Arousal-mediated memory consolidation: Role of the medial temporal lobe inhumans

Although the influence of emotional arousal on declarative memory has been documented behaviorally the mechanisms underlying arousal-memory interactio ns and their representation in the human brain remain uncertain. One route through which arousal achieves its effects on memory performance is by regu lating consolidation processes. Animal research has revealed that the amygd ala strengthens hippocampal-dependent memory consolidation in a limited tim e window following participation in an arousing task. To examine whether th is integrative function of amygdalo-hippocampal structures extends to the h uman brain, we tested unilateral-temporal-lobectomy patients on an adaptati on of a classic paradigm in which levels of physiological arousal at encodi ng modulate retention over time. Subjects rated emotionally arousing (taboo ) and neutral words on an arousal scale while their skin conductance respon ses (SCRs) were monitored Recall for the words was assessed immediately and after a I-hr delay. Both temporal-lobectomy patients and control subjects generated enhanced SCRs and arousal ratings for the arousing words at the t ime of encoding. However; only control subjects exhibited an increase in me mory for the arousing words over time. This group difference in the effect of arousal on the rate of forgetting suggests that the role of medial tempo ral lobe structures in memory consolidation for arousing events is conserve d across species.