From Science:
Using an array of hair-thin electrodes implanted in his brain, a 25-year-old quadriplegic man was able to operate a computer, open and close a prosthetic hand, and manipulate a robotic arm just by thinking about it, according to a new study. Such a brain-computer interface may one day help restore movement and communication to people paralyzed from spinal cord injuries, strokes, and disorders such as muscular dystrophy and amyotrophic lateral sclerosis.
Researchers have previously inserted single electrodes into paralyzed people, providing them with limited computer cursor control. They’ve also put more complicated electrode arrays into monkeys. But no one had ever put a large number of microelectrodes into a paralyzed person; indeed, no one knew whether neurons in the motor cortex, the brain region primarily responsible for movement control, would still produce decipherable signals after years of disuse.
More here.