Welcome to On the brain, a new Conversation series by people whose job it is to know as much as there is to know about the body’s most complex organ. Here, Professor Geoffrey Donnan, a world-renowned stroke researcher and director of the Florey Neuroscience Institute, summarises major highlights in brain diagnoses and ponders the future of treatments for brain disease. Enjoy.
The past 30 years have seen the most remarkable advances in the study of the brain. And the past ten have seen more advances in our understanding than all the other years combined.
These range from the most fundamental changes within cells right through to how the brain interconnects and functions.
Enormous strides were made in brain research during the 19th century and consolidated during the latter half of the 20th century. But then, while our knowledge of brain disease plateaued, significant advances were being made in unravelling our understanding of disease processes in accessible organs such as the heart, liver, kidney and blood.
So much so that exciting new treatments were developed for diseases of these organs.
Meanwhile, progress in neuroscience research remained frustratingly slow as the brain remained in its lofty and boney chamber, isolated, often ravaged by disease and largely untreated.
Up until the mid-1970s, the only way to really access the brain was either during surgical operations or, less fortunately, at autopsy. There were some incredibly crude imaging techniques that offered limited and indirect insight into brain structure – and which were, frankly, dangerous.
The most invasive procedure involved injecting air into the ventricles of the brain via the lumbar spinal region. This took advantage of the continuity of the ventricles with the fluid spaces surrounding the spinal cord.
Interestingly, the technique was an extension of a serendipitous finding by clinicians during the First World War. They found that, when penetrating injuries to the brain allowed air entry to the ventricles, plain X-rays would clearly outline the ventricular contours in sharp relief.
In Melbourne, we had the world expert in research into the interpretation on these images, Dr E Graeme Robertson. This did not diminish the discomfort felt by most patients who were subjected to the procedure: most were left with quite a headache.
Fortunately, the imaging revolution was not far away. During a remarkable decade from the mid-1970s to the mid-1980s, X-ray computed tomography (CT) took us all to another level.
For the first time, neurologists could actually see brain pathologies such as intracerebral haemorrhage – when a blood vessel bursts within the brain – with startling clarity.
The technological advance of computing had allowed a stereotaxic computation of multiple X-ray images accrued by rotating gantry (see below) to be displayed as a simple image.
As if this was not enough, almost overnight, in the 1970s, along came another even more sophisticated technique: magnetic resonance imaging (MRI). Here, scientists had taken advantage of the differing response of atomic structures, particularly protons, to perturbations by radio frequency waves within a magnetic field.
In practice, this meant high-powered computing could generate maps of these protons. Even better, brain blood vessel flow and brain function could be studied.
At about the same time, another technique, Positron Emission Tomography (PET), a nuclear imaging technique, was developed which allowed the distribution of chemical reactions within the brain to be mapped. The sky seemed the limit.
Even the location of human emotions could be mapped to specific locations. If there was ever any doubt the brain ruled the body, this was being dispelled almost weekly as we learned how brain function interpreted the senses and drove motor function.
While these extraordinary advances were occurring in imaging the entire brain and its function, similar developments were occurring in imaging individual cells and their function.