Representation of central and peripheral vision in the primate cerebral cortex: Insights from studies of the marmoset brain.

How the visual field is represented by neurons in the cerebral cortex is one of the most basic questions in visual neuroscience. However, research to date has focused heavily on the small part of the visual field within, and immediately surrounding the fovea. Studies on the cortical representation of the full visual field in the primate brain are still scarce. We have been investigating this issue with electrophysiological and anatomical methods, taking advantage of the small and lissencephalic marmoset brain, which allows easy access to the representation of the full visual field in many cortical areas. This review summarizes our main findings to date, and relates the results to a broader question: is the peripheral visual field processed in a similar manner to the central visual field, but with lower spatial acuity? Given the organization of the visual cortex, the issue can be addressed by asking: (1) Is visual information processed in the same way within a single cortical area? and (2) Are different cortical areas specialized for different parts of the visual field? The electrophysiological data from the primary visual cortex indicate that many aspects of spatiotemporal computation are remarkably similar across the visual field, although subtle variations are detectable. Our anatomical and electrophysiological studies of the extrastriate cortex, on the other hand, suggest that visual processing in the far peripheral visual field is likely to involve a distinct network of specialized cortical areas, located in the depths of the calcarine sulcus and interhemispheric fissure.