Stress and the Dynamic Fear Memory: Synaptic–Cellular Bases and Their Implication for Psychiatry Disorders

Abstract

There is consensus that the acquisition and storage of relevant aversive information allows organisms to cope with threat situations. Such a mnemonic process is supported by lasting modifications in the aversive neuronal circuitry, resulting in changes in the behavioral response. In this way, the capacity to form long-lasting emotional memories makes it possible to predict and anticipate a potential threat in future situations, thus favoring, from an evolutionary point of view, survival conditions.In this context, one of the relevant questions is how the perturbations to the modulatory mechanism involved in the adaptive response result in an excessive and inappropriate state of fear and anxiety.Associative learning related to the emergence of a long-lasting fear memory is critically implicated in the pathogenesis of anxiety disorders, including post-traumatic stress disorder, phobia, and panic. Consonant with such a view, most of the symptoms of these psychiatry entities are due to the persistence and the re-experience of traumatic memories.Consequently, understanding the neurobiological changes associated with the formation of long-lasting fear memory under particular negative emotional states is relevant for the comprehension of the underlying mechanisms involved in the occurrence of traumatic and persistent memories, as well as for the rebuilding of potential therapeutic tools that could reestablish the adaptive dynamic of the fear memory trace.In this chapter, we focus on the relevant outcomes observed in animal models of fear learning and memory and their interaction with stressful experiences, along with the observations performed in humans suffering the psychiatric illnesses previously mentioned.