Disrupted Timing of Discontinuous But Not Continuous Movements

Patients with cerebellar damage are known to exhibit deficits in the temporal control of movements. We report that these deficits are restricted to discon-tinuous movements. Cerebellar patients exhibited no deficit in temporal vari-ability when producing continuous, rhythmic movements. We hypothesize that the temporal properties of continuousmovements are emergent and reflect the operation of other control parameters not associated with the cerebellum. In contrast, discontinuous movements require an explicit representation of the temporal goal, a function of the cerebellum. The requirement for explicit temporal representation provides a parsimonious account of cerebellar in-volvement in a range of tasks. Lesions of the cerebellum disrupt the temporal properties of voluntary movements. Individuals with cerebellar lesions exhibit increased tempo-ral variability on numerous motor tasks (1–3) and are impaired on nonmotor tasks that requir