Some colors appear “warm”, others “cool”. This distinction is universal across cultures and languages, but its neural basis is unknown. Recent work demonstrated the existence of systematic hue maps in the primate visual cortex, in which peaks of regions activated by perceptually similar hues tend to be near each other. Here I show that the spatial activation patterns elicited in the primate striate cortex (area V1) by warm and cool hues differ. Stimuli associated with them also have opposite (L-M) cone contrasts: warm hues positive, cool hues negative. My results suggest that the hue maps in area V1 play an important role in color perception, and contribute to the perceptual distinction between warm and cool colors.
The relative angular distances separating hues in the CIELUV chromaticity diagram represent the perceptual distances separating these hues, but the neural basis for establishing these perceptual distances is unknown. Here I also show that the relative hue angles in the CIELUV chromaticity diagram can be accounted for by the spatial activation patterns elicited in area V1. These additional results suggest that the hue maps in area V1 play an important role in color perception, and contribute to the perceptual distances between hues. The very high and dependable correlation between hue angles in the CIELUV chromaticity diagram and corresponding angles found in the spatial activation patterns in V1 (in the principal components of variation in the spatial activation patterns) combined with the nearly congruent transformation of the geometry of hue space that was observed, suggest that the familiar “color wheels” exist already in V1. Noise in the cortical images would necessarily cause a slight departure from topological closure in these “color wheels.” In fact, this is what was observed.
Responses to chroma in V1 were also investigated. The Euclidean distances separating hues from the achromatic point in the CIELUV chromaticity diagram are a measure of chroma. Finally, I also show that the distances of hues from the achromatic point in the CIELUV chromaticity diagram reveal themselves in the elicited spatial activation patterns in V1. The very high and dependable correlation between perceptual distances separating both hues and chromas, individually, with the spatial activation patterns in V1 suggest that perceptually uniform chromaticity maps exist in V1.
|Advisor:||Kaplan, Ehud, Brezina, Vladimir|
|Commitee:||Brezina, Vladimir, Casti, Alex, Gordon, James, Uglesich, Robert|
|School:||Mount Sinai School of Medicine of New York University|
|School Location:||United States -- New York|
|Source:||DAI-B 71/07, Dissertation Abstracts International|
|Keywords:||Color, Color temperature, Color wheel, Map, Perception, Primate striate cortex|
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