Topographical organization of climbing fiber pathway from the superior colliculus to cerebellar vermal lobules VI-VII in the cat.

Topographical distribution of the climbing fiber responses induced by stimulation of the superior colliculus was investigated in the cerebellar posterior vermis (lobules VI-VII) of the cat. The climbing fiber-responsive areas were distributed longitudinally forming sagittal zones. The sagittal zones responsive to stimulation of the left and right superior colliculus were located on the side ipsilateral to the stimulation, and they were completely segregated. The sagittal zones responsive to stimulation of the caudal superior colliculus were distributed more laterally than those responsive to stimulation of the rostral superior colliculus. Study of the extracellular unit in the inferior olive demonstrated that the climbing fiber responses were relayed in the caudomedial part of the medial accessory olive contralateral to the stimulation.