Simultaneous auditory stimuli shorten saccade latencies

Eye movement responses induced by vestibular, smooth pursuit, and optokinetic stimulation are largely dependent on the velocity of the stimulus. Saccade latencies, on the other hand, are a function of the anatomic and physiologic components of the reflex. By producing an audible click simultaneously with the movement of a visual target used to stimulate a saccadic eye movement, the saccade latency is significantly shortened. This does not appear to be due to alerting. It is probably due to an auditory input to the superior colliculus which decreased threshold for initiating a saccadic eye movement. Twenty normal participants were tested with or without the click stimulus. Latencies were significantly shorter when the click stimulus was presented simultaneously with the eye movement. The anatomic pathways in this reflex are reviewed in the presentation. This study provides further information on sensory interaction in saccade reflexes and emphasizes the need to control stimulus conditions during saccade testing.