Vision drives the neural construction of a two-stage hierarchy of spatial processing in infancy

Here, we demonstrate the critical role of developmental vision in the origins of a neural processing hierarchy in which somatosensory events are mapped from somatotopic locations onto a body representation with respect to external space. Both sighted and severely visually impaired infants showed prominent contralateral somatosensory activation in uncrossed- and crossed-hands postures in the early feedforward stages of processing (45-65 ms). By 105-120 ms following the somatosensory stimulus, anatomically ipsilateral activation was observed in the crossed-hands posture in sighted infants only, which was directly related to behavioral orienting toward the incorrect hand, reflecting a remapping of touches with reference to the position of the limbs in external space. Severely visually impaired infants exhibited a somatosensory response that was persistent contralateral across early and later processing stages, with the early responses associated with behavior. These findings demonstrate how visual experience in early postnatal development constructs the neural-behavioral basis of embodied spatial perception.