I'd like to thank you... with all my heart because you enabled me to become an ABC sharpshooter," wrote Hans-Peter Balzmann, 45, in German. "This deserves a celebration to which I would like to invite you... Hopefully there will be an opportunity soon."
It wasn't the most flowery letter that Niels Birbaumer, a neurobiologist at Germany's University of Tubingen, had ever received, and far from the most verbose. But there was a reason Balzmann kept his prose spare. The former lawyer suffers from such severe amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease) that for the last four years he has relied on a respirator and a feeding tube. Worst of all, locked within his paralyzed body is a perfectly sentient mind, like a caged bird that knew freedom once and never will again. Or so it seemed. Now Balzmann and six other Tubingen patients are learning to communicate through sheer brainpower, the scientists report this week in the journal Nature. Using the aptly named "thought translation device," patients amplify and dampen their brain waves in a way that allows them to select letters on a video screen and spell out messages. "For the first time," says Birbaumer, "we have shown that it is possible to communicate with nothing but one's own brain" (and, to be fair, a pile of electronics), "and to escape, at least verbally, the locked-in state."
It has long been a dream of brain researchers to harness the power of mind to move matter. Although bending spoons is just a parlor trick, thoughts, intentions and memories are not mere will-o'-the-wisps, ephemera with no physicality. They are, instead, electrical signals. As such, they are easily picked up by an electroencephalograph (EEG). In just the last few months, neuroscientists have racked up a string of successes translating brain waves into action. Last March a patient paralyzed from the neck down by a stroke had two electrodes implanted in his brain's motor cortex, the region that controls muscle movement. Developed by Dr. Philip Kennedy of Emory University, the electrode receives electrical signals generated whenever the man thinks about moving his hand, tongue or eye. Sensors on his scalp pick up the signals, amplify them and shoot them over to a computer, which translates them into movements of a cursor on a nearby computer screen. The man can now spell, or hit icons for "I'm cold." At Caltech, researchers led by Richard Andersen and Krishna Shenoy will soon implant an electrode in the part of a monkey's brain called the parietal lobes. That's where intentions arise. If all goes well, the electrode will pick up the monkey's determination to move a limb displayed on a video screen. Andersen hopes to implant an electrode in a human, probably next year. "Our hope," he says, "is to let patients interact with the world just by thinking."
The Tubingen team's triumph was to do that without electrode-implanting brain surgery. Instead, they place one electrode behind the patient's ear and one on the scalp. The electrodes detect brain waves. Wires carry the electrical signals to an EEG, which plucks out a single type of wave from a sea of noise as a mother picks out her child's voice from the playground cacophony. The wave is called a slow cortical potential. It takes hundreds of hours of practice, but after painstaking training patients learn to modulate this wave: when they hear an audio tone, they concentrate on changing the strength of this brain wave through a technique that neuroscientist Edward Taub of the University of Alabama at Birmingham calls passive attention. Although he can't describe precisely how the patients do it, "somehow they learn to put their [brain waves] under voluntary control." Once they do, they're ready to spell, by choosing letters from those displayed on a video screen (graphic).
Birbaumer is trying to speed up the system, now about two characters per minute. But the scientists have dreams beyond the ABCs. "If someone can learn to control the amplitude [of his brain wave]," says Taub, "that response can operate any aspect of the environment a programmer can hook up." In other words, the electronics can be wired so that the brain wave controls light switches, or window blinds, or a wheelchair. Even more visionary is the possibility of going wireless. If the electronics are sensitive enough, they might be able to grab brain waves out of the air. And then thinking really will make it so.