August 8, 1997
Media Contact: Marc Kusinitz
Researchers at Johns Hopkins and the University of Maryland have shown that people use one part of their brains to learn new physical skills, and store that memory within six hours in another part of the brain. The finding helps explain how skills as varied as tying a shoe and dancing on ice skates become automatic after a person learns how to do them.
The study also shows that the cerebellum, a lower part of the brain known to help control physical activity, is not involved in learning the skill. Instead, areas on the top and side of the brain learn the skill, which is then stored in the cerebellum.
"Our study supports the idea that the brain creates a blueprint, or model, for performing a particular task," says Reza Shadmehr, assistant professor of medicine and biomedical engineering at Johns Hopkins. "Once that blueprint is stored in the cerebellum, the brain uses it as a guide for controlling the movement of muscles used to perform that task."
The finding could help researchers learn how disruption of blood flow to the cerebellum because of drugs or injury affects the ability to remember how to perform physical tasks. This may help development of treatments that prevent the loss of physical skills, the scientists say. The study, co-authored by Henry H. Holcomb of the University of Maryland and the Department of Radiology at Hopkins, appears in the August 8 issue of Science.
"We showed that when someone first masters a physical skill, their brain needs time to store the memory of how to perform that skill correctly," says Shadmehr. "This memory wasn't laid down in the cerebellum while volunteers practiced the skill in the lab. It occurred hours after the practice session had ended and the volunteers had left the room."
Using a positron emission tomography (PET) scanner to study changes in the blood flow in the brain, the researchers showed that, as volunteers learned a physical skill, there was increased blood flow in a part of the brain called the dorsolateral prefrontal cortex. This part of the brain is responsible for working memories, that is, memories that are regularly used, such as remembering how to prepare a favorite meal.
There was no increase in blood flow in the cerebellum during the learning process, or when volunteers performed only random physical tasks that they did not memorize. In both cases, increased brain activity as measured by blood flow was confined to the cortex.
But after the volunteers had mastered a skill, the increase in brain activity shifted from the cortex to the cerebellum during performance of the task.
"That is, the brain didn't have to use its higher centers of thinking to do the task, because performing the task became automatic," says Shadmehr.
The researchers studied the formation of memory in volunteers lying on their backs with their head in a PET scanner. The volunteers used a robot arm to place a pointer onto targets that appeared on a TV screen. The targets appeared in rapid succession in different areas of the screen, forcing the volunteers to learn how to move and control the robot arm quickly and effectively.
The study was funded in part by the Whitaker Foundation, the National Institute of Mental Health and the Office of Naval Research.