Electrophysiological analysis of the tecto-olivo-cerebellar (lobulus simplex) projection in the rat.

In albino rats the deep layers of the superior colliculus were stimulated, and climbing fiber responses of Purkinje cells were explored in the medial region of the lobulus simplex. They were identified in a strip (ca. 0.7-1.0 mm wide) in the most medial region of folium b. In the tectorecipient zone of the medial accessory olive antidromically evoked potentials from the lobulus simplex were recorded laterally to those from lobule VII. Evidence is presented that climbing fibers innervating the zone in the lobulus simplex are axon collaterals of the inferior olivary neurons which project to crus II.