Robotic Arm Gives Shadmehr Hand Seeing How Brain Learns By Ken Keatley Here today, gone tomorrow. Sometimes. That's one of the conclusions Reza Shadmehr, assistant professor of biomedical engineering, has made in a study of how the human brain learns new motor skills. The study has been undertaken in collaboration with Emilio Bizzi and Tom Brashers-Krug, scientists at the Massachusetts Institute of Technology. The key to his research is a portable, desktop-sized, multi-joint robotic arm that physically interacts with the human arm. In one of the experiments, Dr. Shadmehr uses the arm to teach human subjects a new task, such as making reaching movements in a particular force field, as directed by the robot. After an hour of practice, the subject learns to control his or her arm in the field; however, the motor memory of how to perform those movements is lost if another new task is learned soon after the first. "But if we increase the time between presentation of the two fields, the memory of the first field is no longer vulnerable," Dr. Shadmehr said. "The subject can be tested on either task, and performance shows good recall. This has suggested to us that, with time, some fundamental properties of motor memories change." Dr. Shadmehr, a recent recipient of an Office of Naval Research Young Investigator Award, is attempting to understand how various motor centers in the brain might participate in formation and retention of motor memories. "We are using robots as a tool to produce virtual mechanical environments," he explained. "This gives us a way to examine origination of motor memories and the process of memory consolidation." To determine how the brain is functioning during the learning process, Dr. Shadmehr plans to move the subject--and the portable robot--into facilities where the subject's brain can be imaged using positron emission tomography. According to Dr. Shadmehr, this type of robotic technology may also have potential in some real world applications, like using robots to create virtual training environments. "One can imagine training a subject--using "mechanical feelings" coupled with a realistic visual display--to perform a task that might otherwise be too difficult to train, because it is dangerous or occurs infrequently," Dr. Shadmehr said. He gave as examples learning to defuse a bomb or perform specialized surgery that is only seen in wartime. An electrical engineering major at Gonzaga University, Dr. Shadmehr became interested in the human motor system while pursuing graduate degrees at the University of Southern California. Robots entered the picture while he conducted postgraduate work at MIT. Dr. Shadmehr only recently arrived at Hopkins, and is in the process of setting up his lab and constructing a new robot. He's hoping to use the brain imaging data to identify regions of the brain that are active in different stages of memory formation, and then test whether patients with brain lesions exhibit predicted deficits. "With our strong link to the medical school, Hopkins provides the most outstanding environment for this kind of interdisciplinary work," Dr. Shadmehr said.
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