The three patients who could respond via EEG did not share any obvious features; they varied in age, in time since the original injury, and in the type of injury suffered. Owen’s team is now using high-resolution functional MRI machines to study these patients’ brains in fine detail in hopes of finding some commonality. “Anything we can do to improve our understanding or to learn more about catastrophic brain injuries can help us understand what’s going on,” says Owen.
They hope to eventually use the EEG setup to ask patients questions, which had been possible with functional MRI. At the moment, researchers can’t read the EEG response in real time, making interaction very difficult. “Our priority now is trying to speed it up; then we’ll move on to communication,” he says.
What exactly the new findings indicate about the patients’ level of consciousness is still controversial. “I think they were entirely aware and conscious of what’s going on,” says Owen. “For them to do this, they have to have understood the instructions we gave them, to have sustained attention, to keep on task, and to respond. These are all things we associated with consciousness.”
Morten Storm Overgaard, head of the Cognitive Neuroscience Research Unit at Aalborg University in Denmark, disagrees. “I think their study is very interesting, but it’s hard to argue that there is a link between command-following and consciousness. And there’s no independent way of making sure,” says Overgaard, who wrote a commentary accompanying the paper. Overgaard does agree, however, that someone who can reliably answer questions via brain activity is likely conscious.
Both Overgaard and Owen say a new classification system is required to accurately reflect the state these patients are in. “While they do meet all the clinical criteria for the vegetative state, we know they are not actually vegetative,” says Owen. One suggestion that has yet to catch on is “behavioral unresponsiveness syndrome.”