Central Nystagmus Elicited by Stimulation of the Meso-Diencephalon in the Rabbit

¹ From the Department of Pharmacology, Hebrew University-Hadassah Medical School, Jerusalem, Israel and the Department of Physiology, University of Basle, Basle, Switzerland

Unilateral stimulation at high frequencies (20–50 cps) of a circumscribed, meso-diencephalic area, including the reticular formation medial to the nucleus reticularis thalami and geniculate bodies in rabbit's brain, produces a ‘central nystagmus’ with its fast component usually directed towards the contralateral side. The reaction is tentatively explained as the result of a primary inhibition of the tonic innervation of the ipsilateral musculus rectus internus and of the contralateral rectus externus of the eyes. The relationship between this higher nystagmogenic area in the meso-diencephalon and the elementary three-neuron reflex arc of the nystagmus is discussed.