As they age, adults experience less negative emotion, come to pay less attention to negative than to positive emotional stimuli, and become less likely to remember negative than positive emotional materials. This profile of findings suggests that, with age, the amygdala may show decreased reactivity to negative information while maintaining or increasing its reactivity to positive information. We used event-related functional magnetic resonance imaging to assess whether amygdala activation in response to positive and negative emotional pictures changes with age. Both older and younger adults showed greater activation in the amygdala for emotional than for neutral pictures; however, for older adults, seeing positive pictures led to greater amygdala activation than seeing negative pictures, whereas this was not the case for younger adults.

Emotional events are bestowed with special prominence in memory. This may reflect greater attention oriented to these events during encoding, and͞or enhancement of memory consolidation after emotional events have passed. Here we show invoked emotional arousal results in a retrograde enhancement of long-term memory, determining what will later be remembered or forgotten. Subjects saw pictures of neutral faces and houses followed by emotionally arousing scenes at varying intervals. Self-reported emotional arousal responses predicted a retrograde enhancement of memory for preceding neutral events in a 1-week delayed recognition memory test. At longer picture-scene intervals, no enhancement was found, implicating a critical window in which emotional arousal must occur for retrograde memory enhancement. Postencoding manipulation of emotional arousal specifically enhanced conscious recollection rather than familiarity-based discrimination. An additional study revealed no retrograde enhancement for pictures preceding highly memorable, but nonarousing, distinctive scenes. These findings indicate an important role for emotional arousal in the postencoding enhancement of episodic memory consolidation.amygdala ͉ consolidation ͉ hippocampus ͉ memory ͉ arousal

The receiver operating characteristic (ROC) has been used to investigate the component processes of recognition memory. Some studies with this technique have been taken to indicate that the hippocampus selectively supports the process of recollection, whereas adjacent cortex in the parahippocampal gyrus supports the process of familiarity. We analyzed ROC data from young adults, memory-impaired patients with limited hippocampal lesions, and age-matched controls. The shape of the ROC changed in similar ways from asymmetric to symmetric, as a function of the strength of memory (strong to weak) in both the young adults and the patients. Moreover, once overall memory strength was similar, the shape of the patient ROC was asymmetric and matched the control ROC. These results suggest that the component processes that determine the shape of the ROC are operative in the absence of the hippocampus, and they argue against the idea that the hippocampus selectively supports the recollection process.