Facial Processing in Infancy

     The ability to detect and process faces is of paramount importance to human survival. Among all other social cues, faces are arguably the most important to humans as they convey critical information about age, sex, identity, and emotion. While the underlying mechanisms of facial processing are well documented in adult research, little is known about how these functions develop in infancy. Furthermore, little is known about the development of these mechanisms under circumstances where face processing is impaired such as in the neurodevelopmental condition, autism spectrum disorder. Research in both of these domains is necessary to provide insight into the underlying mechanisms of facial processing in infancy. 

    In the article, “Face-sensitive brain responses in the first year of life” by Conte et al., the researchers sought to discover the underlying brain regions responsible for facial processing during the first year of age. To do this, they analyzed changes in event-related potential (ERP) responses of infants aged 4.5 to 12 months as they viewed images of faces and objects. The researchers found that certain ERP components such as the P1 and N290 demonstrate specificity for human faces. These components elicited larger responses to faces than objects, and this response was primarily found in the lingual and middle/posterior fusiform gyri. The research findings by Conte et al. are particularly important because they open doors to building greater understandings of circumstances where facial processing is impaired. One significant example of this is in the neurodevelopmental condition, autism spectrum disorder. By comparing ERP responses of neurotypical infants with ERP responses of infants at high risk for developing autism, researchers can begin to find neurological markers for susceptibility to autism. 

    In the article, “Neural and behavioral indices of face processing in siblings of children with autism spectrum disorder (ASD): A longitudinal study from infancy to mid-childhood” by Shephard et al., the researchers investigated the development of facial processing in siblings at high and low familial risk for autism. They compared ERP responses of high and low-risk siblings at 7 months of age and again at 7 years of age. Interestingly, the researchers found that high-risk siblings for ASD demonstrated atypical P1 and N170 responses during facial processing in mid-childhood. Even more shockingly though, they discovered that atypical facial processing (as demonstrated by abnormal N170 amplitudes) and greater social-communication problems in mid-childhood were associated with atypical ERP responses during object processing, and not facial processing, in infancy. These findings suggest that compromised P1 and N170 functioning plays an important role in the development of ASD symptoms and that disruptions in object processing during infancy may influence facial processing and social functioning later in life. 

    Both of these studies look at the neurological mechanisms of facial processing during the developmental period. While Dr. Conte and her teammates studied the underlying mechanisms of facial processing in healthy infants, Dr. Shphard and her teammates studied the underlying mechanisms of facial processing in high and low-risk siblings for ASD. In both studies, the P1 and N170 (or the infant equivalent of N290) ERP components played a significant role in facial processing. As demonstrated in Dr. Shephard’s study, impaired functioning of these components acted as a significant marker for the development of ASD symptoms and diminished social functioning later in life. Taken together, these studies provide insight into the nature of face processing in infancy as well as in the developmental trajectory of face processing in ASD. 

Citations:

Conte, S., Richards, J. E., Guy, M. W., Xie, W., & Roberts, J. E. (2020). Face-sensitive brain responses in the first year of life. NeuroImage, 211, 116602. https://doi.org/10.1016/j.neuroimage.2020.116602 

Shephard, E., Milosavljevic, B., Mason, L., Elsabbagh, M., Tye, C., Gliga, T., ... & Volein, A. (2020). Neural and behavioural indices of face processing in siblings of children with autism spectrum disorder (ASD): A longitudinal study from infancy to mid-childhood. cortex, 127, 162-179.