Magnification factor and receptive field size in foveal striate cortex of the monkey

Receptive field size and magnification have been studied in striate cortex of awake, behaving rhesus monkeys at visual eccentricities in the range of 5-160 min. The major findings that emerge are (1) magnification in the foveola achieves values in the range of 30 mm/deg, (2) mean field size is not proportional to inverse magnification in contrast with previous reports, and (3) the product, magnification X aggregate field size, is greater in central vision than in peripheral vision. Thus, a point of light projected onto foveal retina is "seen" by larger numbers of striate cortical cells than a point of light projected onto peripheral retina. Implications of these findings for visual localization and two-point discrimination are discussed.