Regional cerebral blood flow during a self-paced sequential finger opposition task in patients with cerebellar degeneration.

The brain regions controlling self-paced sequential finger movements in patients with cerebellar degeneration were studied by measuring changes in regional cerebral blood flow (rCBF) in eight patients using bolus injections of H2(15)O and PET. The results were compared with those obtained in eight normal age-matched control subjects. Patients and control subjects performed a self-paced sequential finger opposition task with the right hand, completing a sequence of movements every 4-6 s. Both groups had strong increases in the adjusted rCBF contralaterally in the primary motor cortex (M1) and ventral premotor area (PMv), in the caudal supplementary motor area (SMA) and cingulate motor area (CMA), and bilaterally in the prefrontal cortex (PFC), the lobus parietalis inferior (LPI), putamen and cerebellum. The cerebellum, PMv, rostral CMA, PFC and LPI were more active in the control subjects than in the patients, and the M1, SMA, caudal CMA and putamen were more active in the patients than in the control subjects. The reduced activity of the cerebellar neurons in the patients produced a complex pattern of rCBF increases and decreases in other brain regions. Our results suggest that for the preparation and execution of sequential finger movements, patients with cerebellar degeneration use a medial premotor system, including the SMA and caudal CMA, as well as the M1 and putamen, rather than the PMv, PFC, LPI and rostral CMA.