Aversive memory and the role of the mesocorticolimbic system in defensive responses-literature review

Abstract

Evidence from both animal and human research indicates that emotionally significant experiences activate hormonal and brain systems that regulate the consolidation of new memories. Mesocorticolimbic dopamine system has been shown to be critical for many processes that drive learning and memory, including motivation, prediction error, incentive salience, memory consolidation, and response output; and it carries signals of valorization, both for stimuli related to gain, and for aversive stimuli. Literature indicates that dopaminergic system is involved in fear conditioning and extinction. Emotional processes are mainly mediated by the amygdala, and when it becomes active, its anatomical connections with the cortex may facilitate the processing of the presented stimuli. The ventral tegmental area encodes the prediction of errors, and signals are transmitted to regions such as nucleus accumbens, amygdala, hippocampus and prefrontal cortex. Advances in neurobiological research favored the understanding of the mechanisms underlying learning and the evocation of the extinction of aversive memory. We review the behavioral and neurobiological literature showing a role for mesocorticolimbic structures in defensive responses and aversive memory.