6 - The Physiology of Color Vision

Abstract

This chapter deals with the physiology of color vision. It reviews the gross anatomy of the visual pathway, from the retina to the occipital cortex. The chapter then examines the physiology of the different stages, beginning with a look at the techniques used to explore it. Relatively little of this work has been undertaken on the human visual system, but a great deal has been done on the visual system of the macaque monkey, which, because its structure is similar to that of the human, is widely thought to be a good model. Recently developed methods can identify in cortex the local changes in blood flow and blood volume associated with increased neural activity. Two of these kinds of measurement, positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), have been used to investigate whether or not mechanisms of color vision are localized in particular cortical regions. The results show that a region in the fusiform gyrus, which lies between the occipital and temporal lobes, seems to be unusually active during the perception of colored patterns, though the degree to which it is specialized for the analysis of color has not been fully explored.