images.theconversation.com/files/436504/original/file-20211208-15-iliwgf.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C6173%2C4112&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Conversation in person usually feels effortless. Conversation over video? Not so much.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/stressed-business-woman-working-from-home-on-laptop-royalty-free-image/1249628154">nensuria/iStock via Getty Images</a></span></figcaption></figure><p>During the pandemic, video calls became a way for me to connect with my aunt in a nursing home and with my extended family during holidays. Zoom was how I enjoyed trivia nights, happy hours and live performances. As a university professor, Zoom was also the way I conducted all of my work meetings, mentoring and teaching. </p>
<p>But I often felt drained after Zoom sessions, even some of those that I had scheduled for fun. <a href="https://news.stanford.edu/2021/02/23/four-causes-zoom-fatigue-solutions/">Several well-known factors</a> – intense eye contact, slightly misaligned eye contact, being on camera, limited body movement, lack of nonverbal communication – contribute to Zoom fatigue. But I was curious about why conversation felt more laborious and awkward over Zoom and other video-conferencing software, compared with in-person interactions.</p>
<p>As a researcher who <a href="https://scholar.google.com/citations?user=8j4_-aYAAAAJ&hl=en">studies psychology and linguistics</a>, I decided to examine the impact of video-conferencing on conversation. Together with three undergraduate students, I ran <a href="https://doi.apa.org/doi/10.1037/xge0001150">two experiments</a>.</p>
<p>The first experiment found that response times to prerecorded yes/no questions more than tripled when the questions were played over Zoom instead of being played from the participant’s own computer. </p>
<p>The second experiment replicated the finding in natural, spontaneous conversation between friends. In that experiment, transition times between speakers averaged 135 milliseconds in person, but 487 milliseconds for the same pair talking over Zoom. While under half a second seems pretty quick, that difference is an eternity in terms of natural conversation rhythms.</p>
<p>We also found that people held the floor for longer during Zoom conversations, so there were fewer transitions between speakers. These experiments suggest that the natural rhythm of conversation is disrupted by videoconferencing apps like Zoom. </p>
<h2>Cognitive anatomy of a conversation</h2>
<p>I already had some expertise in studying conversation. Pre-pandemic, I conducted several experiments investigating how topic shifts and working memory load affect the timing of when speakers in a conversation take turns.</p>
<p>In that research, I found that <a href="https://cogsci.mindmodeling.org/2019/papers/0048/index.html">pauses between speakers were longer</a> when the two speakers were talking about different things, or if a speaker was distracted by another task while conversing. I originally became interested in the timing of turn transitions because planning a response during conversation is a complex process that people accomplish with lightning speed. </p>
<p>The average pause between speakers in two-party conversations is about one-fifth of a second. In comparison, it takes more than a half-second to <a href="https://doi.org/10.1080/00140139508925238">move your foot from the accelerator to the brake</a> while driving – more than twice as long. </p>
<p>The speed of turn transitions indicates that listeners don’t wait until the end of a speaker’s utterance to begin planning a response. Rather, listeners simultaneously comprehend the current speaker, plan a response and predict the appropriate time to initiate that response. All of this multitasking ought to make conversation quite laborious, but it is not. </p>
<h2>Getting in sync</h2>
<p>Brainwaves are the rhythmic firing, or oscillation, of neurons in your brain. These oscillations may be one factor that helps make conversation effortless. <a href="https://doi.org/10.1017/9781108610728">Several</a> <a href="https://doi.org/10.3758/BF03206432">researchers</a> have proposed that a neural oscillatory mechanism automatically synchronizes the firing rate of a group of neurons to the speech rate of your conversation partner. This oscillatory timing mechanism would relieve some of the mental effort in planning when to begin speaking, especially if it was <a href="https://doi.org/10.7554/eLife.68066">combined with predictions</a> about the remainder of your partner’s utterance.</p>
<p>While there are many open questions about how oscillatory mechanisms affect perception and behavior, there is <a href="https://doi.org/10.3389/fpsyg.2012.00320">direct</a> <a href="https://doi.org/10.1038/nn.4186">evidence</a> for neural oscillators that track syllable rate when syllables are presented at regular intervals. For example, when you hear syllables four times a second, the electrical activity in your brain <a href="https://doi.org/10.1038/nn.4186">peaks at the same rate</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A spectrograph of human speech with a rough sine wave overlaid on it" src="https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=115&fit=crop&dpr=1 600w, https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=115&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=115&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=145&fit=crop&dpr=1 754w, https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=145&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/435178/original/file-20211201-15-how79x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=145&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">This acoustic spectrogram of the utterance ‘Do you think surfers are scared of being bitten by a shark?’ has an overlaid oscillatory function (blue wave). This shows that midpoints of most syllables (numbered hash marks) occur at or near the wave troughs, regardless of syllable length. The hash marks were generated with a Praat script written by deJong and Wempe.</span>
<span class="attribution"><span class="source">Julie Boland</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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<p>There is also evidence that <a href="https://doi.org/10.1093/oso/9780190618216.001.0001">oscillators can accommodate some variability</a> in syllable rate. This makes the notion that an automatic neural oscillator could track the fuzzy rhythms of speech plausible. For example, an oscillator with a period of 100 milliseconds could keep in sync with speech that varies from 80 milliseconds to 120 milliseconds per short syllable. Longer syllables are not a problem if their duration is a multiple of the duration for short syllables.</p>
<h2>Internet lag is a wrench in the mental gears</h2>
<p>My hunch was that this proposed oscillatory mechanism couldn’t function very well over Zoom due to variable transmission lags. In a video call, the audio and video signals are split into packets that zip across the internet. In our studies, each packet took around 30 to 70 milliseconds to travel from sender to receiver, including disassembly and reassembly.</p>
<p>While this is very fast, it adds too much additional variability for brainwaves to sync with speech rates automatically, and more arduous mental operations have to take over. This could help explain my sense that Zoom conversations were more fatiguing than having the same conversation in person would have been.</p>
<p><a href="https://doi.apa.org/doi/10.1037/xge0001150">Our experiments</a> demonstrated that the natural rhythm of turn transitions between speakers is disrupted by Zoom. This disruption is consistent with what would happen if the neural ensemble that <a href="https://doi.org/10.1093/oso/9780190618216.001.0001">researchers believe normally synchronizes with speech</a> fell out of sync due to electronic transmission delays. </p>
<p>Our evidence supporting this explanation is indirect. We did not measure cortical oscillations, nor did we manipulate the electronic transmission delays. Research into the connection between neural oscillatory timing mechanisms and speech in general <a href="https://doi.org/10.1038/s41583-020-0304-4">is promising</a> but not definitive.</p>
<p>Researchers in the field need to pin down an oscillatory mechanism for naturally occurring speech. From there, cortical tracking techniques could show whether such a mechanism is more stable in face-to-face conversations than with video-conferencing conversations, and how much lag and how much variability cause disruption. </p>
<p>Could the syllable-tracking oscillator tolerate relatively short but realistic electronic lags below 40 milliseconds, even if they varied dynamically from 15 to 39 milliseconds? Could it tolerate relatively long lags of 100 milliseconds if the transmission lag were constant instead of variable?</p>
<p>The knowledge gained from such research could open the door to technological improvements that help people get in sync and make videoconferencing conversations less of a cognitive drag.</p>
<p>[<em>Understand new developments in science, health and technology, each week.</em> <a href="https://theconversation.com/us/newsletters/science-editors-picks-71/?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=science-understand">Subscribe to The Conversation’s science newsletter</a>.]</p><img src="https://counter.theconversation.com/content/172380/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julie Boland does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It appears that the rhythms of your brain waves get in sync with the speech patterns of the person you’re conversing with. Videoconferencing throws off that syncing process.Julie Boland, Professor of Psychology and Linguistics, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1321972020-02-25T03:43:55Z2020-02-25T03:43:55ZSounds like hype: there’s scant evidence the ‘binaural beats’ illusion relaxes your brain<figure><img src="https://images.theconversation.com/files/316997/original/file-20200225-24651-1wxens8.jpg?ixlib=rb-1.1.0&rect=8%2C34%2C5734%2C3768&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">shutterstock</span> <span class="attribution"><span class="source">Shutterstock.com</span></span></figcaption></figure><p>You may have heard of binaural beats, an auditory illusion that has been touted as having stress-busing properties, and is the subject of countless <a href="https://www.youtube.com/watch?v=bVkXKowg3b0">hours of videos</a> on YouTube and elsewhere.</p>
<p>Proponents claim that listening to binaural beats can boost <a href="https://www.youtube.com/watch?v=F5Tt3LoygCQ">focus and concentration</a>, promote <a href="https://www.youtube.com/watch?v=mEM0pXE1twA">relaxation</a>, and <a href="https://www.youtube.com/watch?v=HnRcvJKZeVM">reduce stress and anxiety</a>.</p>
<p>But in a <a href="https://www.eneuro.org/content/early/2020/02/07/ENEURO.0232-19.2020">study published this month</a>, researchers concluded that “whether binaural beats have an impact on cognitive performance or other mood measurements remains to be seen”.</p>
<p>It prompted media reports that the claimed mood-altering effects are <a href="https://www.zmescience.com/science/binaural-beats-placebo-0523/">probably no stronger than for other types of relaxing sounds</a>, and that the touted effects may be <a href="https://www.sciencedaily.com/releases/2020/02/200217143447.htm">just a placebo</a>.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/SAyA7rfyF38?wmode=transparent&start=28" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Here’s three hours’ worth – are you relaxed yet?</span></figcaption>
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<h2>What are binaural beats?</h2>
<p><a href="https://www.scientificamerican.com/article/auditory-beats-in-the-brain/">Binaural beats</a> is a perceptual illusion that occurs when two slightly different frequencies (notes) are played into each ear separately, typically using headphones. The resonance between the two frequencies is interpreted as a third sound (termed a “binaural beat”, because it involves two sound inputs, and is heard as a frequency in between the two played frequencies).</p>
<p>It has been claimed that this third frequency prompts brain cells to begin firing at the same frequency – a process called “entrainment”.</p>
<p>The purported relaxing effect is allegedly due to the fact that these frequencies are similar to the frequency of brain waves that occur during deep sleep, as opposed to the higher-frequency brain waves associated with conscious activities. </p>
<p>In other words, listening to binaural beats allegedly promotes brain waves associated with our most relaxed states.</p>
<h2>What are these different types of brain waves?</h2>
<p>The brain is made of billions of nerve cells (neurons), which transmit information to one another across huge networks of interconnections. It is thought that large groups of neurons can fire together to share information within the brain. The frequency of this synchronous firing can be measured with <a href="https://www.mayoclinic.org/tests-procedures/eeg/about/pac-20393875">EEG</a> (electroencephalograpy) electrodes on the head. </p>
<p>Specific frequencies are thought to be involved in specific <a href="https://www.cell.com/trends/cognitive-sciences/fulltext/S1364-6613(03)00289-4?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS1364661303002894%3Fshowall%3Dtrue">cognitive tasks</a>. For example, during deep sleep the predominant brain activity happens with frequencies of between 1 and 4 Hertz, so-called delta waves. Delta waves are also associated with learning and motivation. <a href="https://www.sciencedirect.com/science/article/abs/pii/S0149763406001163">Theta waves</a> (4-7Hz), meanwhile, are linked to memory and emotional regulation. </p>
