Gaze behavior, facial emotion processing, and neural underpinnings: A comparison of adolescents with autism spectrum disorder and conduct disorder.

BACKGROUND Facial emotion processing deficits and atypical eye gaze are often described in individuals with autism spectrum disorder (ASD) and those with conduct disorder (CD) and high callous unemotional (CU) traits. Yet, the underlying neural mechanisms of these deficits are still unclear. The aim of this study was to investigate if eye gaze can partially account for the differences in brain activation in youth with ASD, with CD, and typically developing youth (TD). METHODS In total, 105 adolescent participants (NCD = 39, NASD = 27, NTD = 39; mean age = 15.59 years) underwent a brain functional imaging session including eye tracking during an implicit emotion processing task while parents/caregivers completed questionnaires. Group differences in gaze behavior (number of fixations to the eye and mouth regions) for different facial expressions (neutral, fearful, angry) presented in the task were investigated using Bayesian analyses. Full-factorial models were used to investigate group differences in brain activation with and without including gaze behavior parameters and focusing on brain regions underlying facial emotion processing (insula, amygdala, and medial prefrontal cortex). RESULTS Youth with ASD showed increased fixations on the mouth compared to TD and CD groups. CD participants with high CU traits tended to show fewer fixations to the eye region compared to TD for all emotions. Brain imaging results show higher right anterior insula activation in the ASD compared with the CD group when angry faces were presented. The inclusion of gaze behavior parameters in the model reduced the size of that cluster. CONCLUSIONS Differences in insula activation may be partially explained by gaze behavior. This implies an important role of gaze behavior in facial emotion processing, which should be considered for future brain imaging studies. In addition, our results suggest that targeting gaze behavior in interventions might be potentially beneficial for disorders showing impairments associated with the processing of emotional faces. The relation between eye gaze, CU traits, and neural function in different diagnoses needs further clarification in larger samples.