Intersection of spatial and numerical cognition in the developing brain.

Early mathematical development is thought to depend on visuospatial processing, yet neural evidence for this relationship in young children has been limited. We examined the neural mechanisms supporting numerical and visuospatial processing in 4- to 8-year-old children and adults using functional magnetic resonance imaging (fMRI), with three tasks: numerical matching, geometric shape matching, and number line estimation. We found that specialization for numerical and geometric processing in parietal cortex exists by 4-8 years of age, and that children exhibited greater conjunctive activation between numerical and geometric tasks throughout the parietal cortex compared to adults. During the number line task, children's neural activity significantly overlapped with activity from both number and geometric shape matching tasks, whereas adults' activity only overlapped with the number task. These findings provide the first neural evidence that number line estimation relies on both numerical and geometric processing in children, whereas it depends primarily on number-specific processing in adults.