Binocular interaction and signal components of optokinetic responses of climbing fiber afferents in the cerebellar flocculus and nodulus of the pigmented rabbit.

Under anesthesia with N2O (70%) and halothane (2-4%), Purkinje cells were extracellularly recorded in the flocculus and nodulus of immobilized pigmented rabbits, and complex spike responses to optokinetic stimulation (OKS) delivered simultaneously to both the ipsi- and contralateral eyes (binocular OKS) were compared with those to OKS monocularly delivered to the ipsi- or contralateral eye (monocular OKS). The complex spike responses to binocular OKS were an approximate summation of monocular responses to ipsi- and contralateral OKS. The complex spike modulation did not correlate with rhythmical slow and quick nystagmic discharges of the oculomotor nerve evoked by horizontal OKS. This suggests that complex spike responses originate largely from 'retinal slip' signals rather than from 'final motor command' signals represented in the discharges of the oculomotor nerve.