A new study offers a potential way to identify comatose patients who might be "covertly aware." University of Cambridge researchers studied the brain waves of 32 coma patients—including "minimally conscious" patients who could, say, squeeze a finger on command; "vegetative" patients who were unmoving; and 26 healthy people. The brain waves were measured with electroencephalography, and as expected, the healthy subjects' brains exhibited "rich and diversely connected networks." Brain networks are characteristically impaired in comatose patients, but as the researchers write in PLOS Computational Biology, they also found that "some vegetative patients who show signs of hidden awareness have remarkably well-preserved networks similar to healthy adults."
As LiveScience explains, when asked to imagine playing tennis, some patients who couldn't otherwise move on command did show activity in the part of the brain tied to movement in a way that was similar to how a healthy person's brain would respond. The researchers describe the portion who did so as a "significant minority." "If a patient's 'awareness' networks are intact, then we know that they are likely to be aware of what is going on around them," one of the study authors tells Cambridge News. The researchers note that more work is needed before a viable diagnostic tool can be created. (A man in a vegetative state recently reacted to a Hitchcock movie.)