ABSTRACT
Fear memories are temporarily suppressed after repeated retrieval, a phenomenon known as memory extinction.How to reduce or even eliminate fear memory is the key to the treatment of fear related diseases such as post-traumatic stress disorder(PTSD). A single extinction training based on Pavlov's fear regulation task could only inhibit the expression of conditioned fear memory traces, but it could not eliminate the acquired conditioned fear memory. However, according to the reconsolidation theory based on memory, the retrieval-extinction paradigm has a more lasting effect on the erasure and rewriting of fear memory, and can effectively prevent the return of fear memory. Studies have shown that extraction-regression is closely related to a variety of neurotransmitter receptors such as glutamate receptor(GluR), dopamine receptor(DAR), L-type voltage-gated calcium channels(LVGCs) and cannabinoid. Moreover, its effect is closely related with factors such as retrieval-extinction memory stage. At present, most of the researches on extracted boundary conditions only stay at the level of behavior, with little understanding and exploration on the level of molecular mechanism. From the perspective of molecular neurobiology, with different stages of memory and different types of receptors and molecular mechanisms, this research reviewed the mechanisms of retrieval-extinction in recent years.It provided valuable signaling pathways, molecular targets and research directions for the treatment of fear-related diseases such as PTSD.