Return Eye Movements, Saccadic Movements, And The Quick Phase Of Nystagmus

Abstract

Electric stimulation of ampullary nerves in the alert cat and monkey induces active diphasic eye movements. These consist of an initial deviation followed by a movement which returns the eyes toward or past their initial position in the orbit. The second movement has been designated a return eye movement and is a central oculomotor reflex. This reflex appears to provide ocular compensation for head movements induced by strong impulses of angular acceleration. Modulating influences on this reflex include vision, head and eye movements, the initial position of the eyes in the orbit and the head on the neck, and the level of alertness. There is a reciprocal relationship between the amplitude of initial deviations and active return movements which varies linearly with changes in eye position. Characteristics of return movements link them closely to saccadic movements and the quick phase of nystagmus, and differentiate them from other compensatory eye movements which have been previously described.