<p>We might almost think of these various types of brain waves as different languages that the brain uses for different functions.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-what-happens-in-our-bodies-when-we-sleep-94301">Curious Kids: What happens in our bodies when we sleep?</a>
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<p>We also know that <a href="https://www.sciencedirect.com/science/article/abs/pii/S0167876015000331?via%3Dihub">brain entrainment</a> is a genuine effect that can occur in response to particular rhythmic frequencies perceived by our senses. A deep-pitched musical tone or a lightbulb flickering a few times a second can indeed cause your brain cells to start firing at the same frequency.</p>
<p>But does this entrainment necessarily have any effect on our mood? As the authors of the new study point out, there is still little convincing evidence for this. </p>
<h2>What did the new research actually find?</h2>
<p>The authors played binaural or monaural (normal) beats to 16 participants, and recorded their brain activity with EEG.</p>
<p>They found that both binaural and monaural beats can entrain the brain to their particular frequency. But when they asked participants to describe any changes to their mood, they found that neither types of sound had any significant effect.</p>
<p>However, the researchers did find that binaural beats can elicit “cross-frequency connectivity”, in which the brain coordinates its activity across different types of brain waves. </p>
<p>Some <a href="https://www.sciencedirect.com/science/article/abs/pii/S1364661310002068">cognitive tasks</a>, such as learning and memory formation, require networks within the brain to communicate with one another despite using different types of brain waves. To return to the analogy of different brain wave frequencies being like different languages, your brain sometimes needs to translate messages from one language into another, and vice versa.</p>
<p>If binaural beats can boost this process, it’s possible that it might have a beneficial effect on some types of cognition, perhaps including memory recall. The authors of the new study did not look at that particular question, although a recent <a href="https://link.springer.com/article/10.1007%2Fs00426-018-1066-8">analysis of 35 studies</a> demonstrated a modest effect on attention, memory, anxiety and pain perception. None of these were tested in the current study. </p>
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Read more:
<a href="https://theconversation.com/heres-why-memories-come-flooding-back-when-you-visit-places-from-your-past-124983">Here's why memories come flooding back when you visit places from your past</a>
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<p>There are other ways to influence our brain function, such as by applying electric currents to the brain via electrodes stuck to the head, a technique known as transcranial current stimulation (tCS). There is evidence this can significantly improve cognitive skills in people affected by <a href="https://www.frontiersin.org/articles/10.3389/fnins.2016.00574/full">neurological disease</a> and in <a href="https://www.sciencedirect.com/science/article/pii/S2352154615000819">healthy individuals</a>.</p>
<p>In the meantime, if you enjoy listening to binaural beats, then by all means keep doing it – it won’t do you any harm. But it may not be doing you quite as much good as you perhaps imagined.</p><img src="https://counter.theconversation.com/content/132197/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Onno van der Groen does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The internet is awash with videos that claim to use ‘binaural beats’ to improve your focus or relieve stress. But while they can influence your brain, the touted mood-enhancing effects may not be.Onno van der Groen, Research Fellow in the school of medical and health sciences, Edith Cowan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1210162019-09-11T12:17:15Z2019-09-11T12:17:15ZHow do brains tune in to one neural signal out of billions?<figure><img src="https://images.theconversation.com/files/291591/original/file-20190909-109935-1d821fo.jpg?ixlib=rb-1.1.0&rect=285%2C1%2C567%2C387&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Your brain is conducting multiple orchestras of information at the same time.</span> <span class="attribution"><a class="source" href="https://enlightenedaudio.com/categories/royalty-free-brainwave-entrainment-music">Enlighted Audio</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The human brain sends <a href="http://discovermagazine.com/2011/mar/10-numbers-the-nervous-system">hundreds of billions of neural signals</a> each second. It’s an extraordinarily complex feat.</p>
<p>A healthy brain must establish an enormous number of correct connections and ensure that they remain accurate for the entire period of the information transfer – that can take seconds, which in “brain time” is pretty long.</p>
<p>How does each signal get to its intended destination?</p>
<p>The challenge for your brain is similar to what you’re faced with when trying to engage in conversation at a noisy cocktail party. You’re able to focus on the person you’re talking to and “mute” the other discussions. This phenomenon is selective hearing – what’s called the <a href="https://www.sciencedaily.com/releases/2012/04/120418135045.htm">cocktail party effect</a>.</p>
<p>When everyone at a large, crowded party talks at roughly the same loudness, the average sound level of the person you’re speaking with is about equal to the average level of all the other partygoers’ chatter combined. If it were a satellite TV system, this roughly equal balance of desired signal and background noise would result in poor reception. Nevertheless, this balance is good enough to let you understand conversation at a bustling party.</p>
<p>How does the human brain do it, distinguishing among billions of ongoing “conversations” within itself and locking on to a specific signal for delivery?</p>
<p><a href="https://scholar.google.com/citations?user=7z-nA_kAAAAJ&hl=en">My team’s research</a> into the neurological networks of the brain shows there are two activities that support its ability to establish reliable connections in the presence of significant biological background noise. Although the brain’s mechanisms are quite complex, these two activities act as what an electrical engineer calls a <a href="https://doi.org/10.1016/j.cub.2016.05.042">matched filter</a> - a processing element used in high-performance radio systems, and now known to exist in nature.</p>
<h2>Neurons singing in harmony</h2>
<p>Let’s take a moment to focus on just one of the hundreds of billions of nerve fibers in the human brain, of which many are typically active at any given point in time. They’re all doing their part to carry out thought processes that allow humans to function successfully and interact meaningfully with each other – supporting abilities such as orientation, attention, memory, problem-solving and executive function.</p>
<p>My research team has developed a model that translates biological brain activity to the human audible range, so we <a href="https://www.youtube.com/watch?v=Jg50wEHqpas">can hear the brain</a> at work. Here’s what a single nerve fiber transmitting its signal sounds like in an ideal, noise-free environment:</p>
<p><audio preload="metadata" controls="controls" data-duration="5" data-image="" data-title="A single nerve fiber's activity translated into the human audible range." data-size="121670" data-source="" data-source-url="" data-license="Author provided (no reuse)" data-license-url="">
<source src="https://cdn.theconversation.com/audio/1697/actionpotential.mp3" type="audio/mpeg">
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A single nerve fiber’s activity translated into the human audible range.
<span class="attribution"><span class="license">Author provided (no reuse)</span><span class="download"><span>119 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1697/actionpotential.mp3">(download)</a></span></span>
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<p>When this chosen nerve fiber transmits a signal to its target destination elsewhere in the brain, it’s up against the background noise caused by the activity of all the other active fibers. Here’s the sound of that same fiber now immersed in the brain’s cocktail party:</p>
<p><audio preload="metadata" controls="controls" data-duration="5" data-image="" data-title="A single nerve fiber's activity, against the background of everything else going on in the brain." data-size="121670" data-source="" data-source-url="" data-license="Author provided (no reuse)" data-license-url="">
<source src="https://cdn.theconversation.com/audio/1698/brainsignal.mp3" type="audio/mpeg">
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<div class="audio-player-caption">
A single nerve fiber’s activity, against the background of everything else going on in the brain.
<span class="attribution"><span class="license">Author provided (no reuse)</span><span class="download"><span>119 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/1698/brainsignal.mp3">(download)</a></span></span>
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<p>The background noise in the brain stimulates a small population of other nerve fibers around our chosen nerve fiber to <a href="https://abdn.pure.elsevier.com/en/publications/understanding-synchronization-induced-by-common-noise">synchronize</a> and transmit roughly the same message. This synchronization reduces the effect of the noise and improves the clarity of the signal.</p>
<p>It does the job, but is not perfect. It’s similar to many voices singing in harmony. Each voice projects sound at its unique frequencies at each moment, with the sum total of the multitude of voices extending the frequency range of each individual voice. Think of a chorus filling a music hall with its song, as opposed to a soloist singing just one part. This strategy enriches the frequency content, raises the level of the transmitted signal and increases the quality of the reception.</p>
<p>Scientists describe this phenomenon as the emergence of a relationship, or coupling, between physically separated subsystems of nerve fibers. It creates a larger, dynamical system. The idea is not so different from the 350-year-old mystery, finally solved, of how <a href="https://www.livescience.com/51644-why-pendulum-clocks-sync-up.html">pendulum clocks</a> mounted on the same wall synchronize through small physical forces exerted on the supporting beam.</p>
<p>My colleagues and I believe that this same ability to “sync up” might lead to the discovery of noninvasive therapeutic treatments for neurological disorders such as <a href="https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7318854">multiple sclerosis</a>. This could be accomplished using a noninvasive neuromodulator device at the surface of the scalp to provide small, nonphysical custom electric field forces to the region of the brain <a href="https://www.nationalmssociety.org/What-is-MS">affected by the disease</a>. By noninvasively altering the patient’s brain signals, these electric field forces would create a healthier neurological network environment for information transfer.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291751/original/file-20190910-190021-1gunhs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Like the drums in a band, brainwaves help ‘keep the beat.’</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/MjIMc6uhwrE">Josh Sorenson/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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</figure>
<h2>Brains rolling the drums</h2>
<p>The second way brains cut through the signal clutter is what neuroscientists refer to as the delivery key. It’s the role played by the <a href="https://doi.org/10.1038/d41586-018-02391-6">brain’s natural rhythms</a>, popularly known as brainwaves.</p>
<p>These brain rhythms are created by nerve cells that fire in specific patterns, causing waves of electrical activity at certain very low frequencies, ranging from about 0.5 to 140 cycles per second. By comparison, smartphones operate at around 5,000,000,000 cycles per second. The waves that help to deliver a signal to a destination in the brain’s noisy environment appear to be either Alpha waves, 8 to 13 cycles per second, or Beta waves, 13 to 32 cycles per second.</p>
<p>In my lab, we refer to this second activity as like “rolling the drums.” The brainwave frequency is similar to that of the sub-bass or bass drum used to mark or keep time in military, rock, pop, jazz and traditional orchestra music.</p>
<p>These low-frequency rhythms act as a delivery key that is impressed on the transmitted signal as an additional frequency. It’s sort of like how <a href="https://www.orolia.com/resources/knowledge-center/gps-clock-synchronization">GPS signals</a> synchronize telecommunications networks. Say that the brainwave signal or delivery key is 10 cycles per second. The time duration of one cycle is a tenth of a second, so the delivery key gives a time marker at the reception point every tenth of a second.</p>
<p>This time marker is extremely helpful in the accurate reception of the transmitted signal. Crucially, this delivery key only opens, or activates, the lock at the intended reception point. The idea is not so different from the use of a password to gain access to specific content.</p>
<p>Neuroscientists believe that the choice of delivery key used <a href="https://doi.org/10.1038/d41586-018-02391-6">depends on the state of the individual</a>. For example, Alpha waves are associated with wakeful rest with eyes closed. Beta waves are associated with normal wakeful consciousness and concentration.</p>
<p>Scientists suppose that associated with each delivery key, or brain rhythm, is a list of cognitive functions consistent with the individual’s state. So, for example, a signal sent with a 10 cycles per second Alpha wave brain rhythm impressed upon it already has information encoded in it about wakeful rest.</p>
