Neurodevelopmental trajectories of face processing in infants: A review and future directions.

This research review looked at how babies' brains respond to faces over the first few years of life. Scientists used special brain monitoring to see differences between babies who later develop autism and those who don't. While these differences might not show up in a single test, tracking babies over time reveals distinct patterns. This research could help identify autism earlier, which is important for getting support services sooner.

This comprehensive review examines 25 years of research on brain responses to faces in infants, focusing on ERP biomarkers (N290, P400, and Nc components). The review synthesizes findings from neurotypical infants and those at risk for or diagnosed with autism spectrum disorder. Key findings indicate that infants at high risk for ASD and those who develop ASD show measurable differences in brain activity when processing faces compared to low-risk infants. While single time-point studies may not detect differences, longitudinal approaches with varied stimuli and source localization techniques reveal distinct patterns.

The authors propose using these neural signatures as potential biomarkers for early ASD prediction and present a novel hypothesis about developmental trajectories in face and non-face processing across neurotypical and ASD populations.

ERP biomarkers of face processing may facilitate earlier autism identification, enabling prompt intervention. However, clinical application requires validation studies and standardized protocols. Current evidence supports continued research into neural biomarkers but is not yet ready for routine clinical screening.

The review does not specify sample sizes, methodological details of included studies, or statistical power. As a narrative review rather than systematic review, selection bias may affect conclusions. The predictive validity of proposed biomarkers requires further validation in prospective studies.

Face perception is integral for social development in infancy, and for skills such as joint attention, recognition, and emotion processing. This review synthesizes research findings over the past 25 years related to ERP biomarkers of face perception in infants. We review this literature as it relates to face perception in neurotypical infants and those at risk for, or diagnosed with, autism spectrum disorder (ASD). Future research may be able to utilize these neural signatures of face processing as 'biomarkers' to predict which infants are most likely to develop ASD, which is important for early diagnosis and intervention.

The N290, P400, and Nc have all been highlighted as ERP components which relate to face processing. We discuss how nuances in these three components respond to face versus non-face stimuli and to emotional facial expressions in neurotypical (NT) infants. Evidence suggests that infants at high risk for ASD and those who go on to develop ASD have measurable differences in brain activity in response to faces compared to those at low risk and who do not go on to have ASD. Although differences in brain activity while viewing faces may not be observed between infants at high risk for ASD and those without at a single time point, longitudinal studies, studies with more varied stimuli, and studies utilizing source localization have uncovered differences.

Finally, we present a novel hypothesis about developmental trajectories in both neurotypical children and those with ASD related to both face and non-face processing.