Comparing visual cortex of children and adults reveals a late-stage change in the architecture of V1

Abstract Adult visual ability differs markedly with stimulus polar angle location: relative to fixation, visual performance is best for stimuli along the horizontal, intermediate for stimuli along the lower vertical, and poorest for stimuli along the upper vertical meridian of the visual field. These polar angle asymmetries in visual performance are paralleled by cortical asymmetries in the visual field representation in primary visual cortex (V1). Whereas children, like adults, have better performance for stimuli along the horizontal than vertical meridian, children show no difference in performance for stimuli along the lower vs upper vertical meridian. Is the difference in visual performance between children and adults matched by a difference in the amount of V1 surface area representing these regions? We used fMRI to measure the distribution of cortical surface representing the visual field in children (n=24) and adults (n=24). Two properties of the V1, V2, and V3 maps were mature in children –overall map surface area and surface area variation as a function of eccentricity. Further, like adults, children had greater V1 surface area representing the horizontal than vertical meridian. However, unlike adults, children did not have greater V1 surface area representing the lower than upper vertical meridian. These data indicate a late-stage change in the architecture of V1 that may drive the emergence of a visual performance asymmetry along the vertical meridian by adulthood.