Somatotopic organization of climbing fiber projections from low threshold cutaneous afferents to pars intermedia of cerebellar cortex in the cat

Abstract

The fine detail of climbing fiber projections to large areas of the pars intermedia of lobule V was demonstrated by means of low threshold natural cutaneous stimulation. These projections formed a complex mediolateral organization of patches that were elongated in the anteroposterior direction. In general, distal forelimb was represented medially and the face represented laterally, although there were also elongated patches of cells that did not respond to any cutaneous stimulus presentation. The entire ipsilateral anterior quadrant of the body was represented in lobules Vb, c, d with the addition of face projections which extended slightly across the midline. Ipsilateral hindlimb patches were observed in lobule Va. Although the boundary between patches was quite sharp, a slight overlap of the patches within the mosaic was often observed. In these areas of overlap, some cells possessed receptive fields that encompassed, either continuously or discontinuously, cutaneous areas of both the adjacent patches. It is proposed that the cerebellar cortex could correlate event timing in the climbing fiber patches with 'on-line' information relating the parameters of movement in the granule cell parallel fiber system, and that the areas described in the present study could mediate 'spatially organized and skilled movements' in the animal's repertoire, which involve paw-face-mouth interaction, such as feeding, cleaning and grooming.