Involvement of the N-methyl-D-aspartate receptors of the vestibular nucleus in the gaze-holding system of the cat.

Eye movements were recorded in alert cats after injections into one of the medial vestibular nuclei (MVN) either of a N-methyl-D-aspartate (NMDA) antagonist or of a non-NMDA antagonist. A gaze-holding failure was caused by the NMDA antagonist when it was injected into the central part of the MVN but not when it was injected into the rostral part of that nucleus. By contrast, injections of the non-NMDA-receptor antagonist into the MVN did not cause any sign of gaze-holding failure. We conclude that the NMDA receptors located in the central part of the MVN are involved in the gaze-holding system.