The neural mechanisms of movement vision and optic nystagmus.

Abstract

The optic nystagmus of the guinea pig, which is elicited by movement of a stimulus pattern of compound visual contours, is based neurologically upon peripheral and central mechanisms possessing inherent balanced relations with one another. Peripherally, responses made to movement of visual patterns in one direction of movement in the horizontal plane are controlled almost exclusively by 1 eye. Centrally, the next important level is the superior colliculus. The right colliculus is indispensable for the response with pursuit to the right, the left colliculus, for pursuit to the left. Besides these retinal and central mechanisms of direct control, in- tegrative balances between the superior colliculi, and between the cerebral cortex and the superior colliculi, are important in determining the characteristics of the responses. The cerebral cortex acts mainly as an inhibitory mechanism in the control of the responses. The superior colliculus opposite that side from which the responses are directly controlled at this level has inhibitory effects upon the responses directed by the opposite side. Some evidence may be adduced that the colliculi are primarily concerned in denning the pursuit phase of the responses, whereas the saccadic phase is detd. by centers below the level of the colliculi. The mechanisms controlling optic nystagmus in the guinea pig have specific relations with the animal''s capacity for discriminating the movement of visual patterns.