Association between amygdala response to emotional faces and social anxiety in autism spectrum disorders

Abstract

Difficulty interpreting facial expressions has been reported in autism spectrum disorders (ASD) and is thought to be associated with amygdala abnormalities. To further explore the neural basis of abnormal emotional face processing in ASD, we conducted an fMRI study of emotional face matching in high-functioning adults with ASD and age, IQ, and gender matched controls. In addition, we investigated whether there was a relationship between self-reported social anxiety and fMRI activation. During fMRI scanning, study participants were instructed to match facial expressions depicting fear or anger. The control condition was a comparable shape-matching task. The control group evidenced significantly increased left prefrontal activation and decreased activation in the occipital lobes compared to the ASD group during emotional face matching. Further, within the ASD group, greater social anxiety was associated with increased activation in right amygdala and left middle temporal gyrus, and decreased activation in the fusiform face area. These results indicate that level of social anxiety mediates the neural response to emotional face perception in ASD.

Figure 1

Between group differences in fMRI activation for the contrast emotional face matching > shape matching. The control group evidenced significantly greater activation in the left prefrontal cortex (blue cluster) whereas the ASD group had significantly greater activation in the occipital lobes (red cluster). All contrasts were corrected for multiple comparisons using cluster threshold correction.

Figure 2

Green clusters signify brain regions showing a significant (p < .05, corrected) correlation between the total score on the Social Anxiety and Distress Scale and activation during the emotional face matching task for the ASD group. Scatter plots are provided for descriptive purposes. For each subject, a mean z-score was obtained by averaging the z-score of all voxels for that participant within the mask, which was defined by significant activation on the group map. Row “A” is the right amygdala cluster (r = .364), row “B” is the right FFA cluster (r = −.450), and row “C” is the left middle temporal gyrus cluster (r = .630). Additional statistical information is provided in Table 3.