Signals from a monkey's brain can control a robotic arm, driving the mechanical limb to mimic the movements of the flesh-and-blood simian arm, researchers report. A similar setup that could "read" human brain signals might lead to movable prosthetic limbs for people who are paralyzed or have lost an arm.
Last year, a team led by neurobiologist Miguel Nicolelis of Duke University in Durham, North Carolina, harnessed brain activity in rats and translated it into commands that made a robot arm push a lever. They wired the rat's motor cortex and patched electrical signals from firing nerves into the robot's command center.
Nicolelis's team has now refined the technique, taking signals from a more complex brain and translating them into more realistic three-dimensional movements. The researchers implanted a bundle of ultrafine electrodes into a few cortical areas in the brains of two owl monkeys. They eavesdropped on local brain signals when the owl monkey moved its arm. First they recorded and analyzed the signals to see if they could guess the arm's trajectory as the monkeys reached for food or other objects. Once the researchers confirmed their predictions, they patched those signals into the robotic arm. When a monkey reached for a chunk of food, the mechanical arm simultaneously aped the movement, the researchers report in the 16 November issue of Nature. To share the success, they sent brain signals from a monkey at Duke over the Internet to the Massachusetts Institute of Technology, where the signals drove another robotic arm.
The study has cleared one of the major obstacles to producing a dexterous prosthetic arm--controlling three-dimensional movements in real time--says neurobiologist Eberhard Fetz of the University of Washington, Seattle. But plenty of formidable challenges remain, he cautions. For one, researchers will have to crack the more demanding problem of controlling fingers. Says Fetz, "It's one thing to make the arm move around in space, it's another thing to get it to pick up eggs."