01:00 PM Oct. 26, 2004 PT

If a monkey is hungry but has his arms pinned, there’s not much he can do about it. Unless that monkey can control a nearby robotic arm with his brain.

This time lapse photo shows a lab monkey at the University of Pittsburgh using a robotic arm to feed itself. The prosthetic limb, the size of a child’s arm, has working shoulder and elbow joints and is equipped with a simple gripper to grasp and hold food.

And that’s exactly what the monkey in Andrew Schwartz’s neurobiology lab at the University of Pittsburgh can do, feeding himself using a prosthetic arm controlled solely by his thoughts.
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The prosthetic limb, the size of a child’s arm, has working shoulder and elbow joints and is equipped with a simple gripper to grasp and hold food. The monkey’s arms are restrained at its sides and as the monkey thinks about bringing the food to his mouth, electrodes in the monkey’s brain intercept the neuronal firings that are taking place in the motor cortex, a region of the brain responsible for voluntary movement.

The brain activity is fed to a computer where an algorithm developed by the University of Pittsburgh interprets the neuronal messages and sends them to the robotic arm. “We have learned to understand the patterns of firing rates and can decode them into movement, direction, velocity and speed,” said Schwartz.
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The unique aspect of Schwartz’s research is that he conducted what is known as “closed loop” brain experiments. In a “closed loop” experiment, the monkey is conscious of the robotic arm and is making an effort to control it.