Yuzo Chino, Ph.D.
Benedict-McFadden Professor
College of Optometry, University of Houston

December 14, 2005
1220 MRB IIIl • 4:10 p.m.

Postnatal Development of Receptive-Field Center-Surround Mechanisms in V1 and V2 of Macaque Monkeys

Infants are capable of detecting and discriminating local stimulus features such as contour orientation in visual scenes soon after birth. However, the perceptual ability of infants to integrate local stimulus features over a large area (e.g., contour integration) does not emerge until relatively late in development. Implicit in these observations is that the functional connections in macaque monkeys that support crude spatial and/or temporal vision are relatively mature in V1 at birth or soon after birth, but that the functional maturation of the extrastriate visual areas that specialize in more complex perceptual tasks may be substantially delayed relative to that in V1. To begin to test this idea, we compared the relative maturation of center/surround mechanisms of V1 and V2 neurons in young infant monkeys. We found that qualitatively adult-like center/surround interactions are already present in the primary visual cortex (V1) as early as 14 postnatal days in macaque monkeys. However, the receptive-field surrounds of V2 neurons were largely absent until 4 weeks of age and, as late as 8 weeks of age, center-surround signal interactions in V2 neurons were relatively immature. Our results suggest that the cortical circuitry underlying the receptive-field centers and surrounds of individual neurons mature considerably later in V2 than in V1 and give critical evidence for the hypothesis that the functional maturation of the primate visual brain proceeds in a hierarchical manner.


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