Spatial-frequency adaptation: evidence for a multiple-channel model of short-wavelength-sensitive-cone spatial vision.
The frequency selective effects of spatial adaptation were measured with vertically-oriented, cosine stimuli upon an intense long-wavelength (yellow) field, which isolated the short-wavelength-sensitive (S) cones. Consistent with isolated-S-cone spatial threshold and masking results, the adaptation measurements demonstrate S-cones input to multiple, orientation selective, spatial frequency mechanisms. Moreover, the adaptation measurements show the minimum number of S-cone mechanisms is three. The frequency tuning of each mechanism was derived from the S-cone threshold and masking results. Two of the tuning curves are bandpass with peak sensitivities in a vicinity of 0.7 and 1.4 c/deg, respectively. These two closely resemble tuning curves derived from results with luminance-modulated stimuli. Confined to the range of frequencies examined (0.25-2.83 c/deg), the third tuning curve is lowpass with a high-frequency cutoff of roughly 2.0 c/deg. However, subsequent measurements of orientation selectivity demonstrate the third mechanism to have bandpass frequency tuning as well.
Humanski
R A
RA
Department of Ophthalmology, University of Chicago, IL 60637.
Wilson
H R
HR
D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D006801:Humans; D008960:Models, Psychological; D010786:Photoreceptor Cells / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D013028:Space Perception / Q000502:physiology*