Completely paralysed and seemingly comatose patients may eventually be able to have real-time conversations using scanning machines that can translate their brain signals into messages, a team of neuroscientists has reported.
The researchers say the machines were able to translate the thoughts of six volunteers into letters, allowing them to spell answers to questions over a one-hour period.
The results of the tests are published online in the journal Current Biology.
The new technology builds on earlier uses of fMRI (functional magnetic resonance imaging) brain scans to assess consciousness in people described as being in a vegetative state and to enable them to answer yes and no questions. fMRI is generally used for clinical and research purposes to track brain activity by measuring blood flow.
While the volunteers performed 27 different mental tasks, each linked to an alphabetical letter or the space key, the fMRI device measured the blood flow in very precise parts of the brain corresponding to these tasks, and determined which character they had chosen.
“The work of Adrian Owen and colleagues led me to wonder whether it might even become possible to use fMRI, mental tasks, and appropriate experimental designs to freely encode thoughts, letter-by-letter, and therewith enable back-and-forth communication in the absence of motor behaviour,” said study leader, Bettina Sorger, of Maastricht University in The Netherlands.
The results substantially extend earlier uses of fMRI by enabling free-letter spelling, said Dr Sorger. “That could make all the difference for people who are completely paralysed and unable to benefit from other means of alternative communication.”
In each communication experiment, the volunteers held a mini-conversation consisting of two open questions and answers. All six participants were able to produce answers within a one-hour session.
Paul Dux, a Senior Lecturer in the School of Psychology at the University of Queensland, said the study was “a nice application of functional magnetic resonance imaging, and shows how this method can be used to interact with those patients who are non-responsive after suffering a severe brain injury.
"This field of research is still in its infancy, however this paper represents another example of how remaining brain function may be able to be assessed in such groups,” said Dr Dux, who was not part of the study. “What is needed now is for this specific spelling technique to be tested in patients, as this paper was a proof of concept with healthy participants.”
Dr Sorger said her team’s next goal is to transfer the fMRI technology it has developed to a more portable and affordable method for measuring blood flow, such as functional near-infrared spectroscopy (fNIRS).