Inside the Vegetative Mind
As a report published in the journal NeuroImage explains, these patients’ thought patterns come through quite clearly on an fMRI scanner, and they’re able to respond to questions in ways that demonstrate that they understand what’s being asked:
To answer yes, [one patient] was told to think of playing tennis, a motor activity. To answer no, he was told to think of wandering from room to room in his home, visualising everything he would expect to see there, creating activity in the part of the brain governing spatial awareness.
Four out of 23 vegetative patients proved their responsiveness to a team led by Cambridge neuroscientists Dr. Adrian Owen and Dr. Steven Laureys, by correctly answering a series of “yes” or “no” questions about their families. Based on these results, the scientists speculate that as many as one fifth of vegetative patients may be able to communicate in this way.
The line between comatose and vegetative is often blurry. Patients in comas typically have no response to stimuli and no sleep/wake cycles, whereas vegetative patients return to partial arousal, exhibiting some normal brain activity – such as sleep and wakefulness – but no responsiveness to the external world.
For years, many scientists had assumed that all vegetative patients were unconscious – but this new data calls that assumption into question: at least some patients who seem vegetative on the outside may still have conscious awareness. Owen says that perhaps 40% of unresponsive patients are misdiagnosed as vegetative, when they may actually be conscious.
And consciousness is only the beginning – as Owen points out, thinking of things like tennis and one’s house requires the ability to use working memory and other high-level cognitive functions.
Laureys adds that this study is only the beginning – he and his colleagues hope to refine their system of communication soon:
It’s early days, but in the future we hope to develop this technique to allow some patients to express their feelings and thoughts, control their environment and increase their quality of life.
Another intriguing set of implications revolves around the idea of synaptic plasticity. If these patients are taught to communicate more effectively, and given real-time feedback from the external world, it’s possible that they could become more responsive overall. This is still speculation – but studies on Alzheimer’s sufferers have yielded encouraging results in this direction.
Since doctors often deny any hope of recovery for most vegetative patients, it’s exciting to think that they may finally get a chance to speak their minds.