Aided by a tiny chip implanted in his brain, a 25-year-old quadriplegic played video games, controlled a television and operated a mechanical arm using only his thoughts, researchers said Wednesday.
The technology, reported in the journal Nature, is the latest step toward enabling people paralyzed by stroke, spinal cord injury or amyotrophic lateral sclerosis, or ALS, to control their wheelchairs or feed themselves simply by thinking about those actions.
Developed by Cyberkinetics Neurotechnology Systems Inc. in Foxborough, Mass., the implant transmits faint electrical signals from the brain to a computer equipped with software that translates thought to action.
Other researchers have achieved similar results using devices that capture brain waves through electrodes on the scalp.
But some scientists think implanted devices hold the greatest promise because they pick up signals directly from the region of the brain responsible for movement.
"This is an important demonstration of what can be done with an implanted system," said Dr. John Chapin, a researcher at the State University of New York in Brooklyn, who is working on other devices for the brain.
The latest experiment, conducted by a team from Brown University, Harvard University and the University of Chicago, used a chip with 96 electrodes capable of reading signals in the brain's motor cortex.
A wire the thickness of a strand of vermicelli carried the impulses from the brain to a half-inch-tall pedestal attached to the skull. From there, an external cable transmitted the signals to a computer.
The patient, Matthew Nagle, played the video game Pong and performed other tasks by imagining he was moving his arm. Researchers said that although Nagle's accuracy was as high as 90%, he couldn't react as quickly as able-bodied people.
Still, Nagle said he often defeated lab technicians who challenged him at Tetris. Nagle said he was able to master the device in four days.
"I didn't have to concentrate that hard," said Nagle, a former high school football star in Weymouth, Mass., whose spinal cord was severed after he was assaulted with a knife in 2001. He was left paralyzed from the neck down and lives at a rehabilitation center in Stoughton, Mass.
Three other people have tested the system, which its developers named BrainGate. Two of them have spinal cord injuries and the third has ALS, or Lou Gehrig's disease.
Researchers acknowledge the technology isn't ready for broad use. The equipment is bulky and requires help from an experienced technician. The company is working to overcome the hurdles, said John P. Donoghue of Brown, a Cyberkinetics co-founder and senior author of the study.
Nagle's equipment malfunctioned after seven months, slowing the transmission of brain signals. Donoghue said researchers suspected a short circuit was the cause.
After a year, Nagle had the implant removed so he could have a different device implanted to improve his respiration. He now uses voice recognition technology to write and send e-mail.
Nagle said he was glad he participated in the experiment.
"I am happy that I could use my situation to give people some hope," he said.