Blog: Monkeys Think, Moving Artificial Arm as Own

Monkeys Think, Moving Artificial Arm as Own
New York Times (05/29/08) P. A1; Carey, Benedict

University of Pittsburgh and Carnegie Mellon University brain-machine researchers have successfully implanted tiny sensors in two monkeys that enable them to control a mechanical arm using only their thoughts. The monkeys have been able to reach for and grab food and adjust for the size and stickiness of the food when necessary. The research suggests that brain-controlled prosthetics, while still impractical, are within reach. In previous studies, researchers demonstrated that paralyzed humans could learn to control a cursor on a computer screen with their brain waves, and that nonhuman primates could use their thoughts to move a mechanical arm, robot hand, or a robot on a treadmill. The new research takes the technology even further. The monkeys' brains seem to have adopted the mechanical appendage as part of the body, refining its movement as it interacted with objects in real time. Experts say the findings are likely to accelerate interest in human testing, particularly because of the need to treat head and spinal injuries in veterans. In the experiment, the monkeys first used a joystick to get a feel for the arm, which has a shoulder joint, an elbow, and a two-fingered grasping claw. Then a grid about the size of a freckle was implanted just beneath the monkeys' skulls on the motor cortex, over a patch of cells known to signal arm and hand movements. The grid contains 100 tiny electrodes, each one connecting to a single neuron. The grid was connected to a computer programmed to analyze the firing of the motor neurons and translate them into arm movements. The scientists helped the monkeys learn to use the arm using biofeedback, but after several days the monkeys needed no help.
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