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Abstract:
Abstract: Patients with fragile X (fraX) syndrome show
deficits in social interaction, particularly in maintaining mutual
eye-contact. We used fMRI to investigate the role of the amygdala
in gaze aversion, since this region has been implicated in
processing behaviorally relevant social cues. Twelve normal female
controls (ages 10-21) and 10 females with fraX (ages 10-22) were
scanned while they viewed images of faces presented in one of four
combinations of face and gaze orientation (face and gaze either
averted or directed forward). Subjects were asked to indicate by
button press if the gaze was directed at or away from them. In the
control condition, subjects viewed isoluminant scrambled images.
Relative to controls, fraX subjects showed impaired performance in
determining whether gaze was directed at them. Control subjects
showed significant task-related activation in the amygdala
bilaterally, bilateral fusiform gyri, right dorsomedial thalamus,
and the left hippocampal/parahippocampal gyrus. No significant
group activation was seen in the amygdala or other brain regions in
fraX subjects. When fraX and control subjects were compared,
controls showed greater activation in the amygdala bilaterally,
left lingual/fusiform gyrus, left hippocampal/parahippocampal
gyrus, and the cerebellar vermis. These results are the first fMRI
demonstration of amygdala involvement in gaze direction processing,
and suggest that dysfunction in the amygdala in females with fraX
may underlie impaired social functioning.
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