INFLUENCE OF THE SUPERIOR COLLICULUS ON THE PRIMATE BLINK REFLEX

In this study we used microstimulation to investigate the influence of the superior colliculus on the trigeminal blink reflex. We report tha t stimulation in the intermediate to deep layers of the tectum produce d inhibition of reflex blinks at a latency of approximately 26 ms. We considered the hypothesis that the blink inhibition was mediated via t he omnipause neurons (OPNs) of the eye movement control system in the brainstem. Our results show that the least effective sites for suppres sion were in the rostral colliculus. This is inconsistent with the pre diction that OPNs should be maximally recruited from the rostral tectu m near the ''fixation zone.'' From these points and other consideratio ns, we conclude that the reflex blink suppression from the superior co lliculus is not directly mediated by the OPNs or the saccadic eye move ment circuits.