How does happen of memory extinction in the brain

Introduction:Previous studies demonstrated that fear extinction is induced when the conditioned stimulus is repeatedly presented without the aversive outcome unconditioned stimulus, resulting in a decline of conditioned fear response. In rodents, fear responses are typically assessed via freezing behavior or the fear-potentiated startle reflex. Also it has been showed that many factors are involved in fear extinction that drives learning and memory. Neurotransmitters released from many areas of the brain can modulate different kinds of learning and memory such as auditory and contextual fear memory within different brain regions including the hippocampus, basolateral amygdala and medial prefrontal cortex. In this review, we discuss about of fear memory extinction. Also we review some behavioral, pharmacological and neurochemical studies from our laboratory on rodents, which might contribute to our understanding of the complex processes of memory extinction. More importantly, we discuss the pre-reactivation (memory extinction) effects of systemic as well as intra-amygdala, intra-hippocampus and intra-infralimbic of medial prefrontal cortex infusions of agonist and antagonist of the certain neurotransmitter systems on fear memory extinction. Our findings indicate that dopaminergic and GABAergic together with endocannabinoids play important role in modulating fear extinction memory in these brain areas.

Keywords:

Fear memory extinction , Amygdala , Hippocampus , Medial prefrontal cortex