Event-related activation in the human amygdala associates with later memory for individual emotional experience

The role of the amygdala in enhancing declarative memory for emotional experiences has been investigated in a number of animal, patient, and brain imaging studies. Brain imaging studies, in particular, have found a correlation between amygdala activation during encoding and subsequent memory. Because of the design of these studies, it is unknown whether this correlation is based on individual differences between participants or within-subject variations in moment-to-moment amygdala activation related to individual stimuli. In this study, participants saw neutral and negative scenes and indicated how emotionally intense they found each scene. Separate functional magnetic resonance imaging responses in the amygdala for each scene were related to the participants' report of their experience at study and to performance in an unexpected memory test 3 weeks after scanning. The amygdala had the greatest response to scenes rated as most emotionally intense. The degree of activity in the left amygdala during encoding was predictive of subsequent memory only for scenes rated as most emotionally intense. These findings support the view that amygdala activation reflects moment-to-moment subjective emotional experience and that this activation enhances memory in relation to the emotional intensity of an experience.