THE HUMAN CEREBELLUM AND TEMPORAL INFORMATION-PROCESSING - RESULTS FROM A PET EXPERIMENT

CHANGES of cerebellar blood flow were studied in normal humans using p ositron emission tomography (PET). A motor driven peg marked pairs of lines on subjects' right hands at different velocities. Subjects had t o decide whether the second line was marked slower or faster than the first. Estimation of velocity (compared with control, i.e. presentatio n of lines at constant velocity) led to increases of regional cerebral blood flow (rCBF) in the left cerebellar hemisphere and vermis. Prese ntation of lines at constant velocity (compared with rest) activated t he right cerebellar hemisphere. We conclude that the cerebellum is inv olved in temporal information processing even in the absence of motor output. This process can be separated from mere presentation of somato sensory stimuli.