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Monkeys Control Robotic Arm With Brain

Could be big step toward artificial limbs for neurologically impaired

THURSDAY, Feb. 17, 2005 (HealthDay News) -- With the help of a computer, monkeys using only their brain signals are now able to move a robotic arm to feed themselves pieces of fruit and vegetables, researchers report.

The achievement could mark a major advance in the development of brain-controlled artificial limbs for people, the scientists said.

"The beneficiaries of such technology will be patients with spinal cord injuries or nervous system disorders such as amyotrophic lateral sclerosis [ALS]," project senior researcher Andrew Schwartz, professor of neurobiology at the University of Pittsburgh School of Medicine, said in a prepared statement.

His team presented their findings Thursday at the annual meeting of the American Association for the Advancement of Science, in Washington, D.C.

In the experiments, monkeys -- their own arms restrained -- were trained to reach for food targets placed at different points in front of them, using the child-sized prosthetic arm.

According to the researchers, signals from a part of the monkey's brain called the motor cortex (responsible for directing movement) pass through electrodes thinner than a human hair and into a specially designed computer algorithm. This program collects and interprets the firing rates of thousands of neurons responsible for directing movement, then converts them into a general instruction as to how to move the robotic arm.

"When the monkey wants to move its arm, cells are activated in the motor cortex," Schwartz explained. "Each of those cells activates at a different intensity depending on the direction the monkey intends to move its arm. The direction that produces the greatest intensity is that cell's preferred direction."

Monkeys successfully directed the arm to reach out and bring food to their mouths from various spots in front of them, the researchers reported. The robotic arm has a fully mobile shoulder and elbow and moves like a normal arm, the researchers said. It also has a simple gripper that allows the monkey to grab and hold food while its own arms are restrained.

Some of this research was also presented last October at a meeting of the Society for Neuroscience.

In recent weeks, the researchers said, they have improved the algorithms in order to make it easier for monkeys to learn to operate the robotic arm. These movements will also help the researchers to develop more sophisticated brain devices that have smoother, more responsive and precise movement. The Pittsburgh team is also working to develop a prosthesis with realistic hand and finger movements.

More information

The Society for Neuroscience has more about robotic limbs.

SOURCE: American Association for the Advancement of Science, news release, Feb. 17, 2005
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