PHYSIOLOGICAL-PROPERTIES OF NEURONS IN SUPERFICIAL LAYERS OF SUPERIORCOLLICULUS OF RABBITS

Neurons in superficial layers of the superior colliculus of the rabbit are classified into three types by their electrophysiological propert ies. Among them, two types belong to projecting neurons which send axo ns to the thalamic pulvinar (N=52) and dorsal lateral geniculate nucle us (N=41) respectively All other neurons are pooled into the third typ e (N=99). Projecting neurons of both types receive monosynaptic visual inputs via optic tract fibers of similar conduction velocity, indicat ing that in the superior colliculus of the rabbit, there is no differe nce in conduction velocity between the two pathways. They also receive trisynaptic inhibitory inputs, most likely via recurrent inhibitory c ircuits. The third type of neurons receives disynaptic optic and trisy naptic inhibitory inputs. The function of neurons of the third type is studied.