Eye movements induced by electrical stimulation in the rabbit's mesodiencephalon.

32 adult albino rabbits were used to investigate the oculomotor function of the mesodiencephalon. Bipolar electrical stimulation was used to induce saccades in unanesthetized rabbits. Saccades were induced from relatively broad regions of the rabbit's mesodiencephalon except for tractus opticus, a part of nucleus lateralis posterior thalami and some parts of nucleus pretectalis anterior. The direction of the saccades was generally ipsilateral to the stimulation site. Although the saccades were not influenced by caloric nystagmus or in blindfolding, the pattern of them was greatly influenced by a lateral recumbent position. Nystagmus was induced from tractus opticus, nucleus pretectalis anterior and nucleus lateralis posterior thalami. The nystagmus became remarkable in blind-folding, or when an eye ipsilateral to the stimulation site was covered. This electrically induced nystagmus did not undergo any modulations by ablation of the flocculus and paraflocculus contralateral to the stimulation site.