The research team, which included faculty from Purdue and University of California-Berkeley, was led by Purdue professor Howard Zelaznik.
The team found that the cerebellum may not be as fully responsible for the timing of "continuous" motions, such as drawing circles repeatedly on paper, as it is for "discontinuous" motions that have a more start-stop nature, such as tapping your finger rhythmically on a table. Patients with cerebellum damage who participated in the study had difficulty tapping a steady beat, but no such trouble with drawing circles in rhythm. The study indicates that stroke victims may retain some motor skills thought to have been lost to cerebellar damage.
"The basic idea is, if the same part of your brain governs timing of all your muscular activity, you should have equally good rhythm when tapping your finger as when you draw circles," said Zelaznik, professor of kinesiology in Purdue's School of Liberal Arts. "But we found that one skill doesn't predict the other. So if part of your brain gets traumatized through injury, you may not necessarily lose all your motor skills."
The research, which appears in the May 30 edition of the journal Science, was the Purdue dissertation project of Rebecca Spencer, who is now at UC Berkeley. It was co-authored by Zelaznik and her colleagues at UC Berkeley, J. Diedrichsen and R. Ivry.
Under the right and left hemispheres of the cerebrum, which handles higher thinking processes, lies a smaller and more ancient section of the brain - the cerebellum. It is here that motor skills - which include movements from walking to blinking to catching a ball- are governed. Strokes can leave damaging lesions on
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