By Nick Fontaine
I’ve always found comas and vegetative states very interesting. They are a prime example of our body’s extreme reactions to extreme circumstances. Not only are they interesting from a biological standpoint, but also an ethical and philosophical one. These diseases of consciousness raise the question of what it really means to be a human, as much of our identity is predicated on consciousness and behavioral response to stimuli. For the longest time, these states of consciousness were not understood at all, and frankly we still do not have a complete understanding of them. But, we are getting closer with the advancements in neuroimaging, largely brought about by functional magnetic resonance imaging (fMRI).
A major advancement in the understanding of what it means to be in one of these states comes from research by Adrian Owens and colleagues from 2006. This groundbreaking study showed that a patient in a vegetative state was able to activate brain regions associated with physical activity (such a playing tennis) and spatial navigation (like walking through your house) while in an fMRI scanner when asked to do so by experimenters. This showed that people who have been diagnosed as being in a vegetative state are able to mentally respond to outside stimuli and are capable of fairly complex mental functions.
This finding could be combined with that from a study done by Bettina Sorger and colleagues in 2012 which used the relatively new technique of real time fMRI. In this study, the researchers were able to create a means of silent communication by having the participant think in certain ways for certain lengths of time. In this very creative design, participants were told to think of motor imagery (such a playing their favorite sport), doing mental math, or having a silent mental conversation with themselves after a delay of 0 seconds, 10 seconds, or 20 seconds. They then either thought of each task for either 10, 20, or 30 seconds. Each of these activities shows activation matching its duration in a different brain region during fMRI. This created a 3x9 grid which was mapped to include every letter of the alphabet and one space to separate words (See figure 1). Seeing as it was shown by Owens that comatose patients are able to carry out these mental exercises when instructed to do so, it is possible that this method may help lend a voice to people who have had theirs taken.
While the debate of what constitutes human consciousness still rages on, we are now perhaps closer to having an answer to if people with diseases of consciousness (such as being in a vegetative state) can really be seen as “conscious”. The findings of the research stated above and the advancement of fMRI as a brain computer interface show the incredible promise of neuroimaging for answering these age old questions, as well as improving the life of some of the medical world’s most ill-understood patients.
References:
Owen, A. M., et al. “Detecting Awareness in the Vegetative State.” Science, vol. 313, no. 5792, 2006, pp. 1402–1402., doi:10.1126/science.1130197.
Sorger, B., Reithler, J., Dahmen, B., & Goebel, R. (2012). A Real-Time fMRI-Based Spelling Device Immediately Enabling Robust Motor-Independent Communication. Current Biology,22(14), 1333-1338. doi:10.1016/j.cub.2012.05.022
I would also like to thank Dr. Hugh Garavan for introducing me to both of these fascinating studies.