Teleceptive Components of the Cerebellar Function

Abstract

This review deals with the auditory and visual components of cerebellar inflow. Among the many sources of afferent inflow which can modify the functional level of the cerebellar cortex, visual and auditory receptors must be considered. Such a modulation is essentially actuated on almost the whole cortex of the dorsal aspect of the corpus cerebelli. The effects are greater in the vermian than in the hemispherical part of it, and betray a focal arrangement. A 1st wave of cerebellar activation is mediated by volleys originating from the tectal centers of the visual and acoustic systems. A 2nd wave depends on the changes in cortical output brought about by the specific response of the cerebral teleceptive projection areas. Broadly speaking, it can be maintained that each cerebral sensory area receives impulses both directly from peripheral receptors and indirectly from the homologous area of cerebellar cortex. The flow through every pathway linked with the cerebellar teleceptive activation is rather strongly influenced by the functional conditions of the preparation. At least in the cat, the visual cerebellar pathways are much more labile than the acoustic ones. Interaction patterns (both occlusive and facilitatory) may develop between cerebellar responses elicited by tactile, proprioceptive, acoustic, visual and cerebro-cerebellar impulses. These patterns have also been observed by conditioning specific responses of the cerebellar teleceptive projection areas with shocks applied to the focal part of the cerebellar audiovisual area. It appears that the regulation of movement could not be satisfactorily achieved if the cortical networks of the cerebellum were not continuously fed with information coming from all peripheral sources. The reciprocal connections linking together with cerebral and cerebellar teleceptive projection areas should not be regarded as necessarily implying some participation of the cerebellum in conscious sensory processes of hearing and sight. Most of the volleys originating from posterior vermis and playing on cerebral teleceptive areas are likely to represent but particular instances of the general action exerted by the cerebellum on the electrocortical activity through the diffusely projecting system.