Neuroscientists at Britain's Cambridge University say functional magnetic resonance imaging or fMRI brain scans appear to show that a woman in a vegetative state seemed to play tennis in her head despite the fact that she had been unconscious for five months after a motor vehicle accident.
The case has emphasised how frustrating it can be to try to establish what is going on in the brain of someone who is immobile and outwardly unresponsive.
The British and Belgian researchers say the fMRI brain scans showed the 23-year-old woman showed evidence of awareness of herself and her environment in response to verbal commands.
She appeared to respond to commands to imagine playing a game of tennis and walking through her home.
The scans were compared with others taken when the patient was presented with acoustically-matched noise sequences.
The woman had been unresponsive since emerging from a coma after a traffic accident and met all the criteria for a persistent vegetative state.
When she was presented with spoken sentences she had increased activity in speech comprehension centers in the brain, which were as seen on the scans.
Adrian M. Owen, Ph.D., and colleagues at Cambridge University and the University of Liege, Belgium, say their study showed the woman was conscious, although she had lain still and silent for five months after the accident.
Her decision to cooperate with the authors by imagining particular tasks when asked to do so, they say represents a clear act of intention, which 'confirmed beyond any doubt that she was consciously aware of herself and her surroundings'.
Experts however are in complete agreement that the case does not mean that many people in apparently vegetative states may in fact be conscious and Owen himself says it is more likely that the woman may in fact have been on the road to recovery and moving to a less severe state known as a minimally unconscious state.
People have been known to survive in such states for years; American Terry Wallace recovered from minimal consciousness in 2003, 19 years after a car accident and experts believe such scans may offer a way to predict which patients are most likely to recover.
Dr. Nicholas Schiff, a neuroscientist at Weill Cornell Medical College in New York, who has been using fMRI in patients in a similar state says he has never seen anything like this, but says there are patients that they will try this on.
Schiff has one of the two labs in the world which perform such tests the other is run by Dr. Steven Laureys at the University of Liege, who worked with Owen to assess the British patient.
Apparently the work is difficult as patients in such states can move, making MRI scans blurred and useless, and it can be difficult to determine when they are asleep and thus unlikely to respond to anything.
Experts say the study shows it is possible to make a mistake in diagnosing a patient as unconscious but it is unclear how often such a discrepancy between the physical exam findings and fMRI findings would be seen, but the case is important because it illustrates the limitations of the physical exam to assess awareness.