Brain Training for Spinal Cord Injury
Bypassing the Injury May Put Brain Back in Charge of Paralyzed Muscles, Study Shows
Oct. 15, 2008 -- Scientists at the University of Washington in Seattle report success in their first attempts to harness the brain to treat paralysis in people with spinal cord injuries.
Their technique isn't ready for patients yet, but researcher Chet Moritz, PhD, says it may one day be used to help paralyzed people walk.
"We haven't studied that directly, so it's all speculation on my part, but certainly it's possible in the next 10-20 years," Moritz said at a news conference.
The basic idea is to bypass the spinal cord injury and create a direct route from the brain to the muscles. It's a concept that hinges on the brain's ability to adapt, with brain cells stepping up to handle tasks that they're not used to doing.
Here's a look at the findings, published in today's advance online edition of Nature.
Moritz and colleagues tested their treatment on monkeys. First, the monkeys learned to play a simple video game which involved flexing and extending the wrist muscles. A little applesauce was all the reward the monkeys needed to master the game.
Then, the researchers temporarily paralyzed the monkeys' wrist muscles with a nerve-blocking drug. The scientists also implanted electrodes in the monkeys' brains to record the activity of certain brain cells.
Those electrodes were hooked up to wires running to a computer and then into the monkeys' wrist muscles -- basically, a direct connection wiring brain cells to the wrist muscles, bypassing the temporary nerve blockage.
With that gear in place and their wrist nerves blocked, the monkeys kept trying to play the video game, still motivated by applesauce. And they managed to do it.
"We found that, remarkably, nearly every neuron that we tested in the brain could be used to control this type of stimulation. We also found that monkeys could learn very rapidly to control newly isolated neurons in order to stimulate their muscles," even with brain cells that don't usually govern the movement of wrist muscles, Moritz says.
The study is "very exciting," says Edelle Field-Fote, who directs the Neuromotor Rehabilitation Research Laboratory at the University of Miami Miller School of Medicine's Miami Project to Cure Paralysis.
Other studies have used a similar approach to control robotic devices, but not the muscles themselves, notes Field-Fote. Still, she sees challenges ahead.
One of those challenges is working the muscles just enough to get the task done -- for instance, picking up a can without crushing it. "Just controlling the muscles isn't enough to give us fine control of muscles to be able to manipulate objects in space," says Field-Fote. She says walking may actually be easier in that regard, because it relies on large muscles more than small muscles moving in several directions.