Functional connectivity of the human face network exhibits right hemispheric lateralization from infancy to adulthood.

Adults typically exhibit right hemispheric dominance in the processing of faces. In this cross-sectional study, we investigated age-dependent changes in face processing lateralization from infancy to adulthood (1-48 years old; N = 194). We co-registered anatomical and resting state functional Magnetic Resonance Imaging (fMRI) scans of toddlers, children, adolescents, and adults into a common space and examined functional connectivity across the face, as well as place, and object-selective regions identified in adults. As expected, functional connectivity between core face-selective regions was stronger in the right compared to the left hemisphere in adults. Most importantly, the same lateralization was evident in all other age groups (infants, children, adolescents) and appeared only in face-selective regions, and not in place or object-selective regions. These findings suggest that the physiological development of face-selective brain areas may differ from that of object and place-selective areas. Specifically, the functional connectivity of the core-face selective regions exhibits rightward lateralization from infancy, years before these areas develop mature face-selective responses.

Rapid forgetting of faces in congenital prosopagnosia.

Congenital prosopagnosia (CP) is a life-long impairment in face recognition that occurs in the absence of any known brain damage. It is still unclear whether this disorder is related to a visual deficit, or to an impairment in encoding, maintaining or retrieving a face from memory. We tested CPs and matched neurotypical controls using a delayed estimation task in which a target face was shown either upright or inverted. Participants were asked to select the target face out of a cyclic space of morphed faces that could either resemble the target face, or not. The inclusion of upright and inverted faces enabled to examine the extent of the face inversion effect, a well-known face specific effect often associated with holistic processing. To enable disentangling visual from mnemonic processing, reports were required either following 1 and 6 sec retention interval, or simultaneously while the target face was still visible. Controls showed slower forgetting of upright compared to inverted faces. In contrast, CPs exhibited rapid forgetting of upright faces that was comparable to their performance and to performance of controls on inverted faces. Such forgetting was evident in random errors in which the selected faces did not resemble the face in memory, implying a time related decrease in the probability to access the correct face in memory. Importantly, CPs exhibited no inversion effect across all retention intervals, including the simultaneous one, suggesting that their abnormal rapid forgetting could be explained by an impairment in holistic visual processing of upright faces.