Reply to: Can the N170 Be Used as an Electrophysiological Biomarker Indexing Face Processing Difficulties in Autism Spectrum Disorder?

Electrophysiological Studies of Reception of Facial Communication in Autism Spectrum Disorder and Schizophrenia

Autism spectrum disorder (ASD) and schizophrenia spectrum disorders (SZ) are characterized by difficulty with social cognition and atypical reception of facial communication - a key area in the Research Domain Criteria framework. To identify areas of overlap and dissociation between ASD and SZ, we review studies of event-related potentials (ERP) to faces across ASD and SZ populations, focusing on ERPs implicated in social perception: P100, N170, N250, and P300. There were many inconsistent findings across studies; however, replication was strongest for delayed N170 latency in ASD and attenuated N170 amplitude in SZ. These results highlight the challenges of replicating research findings in heterogeneous clinical populations and the need for transdiagnostic research that continuously quantifies behavior and neural activity across neurodevelopmental disorders.

The Unfulfilled Promise of the N170 as a Social Biomarker

BACKGROUND

Greater affordability and accessibility of noninvasive brain imaging techniques have led to an increased interest in identifying biomarkers of various cognitive processes, particularly in the field of neurodevelopmental disabilities. Autism spectrum disorder (ASD) is one area of research in which strong claims in support of brain-based biomarkers, such as the face-sensitive N170 event-related potential response, are currently emerging. This study systematically examined the possibility of the N170 amplitude and latency measures serving as a biomarker of social information processing in ASD.

METHODS

The N170 response to faces and houses was recorded during passive picture viewing in 77 children with ASD, 7 to 16 years of age, at 2 time points (before and after a social skills intervention) 3 months apart. Social functioning was assessed using standardized behavioral tests, caregiver reports, and observational measures of naturalistic social interactions.

RESULTS

The results replicated prior findings of larger N170 amplitudes in response to faces than to houses, but the associations with the behavioral measures of social functioning were modest and not consistently present across the 2 assessment time points. Neither the amplitude nor the latency of the N170 response to faces was sensitive to the effects of a social skills intervention that produced behavioral improvements.

CONCLUSIONS

The N170 is a reliable event-related potential response reflecting the sensory-perceptual stage of face processing, but it does not fit the definition of a biomarker of social deficits in ASD because it is not sufficiently informative about heterogeneity of social functioning and is not sensitive to treatment effects.