THE REPRESENTATION OF BRIGHTNESS IN PRIMARY VISUAL-CORTEX

Although neurons in primary visual cortex are sensitive to the spatial distribution and intensity of light, their responses have not been th ought to correlate with the perception of brightness. Indeed, primary visual cortex is often described as an initial processing stage that s ends information to higher cortical areas where perception of brightne ss, color, and form occurs. However, a significant percentage of neuro ns in primary visual cortex were shown to respond in a manner correlat ed with perceived brightness, rather than responding strictly to the l ight level in the receptive fields of the cells. This finding suggests that even at the first stage of visual cortical processing, spatial i ntegration of information yields perceptual qualities that are only in directly related to the pattern of illumination of the retina.