Neural representation of form-contingent color filling-in in the early visual cortex

• Published in: Journal of vision (Charlottesville, Va.) Va.), 2017-11, Vol.17 (13), p.10-10
• Main Authors: Hong, Sang Wook, Tong, Frank
• Format: Article
• Language: English
• Subjects: Adult; Color Perception - physiology; Female; Humans; Illusions; Magnetic Resonance Imaging; Male; Neurons - physiology; Photic Stimulation; Retina - physiology; Surface Properties; Visual Cortex - physiology
• ISSN: 1534-7362; 1534-7362
• DOI: 10.1167/17.13.10

Perceptual filling-in exemplifies the constructive nature of visual processing. Color, a prominent surface property of visual objects, can appear to spread to neighboring areas that lack any color. We investigated cortical responses to a color filling-in illusion that effectively dissociates perceived color from the retinal input (van Lier, Vergeer, & Anstis, 2009). Observers adapted to a star-shaped stimulus with alternating red- and cyan-colored points to elicit a complementary afterimage. By presenting an achromatic outline that enclosed one of the two afterimage colors, perceptual filling-in of that color was induced in the unadapted central region. Visual cortical activity was monitored with fMRI, and analyzed using multivariate pattern analysis. Activity patterns in early visual areas (V1-V4) reliably distinguished between the two color-induced filled-in conditions, but only higher extrastriate visual areas showed the predicted correspondence with color perception. Activity patterns allowed for reliable generalization between filled-in colors and physical presentations of perceptually matched colors in areas V3 and V4, but not in earlier visual areas. These findings suggest that the perception of filled-in surface color likely requires more extensive processing by extrastriate visual areas, in order for the neural representation of surface color to become aligned with perceptually matched real colors.