Within the visual system, a prominent topographic representation is the visual field map, in which the receptive fields (RFs) of adjacent neurons along the cortical surface typically receive input from adjacent points on the surface of the retina. These topographic representations are commonly thought of as fundamental organizational principles for the processing of sensory information ( Mountcastle, 1957 Kaas, 1997). We propose that V3 and V4 play a critical role in this supra-areal organization by filtering information about the visual environment along parallel pathways across higher-order cortex.Ī large portion of cortex, including auditory, motor, somatosensory, and visual cortex, consists of orderly representations of our environment along sensory surfaces. Specifically, we propose that the visuotopic organization of V3 and V4, which provides the criteria for differentiating these areas, also unifies these areas into the supra-areal organization of early visual cortex. This complicates the traditional view of these regions as individual functional “areas.” Here, we will review the criteria for defining areas V3 and V4 and will discuss functional and anatomical studies in humans and monkeys that emphasize the integration of individual visual areas into broad, supra-areal clusters that work in concert for a common computational goal. In addition, connectivity patterns across visual cortex appear to vary within these areas as a function of their supra-areal eccentricity organization. Specifically, the visuotopic organization of V3 and V4 appears to be part of a larger, supra-areal organization, clustering these areas with early visual areas V1 and V2. Yet, large-scale functional and anatomical organization patterns not only emphasize distinctions within each area, but also links across visual cortex.
Areas V3 and V4 are commonly thought of as individual entities in the primate visual system, based on definition criteria such as their representation of visual space, connectivity, functional response properties, and relative anatomical location in cortex.
0 kommentar(er)
