But studies of such patients have not pointed to a single location for motor skills. Shadmehr, a professor of biomedical engineering with an expertise in building robots, comes at this research indirectly. To learn how to build robot control systems, he turned to studying the brain, specifically asking how the brain learns to control the arm. The arm was programmed with a particular force so that participants felt they were dragging a very light object through a viscous medium. The volunteers practiced first in the morning and then returned to the lab six hours later to repeat the task.
PET shows cerebral blood flow, a measure of neural activity.
The researchers found that during the first learning phase, volunteers' PET scans showed activity in the dorsolateral prefrontal cortex, a region toward the front of the brain responsible for temporary storage of information. During this process, he adds, the brain appears to transform a fragile memory into a stable one. The time period appears to be a critical one. In research published last year in Nature, Shadmehr found that volunteers could disrupt the long-term memory of a new motor skill if, during the hours between initial learning and memory consolidation, they attempted to learn a second, similar task, such as using the robotic arm to manipulate a new object. No such luck, says Shadmehr.