Comparing retinotopic maps of children and adults reveals a late-stage change in how V1 samples the visual field

Adult visual performance differs with angular location – it is better for stimuli along the horizontal than vertical, and lower than upper vertical meridian of the visual field. These perceptual asymmetries are paralleled by asymmetries in cortical surface area in primary visual cortex (V1). Children, unlike adults, have similar visual performance at the lower and upper vertical meridian. Do children have similar V1 surface area representing the upper and lower vertical meridian? Using MRI we measured the surface area of retinotopic maps (V1-V3) in children and adults. Many features of the maps are similar between groups, including greater V1 surface area for the horizontal than vertical meridian. However, unlike adults, children have a similar amount of V1 surface area representing the lower and upper vertical meridian. These findings reveal a late-stage change in V1 organization that may drive the emergence of the visual performance asymmetry along the vertical meridian by adulthood.