The Specific Cognitive And Neural Mechanism Of Emotional Memory

It is easier to remember emotionally arousing events than it is to recall those that are neutral.This phenomenon is known as the emotional enhancement of memory(EEM).A new focus in the field of emotional memory is the study of sex-related differences.Whether the sex-related lateralization of amygdala function (i.e.,the female-left/male-right effect) in the emotional enhancement of memory (EEM) is time-dependent remains unclear.To evaluate this phenomenon,we conducted a two time-point study(20 min vs.24 hr) using fMRI and behavioral paradigms.Analyses of the present and previous studies indicate that sex-related lateralization of amygdala function occurs in the 2- to 3-week EEM,but it does not occur in the 1-week,24-hr,or less than 30-min EEM,suggesting that this effect on emotional memory may be time-dependent.We found that the right amygdala predicted 20-min EEM,while the left amygdala predicted 24-hr EEM.Our results further confirm and extend the idea that the amygdala exhibits a lateralized and time-dependent dissociation.Generally transient and sustained effects exist in cognitive and emotional processes.Recent study with fMRI indicated that a combined design of event-related with blocked design could investigate the sustained and transient effect in the encoding process for memory simultaneously.By now,there have no report about the study on emotion memory by means of this design.Moreover, there is positive emotion bias behaviorally in the old.The mechanism of age-related difference is still unclear.The purpose of this study is to investigate the sustained and transient effect of emotion memory in the young and old,and the differences between the young and the old.Our results indicated that the memory ability declined in the old,but there still exists emotional enhancement effect and relative positive bias.The right amygdala is related to sustained effect of fear on EEM,while the left amygdala is correlated with transient effect in either young or old.Sustained and transient effect play different role in the emotional memory of the young and the old.More emotional enhancement effect mainly depends on sustained effect in the young.Corresponding to the young,sustained function of medial temporal lobe reduces in the old and the transient effect mainly play more important role in emotional enhancement effect for the old.