Monkey think, monkey do: with robotic arm

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"They are using a motorized prosthetic arm to reach out, grab and bring the food back to their face," said Andrew Schwartz of the University of Pittsburgh School of Medicine, whose study will appear in an upcoming issue of the journal Nature.

Schwartz said the technology behind this feat may lead to brain-powered prosthetic limbs for people with spinal cord injuries or disabling diseases that make such simple tasks impossible.

Until now, such brain-machine interfaces have been used to control cursor movements on a computer screen. Schwartz and colleagues wanted to apply the technology to real-world tasks.

The monkey guides the robot arm the same way it does its natural limbs, through brain signals.

Schwartz' team picks up those signals through an array of microelectrodes half the size of a thumbtack that has been implanted in the monkey's brain. These signals are amplified and relayed to a computer that operates the robotic arm.

Schwartz said his team has learned that certain motor neurons fire rapidly when the monkey wants to move a certain way. "What is important is each neuron seems to have a preferred direction," Schwartz said in a telephone interview.

"One cell will fire a lot if you move upward. Another cell will fire a lot if you move to the right. All you really need to do is listen to these neurons at the same time to determine which direction the animal wants to move in," he said.

COMPUTER CONTROL

"We record those patterns of action potential, interpret them with a computer and extract the monkey's intention to move. That serves as a control signal to the robot."

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