Developmental Differences in the N170 in Individuals with Autism Spectrum Disorder

Background:

Individuals with autism spectrum disorder (ASD) demonstrate deficits in processing both high and low intensity emotions in faces (Garman et al., 2016). However, changes in efficiency of processing across development remain unclear. The N170 event-related potential (ERP) component, recorded via electroencephalogram (EEG), is an early neural index of face processing (Bentin et al., 1996; Eimer, 2000; Nelson & McCleery, 2008). Previous research has shown that as children increase in age (regardless of ASD status), their N170 latencies decrease until age ~11 (Batty & Taylor, 2006 Hileman et al., 2011; Batty et al., 2011). However, in typically developing (TD) children, this process seems to plateau around age 14 (Batty & Taylor, 2006). No known studies have examined the relationship between N170 latencies and facial processing from childhood into adulthood. Additionally, previous research using the Diagnostic Analysis for Nonverbal Accuracy-2 (DANVA-2; Nowicki, 2004), a standardized paradigm assessing facial emotion recognition, has demonstrated that N170 latencies to high and low intensity emotional face stimuli are slower in ASD compared to TD individuals (McPartland et al., 2011). Studies have not examined how deficits in facial emotion processing or symptom severity in individuals with ASD may affect the relationship between age and N170.

Objectives:

The current study 1) examined if age correlated with N170 latencies in response to high and low intensity emotional facial stimuli in a sample of individuals with ASD spanning childhood and adulthood. Additionally, 2) we examine whether ASD severity and performance on the emotion recognition task, moderated the relationship between age and N170.

Methods:

Thirty-seven individuals (29 male; M_age = 17.62 SD_age = 8.55) with ADOS-2-confirmed ASD, completed the DANVA-2 emotion recognition task while concurrent EEG was recorded. N170 latency to high and low intensity faces were extracted. Additionally, the Social Responsiveness Scale (SRS; Constantino & Gruber, 2005) was administered to adult participants as well as parents of youth participants to measure ASD symptom severity.

Results:

Age correlated negatively with N170 latency to overall faces (-0.415 p = 0.011) as well as to high intensity faces (r = -0.332 p = 0.045) and low intensity faces (r = -0.375 p = 0.022). Neither SRS-2 scores nor errors made on the DANVA-2 moderated the relationship between age and N170 latency to overall, high intensity, or low intensity faces.

Conclusions:

N170 latencies to overall emotional faces were negatively correlated with age from childhood into adulthood. Additionally, the relationship between age and N170 was not moderated by ASD severity nor DANVA-2 performance. These results suggest that individuals with ASD evince increased processing efficiency (shorter N170 latency) with age regardless of level of ASD symptomatology or performance on the emotion recognition task. These findings also indicate that neurodevelopment of basic face processing (across levels of emotional intensity) may continue in individuals with ASD beyond the period in which this is evident in TD individuals. As such, this intimates the possibility of either delayed development of social-emotional neural systems, opportunities for enduring neuroplasticity (and therefore intervention) into young adulthood in this population, or both.