Origins of Face Responses in the Human Cortex: fNIRS and fMRI Evidence From Infants

In adults, cortical regions in the fusiform face area (FFA), superior temporal sulcus (STS), and medial prefrontal cortex (MPFC) respond selectively to faces, but underlie distinct perceptual and social processes. When do each of these regions, and their distinctive functions, develop? We review recent studies of awake human infants' cortical responses to faces using functional near infrared spectroscopy (fNIRS) and functional magnetic resonance imaging (fMRI). The results converge, and argue against slow sequential posterior-to-anterior development of face-selective responses. Instead, cortical face-selective responses arise very early and simultaneously in infancy, and may reflect distinctively social processes from the start.