Temporal dynamic of the hippocampal structural plasticity associated to contextual fear memory: influence of the destabilization/reconsolidation process

Congreso; XXXIII Congreso anual de la Sociedad Argentina de Investigación en Neurociencias.; 2018

Poster 157. Increasing experimental evidence indicates that fear memory reactivation induces a transient plastic state that presumably activates the neuronal circuit involved in the encoding of the long term fear memory. Under certain circumstances, such reactivation allows the incorporation and integration of new information to the original memory trace. Here, we evaluated whether fear memory reactivation impacts on the dendritic spines remodeling in CA1 region of the dorsal hippocampus associated with the formation of the contextual fear memory. In the same way, we tested whether stress exposure affects such dendritic spine remodeling. Thus, stressed and control animals were fear conditioned and sacrificed 24 hr postconditioning (preretrieval), 60 min postretrieval or 24 hr postretrieval. A higher dendritic spines density, particularly mature ones, were observed after fear encoding and later reduced to basal levels 60 min after fear reactivation, returning to higher levels 24 hr postretrieval. This temporal dynamic structural plasticity was prevented by pharmacologically blocking the destabilization/reconsolidation process in the basolateral amygdala complex or by a single stress exposure just before fear memory conditioning. Thus, the destabilization/reconsolidation process was evidenced by a change in the hippocampal structural plasticity immediately following reactivation, a plausible necessary step for the integration of new information.