title: The effects of adaptation to visual stimuli on the velocity of subsequent ocular following responses.
abstract: We examined the effect of prior adaptation to moving and flickering stimuli on the velocity of subsequent ocular following responses in man. Experiments consisted of two phases: an adaptation phase in which moving or flickering stimuli were presented while the eyes fixated a small spot and a test phase in which ocular following responses were free to occur. The effects resulting from prior adaptation were characterized by determining the mean initial eye velocities in the period 200-500 ms after the onset of the test stimulus. It was found that 8 s of prior exposure to a grating pattern moving at between 1.5 and 4 cycles.s-1 significantly reduced initial eye velocities in all subjects. Prior exposure to a flickering stimulus (temporal frequency 3.2 cycles.s-1) also attenuated the velocities of initial eye movements, but to a far lesser extent. These results suggest that a motion-dependent and a weaker flicker-dependent process have an adaptive influence on the generation of ocular following responses. Initial eye velocities were measured as a function of the contrast of the prior adapting gratings. The velocities were found to decrease with increasing adapting contrast. The reductions in eye velocity were well described by a decaying exponential function. The motion-dependent adaptive effect showed significant inter-ocular transfer and had the same temporal tuning when transferred (i.e. optimum adaptation at between 1.5 and 4 cycles.s-1). The flicker-dependent effect did not show inter-ocular transfer. There is a distinct similarity between the adaptive process that causes attenuation of ocular following velocities and the adaptive mechanism that induces perceptual motion after-effects. This similarity is discussed.
authors.affiliation: Centre for Visual Science, Research School of Biological Sciences, Australian National University, Canberra.
authors.forename: M R
authors.initials: MR
authors.lastname: Ibbotson
authors.forename: T
authors.initials: T
authors.lastname: Maddess
mesh_terms: D000054:Acceleration; D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D005366:Figural Aftereffect / Q000502:physiology; D006801:Humans; D007259:Infrared Rays; D009039:Motion Perception / Q000502:physiology; D009760:Nystagmus, Physiologic / Q000502:physiology*; D010775:Photic Stimulation; D015348:Vision, Binocular / Q000502:physiology