Naso-temporal asymmetry of the N170 for processing faces in normal viewers but not in developmental prosopagnosia

Some elementary aspects of faces can be processed before cortical maturation or after lesion of primary visual cortex. Recent findings suggesting a role of an evolutionary ancient visual system in face processing have exploited the relative advantage of the temporal hemifield (nasal hemiretina). Here, we investigated whether under some circumstances face processing also shows a temporal hemifield advantage. We measured the face sensitive N170 to laterally presented faces viewed passively under monocular conditions and compared face recognition in the temporal and nasal hemiretina. A N170 response for upright faces was observed which was larger for projections to the nasal hemiretina/temporal hemifields. This pattern was not observed in a developmental prosopagnosic. These results point to the importance of the early stages of face processing for normal face recognition abilities and suggest a potentially important factor in the origins of developmental prosopagnosia.