It is generally considered to be involved in a feedback circuit governing the activity of the extrapyramidal motor system, and has long been considered as a error detection device, receiving error signals from the inferior olive and using both efferent copy and sensory feedback to adjust some kind of calibrating signal to correct subsequent movements. The most important information to the cerebellar cortex about movement error is delivered by the climbing fibers. As an important part of the motor system, it also controls muscle tone and involuntary movements and provides coordination and integration of movements, as well as other timing functions in behavior. Damage to the cerebellum impairs motor learning. The motor functions of the cerebellum were initially discovered Luigi Rolando (1773-1831) and Marie-Jean Pierre Flourens (1794-1867) at the beginning of the 19th century derived from their observations of animals with cerebellar damage, and in 1917 confirmed in humans by Gordon Holmes (1876-1965) based on his studies of patients with gunshot wounds. Beyond this well-known depiction of the role of the cerebellum in motor control, recent research is revealing that it has a host of’non-motor’ functions. One derives from PET studies using the so-called generation task [i.e., where a verb (e.g., ‘eat’) has to be matched with an appropriate noun (e.g., ‘apple’)] with or without speech. Such studies have shown that the right cerebellum becomes active when the task is performed without speech. Accordingly, the cerebellum might guide the conscious selection of appropriate verbs in ways similar to guiding movements. Consequently, this sort of finding might implicate the right cerebellum in reading abilities. Furthermore, neurological studies with brain-damaged patients and neuroimaging with healthy individuals have implicated the cerebellum in a variety of sensory and cognitive tasks, as well as in certain motor (or sensory-motor) tasks. In particular, these data suggest cerebellar involvement in: the generation of words according to a semantic rule, timing of events, solving perceptual and spatial reasoning problems, mental rotation, visual information processing, cutaneous and tactile discrimination, kinesthetic sensation, mental imagery, and working memory, among other processes (e.g., sensory process involved in thirst).
See Brain (neuro-imaging), Cerebellum (anatomy), Cerebellum (development), Cerebellum (disorders), Coordination, Efference copy (or corollary discharge), Extrapyramidal system, Inferior olive (olivary) nucleus, Kinesthesis, Mossy fibers, Motor learning, Movement coordination, Muscle tone (or power), Prefrontal cortex, Working memory