<p>Brainwaves of electrical activity were <a href="https://doi.org/10.1038/d41586-018-02391-6">identified almost 100 years ago</a>, and researchers are constantly learning more about them and their role in behavior and brain function.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291752/original/file-20190910-190016-l9s04c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">To improve telecommunications systems, researchers can learn from how the brain does its work.</span>
<span class="attribution"><a class="source" href="https://unsplash.com/photos/0C9VmZUqcT8">Mario Caruso/Unsplash</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Modeling built systems on the brain</h2>
<p>My lab’s research into neurological networks has implications for not only understanding the human brain and developing noninvasive diagnostic procedures and therapeutic treatments for a variety of neurological dysfunctions, but also for designing improved systems for telecommunications, networking, cybersecurity, artificial intelligence and robotics.</p>
<p>For example, the human brain demonstrates just how much more advanced telecommunications network system designs could be. <a href="https://theconversation.com/advanced-digital-networks-look-a-lot-like-the-human-nervous-system-108319">5G cellular networks</a> hope to serve about 1 million devices in a square mile. In contrast, the human brain can rapidly establish at least 1 million connections within a <a href="https://www.rc.fas.harvard.edu/case-studies/connections-in-the-brain/">cubic inch of brain tissue</a>.</p>
<p>Today’s telecommunications network system designs are constrained because they essentially draw from the principles of one discipline – electrical and computer engineering. Even the simplest circuits of the brain, the nerve fibers, which are like the links in a telecommunications network, operate in exceedingly complex ways according to combined principles of biology, chemical engineering, mechanical engineering and electrical and computer engineering.</p>
<p>Designing systems similar in capability to the human brain will require the much more multidisciplinary approach reflected in my research group – a team drawn from experts in medicine, life sciences, engineering and advanced materials – and <a href="https://www.scripps.edu/">research</a> <a href="https://mpfi.org/">partners</a>.</p>
<p>[ <em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>. ]</p><img src="https://counter.theconversation.com/content/121016/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Salvatore Domenic Morgera has received funding for research in networks from the Natural Sciences and Engineering Research Council of Canada, The Fonds de recherche du Québec - Nature et technologies, National Science Foundation, United States Special Operations Command, IBM, Harris Corporation, CMC Electronics, Motorola, Bell Canada, and other public and private agencies.</span></em></p>Like a cocktail partygoer able to focus on one discussion in a noisy room, brains are able to make reliable connections against a busy neural background. Here are two phenomena that help it happen.Salvatore Domenic Morgera, Professor of Electrical Engineering and Bioengineering, University of South FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1135362019-03-18T17:01:05Z2019-03-18T17:01:05ZNew evidence for a human magnetic sense that lets your brain detect the Earth’s magnetic field<figure><img src="https://images.theconversation.com/files/264258/original/file-20190317-28505-1b1zf7w.jpg?ixlib=rb-1.1.0&rect=17%2C247%2C2849%2C1818&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Do you have a magnetic compass in your head?</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/moral-compass-career-path-concept-human-115938361">Lightspring/Shutterstock.com</a></span></figcaption></figure><p>Do human beings have a magnetic sense? <a href="https://www.springer.com/us/book/9783642797514">Biologists know</a> <a href="https://doi.org/10.1016/S0959-4388(00)00235-X">other animals do</a>. They think it helps creatures including bees, turtles and birds <a href="https://doi.org/10.1016/S0959-4388(02)00389-6">navigate through the world</a>.</p>
<p>Scientists have tried to investigate whether humans belong on the list of magnetically sensitive organisms. For decades, there’s been a back-and-forth between <a href="https://www.worldcat.org/title/human-navigation-and-the-sixth-sense/oclc/11022691&referer=brief_results">positive reports</a> and <a href="https://www.jstor.org/stable/1685499">failures to demonstrate</a> the trait in people, with <a href="https://www.springer.com/us/book/9781461379928">seemingly endless controversy</a>.</p>
<p>The mixed results in people may be due to the fact that virtually all past studies relied on behavioral decisions from the participants. If human beings do possess a magnetic sense, daily experience suggests that it would be very weak or deeply subconscious. Such faint impressions could easily be misinterpreted – or just plain missed – when trying to make decisions.</p>
<p>So our research group – including a <a href="https://maglab.caltech.edu/">geophysical biologist</a>, a <a href="https://neuro.caltech.edu">cognitive neuroscientist</a> and a <a href="http://www.isp.ac/index_e.html">neuroengineer</a> – took another approach. <a href="https://maglab.caltech.edu/human-magnetic-reception-laboratory/">What we found</a> arguably provides the first concrete neuroscientific <a href="https://doi.org/10.1523/ENEURO.0483-18.2019">evidence that humans do have a geomagnetic sense</a>. </p>
<h2>How does a biological geomagnetic sense work?</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=515&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=515&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=515&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264257/original/file-20190317-28479-jh5hpf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Life on Earth is exposed to the planet’s ever-present geomagnetic field that varies in intensity and direction across the planetary surface.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/illustration-physics-magnetic-field-that-extends-1165968205">Nasky/Shutterstock.com</a></span>
</figcaption>
</figure>
<p>The Earth is surrounded by a magnetic field, generated by the movement of the planet’s liquid core. It’s why a magnetic compass points north. At Earth’s surface, this magnetic field is fairly weak, <a href="https://nationalmaglab.org/about/maglab-dictionary/tesla">about 100 times weaker</a> than that of a refrigerator magnet.</p>
<p>Over the past 50 years or so, scientists have shown that hundreds of organisms in nearly all branches of the bacterial, <a href="https://www.livescience.com/54242-protists.html">protist</a> and animal kingdoms have the ability to detect and respond to this geomagnetic field. In some animals – <a href="https://doi.org/10.1007/BF00611096">such as honey bees</a> – the geomagnetic behavioral responses are <a href="https://pdfs.semanticscholar.org/750f/ce1b8f4723b09dd2fb1324fc916c9578c77b.pdf">as strong as the responses</a> to light, odor or touch. Biologists have identified strong responses in vertebrates ranging from <a href="https://doi.org/10.1038/37057">fish</a>, <a href="http://jeb.biologists.org/content/205/24/3903.full">amphibians</a>, <a href="https://doi.org/10.1126/science.1064557">reptiles</a>, numerous birds and a diverse variety of mammals including <a href="http://jeb.biologists.org/content/120/1/1.short">whales</a>, <a href="https://doi.org/10.1038/srep09917">rodents</a>, <a href="https://doi.org/10.1371/journal.pone.0001676">bats</a>, <a href="https://doi.org/10.1073/pnas.0803650105">cows</a> and <a href="https://doi.org/10.7717/peerj.6117">dogs</a> – the last of which can be trained to find a hidden bar magnet. In all of these cases, the animals are using the geomagnetic field as components of their homing and navigation abilities, along with other cues like sight, smell and hearing.</p>
<p>Skeptics dismissed early reports of these responses, largely because there didn’t seem to be a biophysical mechanism that could translate the Earth’s weak geomagnetic field into strong neural signals. This view was dramatically changed by the <a href="https://pubs.geoscienceworld.org/gsa/gsabulletin/article-abstract/73/4/435/5435">discovery that living cells</a> have the <a href="https://doi.org/10.1126/science.472725">ability to</a> build nanocrystals of the <a href="https://doi.org/10.1126/science.201.4360.1026">ferromagnetic</a> <a href="http://jeb.biologists.org/content/140/1/35.short">mineral magnetite</a> – basically, tiny iron magnets. Biogenic crystals of magnetite were first seen in the teeth of one group of mollusks, later in <a href="https://doi.org/10.1126/science.170679">bacteria</a>, and then in a variety of other organisms ranging from protists and animals such as insects, fish and mammals, <a href="https://doi.org/10.1073/pnas.89.16.7683">including within tissues of the human brain</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=267&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=267&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=267&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=336&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=336&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264240/original/file-20190317-28475-1vhbs80.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=336&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chains of magnetosomes from a sockeye salmon.</span>
<span class="attribution"><span class="source">Mann, Sparks, Walker & Kirschvink, 1988</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Nevertheless, scientists haven’t considered humans to be magnetically sensitive organisms.</p>
<h2>Manipulating the magnetic field</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=596&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=596&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=596&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=749&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=749&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264038/original/file-20190314-28479-1665yfc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=749&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Schematic drawing of the human magnetoreception test chamber at Caltech.</span>
<span class="attribution"><span class="source">Modified from 'Center of attraction' by C. Bickel (Hand, 2016).</span></span>
</figcaption>
</figure>
<p>In our new study, we asked 34 participants simply to sit in our testing chamber while we directly recorded electrical activity in their brains with electroencephalography (EEG). Our modified <a href="https://science.howstuffworks.com/faraday-cage.htm">Faraday cage</a> included a set of 3-axis coils that let us create controlled magnetic fields of high uniformity via electric current we ran through its wires. Since we live in mid-latitudes of the Northern Hemisphere, the environmental magnetic field in our lab dips downwards to the north at about 60 degrees from horizontal. </p>
<p>In normal life, when someone rotates their head – say, nodding up and down or turning the head from left to right – the direction of the geomagnetic field (which remains constant in space) will shift relative to their skull. This is no surprise to the subject’s brain, as it directed the muscles to move the head in the appropriate fashion in the first place.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=513&fit=crop&dpr=1 600w, https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=513&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=513&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=645&fit=crop&dpr=1 754w, https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=645&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/264239/original/file-20190317-28492-1jg4d65.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=645&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Study participants sat in the experimental chamber facing north, while the downwards-pointing field rotated clockwise (blue arrow) from northwest to northeast or counterclockwise (red arrow) from northeast to northwest.</span>
<span class="attribution"><span class="source">Magnetic Field Laboratory, Caltech</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>In our experimental chamber, we can move the magnetic field silently relative to the brain, but without the brain having initiated any signal to move the head. This is comparable to situations when your head or trunk is passively rotated by somebody else, or when you’re a passenger in a vehicle which rotates. In those cases, though, your body will still register vestibular signals about its position in space, along with the magnetic field changes – in contrast, our experimental stimulation was only a magnetic field shift. When we shifted the magnetic field in the chamber, our participants did not experience any obvious feelings.</p>
<p>The EEG data, on the other hand, revealed that certain magnetic field rotations could trigger strong and reproducible brain responses. One EEG pattern known from existing research, called alpha-ERD (event-related desynchronization), typically shows up when a person suddenly detects and processes a sensory stimulus. The brains were “concerned” with the unexpected change in the magnetic field direction, and this triggered the alpha-wave reduction. That we saw such alpha-ERD patterns in response to simple magnetic rotations is powerful evidence for human magnetoreception. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6Y4S2eG9BJA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Video shows the dramatic, widespread drop in alpha wave amplitude (deep blue color on leftmost head) following counterclockwise rotations. No drop is observed after clockwise rotation or in the fixed condition. <i>Connie Wang, Caltech</i></span></figcaption>
