The robotic arm, or neural prosthesis, is about the size of a child's arm and moves much like a natural arm, with a fully mobile shoulder and elbow and a simple gripper that allows the monkey to grasp and hold food while its own arms are restrained.

The arm is wired into the monkey's brain and intercepts signals through electrodes attached to tiny probes that tap into neuronal pathways in the motor cortex, a region of the brain responsible for voluntary movement. The neurons' collective activity is fed through an algorithm developed at the University of Pittsburgh and then sent to the arm to tell it what direction to go.

"This is a breakthrough in the development of neural prosthetic devices that will someday lead to devices that could help people who are paralyzed or who have lost limbs," said Andrew Schwartz, Ph.D., professor of neurobiology at the University of Pittsburgh School of Medicine and senior researcher on the project.

The research was detailed in a press conference today at the 2004 Annual Meeting of the Society for Neuroscience in San Diego.

According to Dr. Schwartz, a part of the brain that controls movement, called the primary motor cortex, contains neurons that fire like a Geiger counter in different directions. The direction to which a neuron fires fastest is called its "preferred direction." Many motor cortical cells change their firing rate for each movement, and this activity from the many neurons is routed through the spinal cord to different muscle groups to generate movement.

It takes thousands of neurons firing in concert to allow even the most simple of movements, and it would be impossible to tap into all of them, so the Pitt t
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26-Oct-2004