ERP Response to Affective Pictures in Children and Adolescents with Autism Spectrum Disorders

Background: Previous research demonstrates that children with autism spectrum disorders (ASD) are typically unresponsive to socio-affective cues such as facial expressions, tone of voice, and emotional subtleties (Grèzes et al., 2009). The neural bases of these deficits remain poorly understood but can be explored utilizing electroencephalogram (EEG) and event-related potentials (ERP) to affective stimuli. The late positive potential (LPP) is an ERP component that reflects facilitated attention directed at emotionally relevant stimuli and has a greater magnitude when individuals view emotionally salient information compared to neutral stimuli (Foti & Hajcak, 2008). The P300 reflects a change in context and motivated attention toward emotionally relevant information (Hajcak, MacNamara & Olvet, 2010). Although children with ASD display impaired social and emotional reciprocity (Bal et al., 2010) the neural correlates of affect recognition have not been thoroughly examined.

Objectives: We investigated the hypothesis that children with ASD will display decreased neural activity relative to typically-developing children when viewing unpleasant affective pictures relative to pleasant or neutral pictures.

Methods: Participants included 29 children and adolescents (3 females) ages 11-16 and diagnosed with an ASD, compared to 21 healthy controls (CON group, 4 females) matched on age (M = 14.2 years) and IQ (mean =108). Electroencephalogram data were collected while participants viewed pictures collected from the International Affective Picture System (IAPS; Lang, Bradley, & Cuthbert, 2001) depicting positive, neutral and negative scenes. The participants viewed 13 scenes of each type, presented 4 times each for 2000 ms followed by a fixation point for 500 ms. The P300 was quantified as the mean amplitude from 400ms to 600ms; the LPP was quantified as the mean amplitude from 600ms to 800ms. 

Results: A 2-Group x 3-Valence ANOVA on LPP amplitudes revealed a significant main effect of valence with larger amplitudes for pleasant and negative pictures relative to neutral pictures (p<.05) but no differences between pleasant and negative valence. There were no significant main effects or interactions as a function of group. Analysis of the P300 showed a trend-level effect for valence and no effects of group or group x valence interaction; pleasant and unpleasant pictures both had higher P300 amplitudes than neutral pictures but showed no differences between each other.

Conclusions: The results indicate that the pictures presented differentiated neural activity to affective picture scenes (i.e., pleasant or unpleasant pictures) relative to neutral pictures, when collapsed across group. There were no between-group differences for diagnosis nor group x condition interactions. Our results indicate that children with ASD process pictures of affective information in a manner similar to that of typically-developing children and do not show decreased attentional bias toward these pictures.