Functional localisation in the cerebral cortex and cerebellum: Lessons from the past

One of the basic questions about the working of the brain is the extent to which its various functions are localised. In the nineteenth century great advances were made in the study of localisation. The control of speech, mov ement, and vision was identified with specific regions of the cerebral cort ex. Although since the nineteenth century lesions of the cerebellum have be en known to produce impaired movement, there has been rather little progres s towards answering more detailed questions about the functions of the cere bellum and cerebellar localisation. The experts are still not agreed on wha t the cerebellum does or how and where it does it. Three examples are given of functions which probably are mediated by the cerebellum; adaptation of the vestibule-ocular reflex, classical conditioning of the nictitating memb rane response, and adaptation of saccadic eye movements. In all three cases the control of these functions has been localised to a specific region of the cerebellar cortex and/or nuclei. The success of localisation studies in the cerebral cortex can serve as a guide. Continued experimentation direct ed at the question of localisation should prove a fruitful approach to unde rstanding more about the functions of the cerebellum.