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Abstract

In spite of the detailed anatomical knowledge available, the functional significance of the cerebellar wiring diagram is still obscure. Since there are no variations in the anatomy throughout the whole cortical plane, it is plausible to assume that the basic operation is the same in all parts of the cerebellum. The ‘wiring’ suggests that local activity must depend on the spatio-temporal organization of the inputs. Neocortical input reaches the cerebellar cortex from nearly all cortical areas via mossy fibers terminating on the granular cells. We simulated such an input to the granular layer in acute slices of rat cerebellar cortex using an array of 11 stimulating electrodes. By successively switching the stimulus current from one electrode to the next, a ‘moving’ input to the granular layer is simulated. Our experiments show that the cerebellar cortex is specifically activated by ‘moving’ stimuli applied to the granular layer. The activation is a function of ‘movement’ direction and velocity. Thus, it enables the cerebellar cortex to act as a movement detector. Such behavior has previously been postulated on anatomical grounds [Braitenberg, J. Theoret. Neurobiol., 2 (1983) 237–241; Braitenberg, In Glickstein et al. (Eds.), Cerebellum and Neuronal Plasticity, Plenum, 1987, pp. 193–207]