Friday, February 5, 2010


A recent Washington Post article titled, 'Brain activity detected in ‘vegetative state,’ reported research by a University of Cambridge neuroscientist which showed evidence of consciousness-like brain activity in a few patients in a persistent vegetative state. (The study itself was published on line in the February 3rd New England Journal of Medicine). Persistent vegetative state is a condition of patients with severe brain damage who were in a coma, but then progressed to a state of wakefulness without detectable awareness. In other words their eyes may be open but they are otherwise unresponsive. PVS results from severe head trauma or prolonged periods no oxygen (for example, when the heart stops for minutes).

One of the Cambridge patients was able to correctly answer yes or no questions by activating different parts of his brain. The activation was measured by functional MRI. (f-MRI is a very sophisticated way of using MRI scans to show changes in brain activity that occur during a mental task – see a previous post.)

This study is important for several reasons. One being that it could theoretically be a way to communicate (albeit very slow and rudimentary) with some patients who cannot move a muscle, not even their eyes, on command.

But each apparent breakthrough has its downside. In this case the fear is that the Cambridge findings will be taken out of context and generalized to all long-term unresponsive patients, and that this, in turn, will reignite the bitter fights like the Terri Schiavo case (the Florida woman in a PVS whose family sparked a national debate over the right-to-die issue.)
It should be emphasized the Cambridge patients had PVS from traumatic brain injury instead of brain damage from lack of oxygen, (as was the case with Terry Schiavo). Although interesting, the changes seen in these patients do not prove consciousness as we know it. As stated in the NEJM editorial that accompanied the article, “The mind is an emergent property of the brain and can not be ‘seen’ in images.”

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