The human cerebellum and temporal information processing - results from a PET experiment

Abstract

Changes of cerebellar blood flow were studied in normal humans using positron emission tomography (PET). A motor driven peg marked pairs of lines on subjects' right hands at different velocities. Subjects had to decide whether the second line was marked slower or faster than the first. Estimation of velocity (compared with control, i.e. presentation of lines at constant velocity) led to increases of regional cerebral blood flow (rCBF) in the left cerebellar hemisphere and vermis. Presentation of lines at constant velocity (compared with rest) activated the right cerebellar hemisphere. We conclude that the cerebellum is involved in temporal information processing even in the absence of motor output. This process can be separated from mere presentation of somatosensory stimuli.