Researchers have used brain scans to communicate with individuals in total vegetative states. Scientists at the University of Cambridge asked "yes" or "no" questions of the patients which they answered by imaging one of two different activities: playing tennis, or just moving around their house. Depending on what they were thinking, different regions of their brains lit up. From New Scientist:
"I think we can be pretty confident that he is entirely conscious," says Owen. "He has to understand instructions, comprehend speech, remember what tennis is and how you do it. So many of his cognitive faculties have to have been intact."
That someone can be capable of all this while appearing completely unaware confounds existing medical definitions of consciousness, Laureys says. "We don't know what to call this; he just doesn't fit a definition."
Doctors traditionally base these diagnoses on how someone behaves: if for example, whether or not they can glance in different directions in response to questions. The new results show that you don't need behavioural indications to identify awareness and even a degree of cognitive proficiency. All you need to do is tap into brain activity directly.
The work "changes everything", says Nicholas Schiff, a neurologist at Weill Cornell Medical College in New York, who is carrying out similar work on patients with consciousness disorders. "Knowing that someone could persist in a state like this and not show evidence of the fact that they can answer yes/no questions should be extremely disturbing to our clinical practice."
One of the most difficult questions you might want to ask someone is whether they want to carry on living. But as Owen and Laureys point out, the scientific, legal and ethical challenges for doctors asking such questions are formidable. "In purely practical terms, yes, it is possible," says Owen. "But it is a bigger step than one might immediately think."