High-Risk Infants' Behavioral and Neural Responses to Faces: An Eye-Tracking and Visual ERP Study

Background: Studies of early development in children at risk for autism spectrum disorders (ASD) have revealed that behavior from a single task or activity does not necessarily predict outcome. This seems related to the inter- and intra-individual heterogeneity in early behavior, and these individual differences are thought to be useful in specifying developmental pathways. Therefore, the effort to better understand the complex endophenotypes associated with risk and outcome requires that we begin to address the role of individual differences, as well as children's responses across a range of tasks. Objectives: The present investigation works towards these goals by (1) employing measures of visual attention and electrophysiological response to faces, and (2) exploring the role of individual differences across these two measures. The aim is to improve our understanding of the relations between children's visual scanning of faces and their electrophysiological response to them. Methods: High-density event-related potentials (ERPs) and eye-tracking tasks were administered to infants at high risk for ASD (HRA, by virtue of having at least one older sibling with ASD), as well as low-risk controls (LRC). The data reported here were collected when the infants were 12 months of age. Eye-tracking data were collected when children were presented with side-by-side images of two faces: their mother and a stranger. ERP data were collected when children were presented a series of single images (their mother and a different stranger, shown in random order). Analyses included facial regions of interest (i.e., eyes, mother only) collected during eye-tracking and relevant components in the ERP (Nc, N290 and P400). These preliminary findings are based on 8 children in the HRA group and 4 LRC. Results: For the HRA group, there were associations between the Nc (a frontal component of attention) and children's visual attention to faces. Specifically, increased attention to mothers' eyes was associated with both larger (r=-.88, p=.004) and faster (r=-.80, p=.02) Ncs to mothers' faces (versus strangers' faces). No such relation was found in the LRC group. Similarly, the HRA group demonstrated associations between a face-sensitive occipital component – the N290 – and visual attention to mothers' faces, such that increased attention to eyes was marginally associated with larger N290s to stranger (r=.67, p=.07). This trend was not observed in the LRC group. Finally, greater attention to mothers' eyes was associated with a P400 (also an occipital, face-sensitive component) that was larger to mothers' faces (versus strangers' faces, r=.75, p=.03) but only in the HRA group. Conclusions: These results suggest that in infants at high risk for ASD, there are meaningful relations between patterns of looking to faces and electrophysiological measures of attention and face-processing. In light of previous findings that atypical face scanning is common in high-risk infants, these results indicate a need to understand better the role that very early visual attention plays in functional brain development.