Monkeys Control Two Virtual Hands with Just Their Thoughts

 In the past few years, scientists have made great advances in developing prosthetic limbs that humans can control with their minds. As part of this trend, a research team led by Miguel Nicolelis of the Duke University Medical Center developed a system that lets monkeys use their thoughts to control the hands of a monkey avatar on a computer screen.The researchers implanted electrodes on the brains of two monkeys. The electrodes recorded data from about 500 neurons. Then the researchers taught the monkeys that they could control their avatars with their minds. Ashley Taylor of Popular Mechanics explains:

How, exactly, do you teach a monkey to do this? The first step is to have the monkeys think about the desired action—in this case, making the avatar's hands grab two objects on the screen—and determine which neurons are firing and in what patterns when the monkeys think about that action. At first, Monkey C was allowed to control the avatar using joysticks, with one joystick for each arm. The computer recorded the neuronal firing patterns as they related to the motion of the avatar's arms onscreen. To give the monkey a goal to work toward, the animal was rewarded with juice when it made the two arms touch a pair of white circles on the screen simultaneously.
In the next phase of training, Monkey C was again encouraged to make the avatar touch the targets and was again allowed to move the joysticks. This time, though, the joysticks weren't controlling the avatar at all: The monkey's neurons, as decoded by the algorithm, were moving the objects on screen.
In phase three, the monkey's arms were lightly restrained during the same task so that it would learn that its thoughts, not the motion of the joystick, were controlling the avatar.