PATIENTS in a vegetative state are, by definition, unable to respond to stimulation with any form of overt behaviour. Recently, however, a group of British and Belgian researchers have shown that some of them respond to simple commands by altering their brain activity while in an MRI scanner. At the annual meeting of the Organisation for Human Brain Mapping in Barcelona on June 7th, the British half of the group described how it has taken an important step towards helping such patients communicate.

Over the past four years, teams led by Adrian Owen at the Medical Research Council's Cognition and Brain Sciences Unit in Cambridge, and Steven Laureys of the Coma Science Group at the University of Liège, have scanned 23 vegetative patients between them. Four were able to respond to yes-no questions correctly and consistently by following instructions to imagine playing tennis when they wanted to give one response, or walking round the house when they wanted to give the other.

Those studies have led Dr Owen to conclude that a significant minority of vegetative patients may be more aware than they seem. Since they are responsive, they are not even technically vegetative, though current diagnostic techniques—which require that they respond physically to instructions, for example by blinking—are not sensitive enough to detect that.

If they are responsive, they are capable of communicating. So the problem is how to facilitate this, given that it is not practical to put them in a scanner every time someone wants to ask them a question. Damian Cruse of the Cambridge group thinks he may have found a solution in electroencephalography (EEG), a cheaper and more portable way of measuring brain activity via electrodes pasted to the patient's scalp.

Dr Cruse and his colleagues first asked six healthy volunteers to imagine either squeezing their right hand or wiggling the toes of both feet when they were presented with an audible tone. They found that their volunteers' brains' responses to the two commands were clearly different. The imagined hand-squeezing produced a response on the left-hand side of the brain, while the toe-wiggling produced one over the centre of the head.

They then applied the same procedure to a patient with “locked-in” syndrome—conscious but almost entirely paralysed—who retains some control of his eye movements. His brain responses were the same as those in the healthy controls. Finally, they gave the instructions to a patient who had been diagnosed as being vegetative two years earlier. They found that, from the EEG signals alone, they could deduce which movement this patient had been instructed to imagine with 100% accuracy.

This result, though preliminary, suggests it might be possible to establish some sort of dialogue with people who had previously been considered all but brain-dead. That would be extraordinary. Given that solitary confinement is one of the harshest punishments known, and that such people are condemned to the worst sort of solitary imaginable, it would also be wonderful.