</figure>
<p>Our participants’ brains only responded when the vertical component of the field was pointing downwards at about 60 degrees (while horizontally rotating), as it does naturally here in Pasadena, California. They did not respond to unnatural directions of the magnetic field – such as when it pointed upwards. We suggest the response is tuned to natural stimuli, reflecting a biological mechanism that has been shaped by natural selection.</p>
<p>Other researchers have shown that animals’ brains filter magnetic signals, only responding to those that are environmentally relevant. It makes sense to reject any magnetic signal that is too far away from the natural values because it most likely is from a magnetic anomaly - a lighting strike, or lodestone deposit in the ground, for example. One early report on birds showed that robins stop using the geomagnetic field if the strength is more than about <a href="https://doi.org/10.1126/science.176.4030.62">25 percent different from what they were used to</a>. It’s possible this tendency might be why previous researchers had trouble identifying this magnetic sense – if they <a href="https://doi.org/10.1016/S1388-2457(02)00186-4">cranked up the strength of the magnetic field</a> to “help” subjects detect it, they might have instead ensured that subjects’ brains ignored it.</p>
<p>Moreover, our series of experiments show that the receptor mechanism – the biological magnetometer in human beings – is not electrical induction, and can tell north from south. This latter feature rules out completely the so-called <a href="https://doi.org/10.1146/annurev-biophys-032116-094545">“quantum compass” or “cryptochrome”</a> mechanism which is popular these days in the animal literature on magnetoreception. Our results are consistent only with functional magnetoreceptor cells based on the <a href="https://doi.org/10.1016/0303-2647(81)90060-5">biological magnetite hypothesis</a>. Note that a magnetite-based system <a href="https://doi.org/10.1098/rsif.2009.0491.focus">can also explain</a> <a href="https://doi.org/10.1098/rsif.2009.0435.focus">all of the behavioral effects in birds</a> that promoted the rise of the quantum compass hypothesis.</p>
<h2>Brains register magnetic shifts, subconsciously</h2>
<p>Our participants were all unaware of the magnetic field shifts and their brain responses. They felt that nothing had happened during the whole experiment – they’d just sat alone in dark silence for an hour. Underneath, though, their brains revealed a wide range of differences. Some brains showed almost no reaction, while other brains had alpha waves that shrank to half their normal size after a magnetic field shift.</p>
<p>It remains to be seen what these hidden reactions might mean for human behavioral capabilities. Do the weak and strong brain responses reflect some kind of individual differences in navigational ability? Can those with weaker brain responses benefit from some kind of training? Can those with strong brain responses be trained to actually feel the magnetic field? </p>
<p>A human response to Earth-strength magnetic fields might seem surprising. But given the evidence for magnetic sensation in our animal ancestors, it might be more surprising if humans had completely lost every last piece of the system. Thus far, we’ve found evidence that people have working magnetic sensors sending signals to the brain – a previously unknown sensory ability in the subconscious human mind. The full extent of our magnetic inheritance remains to be discovered.</p><img src="https://counter.theconversation.com/content/113536/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Shinsuke Shimojo received funding from Human Frontier Science Program (HFSP), Japanese Science and Technology Agency (JST), and currently receives funding from DARPA. </span></em></p><p class="fine-print"><em><span>Daw-An Wu receives funding from DARPA. </span></em></p><p class="fine-print"><em><span>Joseph Kirschvink receives funding from the RadioBio program of DARPA, and previous support for this work was from the Human Frontiers Science Program (HFSP).</span></em></p>Your brain’s sensory talents go way beyond those traditional five senses. A team of geoscientists and neurobiologists explored how the human brain monitors and responds to magnetic fields.Shinsuke Shimojo, Gertrude Baltimore Professor of Experimental Psychology, California Institute of TechnologyDaw-An Wu, California Institute of TechnologyJoseph Kirschvink, Nico and Marilyn Van Wingen Professor of Geobiology, California Institute of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/986912018-10-25T10:44:56Z2018-10-25T10:44:56ZMy thoughts are my password, because my brain reactions are unique<figure><img src="https://images.theconversation.com/files/241249/original/file-20181018-67185-dbf3km.png?ixlib=rb-1.1.0&rect=8%2C0%2C466%2C432&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A test subject entering a brain password.</span> <span class="attribution"><span class="source">Wenyao Xu, et al.</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Your brain is an inexhaustible source of secure passwords – but you might not have to remember anything. Passwords and PINs with letters and numbers are <a href="http://time.com/3643678/password-hack/">relatively easily hacked</a>, hard to remember and generally insecure. Biometrics are starting to take their place, with fingerprints, facial recognition and retina scanning becoming common even in routine logins for computers, smartphones and other common devices. </p>
<p>They’re more secure because they’re harder to fake, but biometrics have a crucial vulnerability: A person only has one face, two retinas and 10 fingerprints. They represent passwords that can’t be reset if they’re compromised.</p>
<p>Like usernames and passwords, biometric credentials are vulnerable to data breaches. In 2015, for instance, the database containing the <a href="https://www.nytimes.com/2015/09/24/world/asia/hackers-took-fingerprints-of-5-6-million-us-workers-government-says.html">fingerprints of 5.6 million U.S. federal employees</a> was breached. Those people shouldn’t use their fingerprints to secure any devices, whether for personal use or at work. The next breach might steal photographs or retina scan data, rendering those biometrics useless for security.</p>
<p><a href="https://scholar.google.com/citations?user=dvvN6qsAAAAJ&hl=en">Our</a> <a href="https://scholar.google.com/citations?user=4EPE1s4AAAAJ&hl=en">team</a> has been <a href="https://www.eurekalert.org/pub_releases/2015-06/bu-brt060215.php">working with collaborators</a> at <a href="https://doi.org/10.1016/j.neucom.2015.04.025">other institutions</a> for years, and has invented a new type of biometric that is both uniquely tied to a single human being and can be reset if needed.</p>
<h2>Inside the mind</h2>
<p>When a person looks at a photograph or hears a piece of music, <a href="https://www.encyclopedia.com/medicine/divisions-diagnostics-and-procedures/medicine/electroencephalography">her brain responds</a> in ways that researchers or medical professionals can measure with electrical sensors placed on her scalp. We have discovered that <a href="https://doi.org/10.1109/TIFS.2016.2543524">every person’s brain responds differently</a> to an external stimulus, so even if two people look at the same photograph, readings of their brain activity will be different.</p>
<p>This process is automatic and unconscious, so a person can’t control what brain response happens. And every time a person sees a photo of a particular celebrity, their brain reacts the same way – though differently from everyone else’s.</p>
<p>We realized that this presents an opportunity for a unique combination that can serve as what we call a “<a href="https://doi.org/10.1145/3210240.3210344">brain password</a>.” It’s not just a physical attribute of their body, like a fingerprint or the pattern of blood vessels in their retina. Instead, it’s a mix of the person’s unique biological brain structure and their involuntary memory that determines how it responds to a particular stimulus.</p>
<h2>Making a brain password</h2>
<p>A person’s brain password is a digital reading of their brain activity while looking at a series of images. Just as passwords are more secure if they include different kinds of characters – letters, numbers and punctuation – a brain password is more secure if it includes brain wave readings of a person looking at a collection of different kinds of pictures.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=444&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=444&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241253/original/file-20181018-67173-hpu8qo.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=444&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A range of visual stimuli generates the best brain password.</span>
<span class="attribution"><span class="source">Wenyao Xu, et al.</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>To set the password, the person would be authenticated some other way – such as coming to work with a passport or other identifying paperwork, or having their fingerprints or face checked against existing records. Then the person would put on a soft comfortable hat or padded helmet with electrical sensors inside. A monitor would display, for example, a picture of a pig, Denzel Washington’s face and the text “Call me Ishmael,” the opening sentence of Herman Meville’s classic “Moby-Dick.”</p>
<p>The sensors would record the person’s brain waves. Just as when <a href="https://www.macworld.co.uk/how-to/iphone/how-use-touch-id-finger-scanning-passcode-3579832/">registering a fingerprint</a> for an iPhone’s Touch ID, multiple readings would be needed to collect a complete initial record. Our research has confirmed that a combination of pictures like this would evoke brain wave readings that are unique to a particular person, and consistent from one login attempt to another.</p>
<p>Later, to login or gain access to a building or secure room, the person would put on the hat and watch the sequence of images. A computer system would compare their brain waves at that moment to what had been stored initially – and either grant access or deny it, depending on the results. It would take about five seconds, not much longer than entering a password or typing a PIN into a number keypad.</p>
<h2>After a hack</h2>
<p>Brain passwords’ real advantage comes into play after the almost inevitable hack of a login database. If a hacker breaks into the system storing the biometric templates or uses electronics to counterfeit a person’s brain signals, that information is no longer useful for security. A person can’t change their face or their fingerprints – but they can change their brain password.</p>
<p>It’s easy enough to authenticate a person’s identity another way, and have them set a new password by looking at three new images – maybe this time with a photo of a dog, a drawing of George Washington and a Gandhi quote. Because they’re different images from the initial password, the brainwave patterns would be different too. Our research has found that the new brain password would be <a href="https://doi.org/10.1016/j.patrec.2017.05.031">very hard for attackers to figure out</a>, even if they tried to use the old brainwave readings as an aid.</p>
<p>Brain passwords are endlessly resettable, because there are so many possible photos and a vast array of combinations that can be made from those images. There’s no way to run out of these biometric-enhanced security measures.</p>
<h2>Secure – and safe</h2>
<p>As researchers, we are aware that it could be worrying or even creepy for an employer or internet service to use authentication that reads people’s brain activity. Part of our research involved figuring out how to take only the minimum amount of readings to ensure reliable results – and proper security – without needing so many measurements that a person might feel violated or concerned that a computer was trying to read their mind.</p>
<p>We initially tried using 32 sensors all over a person’s head, and found the results were reliable. Then we progressively reduced the number of sensors to see how many were really needed – and found that we could get clear and secure results with just three properly located sensors.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=598&fit=crop&dpr=1 600w, https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=598&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=598&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=751&fit=crop&dpr=1 754w, https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=751&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/241247/original/file-20181018-67167-12xh32s.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=751&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Three electrodes high on the back of a user’s head are enough to detect a brain password.</span>
<span class="attribution"><span class="source">Wenyao Xu et al.</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This means our sensor device is so small that it can fit invisibly inside a hat or a virtual-reality headset. That opens the door for many potential uses. A person wearing smart headwear, for example, could easily unlock doors or computers with brain passwords. Our method could also make cars harder to steal – before starting up, the driver would have to put on a hat and look at a few images displayed on a dashboard screen.</p>
<p>Other avenues are opening as new technologies emerge. The Chinese e-commerce giant Alibaba recently unveiled a system for <a href="https://news.vice.com/en_us/article/ev5gmw/alibaba-vr-shopping-buy-singles-day">using virtual reality to shop</a> for items – including making purchases online right in the VR environment. If the payment information is stored in the VR headset, anyone who
