Role of the cerebellum in eyeblink conditioning.

The mammalian cerebellum is thought to participate in motor control and motor learning. The specific cerebellar contribution to these processes is not clear, however. Advances in understanding cerebellar function have been relatively slow, because, at least in most cases, the cerebellum appears to play only an ancillary role in the behaviors studied to date. A remarkable exception is classical conditioning of eyeblink responses in the rabbit. In this model, an intact cerebellum is critical for both the acquisition and expression of conditioned responses. Recent experiments suggest that the cerebellar role in classical conditioning might be similar in all mammals, including the human. Moreover, anticipatory defensive reflexes in other effector systems show a similar dependence on the intermediate cerebellum. Further developments in our understanding of cerebellar function will depend on examination of a wider array of cerebellar-involved neural networks. There is also need for the development of new experimental approaches to associative learning in both the nonhuman primate and the human.