Writing Without Moving a Muscle

Most victims of paralysis retain, at the very least, the ability to communicate. Even with limbs, tongue, lips and vocal cords immobilized, patients can blink their eyes to answer yes or no. But for a few patients--such as those with advanced cases of amyotrophic lateral sclerosis (ALS), or Lou Gehrig's disease, in which the voluntary nervous system is utterly destroyed--even that minimal dialogue is impossible. These people are at the mercy of others in the deepest imaginable way.

That's what makes a report in the current Nature so promising. U.S. and European scientists have shown that patients can learn, by trial and error, to control a type of brain waves called slow cortical potentials. By hooking the patients up to a computer via an electroencephalogram, the researchers taught two ALS sufferers to mentally signal the computer to pick out letters on a screen, spelling out messages. The process is agonizingly slow--the average pace is about two characters a minute--but it should eventually improve. And compared with utter silence, it must seem blistering.