Differential amygdala response to lower face in patients with autistic spectrum disorders: An fMRI study

Abstract

Much functional neuroimaging evidence indicates that autistic spectrum disorders (ASD) demonstrate marked brain abnormalities in face processing. Most of these findings were obtained from studies using tasks related to whole faces. However, individuals with ASD tend to rely more on individual parts of the face for identification than on the overall configuration. Therefore, this neuroimaging evidence might reflect differential visual attention systems in face recognition. It was hypothesized that differential brain function is shown between ASD and control participants with face recognition tasks presenting parts of faces separately. Nine adults with high-functioning ASD and 24 age-matched normal comparison participants were studied using a 3T-MR scanner. We investigated brain activation when processing whole faces and parts of faces displaying positive or negative expressions. The control group showed bilateral amygdalae activation to the whole face, but not to parts of the face. The ASD group showed bilateral amygdalae activation to the lower face (mainly mouth region), but not to the whole face and upper face (mainly eye region). These findings suggest that differential amygdala function for face processing exists in ASD. This aberrant amygdala function might cause abnormalities in gaze processing or recognition of emotional expressions, shown clinically in ASD.