Abstract
The traditional view that the cerebellum is involved solely in the control of movement has been challenged in recent years. One of the pivotal reasons for this reappraisal has been new information about cerebellar connections with the cerebral cortex. The use of transneuronal transport of neurotropic viruses has enabled us to identify cerebello- thalamocortical pathways to selected motor (Hoover & Strick, ‘93,‘99; Dum & Strick, ‘03), prefrontal (Middleton & Strick, ‘94,‘00,‘01; Kelly & Strick, ‘03) and posterior parietal areas of cortex (Clower et al., ‘01, ‘04). Thus, our results indicate that cerebello- thalamocortical pathways project to a wider set of cortical areas than previously imagined. The output stage of cerebellar processing displays a surprising degree of topographic organization. We proposed that localized regions within the dentate form distinct output channels that are directed at specific cortical areas. As the data on these circuits has accumulated, a general rule has emerged- each cortical area that projects to the input stage of cerebellar processing receives (via the thalamus) efferents from the output stage of cerebellar processing. This rule implies that multiple closed loops represent a fundamental unit of cerebro-cerebellar circuitry. These circuits provide the cerebellum with the neural substrate to influence not only the generation and control of movement, but also aspects of cognition and visuo-spatial perception. Support: VA Medical Research Service, USPHS grants NS24328 & MH56661. [Jpn J Physiol 55 Suppl:S2 (2005)]
