Monkeys Use Mind to Control Virtual Arms

Scientists at Duke University have successfully wired monkeys to be able to control virtual arms on an avatar of themselves using only their brains, opening the door for the technology to eventually be used to restore arm movement for paralyzed humans.

Monkeys were first taught how to control virtual avatars of themselves using a joystick—if they moved them correctly, they would get a reward. Then lead researcher Miguel Nicolelis took away the joysticks and gave them a brain-machine interface that allowed them to control the virtual arms as well. The machine decodes the monkey’s brain activity and moves the avatar to correspond with brain waves. According to Nicolelis, it’s the first time a brain-machine interface has been used to control two arms independently.

“So far, BMIs have enabled only one arm to be moved at a time,” according to the study, published in Science Translational Medicine. “Control of bimanual arm movements remains a major challenge. We have developed and tested a bimanual BMI that enables rhesus monkeys to control two avatar arms simultaneously.”

To make it work, the BMI recorded the activity of nearly 500 individual neurons in the monkeys brains. At first, the monkeys moved their real arms to correspond with movement on screen, but after two weeks, they began to sit motionlessly as they performed the task. Eventually, the monkeys’ brains began to “assimilate” the virtual arms, meaning the brain response was very similar to what you’d expect if the monkeys were moving their actual arms.

Moving two arms has been a tricky hurdle for scientists to overcome in the field: There’s not simply one or several neurons that control for, say, moving your right arm. They overlap, and many hundreds of neurons can be involved with any one movement. But by recording so many neurons, Nicolelis and his team were able to make moving both arms seem like second nature. The movement and decoding happens in real time.

This technology might not be so far off from being translated to human patients. Nicolelis suggests that brain machine interfaces can be used to bypass the spinal cord, meaning paralyzed patients who still have working arms, but no way of sending neurological signals to them, may one day be able to have at least some function.

“Our findings suggest that BMI technology can be applied to the challenging task of enabling bimanual control in subjects who do not produce overt arm movements,” the study said. “Future clinical applications of BMIs aimed at restoring mobility in paralyzed patients will benefit greatly from the incorporation of multiple limbs. It still remains to be tested how well BMIs would control motor activities requiring precise inter limb coordination.”

It’s another cool breakthrough from the Duke’s Center for Neuroengineering, which is doing some of the most cutting-edge research in the field. Earlier this year, Nicolelis announced that he had enabled telepathic communication between rats. In that study, a brain-machine interface was set up between two rats. One rat was given a visual cue as to which lever to push to release food, which corresponded with a lever in the other rat’s chamber. If the second rat pressed the correct lever, the first rat got an extra piece of food, which incentivized them to work together. In that experiment, the second rat chose the correct lever 70 percent of the time.

At the time, Nicolelis told me the rat breakthrough was instrumental to his work with monkeys and that it opened a “completely new line of research.”

“Once we got it to work in rats, we were able to unlock the secret to this technology,” he said. “We’re already doing very much more sophisticated experiments with monkeys. They’re learning to play games, controlling avatars of themselves on a screen.”

For Nicolelis, the discoveries have been coming quickly, so it’s no surprise that his next project is already in the works. He’s working on developing a brain-controlled exoskeleton for humans that could be ready to debut during the opening ceremonies of the 2014 World Cup in Brazil.