The deficit of emotional sensitivity to facial expression in Autism Spectrum Disorder: task-based analyses and insights into intervention

Abstract

Numerous studies have indicated the common deficit of Autism Spectrum Disorder (ASD) in recognizing and understanding facial expressions, which is a major cause of the ASD’s social dysfunction. Emotional sensitivity to facial expression is a prerequisite of understanding and recognizing facial expression. However, the emotion sensitivity to facial expressions in ASD has yet to be systematically analyzed to date. After systematic analysis of existing studies about ASD and the perception of facial expression, we found that the existing literature could be sorted into three task categories: explicit observation of facial emotion, fixation-oriented observation of facial emotion, or implicit observation of facial emotion. We then analyzed the peripheral physiological and neuroimaging data of ASD and facial emotion perception under those three conditions. We found that the lack of emotion sensitivity to facial expressions was mainly observed in the explicit or fixation-oriented affect recognition tasks, either of which required intentional focus on key features of facial expression. By contrast, subjects with ASD exhibited similar or even larger amygdala activation compared to healthy subjects when implicitly processing emotional facial expressions. These results suggest that individuals with ASD are not lacking emotional sensitivity to facial expression in nature. Instead, the insufficient face adaptation and the face-specific hyperarousal that characterize ASD may lead the patients to avoid attention orienting to facial expression, which in turn leads to deficient activation in emotion-related neural circuits. Based on these evidences, we propose a new method of intervention for improving the facial emotion sensitivity in ASD patients. That is, training ASD patients to perceive emotional faces implicitly, without conscious awareness of facial emotion observation, is a potentially promising approach to improve autistic individuals’ neural sensitivity and adaptation to facial expressions. This may be an important candidate method for the intervention of autistic symptoms and the enhancement of their social functions.