Mind Over Machine

With this extra set of neurons, Nicolelis explains, "the brain is assimilating the robot. It’s creating a representation of it in different areas of the motor cortex"—the part of the monkey’s brain where movement commands are generated. As the brain carves out a special place for its representation of the robot, Nicolelis speculates, it’s possible that the robot begins to feel as much a part of the body as the monkey’s own arm.

If he’s correct, this is very good news for people who might someday try to use his prosthetic limb. Their brains will reorganize themselves to master the limb, which will take on a natural feel. And since humans can be told what they should be learning—instead of figuring it out on their own as monkeys do—the training process may take even less time. "This could be done in a matter of a few trials, because you could instruct a human what to do," says Nicolelis.

The fact that the monkeys’ brains adapt so readily gives the Duke researchers confidence in the face of all the challenges that lie ahead. While it’s too soon to say whether brain-machine interfaces are going to turn up on the battlefield, they are almost certainly headed for the doctor’s office. "We have a plan for every part of the puzzle," says Patrick Wolf, who strongly believes that the Duke team will meet its five-year deadline. "I don’t see any showstopper."