Computational Neuroimaging: Color Signals in the Visual Pathways

This review describes measurements of visual field maps and color signals in human visual cortex. One of the most exciting advances in recent years has been the ability to measure more than a dozen visual field maps in human visual cortex. These maps are grouped into small clusters that share a common eccentricity representation; we speculate that maps within a cluster have shared visual functions. The distribution of color (cone photoreceptor) signals differs strikingly across these clusters. The cluster of maps in ventral occipital cortex responds to all three color dimensions powerfully, and lesions within these maps disturb color appearance. The ventral occipital maps appear to be essential for normal interpretation of colors. Dorsal regions receive input from all three cone classes, but dorsal color coding but the signals are quite unlike human visual perception. Quantitative measurements of the responses in these dorsal and ventral regions promise to clarify the cortical circuitry that is essential for color appearance and related color phenomena. (Neuro-ophthalmol Jpn 23: 000~000, 2006)