Johns Hopkins Gazette: May 1, 1995

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

     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

     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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