uses it, or steals it, will be able to buy anything that’s available. A headset that reads its user’s brainwaves would make purchases, logins or physical access to sensitive areas much more secure.</p><img src="https://counter.theconversation.com/content/98691/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Wenyao Xu receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Zhanpeng Jin receives funding from the National Science Foundation. </span></em></p><p class="fine-print"><em><span>Feng Lin does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Biometrics are more secure than passwords – but when they’re compromised fingerprints and retina scans are hard to reset. Brain responses to specific stimuli are as secure and, crucially, resettable.Wenyao Xu, Assistant Professor of Computer Science and Engineering, University at BuffaloFeng Lin, Assistant Professor of Computer Science and Engineering, University of Colorado DenverZhanpeng Jin, Associate Professor of Computer Science and Engineering, University at BuffaloLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1039452018-09-28T12:38:51Z2018-09-28T12:38:51ZGolf: the neuroscience of the perfect putt<figure><img src="https://images.theconversation.com/files/238302/original/file-20180927-48650-11rpblt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Listen to your brain.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/male-golf-player-putting-green-beautiful-276857315?src=KwvzSByAxfd7YeCNXEbILA-1-38">OtmarW/shutterstock</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Sports fans across the world watched the American golfer Tiger Woods roll in a putt to win the <a href="https://en.wikipedia.org/wiki/PGA_Tour">PGA tour’s</a> season ending Tour Championship on September 23. His victory caps a remarkable comeback from personal struggles and injuries that caused him to plummet to 1,199 in the world rankings less than a year ago, and restores him as one of the world’s best. </p>
<p>With the PGA Tour finale now complete, the eyes of the golfing world are on Paris for the <a href="https://www.rydercup.com/">Ryder Cup</a> – golf’s biannual team contest pitching the best players from the USA against the cream of Europe. But what makes a successful golfer? My research explores the neuroscience of golf putting – and ways that the brain can be trained to increase putting success. </p>
<p>Golfers carry 14 clubs, but the putter is by far the most used, <a href="https://www.pgatour.com/stats.html">accounting for around 41% of shots</a>. Successfully striking the 1.68-inch diameter golf ball into the 4.25-inch golf hole requires precision programming of force and direction. You have to take into account factors such as slope, direction of the blades of grass and weather effects including temperature, wind and rain.</p>
<p>My research has identified <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1111/psyp.12182">a type of “brainwave”</a>, produced by electrical pulses resulting from brain cells communicating with each other, that can predict golfing success. They can easily be recorded by simply putting sensors on the scalp. In a brain imaging study where 20 expert and novice golfers each hit 120 putts, I found that the intensity of activity of a brainwave at the frequency of 10-12 Hz, recorded before the backswing, could clearly distinguish putts that went in the hole from those that missed. </p>
<p>More specifically, intense activity at sensors placed on frontal parts of the scalp, over the <a href="https://www.ncbi.nlm.nih.gov/books/NBK10796/">premotor cortex</a>, was key for putting success. This finding has since been <a href="http://psycnet.apa.org/fulltext/2015-56326-001.pdf">supported by other research</a>, which also found that reduced activity at sensors placed on the <a href="https://sciencing.com/the-functions-of-the-left-temporal-lobe-12214661.html">left-temporal</a> parts of the scalp (close to the left ear) can further contribute to the recipe for proficient putting. </p>
<p>This makes sense, as the premotor cortex is implicated in movement planning, and the left-temporal region is associated with verbal-analytic processing. So it looks as if the brain intently focuses on accurately planning force and direction, while blocking out verbal intrusions, immediately before successful putts.</p>
<h2>Training the brain to drain putts</h2>
<p>Having identified neural signatures associated with putting success, scientists are now exploring whether you can train golfers to produce this pattern of brain activity and recognise what it feels like. The trick is to only hit putts when the appropriate activation-level is produced (when they are “in the zone”).</p>
<p>Such brain training can be achieved using a technique called “neurofeedback”, which involves measuring brain activity and displaying it back in real time (in the form of auditory tones, or graphs on a computer screen) so that recipients can develop ways of consciously controlling their brain activity levels. It may seem far fetched, but the technology and equipment are readily available, portable and relatively cheap – starting at less than £300 for a wireless electroencephalographic (EEG) neurofeedback headset.</p>
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<img alt="" src="https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/238425/original/file-20180928-48662-xyqnhg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Jason Day: brain trained.</span>
<span class="attribution"><span class="source">Keith Allison/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>In a 2015 study, I used wireless neurofeedback technology to train 12 amateur golfers <a href="https://www.sciencedirect.com/science/article/pii/S1469029214001125">to produce the pattern</a> of brainwaves that I’d previously associated with success before they hit putts. This took place during three separate one-hour training sessions. On their return to the laboratory a few days later, the golfers were able to reliably produce the pattern of 10-12 Hz brain activity that I had prescribed. </p>
<p>What’s more, their putting had improved (on average, 8ft putts finished 21% closer to the hole after the training). Admittedly though, this was not to a sufficient extent to exclude the possibility of a placebo effect. Notwithstanding, the results are encouraging, and have been <a href="https://www.tandfonline.com/doi/abs/10.1080/10874200802149656%20and">bolstered by similar findings</a> from researchers in other parts of the world. </p>
<h2>From the lab to the golf course</h2>
<p>While the scientists are still experimenting before making firm and unequivocal statements about neurofeedback’s effectiveness, there are some members of the golfing elite who are already convinced of the benefits of brain training. Australian Jason Day, the current world number 11, has used neurofeedback for a number of years and said that it has yielded “<a href="https://www.news.com.au/sport/golf/jason-day-turns-to-brain-training-to-improve-mental-strength/news-story/7e609fb8a67fb1ef5e1973cae7ab2bcf">a 110% improvement” in his mental game</a>. So it may be no coincidence that he was <a href="https://www.pgatour.com/stats/stat.02564.html">ranked as the best putter</a> on the 2018 PGA Tour.</p>
<p>Meanwhile, a more recent convert who’ll be on show in Paris is American Bryson DeChambeau. The current <a href="https://www.pgatour.com/stats/stat.02428.html">world number seven</a> revealed details of his brain training regime in August 2018, before winning two out of the four season-ending <a href="https://www.pgatour.com/fedexcup.html">FedEx Cup</a> playoff events. With 21 professional victories between them, Day and DeChambeau are certainly doing something right. </p>
<p>Much is made about the Ryder Cup being a team event, a stark diversion from the individual contests that characterise regular tournaments on the PGA and European Tours. While this undoubtedly adds new dynamics that capture the attention of the sporting world, it will still, in all likelihood, boil down to an individual putt by an individual player to determine which continent lifts golfs’ premier prize. </p>
<p>As a proud European, I hope that player is wearing European blue, and can optimally shape his 10-12Hz brainpower during those crucial moments.</p><img src="https://counter.theconversation.com/content/103945/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Michael Cooke has received funding from the Economic and Social Research Council grants PTA-02627-2696 and RES-000-22-4523. </span></em></p>How to win at golf …with a little help from neuroscience.Andrew Michael Cooke, Lecturer in Performance Psychology, Bangor UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/959302018-05-04T00:40:47Z2018-05-04T00:40:47ZTake it from me: neuroscience is advancing, but we’re a long way off head transplants<figure><img src="https://images.theconversation.com/files/217499/original/file-20180503-153869-fatn9r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pick a head, any head! </span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/tambov-russian-federation-march-24-2015-263582948?src=OeDSzC_8kcB1aiLCcEVEsw-1-0">from www.shutterstock.com </a></span></figcaption></figure><p><em><strong>Take it from me</strong> is a new series in Science and Technology, where we find an expert to provide a personal but informed perspective on a topical issue.</em></p>
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<p>In the 1983 film <a href="https://www.imdb.com/title/tt0085894/">The Man with Two Brains</a>, Steve Martin’s character falls in love with the disembodied brain of a woman named Anne. </p>
<p>But what once sat in the realm of movies and science fiction novels now seems slightly more plausible. Recent advances in neuroscience have lead to human cells being grown into “<a href="https://arstechnica.com/science/2018/04/the-ethics-of-growing-complex-structures-with-human-brain-cells/">mini brains</a>” in the lab, and brains of decapitated pigs being “<a href="http://www.bbc.com/news/science-environment-43928318">kept alive</a>” for a day and a half. </p>
<p>So are we closer to a time when brains may be able to function in isolation from a body – leading to head transplants or even brains frozen and brought back to life in the future? </p>
<p>I think such possibilities are a long way off. </p>
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<h2>A brain without a body</h2>
<p>Professor Nenad Sestan of Yale University <a href="http://www.bbc.com/news/science-environment-43928318">reported</a> in March that he and his team restored blood circulation to the brains of decapitated pigs, and kept brain cells alive and functioning for up to 36 hours. </p>
<p>This technology, called “<a href="https://www.technologyreview.com/s/611007/researchers-are-keeping-pig-brains-alive-outside-the-body/amp/">BrainEx</a>”, restores circulation by connecting the brain to a series of pumps and heaters that pump artificial blood and carry oxygen to key regions, including areas deep inside the brain. This allows even <a href="http://www.perimed-instruments.com/introduction-to-microcirculation">microcirculation</a> – the flow of blood to the smallest blood vessels and cells – to be restored. </p>
<p>This work opens up a number of potential future research avenues, including the ability to test new treatments for Alzheimer’s disease and other neurological conditions. </p>
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Read more:
<a href="https://theconversation.com/we-can-change-our-brain-and-its-ability-to-cope-with-disease-with-simple-lifestyle-choices-91699">We can change our brain and its ability to cope with disease with simple lifestyle choices</a>
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<p>A more developed area of neuroscience is the generation of <a href="https://arstechnica.com/science/2018/04/the-ethics-of-growing-complex-structures-with-human-brain-cells/">brain organoids</a>, “mini brains” grown from human <a href="http://stemcell.childrenshospital.org/about-stem-cells/pluripotent-stem-cells-101/">stem cells</a> and kept alive in the laboratory. </p>
<p>These organoids mimic features of the developing brain, allowing researchers to undertake research into conditions such as <a href="https://www.sciencedirect.com/science/article/pii/S0006322317321972">autism spectrum disorders</a> and <a href="https://www.nature.com/articles/s41398-017-0054-x">schizophrenia</a>. </p>
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<figcaption><span class="caption">It doesn’t get much kookier than this 1983 trailer.</span></figcaption>
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<h2>Are the brains really alive?</h2>
<p>Sestan believes his approach to keeping pig brains alive is likely to work in other species, including <a href="https://www.technologyreview.com/s/611007/researchers-are-keeping-pig-brains-alive-outside-the-body/amp/">primates</a>. </p>
<p>But what might keeping brains “alive” mean for the individual? Might it be possible for the disembodied brain to retain its consciousness and memory, devoid of any sensory input or ability to communicate? </p>
<p>Monitoring of the pig brains via a technique known as <a href="https://www.healthline.com/health/eeg">EEG</a> showed <a href="https://www.technologyreview.com/s/611007/researchers-are-keeping-pig-brains-alive-outside-the-body/">no sign</a> of complex electrical activity indicating thought or sensation. This could be due to lowered activity or damage of brain cells during the procedure. </p>
<p>But <a href="http://www.jhunewsletter.com/article/2013/10/hope-is-found-even-in-flat-lined-eeg-13855/">some research</a> has indicated that, even when the EEG is a flat line, there may still be some <a href="https://www.huffingtonpost.com/2013/09/19/brain-activity-coma_n_3953473.html">activity</a> in deep brain structures such as the hippocampus, a brain area critical for memory.</p>
