Abstract
An important hallmark of the visual system are the receptive fields of its neurons, the area over which information is pooled from the visual field. We can measure this area from the population of neurons within a voxel during fMRI, referred to as the population receptive field (pRF). While recent work has begun to chart the development of these fundamental processing units within the ventral visual stream, how pRFs of the dorsal stream change with development has yet to be quantified. Here, in a set of n=18 children (5-12 years old) and n=23 adults we delineate the maps composing the human dorsal stream, beginning in V1 and ascending the intraparietal sulcus (IPS) from maps V3AB, IPS0 up to IPS1. While the volume and model fit of maps is developmentally stable, pRF properties of dorsal field maps undergo developmental changes, contrasting the stability previously measured within ventral field maps. Both the size and eccentricity of pRFs increase beginning in V3AB and age-related differences are largest in IPS1 where pRFs are 25% larger in adults compared to children (t(29)=2.1, p=0.049), and have 30% more eccentric pRF centers (t(29)=2.5, p=0.017). These developmental changes alter the way that the visual field is tiled by dorsal stream maps. From childhood to adulthood, the peripheral visual field becomes increasingly represented by dorsal stream maps, especially the ipsilateral visual field. This effect seems to increase as one ascends the dorsal stream, where eccentricities greater than 2 degrees of visual angle are 20-30% more densely covered by pRFs in adults compared to children within IPS1. Together, these findings demonstrate that the dorsal stream undergoes protracted development compared to ventral stream field maps and may suggest the fidelity of attention across the visual field may increase with development, which future studies manipulating attentional locus and scale can quantify.