Scientists in Cambridge, England have found hidden signatures in the brains of people in a vegetative state that point to networks that could support consciousness — even when a patient appears to be unconscious and unresponsive. The study could help doctors identify patients who are aware despite being unable to communicate. Although unable to move and respond, some patients in a vegetative state are able to carry out tasks such as imagining playing a game of tennis, the scientists note. Using a functional magnetic resonance imaging (fMRI) scanner, researchers have previously been able to record activity in the pre-motor cortex, the part of the brain that deals with movement, in apparently unconscious patients asked to imagine playing tennis.
Now, a team of researchers led by scientists at the University of Cambridge and the MRC Cognition and Brain Sciences Unit, Cambridge, have used high-density electroencephalographs (EEG) and graph theory to study networks of activity in the brains of 32 patients diagnosed as vegetative and minimally conscious and compare them to healthy adults. The researchers showed that the connectome — the rich and diversely connected networks that support awareness in the healthy brain — are typically impaired in patients in a vegetative state. But they also found that some vegetative patients had well-preserved brain networks that look similar to those of healthy adults — these patients were those who had shown signs of hidden awareness by following commands such as imagining playing tennis.