NMDA RECEPTORS ARE INVOLVED IN TEMPORAL INTEGRATION IN THE OCULOMOTORSYSTEM OF THE CAT

SPONTANEOUS eye movements were recorded before and after a microinject ion (0.1-0.2 mu l) of either APV (an NMDA receptor antagonist) or NBQX (a non-NMDA receptor antagonist) into the nucleus prepositus hypoglos si (NPH) of the alert cat. A unilateral injection of APV caused bilate ral failure of the horizontal gaze-holding system: in the light, each saccade was followed by a postsaccadic drift. A unilateral injection o f NBQX caused no sign of gaze-holding failure; in the light, spontaneo us eye movements were unaffected; in complete darkness, a nystagmus wi th linear slow phases directed towards the injected side was observed. We conclude that NMDA receptors of the NPH neurones are involved in t he gaze-holding system.