Neural correlates of encoding emotional memories: a review of functional neuroimaging evidence

In recent years, emotion research has gained considerable interest from cognitive neuroscientists, who generally agree that emotion influences virtually all aspects of cognition. The mechanisms underlying the impact of emotion on memory have received particular interest, and have been extensively investigated in both humans and non-humans. Here, we review evidence from brain imaging studies investigating the neural correlates of the memory-enhancing effect of emotion in humans, with a focus on the early stages of memory formation - i.e., encoding and early consolidation. The vast majority of the evidence has resulted from studies on young participants, but evidence from recent studies investigating age-related differences in emotion processing is also available. The extant evidence highlights the role of two main brain regions that have been systematically associated with memory processes: the medial-temporal lobe (MTL) and the prefrontal cortex (PFC). The main findings from studies on young groups show that enhanced memory for emotional events benefits from joint contribution from both MTL- and PFC-based mechanisms, and that emotional arousal plays a critical role in mediating these effects. The studies on older participants provide evidence for preserved emotion processing with aging, as well as identify age-related differences that may reflect enhanced cognitive control of emotion and the engagement of compensatory mechanisms associated with healthy aging. These findings resulting from studies of healthy populations provide novel insight into understanding alterations in the neural circuitry underlying emotion- memory interaction that may lead to mood and anxiety disorders.