Influence of emotional expression on memory recognition bias: a functional magnetic resonance imaging study.

Background: Most studies of the influence of emotion on memory performance have focused on accuracy. However, there is evidence that emotion can influence other aspects of memory, in particular response bias (overall tendency to classify items as new or old regardless of the accuracy of the response). Here we investigated the behavioral and neural-related modulation of response bias by emotion. Methods: Nineteen healthy individuals performed a recognition memory task on faces with happy, sad, and neutral expressions while undergoing functional magnetic resonance imaging (fMRI). Results: We observed a familiarity (tendency to say "old") and novelty (tendency to say "new") bias for sad and happy faces, respectively. Novelty response bias was associated with amygdala and prefrontal cortex activity, whereas familiarity bias correlated with superior temporal gyrus activation. Conclusions: These results show that emotional expressions can have an influence on memory beyond simple accuracy and that this effect is in part mediated by the amygdala, a region previously implicated in emotional perception and memory. Our findings might have important clinical relevance, because they could help explain some of the inconsistencies in the literature regarding emotional memory deficits in psychiatric populations.