Simple spike modulation of Purkinje cells in the cerebellar nodulus of the pigmented rabbit to optokinetic stimulation.

In immobilized pigmented rabbit anesthetized with N2O (70%) and halothane (2-4%), simple and complex spike responses of Purkinje cells in the cerebellar nodulus to large field optokinetic stimulation (OKS) was studied. About half of the cells showed significant simple spike modulation to OKS delivered to ipsilateral (25/57) or contralateral (18/31) eye. The preferred direction and the amplitude of modulation of simple spike responses did not necessarily correlate with those of complex spike responses, suggesting that the simple spike modulation is not secondary to complex spike modulation but due to modulation of mossy fiber activity to OKS.