The amygdala's role in long-term declarative memory for gist and detail.

In humans, the emotional nature of stimuli appears to have a complex influence on long-term declarative memory for those stimuli: Whereas emotion enhances memory for gist, it may suppress memory for detail. On the basis of prior studies, the authors hypothesized that the amygdala helps mediate the above 2 effects. Long-term memory for gist and for visual detail of aversive and neutral scenes was assessed in 20 subjects with unilateral amygdala damage and 1 rare subject with bilateral amygdala damage. Comparisons with 2 control groups (15 brain-damaged and 47 healthy) provided evidence that bilateral, but not unilateral, damage to the amygdala results in poorer memory for gist but superior memory for visual details. The pattern of findings provides preliminary support for the idea that the amygdala may help filter the encoding of relevant information from stimuli that signal threat or danger.