Monkeys' Brains Operate Robotic Arm

Brian Handwerk
for National Geographic News
May 28, 2008

In a mental meeting of monkey and machine, two primates have learned to feed themselves with a robotic arm by controlling the appendage with signals from their brains.

The success boosts hopes for mind-controlled robotic prosthetics that may help disabled humans achieve some mobility.

The experiment employed "visualization" methods of learning that study leader Andrew Schwartz likens to those employed by many professional athletes.

"You show the animal what you want him to do, and neurons in the brain go off as if he were actually doing it," said Schwartz, a neurobiologist at the University of Pittsburgh School of Medicine.

Mapping that brain activity enabled Schwartz and colleagues to figure out what nerve cell activity produced the desired physical actions.

Recording the Brain

Probes the width of a human hair were inserted into the neuronal pathways of the monkeys' motor cortex—a brain region that controls voluntary muscle movement.

Physical movement begins as electrical impulses generated by the activity of thousands of nerve cells.

When a monkey envisioned moving the arm, probes captured the neural activity and sent the information to a computer, which mapped that data to specific physical motions. (Related: "'Brain Reading' Device Can Predict What People See [March 5, 2008].)

Because brain activity is so complex, it is impossible to map the activity of all the neurons associated with motion. But the team developed an algorithm that was able to simulate and recreate much of the activity from the limited data detected by the probes.

This neuron-activity blueprint was then delivered to the robotic arm, which features working shoulder and elbow joints and a clawlike "hand."

Monkeys were able operate the arm merely by thinking. The animals fed themselves meals of marshmallows and fruit even when their real arms were restrained.

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