Some of these systems allow for motor control which in turn permits to overcome the pitfalls of a possible motor paralysis that the patient might be experiencing. Importantly, brain-computer interfaces assume that the patient in question still understands language. Hence, the principle of these systems, like that of the neuroimaging exams mentioned above, is to measure brain activity while the patient is requested to perform a mental task. An example of such tasks would, for example, require the patient to concentrate on a visual or auditory stimulus. But, as we have already seen, patients may suffer from sensory deficiencies (blindness, deafness...), language problems (aphasia) or attention deficit disorders. Such diagnostic approach is therefore obsolete.

How can this difficulty be resolved? In an article which was published in Brain(3) in September 2015, researchers from the Coma Science Group and the Massachusetts Institute of Technology (MIT), in Boston, demonstrated that it was possible to solve the problem by using functional MRI “in the resting state”, that is to say in awake subjects who are not performing any tasks. However, even when the mind is at leisure to do nothing, wandering consciousness always spontaneously leads to thoughts and feelings. Therefore, in every individual, there is some default brain activity. In fact, the word “resting” is misleading when speaking about the brain because it is never completely inactive except where brain death has occurred. This intrinsic inactivity which is characteristic of a so-called “resting” brain is quantifiable by means of fMRI and has provided the basis for the development of a method for distinguishing patients in a minimally conscious state from those in a vegetative/non-responsive state.

What traffic is on the motorway?

Recordings by means of fMRI in resting subjects makes it possible to identify six networks. The first of these, which is made up of medial associative regions (the precuneus, the anterior and posterior cingulate cortex, the medial frontal and lateral cortices and the posterior temporal cortex), is linked to self-awareness which is understood as the fact of being focussed on one’s inner world – What am I going to do this evening? Will I manage to finish my work on time? “This is the realm of the little inner voice that speaks to us and is also the realm of mental imagery”, explains Steven Laureys. The second network which activates lateral frontoparietal regions, is focussed on knowledge of the external world which is built by our perceptions – It’s warm in this room. I’m getting a pain in my back... The third network: that of salience, including the insula. Its function is to identify, among others, certain emotionally marked stimuli which are seen to be important for the organism such as pain or anxiety.

(3) Demertzi, A., Antonopoulos, G., Heine, L., Voss, H. U., Crone, J. S., de Los Angeles, C., Bahri, M. A., Di Perri, C., Vanhaudenhuyse, A., Charland-Verville, V., Kronbichler, M., Trinka, E., Phillips, C., Gomez, F., Tshibanda, L., Soddu, A., Schiff, N. D., Whitfield-Gabrieli, S., & Laureys, S. (2015). Intrinsic functional connectivity differentiates minimally conscious from unresponsive patients. Brain: a journal of neurology, 138, 2619-2631.