St. Louis, Oct. 5, 1998 -- The parts of the brain that enable you to do a familiar task are different from those that learn that task, a new study confirms.
Researchers at Washington University School of Medicine in St. Louis reached this conclusion after obtaining positron emission tomography (PET) images of people tracing maze patterns. PET is one of the techniques that can reveal which areas of the brain are active.
"Our volunteers used some areas of the brain to learn the maze task but shifted to other areas after practice," says lead researcher Steven E. Petersen, Ph.D., professor of neurology, neurobiology and radiology.
The researchers report their results in the October issue of the Journal of Neurophysiology. Research assistant professor Hanneke van Mier, Ph.D., is first author.
Thirty-two right-handed volunteers took part in the study. They had to move a pen through cut-out mazes while keeping their eyes closed. Half traced with the left hand, half with the right.
When the volunteers first traced a maze, they moved the pen slowly and made many false turns. During this learning period, parts of the brain called the right premotor cortex, the right parietal cortex and the left cerebellum became active, PET images revealed.
After 10 minutes of practice, the volunteers provided another set of images. As they moved the pen through the maze quickly and without making errors, the supplementary motor area, near the junction of the brain's two hemispheres, became active. The areas that were active during learning were quiescent now that the volunteers had gained expertise.
Surprisingly, the hand used to perform the task made no difference to the results, suggesting that some learning areas code abstract information rather than motor instructions. Usually, the right arm activates the left side of the brain, and the left arm activates the right.
The researchers performed this work because a 1994 Washington University study uncovered a circuit shift after a verbal task was learned. "So this seems to be a general phenomenon," van Mier says.
Petersen suggests the brain uses general-purpose processors when faced with a new task. "But if the world asks you to do the same thing over and over," he says, "you develop circuits dedicated to that task."
van Mier H, Tempel LW, Perlmutter JS, Raichle ME, Petersen SE (1998). Changes in brain activity during motor learning measured with PET: Effects of hand of performance and practice. Journal of Neurophysiology, 80, 2177-2200.
The research was funded by the National Institutes of Health and Washington University's McDonnell Center for the Study of Higher Brain Function.