Functional organization for color and orientation in macaque V4

Visual area V4 in the macaque monkey is a cortical area that is strongly involved in color and shape perception. However, fundamental questions about V4 are still debated. V4 was initially characterized as a color-processing area, but subsequent studies revealed that it contains a diverse complement of cells, including those with preference for color, orientation, disparity and higher-order feature preferences. This has led to disputes and uncertainty about the role of V4 in vision. Using intrinsic signal optical imaging methods in awake, behaving monkeys, we found that different feature preferences are functionally organized in V4. Optical images revealed that regions with preferential response to color were largely separate from orientation-selective regions. Our results help to resolve long-standing controversies regarding functional diversity and retinotopy in V4 and indicate the presence of spatially biased distribution of featural representation in V4 in the ventral visual pathway.