Abstract
To clarify the mechanism underlying the differences between voluntary saccade and the quick phase of optokinetic and vestibular nystagmus, the characteristics of the adducting and abducting eye movements were verified. During alternating saccades to lateral fixation targets, the adducting eye started behind the abducting eye, but quickly overtook it, reaching the fixation target first. The small delay in the onset of the adducting movement could be attributed to one more neural tract that the lateral fixation cue drives than the abducting eye. The quick-phase movements during optokinetic and caloric nystagmus showed similar characteristics, although during caloric stimulation, the abducting eye sometimes was not overtaken by the adducting eye. This likely reflects the different firing patterns of the burst neurons caused by the different neural circuits.
