Abstract
Adult visual performance is better along the horizontal than vertical meridian, and along the lower than upper vertical meridian of the visual field. These perceptual asymmetries are matched by an asymmetric distribution of cortical tissue in adult primary visual cortex (V1). Children, like adults, have better visual performance along the horizontal than vertical meridian. However, unlike adults, children have similar visual performance along the upper and lower vertical meridians. Last year, we reported that children, unlike adults, have a similar V1 surface area representing the upper and lower vertical meridians. Here, we expanded our sample of children (n=17 to 25) and included a new sample of adults (n=24), whose data was collected and analyzed with the same methods as the children. We asked whether the cortical representation of the visual field differs between children and adults. Methods: We used fMRI population receptive field (pRF) mapping to measure retinotopic maps in children (5-12 yrs) and adults (≥ 22 yrs). We make these data publicly available. We calculated the amount of surface area representing different regions of the V1-V3 maps, including the polar angle meridians in V1. Results: Adults and children had ~80% more V1 surface area representing the horizontal than vertical meridian (±25° of polar angle, 1-7° eccentricity). Adults had ~40% more V1 surface area representing the lower than upper vertical meridian, whereas children had a similar surface area representing the lower and upper vertical meridian. Comparing the groups showed that children had a narrower cortical representation of the lower vertical meridian, relative to adults. Conclusion: These data provide evidence for unexpectedly large, late-stage change in the functional organization of V1. We speculate that the increase in the V1 representation of the lower vertical meridian between child- and adulthood drives the visual performance asymmetry along the vertical meridian seen in adults.