Walsh & Hoyt: Cortical Area V4

Visual detection of the shape of an object requires the integration of neuronal responses from pixels of the visual scene that encompass the object of regard. The visual integration to determine "form" seems to occur within the ventral visual pathway, which derives from input primarily from areas V1 and V2. An intermediate step along the ventral pathway occurs at area V4, which in humans is located in the lingual and fusiform gyri, with a caudal region that extends into area 18 of Brodmann. Area V4 receives projections from the CO-rich thin stripes and the CO-poor interstripe regions of V2. Area V4 contains a complete topographic representation of the contralateral visual field. The receptive fields of V4 are larger than those of V3, which are in turn larger than the more proximal visual cortices. The major projection of V4 is to IT (i.e., inferotemporal cortex, discussed later), but there is also a significant projection to the posterior parietal cortex.