Spectral sensitivity of dichromats: role of postreceptoral processes.
Increment spectral sensitivity functions were determined for dichromatic subjects; these functions were interpreted in the context of parvo and magno pathways. Increments of either 200 or 10 msec in duration were presented on a spatially coincident, 1000 td white background. When compared to the control trichromatic data, the 200 msec functions of dichromats manifest a reduction in sensitivity at middle and long wavelengths. These data are consistent with the notion that 200 msec threshold increments reveal the sensitivity of the parvo pathway; the sensitivity of this pathway is reduced in dichromacy due to pigment replacement with a resultant loss of spectral opponency. The 10 msec functions of dichromats do not show a comparable reduction in sensitivity. Therefore, it is concluded that 10 msec increments reveal the sensitivity of a pathway whose spectral-opponent status is not substantially altered in dichromacy, presumably the magno pathway.
Department of Biomedical Sciences, Southern College of Optometry, Memphis, TN 38104.
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Schwartz
D000328:Adult; D003118:Color Perception / Q000502:physiology*; D003117:Color Vision Defects / Q000503:physiopathology / Q000523:psychology*; D006801:Humans; D008297:Male; D011601:Psychophysics; D013997:Time Factors; D014795:Visual Pathways / Q000503:physiopathology*