Researchers at Chicago's Northwestern University have found a way to bypass the spinal cord in order to let the brain directly control otherwise-paralyzed muscles. The team used a method called functional electrical stimulation (FES), which causes muscles to contract in patterns that mimic natural grasps or other movement. After implanting small electrodes in the brains of two monkey test subjects, the researchers injected anesthetic into the monkeys' lower arms, simulating the effects of a paralyzed wrist and hand. The monkeys then tried to throw a ball into a chute, something they'd been trained to do earlier. With no stimulation, their hands were unable to grasp the ball. Once it was turned on, though, the electrical stimulus gave them almost complete control over grabbing and throwing it. The video below shows the frankly amazing difference between the two states.
In the research paper, published in a recent issue of Nature, the authors note that FES has been used before. Usually, however, each movement must be triggered manually in some way, whereas these electrodes let the current be directly activated by the brain. That both streamlines the interface and makes it simpler to create a wide array of potential motions. It also means that human patients with almost complete paralysis could activate muscle movement simply by thinking about it, rather than having to try to physically move some part of their body as a trigger. The researchers cautioned, however, that this test doesn't account for the changes that occur with long-term paralysis, so they'll need to continue tests with permanently paralyzed animal subjects.