<p>The question of measuring activity is also relevant to the brain organoids. With improvements in techniques, there is the potential that organoids may become more complex. Although it’s still very unlikely, it’s possible they may take on aspects of higher-order brain functioning, such as feeling pleasure and pain, storing memories, or even experiencing some degree of consciousness.</p>
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<h2>What is consciousness?</h2>
<p>Consciousness is one of the most difficult brain phenomena to explain, and a question that modern neuroscience is just beginning to make progress on. It’s even difficult to actually define what consciousness <em>is</em>. </p>
<p>Australian philosopher David Chalmers has referred to these challenges as the <a href="https://www.psychologytoday.com/us/blog/the-superhuman-mind/201303/what-is-consciousness">“hard problem” of consciousness</a> – understanding why consciousness occurs. </p>
<p>Multiple theories and models of consciousness have been proposed, and experts tussle back and forth about which is most accurate. Some critics even claim that most theories of consciousness are “<a href="https://www.theatlantic.com/science/archive/2016/03/phlegm-theories-of-consciousness/472812/">worse than wrong</a>” – they don’t actually explain anything. </p>
<p>Physiologically, the EEG is still the most sensitive measure to indicate consciousness. When an individual is awake and alert, the EEG is “<a href="https://www.medicine.mcgill.ca/physio/vlab/biomed_signals/eeg_n.htm">activated</a>”, characterised by low voltage, high frequency fast brain waves. </p>
<p>When there is a loss of consciousness, brain waves slow down and get higher in amplitude as brain cells alter their firing rates. </p>
<p>Parts of the brain thought to be involved in consciousness include the rear part of the cerebral cortex (at the surface), and also deeper structures such as the brainstem. EEG activity in specific areas of the brain may be one of the most effective ways to discriminate between conscious and unconscious individuals.</p>
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<h2>Can a brain without a body be conscious?</h2>
<p>Currently we are a long way from experimental models of the human brain – such as brain organoids or disembodied brains – being conscious. However, we could need to confront such a possibility as technology advances and models become more sophisticated.</p>
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<img alt="" src="https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217461/original/file-20180503-153869-1docab7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Pigs are very smart animals – they can be taught to play computer games.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/young-pigs-on-farm-134362790?src=EkNc7C_di4wLG8HcviEabg-1-44">from www.shutterstock.com</a></span>
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<p>Indeed, the hope of this has led to initiatives such as cryogenically preserving (freezing) brains, and even proposed head transplants. </p>
<p>But I wouldn’t rush out and put my name down for these procedures just yet. In the case of <a href="http://www.bbc.com/news/av/technology-42835119/cryonics-your-body-preserved-for-future-revival">cryogenically</a> preserving tissue, evidence has yet to demonstrate that all areas of the brain are reached with the antifreeze used to protect tissue from fracturing at the extremely low temperatures. </p>
<p>Even if the tissue can somehow be protected from freezing damage, warming that tissue back up again is likely to result in further <a href="https://www.telegraph.co.uk/science/2016/11/18/scientific-backlash-after-high-court-rules-teenager-can-be-froze/">extensive problems</a>. This would make it difficult, if not impossible, to ever return the brain to a conscious state – and that’s all before you deal with the issues inherent in actually transplanting the brain into another body.</p>
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Read more:
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<p>Many unknowns also exist with head transplants. While Italian neurosurgeon Professor Sergio Canavero has claimed that he will carry out the first <a href="https://www.telegraph.co.uk/science/2017/04/27/cryogenically-frozen-brains-will-woken-transplanted-donor-bodies/">human head transplant</a> in 2018, many neuroscientists are sceptical. </p>
<p>There are a host of <a href="http://www.popsci.com.au/tech/military/no-human-head-transplants-will-not-be-possible-by-2017,401150">issues</a> with such a procedure. There’s the possibility of rejection of the head by the donor body, and the difficulty of connecting the spinal cord to the brain in a way that the brain can control the donor body. Additionally, even if it did work in a physical sense, there are problems around how such a procedure might affect the individual’s sense of self-awareness or consciousness.</p>
<h2>Where should the field go from here?</h2>
<p>There are many ethical concerns linked to the idea of brains in culture or removed from bodies – including what protections are necessary, how to address issues around consent, ownership and post-research tissue handling, and even how to define death. </p>
<p>In late April, 17 experts in neuroscience, stem-cell biology, ethics and philosophy published an editorial in <a href="https://www.nature.com/articles/d41586-018-04813-x#ref-CR15">Nature</a> outlining many of the issues that need to be considered and calling for “clear guidelines for research”. </p>
<p>Such conversations also need to be held outside of academic circles and should engage ethics committees, research funding bodies, and, most importantly, the wider <a href="https://www.nature.com/news/historic-decision-allows-uk-researchers-to-trial-three-person-babies-1.21182">public</a>. </p>
<p>While there has never been a more exciting time to work in neuroscience, it is critical that proper safeguards be put in place now as models continue to advance.</p>
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<img src="https://counter.theconversation.com/content/95930/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lyndsey Collins-Praino receives funding from the NeuroSurgical Research Foundation and the Commercial Accelerator Scheme.</span></em></p>‘Mini brains’ can be grown in the lab, and brains of decapitated pigs were recently ‘kept alive’ for a day and a half. But what makes a conscious brain?Lyndsey Collins-Praino, Senior Lecturer in School of Medicine, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/755782017-06-09T03:55:04Z2017-06-09T03:55:04ZTourette syndrome: Finally, something to shout about<figure><img src="https://images.theconversation.com/files/172340/original/file-20170605-16849-1frmy02.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Campers at Twitch and Shout, a camp for teenagers with Tourette, in Winder, Georgia, say goodbye in this 2014 file photo. </span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Tourette-Syndrome-Summer-Camp/cc5d6c65ba66466cbbc62cb6a7e46a14/70/0">David Goldman/AP</a></span></figcaption></figure><p>Tourette syndrome is a mysterious medical curiosity that has puzzled doctors for more than a century. People who have it suffer from tics and other behavioral problems, such as obsessive compulsive traits and attention deficit disorder. </p>
<p>In addition, they are cursed by a stereotype that they swear loudly and inappropriately. In reality, 10 percent actually experience these verbal outbursts, but many are stigmatized and isolated nonetheless. </p>
<p>I have studied <a href="https://www.amazon.com/dp/1542484219">Tourette syndrome</a> for years, and recently <a href="https://www.amazon.com/Tourette-Syndrome-Secrets-Happier-Treatment/dp/1542484219">published a book </a>about treatments and the common spectrum of behavioral disorders associated with it. Swearing isn’t even one of the more frequent ones. </p>
<p>The fact is that over the last several years, many exciting and life-altering treatments have become available to Tourette patients and their families. We have reached a crossroads in this disease where it will become increasingly critical to reeducate the public and to make new therapies widely available. </p>
<h2>Twitches and tics</h2>
<p>French scientist <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3064755/">Jean-Martin Charcot</a>, the founder of modern clinical neurology, coined the eponym “Tourette syndrome” after his student, Georges Albert Gilles de la Tourette, who in 1885 described nine patients suffering from the tic “malady.” </p>
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<img alt="" src="https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=791&fit=crop&dpr=1 600w, https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=791&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=791&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=994&fit=crop&dpr=1 754w, https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=994&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/172490/original/file-20170606-3665-1qg14c8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=994&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Jean-Martin Charcot, considered the founder of neurology.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/Jean-Martin_Charcot#/media/File:Jean-Martin_Charcot.jpg">From wikimedia.com</a></span>
</figcaption>
</figure>
<p>Researchers soon noticed that Tourette occurred among multiple family members across multiple generations. </p>
<p>Over the generations, however, new knowledge came slowly. Critical gaps in our understanding of the syndrome remain, and half of all cases remain undiagnosed. </p>
<p>Even the precise number of people affected has been hard to know. For example, the Centers for Disease Control and Prevention (CDC) estimates that one in 362 children, or 0.3 percent, has Tourette. The <a href="https://www.tourette.org/about-tourette/overview/what-is-tourette/">Tourette Association of America,</a> on the other hand, estimates the disease is twice as common, with one in 166 kids (0.6 percent) affected. </p>
<p>Some <a href="https://www.tourette.org/about-tourette/overview/what-is-tourette/">Tourette syndrome</a> cases are mild, with symptoms such as nonbothersome eye blinking, or mild body twitching. In many cases, the motor tics will resolve in late adolescence or early adulthood. Many patients will even lead relatively normal lives.</p>
<h2>Lessons from the brain yield advances</h2>
<p>Knowledge of the syndrome has increased as scientists have learned more in general about the brain.</p>
<p>The normal functions of the human brain seem to be dictated by rhythmic oscillations that continuously repeat over and over, much like a popular song on the radio. These <a href="https://clinicaltrials.gov/ct2/show/NCT02056873">oscillations change and modulate</a>, and they act to control various human behaviors. </p>
<p>If an oscillation “goes bad,” it can result in a disabling tic or other behavioral symptoms of Tourette syndrome. </p>
<p>An important secret to the development of new therapies for Tourette is that we can alter these oscillations with rehabilitative therapies, cognitive behavioral intervention therapy (CBIT), medications such as <a href="http://www.webmd.com/drugs/2/drug-151522/tetrabenazine-oral/details">tetrabenazine</a> or even deep brain stimulation, which involves a
small straw-like probe being inserted into the brain. Electricity can be delivered through this probe to disrupt the abnormal oscillations responsible for tics. </p>
<h2>Continued study also helping</h2>
<p>The genetics of Tourette remain opaque. Despite the fact that the disease tends to run in families, no one has discovered a <a href="https://www.amazon.com/dp/1542484219">single DNA abnormality</a> linking all, or even most, cases.</p>
<p>In the meantime, however, technology is offering new means of detection and treatment. Scientists have recorded tic signals from the human brain and even deployed the first smart devices to detect and suppress tics. </p>
<p>Some investigators are studying newer generations of medicines that decrease the complications that can occur with old-fashioned drugs, such as<a href="https://medlineplus.gov/druginfo/meds/a682180.html"> Haloperidol</a>, that have traditionally been used to treat Tourette. Scientists are also looking for way to suppress or modulate inappropriate brain signals, spurring development of new drugs with novel brain targets, such as <a href="https://www.ncbi.nlm.nih.gov/pubmed/28464701">cannabinoid receptors</a>. </p>
<p>Using <a href="http://www.medicalmarijuanainc.com/tourette-syndrome-medical-marijuana-research/">marijuana to treat the symptoms of Tourette</a> syndrome makes some scientific sense. Cannabinoids occur naturally in the body, and cannabinoid receptors are found throughout many brain regions. In fact, CB1 cannabinoid receptors are located in high concentrations in regions of the brain thought to be involved in Tourette syndrome. </p>
<h2>Living with Tourette syndrome</h2>
<p>While it may appear to the casual observer that someone with Tourette syndrome outgrows it in adolescence or early adulthood, in fact most do not. While the motor and vocal tics wane in most cases, the obsessive-compulsive and behavioral features may persist and even escalate. </p>
<p>These behavioral features in Tourette syndrome, if left undiagnosed and untreated, will make it harder to live a normal life and will affect the person more than the noticeable motor and vocal tics.</p>
<p>While new treatments may lie in the future, there are many things that patients and their families can do today. Many changes, often very simple, can be incorporated into patients’ lives. </p>
<p>Comprehensive care teams from different disciplines play a key role.
