Time-course of S-cone system adaptation to simple and complex fields

• Published in: Vision research (Oxford) 2003-05, Vol.43 (10), p.1135-1147
• Main Authors: Shapiro, Arthur G, Beere, Jennifer L, Zaidi, Qasim
• Format: Article
• Language: English
• Subjects: Adaptation, Ocular - physiology; Biological and medical sciences; Color Perception - physiology; Eye and associated structures. Visual pathways and centers. Vision; Female; Fundamental and applied biological sciences. Psychology; Humans; Male; Psychophysics; Retinal Cone Photoreceptor Cells - physiology; Vertebrates: nervous system and sense organs
• ISSN: 0042-6989; 1878-5646
• DOI: 10.1016/S0042-6989(02)00687-9

We examine the temporal nature of adaptation at different stages of the S-cone color system. All lights were restricted to the S-cone-only (a constant L and M) cardinal axis in color space passing through mid-white ( W). The observer initially adapted to a steady uniform field with a chromaticity on the − S end of the axis or on the + S end of the axis or a complex field composed of chromaticy − S and + S (± S adaptation). The observer then readapted to a steady uniform field of chromaticity W for a variable length of time (i.e., 0, 0.1, 0.25, 0.5, 1.0, or 2.0 s). A probe–flash technique was used to measure S-cone discrimination at various points along the S-cone-only cardinal axis. This allowed estimation of the response of the S-cone system over an extended response range. Following exposure to the − S and + S uniform fields, sensitivity was maximal at or near the chromaticity of the initial adaptation field and decreased linearly away from the adapting point. The shift from + S to W occurred more rapidly than the shift from − S to W; both of these shifts can be described by a multiplicative scaling of the S-cone signal. Following ± S adaptation the threshold curve initially had a shape similar to that measured following − S adaptation, but returned rapidly to the W adaptation state. The shift following ± S adaptation cannot be described by the multiplicative model, but can be explained by a change in the shape of the non-linearity. The results suggest the existence of fast post-receptoral processes.