Does the Cerebellum contribute to cognitive processes?

Does cerebellum contribute to cognition? Although the cerebellum has been traditionally considered to be exclusively involved in motor control and learning, recent anatomical and clinical studies suggest that it may also have a role in cognition with no electrophysiological evidence supporting the claim. Here we studied the activity of simple spikes of hand-movement related Purkinje cells in the mid-lateral cerebellum when monkeys learned to associate a well-learned hand movement with visual symbols. During learning, but not when the associations were overlearnt, the Purkinje neurons reported the outcome of the trial: simple spike activity differed between correct and wrong trials, but only in a particular epoch of the trial, different for each neuron. Across the population, these epochs tiled the whole trial period. Furthermore, we found trial over trial changes in neural activity through learning; that is, the neurons used this information about the trial outcome to learn the new visuomotor associations. Our results suggest a role of cerebellum in visuomotor associative learning and gather evidence that cerebellum, rather than being regarded just as a motor control system, could be a generalized learning system, essential in cognitive rule learning as well as motor learning and adaptation.