For example, a social worker can help to set up an individualized school education plan and connect families to resources that can transform difficult school situations into success stories. A <a href="https://www.ncbi.nlm.nih.gov/pubmed/20483969">rehabilitative therapist</a> can now in many cases successfully address tics without the use of a single medication. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/172496/original/file-20170606-3674-1x3rb4m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Children and teens celebrate at the end of a week of camp at Twitch and Shout in Winder, Georgia in 2014. Building relationships with others who have Tourette syndrome is believed to be beneficial for young people.</span>
<span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Tourette-Syndrome-Summer-Camp/aa86498ea747424292bbb4d65ea6a6d7/19/0">David Goldman/AP</a></span>
</figcaption>
</figure>
<p>Our care team has taken care of close to 10,000 movement disorder patients at the University of Florida and tens of thousands more with our colleagues in the <a href="https://www.tourette.org/about-tourette/overview/centers-of-excellence/center-excellence-locations/">Southeast Regional Tourette Association of America Center of Excellence</a>, which also includes neurologists, psychiatrists, rehabilitative specialists, social workers and scientists at the University of South Florida, Emory University, University of Alabama and the University of South Carolina.</p>
<p>There are good reasons to try different treatments, even if none seems to work. Patients need to learn how to recognize when a plan or therapy isn’t working and how to speak with their doctors and care team about trying something else. The point is that left unchecked, brain vibrations can, in some Tourette cases, lead to neck-snapping tics which can cause injuries, even paralysis. Today even the most severe cases have a chance for treatment with deep brain stimulation.</p>
<p>Though Tourette syndrome remains mysterious in the public eye, it is important that we teach families about the broad palette of options that provide tangible benefits for quality of life. That is definitely something worth shouting about.</p><img src="https://counter.theconversation.com/content/75578/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Okun receives research funding from the National Institutes of Health and the Tourette Association of America. He is affiliated with the Tourette Association of America as an unpaid member of the medical advisory board. </span></em></p>There’s more to Tourette syndrome than swearing and shouting. Over the last several years, many life-altering treatments of this tic disorder have become available to patients and their families.Michael Okun, Professor of Neurology, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/753212017-03-31T14:41:21Z2017-03-31T14:41:21ZElon Musk wants to merge man and machine – here’s what he’ll need to work out<figure><img src="https://images.theconversation.com/files/163188/original/image-20170329-8553-1i49aph.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/3d-rendering-human-brain-on-technology-495797320?src=_2ehgqnu5HEUeu__jyQyrA-1-26"> whiteMocca/Shutterstock</a></span></figcaption></figure><p>Computers and brains already talk to each other daily in high-tech labs – and they do it better and better. For example, disabled people can now learn to govern robotic limbs by the sheer power of their mind. The hope is that we may one day be able to operate <a href="http://neurogadget.net/2013/02/07/collaborative-bci-two-minds-are-better-than-one-at-steering-a-thought-controlled-virtual-spacecraft/7014">spaceships with our thoughts</a>, <a href="https://theconversation.com/could-we-upload-a-brain-to-a-computer-and-should-we-even-try-61928">upload our brains to computers</a> and, ultimately, create cyborgs.</p>
<p>Now Elon Musk <a href="https://www.theguardian.com/technology/2017/mar/28/elon-musk-merge-brains-computers-neuralink">is joining the race</a>. The CEO of Tesla and SpaceX has acquired <a href="https://neuralink.com/">Neuralink</a>, a company aiming to establish a direct link between the mind and the computer. Musk has already shown how expensive space technology can be run as a private enterprise. But just how feasible is his latest endeavour?</p>
<p>Neurotechnology was born in the 1970s when <a href="http://web.cs.ucla.edu/%7Evidal/vidal.html">Jaques Vidal</a> proposed that electroencephalography (EEG), which tracks and records brain-wave patterns via sensors placed on the scalp (electrodes), could be used to create systems that <a href="http://web.cs.ucla.edu/%7Evidal/BCI.pdf">allow people to control external devices directly with their mind</a>. The idea was to use computer algorithms to transform the recorded EEG signals into commands. Since then, interest in the idea has been growing rapidly. </p>
<p>Indeed, these “brain-computer interfaces” have driven a revolution in the area of assistive technologies – <a href="https://www.youtube.com/watch?v=76lIQtE8oDY">letting people with quadriplegia feed themselves</a> and even <a href="http://uk.businessinsider.com/a-paraplegic-man-walked-for-the-first-time-thanks-to-this-technology-2015-9">walk again</a>. In the past few years, major investments in brain research from the US (<a href="https://www.braininitiative.nih.gov/">the BRAIN initiative</a>) and the EU (<a href="https://www.humanbrainproject.eu/">the Human Brain project</a>) have further advanced research on them. This has pushed applications of this technology into the area of “human augmentation” – using the technology to improve our cognition and other abilities. </p>
<p>The combination of humans and technology could be <a href="http://io9.gizmodo.com/humans-with-amplified-intelligence-could-be-more-powerf-509309984">more powerful than artificial intelligence</a>. For example, when we make decisions based on a combination of perception and reasoning, <a href="http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7539383">neurotechnologies could be used to augment our perception</a>. This could help us in situations such when seeing a very blurry image from a security camera and having to decide whether to intervene or not.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/163182/original/image-20170329-8560-1nu2pcf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">EEG recording cap.</span>
<span class="attribution"><span class="source">Chris Hope/wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Despite investments, the transition from using the technology in research labs to everyday life is still slow. The EEG hardware is totally safe for the user, but records very noisy signals. Also, research labs have been mainly focused on using it to understand the brain and to propose <a href="https://www.weforum.org/agenda/2016/11/could-you-soon-fly-an-airplane-with-your-mind">innovative applications</a> without any follow-up in commercial products. Other very promising initiatives, such as using commercial EEG systems to <a href="https://popularelectronics.technicacuriosa.com/2017/03/15/teslapathic-mind-control-for-your-car/">let people drive a car with their thoughts</a>, have remained isolated.</p>
<p>To try to overcome some of these limitations, several major companies have recently announced investments in research into brain-computer interfaces. Bryan Johnson from human intelligence company <a href="http://kernel.co/">Kernel</a> <a href="https://medium.com/@bryan_johnson/kernel-acquires-krs-to-build-next-generation-neural-interfaces-d5dd60662b6c">recently acquired the MIT spin-off firm KRS</a>, which is promising to make a data-driven revolution in understanding neurodegenerative diseases. Facebook is <a href="https://www.facebook.com/careers/jobs/a0I1200000JXqeWEAT/">hiring a brain-computer interface engineer</a> to work in its secretive hardware division, <a href="http://www.thedrum.com/news/2016/11/08/facebooks-building-8-secret-unit-may-be-creating-the-next-phone-0">Building 8</a>.</p>
<h2>Pie in the sky?</h2>
<p>Musk’s company is the latest. Its “neural lace” technology involves implanting electrodes in the brain to measure signals. This would allow getting neural signals of much better quality than EEG – but it requires surgery. The project is still quite mysterious, <a href="https://twitter.com/elonmusk/status/846580443797368832">although Musk has promised</a> more details about it soon. Last year <a href="http://uk.businessinsider.com/elon-musk-on-neural-lace-2016-6">he stated that brain-computer interfaces are needed</a> to confirm humans’ supremacy over artificial intelligence. </p>
<p>The project might seem ambitious, considering the limits of current technology. <a href="https://popularelectronics.technicacuriosa.com/2017/03/15/teslapathic-mind-control-for-your-car/">BCI spellers</a>, which allow people to spell out words by looking at letters on a screen, are still much slower than traditional communication means, which Musk <a href="https://www.youtube.com/watch?v=ZrGPuUQsDjo">has already defined</a> as “incredibly slow”. Similar speed limitations apply when using the <a href="https://www.ncbi.nlm.nih.gov/pubmed/25116904">brain to control a video game</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=499&fit=crop&dpr=1 600w, https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=499&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=499&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=627&fit=crop&dpr=1 754w, https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=627&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/163189/original/image-20170329-8584-oh5dy4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=627&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">After cars and space, will Musk revolutionise neurotechnologies?</span>
<span class="attribution"><span class="source">Maurizio Pesce from Milan, Italia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>What we really need to make the technology reliable is more accurate, non-invasive techniques to measure brain activity. We also need to improve our understanding of the brain processes and how to decode them. Indeed, the <a href="https://theconversation.com/could-we-upload-a-brain-to-a-computer-and-should-we-even-try-61928">idea of uploading or downloading our thoughts</a> to or from a computer is simply impossible with our current knowledge of the human brain. Many processes related to memory are still not understood by neuroscientists. <a href="http://io9.gizmodo.com/how-much-longer-until-humanity-becomes-a-hive-mind-453848055">The most optimistic forecasts</a> say it will be at least 20 years before brain-computer interfaces will become technologies that we use in our daily lives.</p>
<p>But that doesn’t make Musk’s initiative useless. The neural lace could initially be used to study the brain mechanisms and <a href="http://uk.businessinsider.com/elon-musk-neuralink-connect-brains-computer-neural-lace-2017-3">treat disorders such as epilepsy or major depression</a>. Together with electrodes for “reading” the brain activity, we could also implant electrodes for stimulating the brain – making it possible to <a href="https://www.scientificamerican.com/article/implant-epilepsy-seizure/">detect and halt epileptic seizures</a>.</p>
<p>Brain-computer interfaces also face <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4115612/">major ethical issues</a>, especially those based on sensors surgically implanted in the brain. Most people are unlikely to want to have brain surgery – or be fit to have it – unless vital for their health. This could significantly limit the number of potential users of Musk’s neural lace. Kernel’s original idea when acquiring the company KRS was also to <a href="https://www.technologyreview.com/s/603771/the-entrepreneur-with-the-100-million-plan-to-link-brains-to-computers/">implant electrodes in people’s brain</a>, but the company changed its plans six months later due to difficulties related to invasive technologies.</p>
<p>It’s easy for billionaires like Musk to be optimistic about the development of brain-computer interfaces. But, rather than dismissing them, let’s remember that these visions are nevertheless crucial. They push the boundaries and help researchers set long-term goals.</p>
<p>There’s every reason to be optimistic. Neurotechnology started only started a few years after man first set foot on the moon – perhaps reflecting the need for a new big challenge after such a giant leap for mankind. And the brain-computer interfaces were indeed pure science fiction at the time. </p>
<p>In 1965, <a href="http://aa-nplus1.tumblr.com/post/18075687043/detail-from-the-december-26-1965-edition-of-the">the Sunday comic strip “Our New Age” stated</a>: </p>
<blockquote>
<p>By 2016, man’s intelligence and intellect will be able to be increased by drugs and by linking human brains directly to computers!</p>
</blockquote>
