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.