For a person with advanced Lou Gehrig's disease, communicating can be an enormous challenge. Patients with this progressive neuromuscular disorder, also known as amyotrophic lateral sclerosis (ALS), can think just fine, but they gradually lose their ability to move, speak, and breathe. Now, a noninvasive device that detects brain waves is helping these patients interact with the world.

The device consists of a cap wired with electrodes to record the electrical signals coming from the brain. The cap is connected to an amplifier, which is in turn connected to a computer that processes the electrical signals. The setup allows a patient to "click" on choices presented on a computer screen just by thinking about them.

The screen displays a matrix of icons representing, for example, the surrounding environment, personal comfort, or word processing. The rows of the matrix are highlighted in a random order; when the row containing the desired item is highlighted, the user's brain emits a characteristic brain wave pattern, which the computer can recognize.

The user can scroll through different menus this way, selecting, say, "environment," then "room temperature," then "warmer." Patients use a similar matrix of letters and numbers to compose e-mails. Scientists say the device could be useful for patients with extensive loss of muscle control, such as those with ALS, spinal-cord injuries, strokes, or cerebral palsy.

The EEG-based system, which uses electroencephalograms to record brain activity, has had significant success in laboratory tests. But now Jonathan Wolpaw and colleagues at the Wadsworth Center, part of the New York State Department of Health, say they are intent on bringing the technology to patients in their homes. They have developed a simplified version of the device and are starting a small-scale, in-home trial with severely disabled patients, such as those with advanced ALS.

"Something like this could make a huge difference in quality of life for someone with ALS and their families," says Jennifer Brand, director of patient services at the ALS Association, a California-based patient advocacy group.

Patients with severe neuromuscular diseases or spinal-cord injuries can sometimes communicate using systems that detect small muscle movements, such as an eyebrow twitch or eye movement. But gradually, some people lose the ability to control even the smallest muscle. "Right now, the options for locked-in patients are extremely limited," says Joseph J. Pancrazio, a program director at the National Institute of Neurological Disorder and Stroke who oversees neuroprosthetics research. "There are eye-blink kinds of interfaces, but I think we're going to find out that the BCI [brain-computer interface] approaches are easier and faster to use."