Device helps monkeys move paralyzed wrists

By Julie Steenhuysen

CHICAGO (Reuters) - Monkeys regained the use of paralyzed wrist muscles with a computer-aided device that uses brain signals to direct movement, U.S. researchers said on Wednesday.

The finding may lead to treatments for people paralyzed with spinal cord or other injuries, they said.

"This was an initial demonstration that this type of technology is possible," said Chet Moritz of the University of Washington in Seattle, who reported his findings in the journal Nature.

The system essentially provides an artificial route for brain signals to reach paralyzed muscles, replacing a natural pathway that may have been disrupted by injury.

While other teams have developed complicated systems that look for brain signals that control movement in specific body parts, Moritz and colleagues wanted to see if the brain could teach itself to use the computerized system.

Researchers implanted monkeys with electrodes that monitor brain cells in the motor cortex, the area of the brain that controls movement. The electrodes sent signals to a computer, which was wired to muscles in the wrist.

The researchers injected drugs into arm muscles of monkeys to induce temporary paralysis, then asked them to play a familiar video game.

"The monkey's task was to play a very, very simple video game where he had to move his wrist back and forth ... in order to acquire targets that were presented on the screen," Moritz said. "The monkey could play this video game before he was paralyzed, so he understood the game."

"Once he was paralyzed, the only way to move his wrist was to change the activity of individual neurons in his brain, which would then subsequently control the stimulation of his muscles."

Only one neuron was needed to control the motion, and many different cells in the motor cortex could be trained to use the system, the researchers said.

"We found that monkeys can learn very rapidly to control newly isolated neurons in order to stimulate their muscles," Moritz said.

He said the system would be intended for use in individuals who are paralyzed from the neck down, but, he said, "We are several decades away from this being a clinical application."

(Editing by Will Dunham)