Face-Selective Responses in FFA and MPFC Emerge Early in Human Infancy

Faces are a rich source of social information that activate many different regions in the human brain. How do these regions develop? According to one prominent hypothesis, face selectivity must emerge in visual regions (e.g., the fusiform face area (FFA)) prior to regions in higher-order association cortex (e.g., the medial prefrontal cortex (MPFC)). To test this hypothesis, we combined functional magnetic resonance neuroimaging (fMRI) datasets from awake human infants (total n=65 infants, aged 2.6-11.9 months) while they watched movies of faces, bodies, objects, and scenes. The youngest and oldest infants in this group had face-selective responses in both the ventral temporal cortex (the approximate location of adult FFA) and MPFC. Although the overall magnitude of responses to visual stimuli increased with age in FFA, face selectivity did not increase significantly with age in either region. Taken together, these results do not support the hypothesis that cortical function develops in visual regions like FFA prior to amodal regions like MPFC, instead suggesting that face-selective responses emerge in parallel across the brain.