The influence of stimulus chromaticity on the isoluminant motion-onset VEP.
Motion-onset visual evoked potentials (VEPs) were elicited by low spatial frequency chromatic isoluminant gratings presented in a central 7 degrees circular field. The chromatic composition of the stimuli was varied so as to modulate along different axes in colour space. For slow speeds (<5 degrees/s) changing the chromatic axis induced large response differences between the S- and L/M-cone VEPs. At faster speeds (5-12 degrees/s) the effects were not as marked. A dichotomy between the slow and fast responses was also shown to exist in terms of their contrast dependencies, the former exhibiting a stronger dependency on contrast than the latter. These findings suggest that neural substrates with chromatic sensitivity are involved in the generation of S- and L/M-cone mediated motion-onset VEPs at low velocities. At higher velocities, responses are generated by different mechanisms that possess little or no chromatic sensitivity.
McKeefry
D J
DJ
Vision Science Research Group, School of Biomedical Sciences, University of Ulster, Coleraine, N. Ireland, BT52 1SA, UK. d.mckeefry@bradford.ac.uk
D000328:Adult; D003118:Color Perception / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006801:Humans; D008029:Lighting; D009039:Motion Perception / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011601:Psychophysics; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology