Emotion and episodic memory in neuropsychiatric disorders

Abstract

It has long been known that emotions can modulate learning and memory processes in humans and non-human mammals. Here we will review evidence from clinical, neuropsychological, neuroimaging and animal research suggesting an important role of emotions for the establishment of long-term episodic memories in the mammalian brain. In the first part of the review the neuroanatomical and neurochemical foundations of the interaction between brain areas generating emotions, such as the amygdala, and those allowing the association of multi-dimensional stimuli into an episodic memory, such as the hippocampus, are delineated. Patients with emotional and affective disorders show changes in memory performance in dependence of the positive or negative valence of the stimulus material. Furthermore, these patients often exhibit a reduced ability to access specific memories of life events with a striking lack of specific detail. Therefore, in the second part the clinical literature on memory impairments observed in patients with emotional and affective disorders, including post-traumatic stress disorder, schizophrenia and major depression, with a special emphasis on episodic memory function, is discussed. Finally, the relationship between memory deficits in Alzheimer's disease and neurodegeneration in brain systems mediating emotions is reviewed.