Mai

Introduction to retinotopy

Early visual areas, located in the posterior occipital lobe, are retinotopically organized: A particular location in the early visual cortex responds to stimulation at a particular location in the visual field, while neighboring locations on the cortical surface respond to neighboring locations in the visual field. This pattern of response maps a representation of the visual field onto the cortical surface.

These early visual areas are mapped with two parameters: eccentricity and polar angle. Eccentricity indicates distance from fovea. The most posterior regions of the early visual areas has a pronounced foveal preference, while more anterior regions prefer more eccentric stimuli. In visualizations of retinotopy, eccentricity mapping appears as concentric "rings" of different colors, each denoting a different eccentricity. Polar angle indicates the angle from the horizontal meridian, so polar angle mapping shows the reversals in angular representations on the cortex, which are used in defining retinotopic maps.

Over the last 15 years, a variety of these retinotopic maps have been discovered.