Abstract
Multiple regions in the human brain respond preferentially to visual face stimuli. Functionally, these regions are organized around a “core” system primarily responsible for perceptual analysis, and an “extended” system associated with non-visual functions related to emotional, semantic, and dynamic analysis of faces. Recent evidence suggests that some of these regions, specifically in the core system, undergo protracted development extending into adolescence; however, few studies have examined the development of face-processing systems using whole-brain measures. Here, we report functional MRI findings from 30 children (6–12 years), 20 adolescents (13–16 years), and 21 adults (18–40 years) tested in a simple blocked-design viewing task for faces, diverse objects, watches, and scrambled stimuli (i.e., localizer task). A region of interest (ROI) analysis focused on the right fusiform face area (rFFA), the area within the fusiform gyrus where a Faces > Objects contrast was significant (p < 0.005). Consistent with recent reports using visual recognition paradigms, FFA volume showed a linear increase with age. Regression analysis of whole-brain BOLD signal intensity showed a positive correlation of age within the right occipital face area (OFA). Thus, two primary components of the core system were positively correlated with age. In striking contrast, children produced significantly greater activation relative to adults in multiple regions outside of ventral occipital-temporal cortex, specifically in regions within the extended system, including bilateral amygdala, precuneus, and inferior frontal gyrus. The findings indicate that a prolonged developmental trajectory is observed in other face preferential regions in addition to areas in the core system. More critically, the activation patterns suggest that children do not modulate activity within the extended system during simple face viewing whereas adults limit face-preferential processing to regions in the core system. Thus, modulation of activation to faces must be a key component in perceptual development.