Brain Training for Spinal Cord Injury
Bypassing the Injury May Put Brain Back in Charge of Paralyzed Muscles, Study Shows
Second Opinion continued...
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.
Another hurdle is that switching muscles on externally activates the biggest muscles first, and those muscles tire out faster than smaller muscles. That's one of the reasons why electrical stimulation of muscles hasn't been widely used in people with spinal cord injury, says Field-Fote.
One way to overcome that might be to stimulate the spinal cord below the patient's spinal cord injury, says Field-Fote. That way, the spinal cord transmits the signal to the muscles, and because the muscles aren't being stimulated externally, they turn on in the right order, from smallest to largest.
That's one of the tasks Moritz and colleagues have already set for themselves. "That's good," says Field-Fote. "It sounds like they're barking up the right tree."
Other challenges include developing a system that can safely be implanted under the skin, improving electrodes' ability to record brain cell activity for longer periods of time, and creating a system where enough brain cells are harnessed so that if one bows out, the patient can still move. And developing a wireless system could cut infection risk, notes University of Washington professor Eberhard Fetz, PhD, who worked on the study.
Moritz predicts that researchers will first target paralysis that only affects one area of the body -- say, teaching the brain to use the hand muscles to pick up a coffee cup or toothbrush.
"If we want to speculate wildly about the future and we want to restore movement to all parts of the body in a quadriplegic patient, where both arms and legs are paralyzed, we're going to need a larger set of neurons that can restore all those movements," Moritz says.
For now, the monkey experiment shows that the technique can work, but "certainly we're several years, if not several decades, away from this being ready for a clinical application," Moritz says.