Hypersensitivity to low intensity fearful faces in autism when fixation is constrained to the eyes

Abstract

Previous studies that showed decreased social brain activation in people with Autism Spectrum Disorder (ASD) viewing expressive faces did not control that participants looked in the eye region. This is problematic because ASD is characterized by abnormal attention to the eyes. In this study, we investigated social brain activation to expressive faces when fixation was maintained in the eyes. Functional magnetic resonance imaging (fMRI) data were collected from 48 male participants (27 with ASD) viewing pictures of neutral faces and faces expressing anger, happiness, and fear at low and high intensity, with a fixation cross between the eyes. We examined group differences in whole brain activity for the contrasts fear vs. neutral, anger vs. neutral and happiness vs. neutral at high and low intensity. We also investigated group differences in neural activity in regions of interest within the social brain, including the fusiform face area (FFA), the amygdala and the ventromedial prefrontal cortex (vmPFC). For the contrast fear vs. neutral at low intensity, we found that ASD participants had more activation in the social brain than controls, and less functional coupling between the amygdala and the vmPFC than controls. We also replicated previous results and found that activation in the FFA was similar in participants with and without ASD. Our results suggest that individuals with ASD are hypersensitive to low intensity fearful faces when they look in the eyes. We speculate that this indicates an excitatory/inhibitory imbalance in their socio-affective processing system, with ASD participants being over-aroused when looking at distressed emotional faces, while lacking emotional regulation capacities. In real life, this could result in social disengagement and avoidance of eye-contact to handle feelings of over-arousal. Our results also highlight the importance of carefully controlling the gaze of participants in experiments addressing neurophysiological correlates of emotional processing in ASD.

Meeting abstract presented at VSS 2017