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Young Adults’ Autistic Behaviors Predict N170 Responses to Emotional Faces
Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by deficits in communication and social interaction. ASD individuals show impairments in emotion identification, especially for negative and complex emotions. This deficit may be related to neural differences in the processing of faces; previous psychophysiological research suggests that autistic individuals show differences in activity in brain areas necessary for facial recognition than non-autistic individuals. In particular, the N170 event-related potential (ERP) has been established to be sensitive to the neural processing of faces. Thus, examining N170 activity during face processing may help reveal the neural correlates of early emotion identification in autism.
Objectives: The purpose of the current study was to test whether the neural processing of emotional facial expressions differs as a function of levels of autistic traits and differs based on task type in a neurotypical adult population. Because ASD is a spectrum condition, using non-clinical samples of individuals on the broader autism phenotype (BAP) can help us understand emotion processing related to ASD. Studying low and high BAP individuals allows us to isolate the effects of autistic traits on emotional processing between groups that are well-matched, limiting confounding variables between groups. The current study uses both full-face and eye region stimuli to control for known behavioral scanning differences and to isolate the resulting impact on neural activity.
Methods:
Neurotypical participants (n=34) completed an emotion identification task while EEG data were recorded. For each trial, a face depicting an emotion (happy, angry, fear, surprise) or a neutral expression was presented for 1000 ms; an inter-stimulus interval of 500 ms was used between trials. In half of the trials, participants indicated if the emotion of the face matched that of the face presented before it (matching task). In the other trials, participants indicated if the emotion of the face was positive or negative (valence task). Each participant completed the Broad Autism Phenotype Questionnaire (BAPQ) to measure their level of autistic traits.
Results:
A 5 (Emotion: Angry, Fear, Happy, Neutral, Surprise) x 2 (Task: Valence, Matching) x 2 (BAPQ: Low, High) mixed model Analyses of Variance (ANOVA) was conducted. For the matching trials, there were no significant effects. For the valence task, however, there was a significant Emotion x BAPQ interaction, F(4,88) = 3.83, p = .025. Simple main effects analyses revealed that for the fear trials, low BAPQ participants demonstrated a larger amplitude N170 than high BAPQ participants, t = -2.68, p = .014. Furthermore, correlational analyses revealed that BAPQ was significantly correlated with N170 amplitude for angry faces, r = .37, p = .033.
Conclusions:
These results provide a better understanding of neural activity during emotion processing for those on the BAP and add to work investigating the neural underpinnings of emotion processing deficits for ASD individuals. By studying social processing within the wider context of the BAP, we are better able to evaluate specific autism-associated behaviors in isolation of other clinical features as well as include a broader community of persons with autistic traits.