June 10, 2002 SAN DIEGO - Moving objects just by thinking. That's something people do almost every time they move their bodies. Scientific work over the last 20 years has shown how neurons in the brain behave when we move our arms. More recently, this work has led to demonstrations of technology that may restore movement to the immobile.
Reporting in the Friday, June 7, issue of the journal, Science, scientists from The Neurosciences Institute here, in conjunction with the Department of Bioengineering at Arizona State University, have recently examined arrays of electrodes implanted in the cerebral cortex of monkeys. They record the electrical discharges of 50-80 individual brain cells as a small sample of the billions of neurons that communicate with each other during movement. The signals intercepted by these electrodes are sent to a computer where they are 'decoded' or matched to different arm movements.
This code is saved in the computer, and used by the animal to move a ball or spherical cursor through a virtual space to a specified target without using its arms. Monkeys 'learn' this task by changing the way these neurons code for movement direction.
"This is the first time learning has been directly visualized at the level of individual neurons in a movement task," said Andrew Schwartz of The Neurosciences Institute. "By tracking these changes with an adaptive decoding algorithm, both the subject and the computer program learn together. This approach leads to very good performance, allowing subjects to move the cursor with direct 'brain control' almost as well as they can with their hands free."
The research team, comprised of Andrew B. Schwartz with the Institute, and Dawn M. Taylor and Stephen I. Helms Tillery, of the Department of Bioengineering, Arizona State University, Tempe, AZ, plans to replace the virtual cursor with a robot arm that will be used by a monkey to reach and retrieve food while its own arms are restrained. Through a sort of 'neural bypass', it is hoped that this approach can be used by human patients with paralyzed arms. As work progresses, functional electrical stimulation of the patients muscles may allow them to use their own limbs instead of robotic devices.
The Neurosciences Institute focuses its research on the fundamental principles of functions of the brain, which is the single most complex organ in the known universe. The Institute is a small, privately funded, not-for-profit organization that utilizes an interdisciplinary approach to scientific investigation.
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