What the cerebellum computes

The brain is an organ that processes information. Brain systems such as the cerebellum receive inputs from other systems and generate outputs according to their internal rules of information processing. Thus, our understanding of the cerebellum is ultimately best expressed in terms of the information processing it accomplishes and how cerebellar neurons and synapses produce this processing. We review evidence that indicates how Pavlovian eyelid conditioning reveals cerebellar processing to be an example of feedforward control. Eyelid conditioning demonstrates a capacity for learning in the cerebellum that is error driven, associative and temporally specific--as is required for feedforward control. This computation-centered view is consistent with a variety of proposed functions of the cerebellum, including sensory-motor integration, motor coordination, motor learning and timing. Moreover, feedforward processing could be the common link between motor and non-motor functions of the cerebellum.