What does post-adaptation color appearance reveal about cortical color representation?

We examine the implications of the hypothesis that color information in the cortex is adaptively coded into a factorial (statistically independent) and gain-controlled representation. We show that this hypothesis explains the results of the recent experiments by Webster and Mollon [(1991) Nature, 349, 235-238] on changes in color appearance following post-receptoral adaptation. We also give a neural network with a deterministically convergent, unsupervised learning algorithm that reproduces the adaptation observed.