Abstract
BackgroundGeneralized social anxiety disorder (gSAD) is associated with a heightened neural sensitivity to signals that convey threat, as evidenced by exaggerated amygdala and/or insula activation when processing face stimuli that express negative emotions. Less clear in the brain pathophysiology of gSAD are cortical top down control mechanisms that moderate reactivity in these subcortical emotion processing regions. This study evaluated amygdala, insula, and anterior cingulate cortex (ACC) activity in gSAD with a novel “Emotional Faces Shifting Attention Task” (EFSAT), an adaptation of perceptual assessment tasks well-known to elicit amygdala response. In healthy volunteers, the task has been shown to engage the amygdala when attention is directed to emotional faces and the ACC when attention is directed to shapes, away from emotional faces.MethodsDuring functional MRI, 29 participants with gSAD and 27 healthy controls viewed images comprising a trio of faces (angry, fear, or happy) alongside a trio of geometric shapes (circles, rectangles, or triangles) within the same field of view. Participants were instructed to match faces or match shapes, effectively directing attention towards or away from emotional information, respectively.ResultsParticipants with gSAD exhibited greater insula, but not amygdala, activation compared to controls when attending to emotional faces. In contrast, when attention was directed away from faces, controls exhibited ACC recruitment, which was not evident in gSAD. Across participants, greater ACC activation was associated with less insula activation.ConclusionsEvidence that individuals with gSAD exhibited exaggerated insula reactivity when attending to emotional faces in EFSAT is consistent with other studies suggesting that the neural basis of gSAD may involve insula hyper-reactivity. Furthermore, greater ACC response in controls than gSAD when sustained goal-directed attention is required to shift attention away from social signals, together with a negative relationship between ACC and bilateral insula activity, indicate the ACC may have served a regulatory role when the focus of attention was directed to shapes amidst emotional faces.
Highlights
Generalized social anxiety disorder is associated with a heightened neural sensitivity to signals that convey threat, as evidenced by exaggerated amygdala and/or insula activation when processing face stimuli that express negative emotions
In a recent study [59], we demonstrated the modification was successful as healthy volunteers engaged the amygdala to “Match Faces” and the rostral anterior cingulate cortex (ACC) to “Match Shapes” indicating the ACC effectively impeded the processing of task-irrelevant emotional faces presented alongside shapes
The main effect of Emotion showed participants were more accurate at matching fearful than angry faces (p < 0.007); no differences were evident for fearful versus happy (p = 0.13) or angry versus happy faces (p = 0.12)
Summary
Generalized social anxiety disorder (gSAD) is associated with a heightened neural sensitivity to signals that convey threat, as evidenced by exaggerated amygdala and/or insula activation when processing face stimuli that express negative emotions. As one example, when coupled with functional neuroimaging, perceptual matching tasks are designed to isolate the influence of emotional face content by contrasting a matching face condition with a sensorimotor control condition (i.e., matching shapes) and to robustly elicit amygdala response in healthy volunteers [13,14,15,16]. Building on this paradigm, studies of gSAD have shown amygdala reactivity to threat exceeds that of healthy individuals [17,18] and the extent of this reactivity has been shown to reflect symptom severity [19]
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