Absence of fear contagion for body expression of emotion in autism spectrum disorder

Background: Social-communication deficits are one of the core symptoms of autism, and a deficit in perceiving emotional signals from others may be one of the underlying causes.

Objectives: To test the hypothesis that emotion perception difficulties in autism are not confined to faces, but also include viewing emotional states of others expressed by the whole body.

Methods: We used fMRI and compared the cortical responses of individuals with autism to the bodily expression of emotion with cortical responses of neurotypicals. To test whether behavioral and functional performance in recognition of bodies expressing emotion is associated with amygdala microstructure, we used DTI and examined differences in FA between ASD and neurotypicals.

Results: We found a lack of condition-specific activity associated with seeing fearful bodily expressions as compared to images of meaningful neutral body actions in subjects with ASD. In neurotypicals, we observed an emotional modulation of the mirror neurons system (MNS) and other brain areas, but this emotional modulation was almost absent in ASD. In addition, we found structural differences in the amygdala between subjects with ASD and neurotypicals, and observed that performance in an emotional behavioral task is correlated with amygdala microstructure.

Conclusions: Emotion expressed by the whole body (but excluding facial expressions) fails to modulate activation in visual areas and the MNS, contrary to what is found in neurotypicals. The synergies between the mechanisms underlying recognition of facial expressions and body expressions may have their source in the amygdala. An abnormality of the amygdala, by compromising basic stimulus-reward learning could lead to a lack of development of areas involved in emotional evaluation, including the MNS. An inappropriate emotional response and a deficient MNS could lead to a lack of mirror activity that could then fail to evoke somatic markers important to the generation of the feeling of emotion.