British and Belgian researchers used a brain scanner called functional magnetic resonance imaging to show the man, who suffered a severe traumatic brain injury in a road accident in 2003, was able to think "yes" or "no" answers to questions by wilfully changing his brain activity.
Experts say the result means all patients in coma-like states should be reassessed and it may change the way they are cared for in future.
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http://www.reuters.com/article/idUSTRE61261J20100203 --------
I would love to know the highest complexity of the questions they were able to ask. What if they had asked him if he wanted to be taken off life support and he thought 'yes'?