The inner voice of people who appear unconscious can now be heard. For the first time, researchers have struck up a conversation with a man diagnosed as being in a vegetative (植物的) state. All they had to do was monitor how his brain responded to specific questions. "They can now have some involvement in their destiny," says Adrian Owen of the University of Cambridge, who led the team doing the work. In an earlier experiment, Owen's team asked a woman previously diagnosed as being in a vegetative state to picture herself carrying out one of two different activities. The resulting brain activity suggested she understood the commands and was therefore conscious. Now Owen's team has taken the idea a step further. A man also diagnosed with VS was able to answer yes and no to specific questions by imagining himself engaging in the same activities. The results suggest that it is possible to give a degree of choice to some people who have no other way of communicating with the outside world. "We are not just showing they are conscious, we are giving them a voice and a way to communicate," says neurologist (神经病学家) Steven Laureys of the University of Liege in Belgium, Owen's partner. Doctors traditionally base these diagnoses on how someone behaves: for example, whether 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 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.