A fascinating article on what doctors find when they perform brain scans on people who are supposedly in "vegetative" states:
One morning just over a year after his accident, Rios was taken to the Sloan Kettering Institute on Manhattan's East Side. There, in a dim room, a group of researchers placed a mask over his eyes, fixed headphones over his ears and guided his head into the bore of an M.R.I. machine. A 40-second loop of a recording made by Rios's sister Maria played through the headphones: she told him that she was there with him, that she loved him. As the sound entered his ears, the M.R.I. machine scanned his brain, mapping changes in activity.(Via Mark Shea.)
Several hours afterward, two researchers, Nicholas D. Schiff and Joy Hirsch, took a look at the images from the scan. They hadn't been sure what to expect -- Rios was among the first people in his condition to have his brain activity measured in this way -- but they certainly weren't expecting what they saw. ''We just stared at these images,'' recalls Schiff, an expert in consciousness disorders at Weill Medical College of Cornell University. ''There didn't seem to be anything missing.'' As the tape of his sister's voice played, several distinct clusters of neurons in Rios's brain had fired in a manner virtually identical to that of a healthy subject. Some clusters that became active were those known to help process spoken language, others to recall memories. Was Rios recognizing his sister's voice, remembering her? ''You couldn't tell the difference between these parts of his brain and the brain of one of my graduate students,'' says Hirsch, an expert in brain imaging at Columbia University. Even the visual centers of Rios's brain had come alive, despite the fact that his eyes were covered. It was as if his sister's words awakened his mind's eye.
To the medical world, Rios and the hundreds of thousands of other Americans who suffer from impaired consciousness present a mystery. Traditionally, there have essentially been only two ways to classify them: as comatose (eyes closed and responses limited to basic reflexes) or vegetative (eyes opening and closing in a cycle of sleeping and waking but without any sign of awareness). In either case, it has been assumed that they have no high-level thought. But Schiff, Hirsch and a small group of like-minded researchers are studying people like Rios and finding that the truth is far more complicated. Their evidence suggests that even after an injury that leaves a brain badly damaged, even after months or years with little sign of consciousness, people may still be capable of complex mental activity.