CONICET | Buscador de Institutos y Recursos Humanos

Episodic memories contain information about our personal experiences.But memories would be useless if we could not retrieve them. Memory retrievalrequires the correct selection of a particular trace to be expressed. However,many memories share cues, so how does the brain control interference betweensimilar memories during retrieval? A system including the medial Prefrontal Cortex(mPFC) has been proposed to mediate response selection and control interference.Serotonin isan important modulator of mPFC function, however it is not clear the role thatthe serotonergic system in general and the serotonin 2a receptors (5-HT2aR) inparticular play in memory interference processes. We employed a recognitionmemory paradigm in rats to address this question. The object-in-context (OIC)task requiresthe animals to recognize the incongruence between the context and one of theobjects presented during the retrieval phase. This task involves multiplebrain regions including the hippocampus and perirhinal cortex (PRH). We foundthat infusion of MDL 11,939, a 5-HT2aR specific antagonist, in the mPFC beforeretrieval affects the ability of this structure to control memory interference duringthe OIC task. Modulation of mPFC activity by 5-HT2aR also regulates the reconsolidationof the memory traces. Infusion of a protein synthesis inhibitor like emetine inthe PRH after theretrieval blocked reconsolidation of only one of the object memories. However,infusion of 5-HT2aR antagonist in mPFC allowed labilization of both memorytraces during the retrieval making them both susceptible to emetine. Theseresults suggest that 5-HT2a receptors in mPFC control memory reactivationallowing the expression and reconsolidation of the most relevant memory tracein the PRH.