Spatial organization of the cerebellar corticovestibular projection in the cat

Abstract Peculiarities of the topographical distribution of the vestibulospinal neurons of Deiters nucleus were studied by means of the microelectrode technique. It was shown that, in contrast to morphological data, the localization of antidromically identified vestibulocervical and vestibulolumbar cells is not restricted to the ventral mid and rostral third (forelimb region) and caudodorsal part (hindlimb region) of the nucleus, but extend, respectively, throughout the ventral and dorsal halves of the nucleus. There is a large overlapping of localization zones of the two groups of neurons: vestibulocervical neurons are also found in the dorsal half of the nucleus, whereas vestibulolumbar neurons occur in its ventrocaudal part. Analysis of distribution of monosynaptic inhibitory postsynaptic potentials in the vestibulospinal neurons, evoked by stimulation of cerebellar Purkinje cells, showed that the vestibulocervical neurons are controlled mainly from the forelimb region of the cerebellar cortex, whereas vestibulolumbar neurons are equally inhibited both from the forelimb as well as hindlimb regions of the anterior lobe of the cerebellar vermal cortex. It was found that topographically restricted effects of the Purkinje cells, reflecting the fractional organization of the cerebellar corticovestibular projection, are combined with convergent and divergent influences of these cells on the activity of vestibulospinal neurons.