Grating and plaid chrominance motion influences the suppressed ocular following response

INVOLUNTARY eye movements to foveal stimulation were measured in a monkey w hile it performed a fixation task. Second-order plaid motion generated high er velocities of eye movements than did first-order gratings, yet the laten cy of the early following response was no different for grating or plaid mo tion. Nevertheless, early suppressed ocular following responses to isolumin ant motion continue to be titrated by stimulus velocity and spatial frequen cy. Motion defined by 60% luminance contrast gratings and plaids generated a motion signal gain of 60% over chrominance motion. The 20% longer latency of eye movements to chrominance motion may reflect the longer conduction l atency of the parvocellular channel and an additional stage in cortical pro cessing en route to motion areas and eye movement control. (C) 1999 Lippinc ott Williams & Wilkins.