A brain-computer interface to diagnose levels of consciousness

Publié le 14 Feb, 2017

European scientists have investigated whether patients who have lost all powers of communication are still fully conscious and still want to live[1].


They found the answer by using a brain-computer interface to communicate with 4 patients who were “locked in” and had lost the ability to make any voluntary movements because of their condition – amyotrophic lateral sclerosis.


When asked “if they loved life” , three of them answered “yes”. They also answered positively to the question, “are you happy?” The fourth patient, a young woman of 23, did not respond openly to the question – her parents feared that her emotional state was too fragile.


Devised by neuroscientist Niels Birbaumer at the Wyss Centre for Bio and Neuroengineering in Geneva, the brain-computer interface is placed on the person’s head and measures oxygen levels in the blood and electrical activity in the brain. “The braincomputer interface technique described in this study uses near infra-red spectroscopy together with an EEG”. To check the efficacy of the method, the Niels Birbaumer team asked patients to answer simple questions over a period of 10 days. The answers showed that they were 70% reliable – a result which is substantially greater than chance. For Niels Birbaumer, “these impressive results challenge my own theory according to which people with locked-in syndrome are incapable of communicating. We found that all four subjects tested were capable of answering the personal questions we asked them using only their thoughts. If we manage to reproduce this study with a bigger patient cohort, I think we could restore useful communication in cases of locked-in syndrome in patients suffering from motor neurone diseases.”


In 2010, neuroscientist Adrian Owen was the first person to demonstrate that changes in blood flow in certain areas of the brain showed that patients initially assessed as being in a vegetative state, were actually conscious.


Some patients might have been misdiagnosed and “classified” all too quickly as being in a vegetative state because of their lack of eye movement. According to Niels Birbaumer and his team, the system could be used in diagnosis and would help to establish who is really conscious and who is awake. The scientist also hopes to develop a technology to allow patients with locked-in syndrome to select letters to communicate beyond simple yes and no responses.


[1] Plos Biology : Brain–Computer Interface–Based Communication in the Locked-In State.

MIT Technology Review (31/01/2017) – Jean-Yves Nau (01/02/2017)

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