Scientists studying people in minimally conscious states have published the results of brain scans showing that these people can retain a surprising amount of brain activity. The New York Times and MSNBC, among others, have written up accounts.

I profiled these scientists for a 2003 article in the New York Times Magazine, when they were at an earlier stage in their research. Things certainly have changed since then. When my article came out, hardly anyone had heard of Terri Schiavo, the Florida woman in a permanent vegetative state who is at the center of a battle between her parents, who want to keep her feeding tube in, and her husband, who wants it taken out. Since then, her case has made national headlines, and a law has been passed in her name. I for one will be keeping close attention to how this new paper is received (and used) in the debate over Terri Schiavo, because I had the displeasure of watching my article get pulled into the debate and distorted for political ends.

The key point to bear in mind about this new research is that there's a difference between people in a permanent vegetative state and people in a minimally conscious state. Neurologists have developed bedside tests to determine which state a given patient is in. People in minimally conscious states show fleeting, but authentic, awareness of their surroundings, for example. People in vegetative states do not. Neurologists cannot make this diagnosis from the reports of family members, because it is easy to see awareness in a loved one when there is, in fact, none. That doesn't mean that family members are necessarily wrong if they say a loved one is aware. It's just that a doctor needs to test a patient objectively, using methods that don't rely on his or her own interpretation.

Some people have argued that this test is circular: people are simply defined minimally conscious if they pass a test for minimal consciousness. But the designers of the test have shown that it does have predictive power. For one thing, people who rise to a minimally conscious state have a small but real chance of recovering consciousness (although they may never return to their former selves). People who stay in a permanent vegetative state for many years, by contrast, almost never recover.

The brain scan findings now being reported also strengthen the notion of a minimally conscious state. The researchers scanned the brains of patients diagnosed as minimally conscious, playing the voice of loved ones through headphones, scratching their skin, and doing other tests to check for the function of their brain. They found that the patients responded in important ways. Some patients responded to the recordings with strong activity in regions of the brain involved in language and memory, for example. But in the absence of stimuli, the brains of the patients used less energy than a person would under anesthesia.

On the other hand, earlier scans of people diagnosed as being in a permanently vegetative state showed at most only isolated islands of activity in the cortex, where higher brain functions take place. So the difference detected by bedside tests is mirrored by a difference detected in the brain scanner.

It's crucial neither to overplay or underplay the importance of this work. People who are coping with the staggering burden of a loved one in a truly permanent vegetative state should not see this as evidence that their loved one is conscious and simply "locked in" to an unresponsive body. Nor should pundits raise false hopes by claiming that this is the case.

But it is also true that people with impaired consciousness are not getting the attention they deserve, starting with a good diagnosis. Thirty percent of people in a permanent vegetative state may actually be minimally conscious. It would be fantastic if some day doctors could make a precise diagnosis of brain-damaged patients simply by running them through some tests in a scanner. For now, though, only a handful of people with impaired consciousness in the entire world have been scanned at all. Eventually, it might be possible to use the knowledge gained from these tests to start finding ways to help people recover more of their consciousness, perhaps through brain stimulation. Today there's nothing a doctor can do but wait and watch.

Unfortunately, people with impaired consciousness are more likely to be simply warehoused, getting hardly any attention from a neurologist. Are we, as a society, ready to give these voiceless people the care they deserve?