<p>We are not there yet, but together we can win the challenge.</p><img src="https://counter.theconversation.com/content/75321/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Davide Valeriani is affiliated with NeuroTechX, a non-profit organization whose mission is to build a strong global neurotechnology community.</span></em></p>It’s a slow process, but billionaires like Musk push boundaries and help researchers set long-term goals for developing brain-computer interfaces.Davide Valeriani, Post-doctoral Researcher in Brain-Computer Interfaces, University of EssexLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/617232016-06-29T20:05:39Z2016-06-29T20:05:39ZEach part of the brain has its own rhythmic ‘fingerprint’<figure><img src="https://images.theconversation.com/files/128537/original/image-20160628-7842-1cev8s1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=EEG&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=173834126">Image Point Fr/Shutterstock.com</a></span></figcaption></figure><p>Since Hans Berger first recorded neural activity from the human scalp with an electroencephalograph (EEG), in 1924, neuroscientists have been trying to make sense of the electrical pulses emitted by our grey matter. Recent studies have focused on brain oscillations (commonly called brain waves) which are thought to be the mechanism by which different brain regions <a href="http://science.sciencemag.org/content/304/5679/1926">communicate with each other</a>. Our latest study has shed some light on these curious oscillations. <a href="http://journals.plos.org/plosbiology/article?id=info:doi/10.1371/journal.pbio.1002498">We have discovered</a> that each region of the brain has a uniquely identifiable pattern of oscillations – their own rhythmic fingerprint.</p>
<p>Berger was the first to notice that neural activity seems to fluctuate at a rate of 10 cycles per second. He called this rhythm the alpha-wave. Since then, the methods to identify rhythmic activity have improved considerably, from counting how often a wave fluctuates within a second, to elaborate mathematical procedures, called spectral analyses. </p>
<p>Alpha is still the most obvious oscillation, but other types of oscillations (faster and slower ones) have been discovered. Neuroscientists have already found out a lot about specific functions of these rhythms, but it is difficult to get a clear picture of oscillations as they seem to be distributed more or less randomly across the brain. </p>
<p>In our study, we looked for patterns in the occurrence of oscillations that would help us to get a more organised view of rhythmic brain activity. We recruited 22 volunteers to participate in the experiment. Their instruction was to rest for a few minutes, with open eyes, while their neural activity was recorded. </p>
<p>We used a magnetoencephalograph (MEG, the magnetic equivalent of EEG) to measure magnetic fields produced by neural activity. From the recording of the magnetic fields it is possible to infer where in the brain the activity came from. This spontaneous brain activity can then be analysed in terms of the rhythms that occur there. By observing these oscillations over several minutes, we found that each brain area has its own characteristic mix of different rhythms over time. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/128666/original/image-20160629-15292-16bm8a3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Unravelling the mysteries of the brain.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&search_tracking_id=g6N70IxCYQOJjyLd7KffZg&searchterm=brain%20anatomy&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=266669666">Jesada Sabai/Shutterstock.com</a></span>
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<p>In some regions, for example the visual cortex, there would only be two relatively slow rhythms (cycling at about ten times per second – the <a href="http://www.jneurosci.org/content/30/25/8692">alpha rhythm</a>. But in other regions, for example in the middle of the brain that is involved in things such as movement, learning and reward, there would be up to nine rhythms at many different time scales. These different oscillations could reflect how a particular region communicates with other regions in the brain. This means that regions with many different rhythms might have more complex tasks that involve communication with many other parts of the brain. </p>
<p>Although people can be quite different from each other in terms of their brain anatomy, we found that these rhythmic fingerprints were very similar across our healthy volunteers. In fact, they were so similar that we could take new data from other participants and label their brain areas based only on their oscillations, without knowing where the oscillations came from. </p>
<h2>Potential diagnostic tool</h2>
<p>Now that we know what pattern of oscillations to expect in each part of the brain in young, healthy adults, it should be possible to find differences in patients with illnesses that are expressed in these oscillations. As patients only have to rest and are not required to perform any tasks, using this as a tool would be possible even with severely impaired people. </p>
<p>Through the detailed analysis of oscillations in each brain part, it is possible to find small abnormalities that are only apparent in one particular rhythm in one brain region. One potential application of this could be to identify abnormal oscillations in a specific brain area in a patient and then use <a href="http://www.sciencedirect.com/science/article/pii/S0960982212007373">electric or magnetic brain stimulation</a> to modulate only these specific oscillations. </p>
<p>These kinds of noninvasive brain stimulation methods have already been proved successful in a few studies. For example, in patients with post-traumatic stress disorder, stimulating the frontal part of the brain with magnetic pulses has been shown to <a href="http://www.psychiatrist.com/JCP/article/Pages/2010/v71n08/v71n0805.aspx">reduce their symptoms</a>, improve mood and reduce anxiety. Knowing exactly how and where to stimulate brain oscillations in patients would be a big step towards improving these conditions.</p><img src="https://counter.theconversation.com/content/61723/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joachim Gross receives funding from Wellcome Trust, MRC and BBSRC. </span></em></p><p class="fine-print"><em><span>Anne Keitel does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>It may prove to be a useful diagnostic tool for brain disorders.Anne Keitel, University of GlasgowJoachim Gross, Professor in Psychology, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/589702016-05-06T11:33:57Z2016-05-06T11:33:57ZIn loud rooms our brains ‘hear’ in a different way – new findings<figure><img src="https://images.theconversation.com/files/121417/original/image-20160505-19851-1mpv95s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">'Receiving you loud and clear.'</span> <span class="attribution"><a class="source" href="http://www.shutterstock.com/s/party+conversation/search.html?page=2&thumb_size=mosaic&inline=244297636">wavebreakmedia</a></span></figcaption></figure><p>When we talk face-to-face, we exchange many more signals than just words. We communicate using our body posture, facial expressions and head and eye movements; but also through the rhythms that are produced when someone is speaking. A good example is the rate at which we produce syllables in continuous speech – about <a href="http://www.nature.com/neuro/journal/v15/n4/full/nn.3063.html">three to seven times a second</a>. In a conversation, a listener <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001752">tunes in</a> to this rhythm and uses it to predict the timing of the syllables that the speaker will use next. This makes it easier for them to follow what is being said. </p>
<p>Many other things are also going on. Using <a href="http://ilabs.washington.edu/what-magnetoencephalography-meg">brain-imaging techniques</a> we know for instance that even when no one is talking, the part of our brain responsible for hearing <a href="http://www.nature.com/neuro/journal/v15/n4/full/nn.3063.html">produces</a> rhythmic activity at a similar rate to the syllables in speech. When we listen to someone talking, these <a href="http://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001752">brain rhythms align</a> to the syllable structure. As a result, the brain rhythms match and track in frequency and time the incoming acoustic speech signal. </p>
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<a href="https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=428&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=428&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=428&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=538&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=538&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121539/original/image-20160506-32044-1p5ql1x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=538&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Hit that perfect beat.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&searchterm=brain%20waves&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=186644801">DesignPrax</a></span>
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<p>When someone speaks, we know their lip movements help the listener, too. Often these movements precede the speech – opening your mouth, for example – and provide important cues about what the person will say. Yet even on their own, lip movements contain enough information to allow trained observers to understand speech without hearing any words – hence some people can lip-read, of course. What has been unclear until now is how these movements are processed in the listener’s brain. </p>
<h2>Lip-synching</h2>
<p>This was the subject of our <a href="https://elifesciences.org/content/5/e14521v1/article-data">latest study</a>. We already <a href="http://journals.plos.org/ploscompbiol/article?id=10.1371/journal.pcbi.1000436">knew that</a> it is not just a speaker’s vocal chords that produce a syllable rhythm, but also their lip movements. We wanted to see whether listeners’ brain waves align to speakers’ lip movements during continuous speech in a comparable way to how they align to the acoustic speech itself – and whether this was important for understanding speech. </p>
<p>Our study has revealed for the first time that this is indeed the case. We recorded the brain activity of 44 healthy volunteers while they watched movies of someone telling a story. Just like the auditory part of the brain, we found that the visual part also produces rhythms. These align themselves to the syllable rhythm that is produced by the speaker’s lips during continuous speech. And when we made the listening conditions more difficult by adding distracting speech, which meant that the storyteller’s lip movements become more important to understand what they were saying, the alignment between the two rhythms became more precise. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=316&fit=crop&dpr=1 600w, https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=316&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=316&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=397&fit=crop&dpr=1 754w, https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=397&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/121540/original/image-20160506-32047-10ucrsc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=397&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Helpful lips.</span>
<span class="attribution"><a class="source" href="http://www.shutterstock.com/cat.mhtml?lang=en&language=en&ref_site=photo&search_source=search_form&version=llv1&anyorall=all&safesearch=1&use_local_boost=1&autocomplete_id=&search_tracking_id=rgyxGMJQKeUeABlIVzSAgw&searchterm=two%20people%20talking&show_color_wheel=1&orient=&commercial_ok=&media_type=images&search_cat=&searchtermx=&photographer_name=&people_gender=&people_age=&people_ethnicity=&people_number=&color=&page=1&inline=232893838">Rocketclips, Inc</a></span>
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<p>In addition, we found that the parts of the listener’s brain that control lip movements also produce brain waves that are aligned to the lip movements of the speaker. And when these waves are better aligned to the waves from the motor part of the speaker’s brain, the listener understands the speech better. This supports the <a href="http://www.cell.com/current-biology/abstract/S0960-9822(15)00500-X?_returnURL=http%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS096098221500500X%3Fshowall%3Dtrue">idea that</a> brain areas that are used for producing speech are also important for understanding speech, and could have implications for studying lip-reading between people with hearing difficulties. Having shown this in relation to a speaker and listener, the next step will be to look at whether the same thing happens with brain rhythms during a two-way conversation.</p>
<p>Why are these insights interesting? If it is correct that speech normally works by establishing a channel for communication through aligning brain rhythms to speech rhythms – similar to tuning a radio to a certain frequency to listen to a certain station – our results suggest that there are other complementary channels that can take over when necessary. Not only can we tune ourselves to the rhythms from someone’s vocal chords, we can tune into the equivalent rhythms from their lip movement. Instead of doing this with the auditory part of our brain, we do it through the parts associated with seeing and movement. </p>
<p>And neither do you need to be a trained lip-reader to benefit – this is why even in a noisy environment such as a pub or a party, most people can still communicate with each other.</p><img src="https://counter.theconversation.com/content/58970/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joachim Gross has received funding in the past from the Wellcome Trust, BBSRC, ESRC, MRC and Volkswagen Stiftung.</span></em></p><p class="fine-print"><em><span>Hyojin Park does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our heads are like radio receivers, and they can tune in to various different channels.Joachim Gross, Professor in Psychology, University of GlasgowHyojin Park, Research Associate, University of GlasgowLicensed as Creative Commons – attribution, no derivatives.