"NewScientist" 6 February 2010
A voice for the voiceless
It is now possible to "talk" to people who seem to be unconscious, by tapping into their brain activity.
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 stae. All they had to do was monitor how his brain responded to specific questions. This means that it may now be possible to give some individuals in the same state a degree of autonomy.
"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, published in 2006, Owen's team asked a woman previously diagnosed as being in a vegetative state (VS) 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 Steven Laureys of the University of Liege in Belgium, Owen's collaborator.
When someone is in a VS, they can breathe unaided, have intact reflexes but seem completely unaware. But it is becoming clear that some people who appear to be vegetative are in fact minimally conscious. They are in a kind of twilight state in which they may feel some pain, experience emotion and communicate to a limited extent. These two states can be distinguished from each other via bedside behavioural tests - but these tests are not perfect and can miss patients who are aware but unable to move. So researchers are looking for ways to detect consciousness with brain imaging.
In their original experiment, Owen and his colleagues used functional MRI to detect wheteher a woman could respond to two spoken commands, which were expected to activate different brain areas. On behavioural tests alone her diagnosis was VS but the brain scan result were astounding. When asked to imagine playing tennis, the woman's supplementary motor area (SMA), which is concerned with complex sequences of movements, lit up. When asked to imagine moving around her house, it was the turn of the parahippocampal gyrus, which represents spatial locations.
Because the correct brain areas lit up at the correct time, the team concluded that the woman was modulating her brain activity to cooperate with the experiment and must have had a degree of consciousness.
In the intervening years, Owen, Laureys and their team repeated the experiment on 23 people in Belgium and the UK diagnosed as being in a VS. Four responded positively and were deemed to possess a degree of consciousness.
To find out whether a simple conversation was possible, the researchers selected on eof the four - a 29-year-old man who had been in a car crash. They asked him to imagine playing tennis if he wanted to answer yes to questions such as: Do you have any sisters? Is you father's name Thomas? Is your father's name Alexander? And if the answer to a question was no, he had to imagine moving round his home.
The man was asked to think of the activity that represented his answer, in 10-second bursts for up to 5 minutes, so that a strong enough signal could be detected by the scanner. His family came up with the questions to ensure that the researchers did not know the answers in advance. What's more, the brain scans were analysed by a team that had never come into contact with the patient or his family.
The team found that either the SMA or the parahippocampal gyrus lit up in response to five of the six questions (see diagram). When the team ran these answers by his family, they were all correct, indicating that the man had understood the task and was able to form an answer. The group also asked healthy volunteers similar questions relating to their own families and found that their brains responded in the same way.
"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 pratice."
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. Ïn purely practical terms, yes, it is possible," says Owen. "But it is a bigger step than one might immediately think."
One problem is that while the brain scans do seem to establish consciousness, there is a lot they don't tell us. "Just because they can answer a yes/no question does not mean they have the capacity to make complex decisions," Owen says.
Even assuming there is a subset of people who cannot move but have enough cognition to answer tough questions, you would still have to convince a court that this is so. "There are many ethical and legal frameworks that would need to be revised before fMRI could be used in this context," says Owen.
There are many challenges. For example, someone in this state can only to respond to specific questions; they can't yet start a conversation of their own. There is also the prospect of developing smaller devices to make conversation more frequent, since MRI scans are expensive and take many hours to analyse.
In the meantime, you can ask someone whether they are in pain or would like to try new drugs that are being tested for their ability to bring patients out of a vegetative state. "For the minority of patients that this will work for, just for them to exercise some autonomy is a massive step forward - it doesn't have to be at the life or death level," Owen says.
