The functional connectivity between amygdala and extrastriate visual cortex activity during emotional picture processing depends on stimulus novelty.

Enhanced perceptual processing of emotional stimuli may be accomplished via amygdala-back-projections into the inferior temporal cortex. In the current study, we investigated the influence of stimulus novelty on the covariation between these brain regions during emotional picture processing. Participants viewed repeatedly presented and novel emotional and neutral pictures during fMRI-scanning. The amygdala showed stronger activation to emotional arousing stimuli that decreased rapidly when the same pictures were presented repeatedly. Emotional modulation of the amygdala was reinstated when novel emotional and neutral pictures were presented. Inferior temporal cortex (ITC) showed increased activation during processing of emotional stimuli irrespective of picture repetition. ITC and amygdala activity were highly correlated only during processing of novel emotional pictures. Therefore, we concluded that enhanced perceptual processing of emotional stimuli is triggered by an initial significance detection and corresponding feedback information by the amygdala but is maintained by other mechanisms.