Temporal Dynamic of the Hippocampal Structural Plasticity Associated to Contextual Fear Memory: Influence of the Destabilization/ Reconsolidation Process

RAMIRO GABRIEL COMAS MUTIS; PABLO JAVIER ESPEJO; IRENE DELIA MARTIJENA; VICTOR ALEJANDRO MOLINA; GASTON DIEGO CALFA

Congreso; Argentine Society for Research in Neurosciences; 2018

Increasing experimental evidence indicates that fear memoryreactivation induces a transient plastic state that presumablyactivates the neuronal circuit involved in the encoding of thelong term fear memory. Under certain circumstances, suchreactivation allows the incorporation and integration of newinformation to the original memory trace. Here, we evaluatedwhether fear memory reactivation impacts on the dendriticspines remodeling in CA1 region of the dorsal hippocampusassociated with the formation of the contextual fearmemory. In the same way, we tested whether stress exposureaffects such dendritic spine remodeling. Thus, stressedand control animals were fear conditioned and sacrificed 24hr postconditioning (preretrieval), 60 min postretrieval or24 hr postretrieval. A higher dendritic spines density, particularlymature ones, were observed after fear encoding andlater reduced to basal levels 60 min after fear reactivation,returning to higher levels 24 hr postretrieval. This temporaldynamic structural plasticity was prevented by pharmacologicallyblocking the destabilization/reconsolidation process inthe basolateral amygdala complex or by a single stress exposurejust before fear memory conditioning. Thus, the destabilization/reconsolidation process was evidenced by achange in the hippocampal structural plasticity immediatelyfollowing reactivation, a plausible necessary step for theintegration of new information.