Exploring the role of the medial prefrontal cortex in the retrieval of episodic memory

Episodic memory can be defined as the memory for unique events. In most situations, reality is ambiguous, and the cues that trigger retrieval are often associated with more than one particular memory. The medial prefrontal cortex (mPFC) controls the retrieval of memory traces, inhibiting the less relevant one, in situations where the cues presented could trigger the expression of more than one and cause interference. We have identified that the mPFC, the ventral hippocampus (vHPC), the dorsal hippocampus (dHPC), as well as the perirhinal cortex (PRH), are involved in the retrieval of context guided recognition memories. But it is still not known the type of information they store and the interaction among them. We have previously shown that the different subregions of the mPFC, prelimbic (PL) and infralimbic (IL), are necessary for the control of interference during a contextual version of the object recognition task. However, it is not clear if both subregions process the same type of information. In order to test if information arising from vHPC is processed by the subregions during retrieval control we performed a series of experiments combining behavioral and chemogenetic tools. Our findings show that vHPC-IL projections but no vHPC-PL are required for the retrieval of an contextually guided object memory. These results suggest that vHPC-IL information might be required for the resolution of interference during retrieval.