A paralyzed man with an implant in his brain was able to operate a television, play a simple video game and flex a robotic hand using only his thoughts, researchers reported in July. They say such devices hold long-term promise for restoring function to paralyzed individuals. But a review of other neural prosthetics indicates that for now, less invasive techniques may provide the same abilities at less risk.

Two years ago a surgeon inserted a 16-square-millimeter, pincushionlike array of electrodes (right) into the motor cortex of 26-year-old Matthew Nagle, whose spinal cord had been severed by a knife wound to the neck. The implant protrudes from the skull and links via a cable to a computer. While connected, Nagle crudely directed an on-screen cursor as he envisioned it moving in various directions. He functioned with the implant for nearly a year. A second recipient had much less consistent control, but two others have shown results similar to Nagle’s, according to neuroscientist John Donoghue of Brown University, who led the experiments and is chief scientist for the marketer for the system, Cyberkinetics Neurotechnology Systems in Foxborough, Mass.

The system could complement existing technology that allows paralyzed people to control a computer through EEG (brain-wave) electrodes on the scalp, Donoghue says, but other investigators do not see the point. “What was achieved could have been done with something off the shelf,” says neurobiologist Miguel Nicolelis of Duke University, who is experimenting with fully implantable electrodes, which would presumably carry less risk of infection than a device that extends from the skull. And “if you can get the same function without putting something into the brain, you’d prefer to do that,” adds neurologist Jonathan Wolpaw of the Wadsworth Center in Albany, N.Y., which is testing a home EEG system. Implanted electrodes, he says, are years away from practical use.