The role of the cerebellum in motor cognition.

Cerebellar data from five experiments using different groups of subjects performing the same motor learning task are presented. Positron emission tomography (pet) as well as functional magnetic resonance imaging (fmri) was used to study changes in cerebellar activations as an effect of learning. Cerebellar brain activations obtained during the performance of a new motor task were compared to activations during the performance of the same task after as well as during practice. To account for changes in velocity and somatosensory processing as an effect of practice, two control conditions were included. Behavioral data showed that as an effect of practice performance speed as well as accuracy increased in all five experiments and groups. Neuroimaging data from adults as well as children showed differential changes in brain activations in different cerebellar areas. In all experiments an area in the left lateral cerebellum showed practice-related decreases, which were most likely related to a decrease in errors. In two experiments a highly significant correlation was found between the decrease in errors and the decrease in left cerebellar activation. An area in the right lateral cerebellum and one in the ipsilateral anterior vermis showed activations that seemed related to the level of capacity at which the subjects were performing and might refer to timing-related aspects of the task.