Fusiform function in children with an autism spectrum disorder is a matter of "Who"

Background: Despite the importance of face processing for normal social development, no functional magnetic resonance imaging studies of face processing in autism have focused exclusively on the childhood years. To fill this gap, 45 children aged 6-12 participated in practice scans. After exclusion due to motion, 11 children with an ASD and 11 age-matched normal control subjects were included in final analyses. Methods: Stimuli consisted of pictures of a familiar adult, familiar child, stranger adult, stranger child, and objects. During the scan, children pressed a button in response to an identical face shown on two consecutive trials. On the basis of our prior research, masks of four anatomic regions of interest (ROIs) including the fusiform gyrus, amygdala, and anterior and posterior cingulate were created for each subject and manually edited for anatomic precision. Following deconvolution analyses, the number of voxels significantly active and percent signal change values that fell within each ROI mask were calculated for each subject. Results: Analyses revealed normal fusiform activity in children with autism when viewing a face of their mother or other children. In contrast, looking at stranger adult faces initiated profound deficits in that the mean number of significantly active voxels in the fusiform bilaterally was approximately 25% of that shown in typically developing children. Conclusions: A selective fusiform deficit in response only to the faces of adult strangers maybe the result of reduced attention and interest during those conditions. Face processing abnormalities found in autism beyond the fusiform likely exist.