Stress, memory and the amygdala

Key Points Emotionally arousing experiences tend to form strong memories and the amygdala has a pivotal role in this process. Stress hormones and stress-activated neurotransmitter systems in the basolateral amygdala are crucially important in the consolidation of emotional memories. A growing body of evidences points to a central role for noradrenaline in mediating the enhancing effects of adrenal stress hormones, such as adrenaline and glucocorticoids, on the consolidation of emotional memories. Basolateral amygdala activity affects memory consolidation and neural plasticity in other brain regions (for example, the hippocampus and various neocortical regions). The basolateral amygdala, and its interactions with the hippocampus and prefrontal cortex, also plays a part in the stress-induced impairment of memory retrieval and working memory. The same amygdala mechanisms that facilitate the robust encoding of emotionally salient memories can become maladaptive under conditions of traumatic and chronic stress. Chronic stress triggers patterns of structural plasticity in the basolateral amygdala, which are strikingly different from those seen in the hippocampus and prefrontal cortex. Chronic immobilization stress leads to dendritic growth and spinogenesis in principal neurons of the basolateral amygdala. Stress-induced neuronal remodelling in animal models reveals unique features of structural plasticity in the amygdala that could be of relevance to studies of humans with mood disorders and post-traumatic stress disorder.