Modulation of hippocampal-prefrontal cortex connectivity during contextual guided episodic memory recall in rodents

JUAN FACUNDO MORICI; NOELIA WEISSTAUB ; CAMILA L. ZOLD

Congreso; XXXV Congreso Anual de la Sociedad Argentina de Investigacion en Neurociencia; 2020

Remembering which experiences occur at a particular context is a complex process that requires the interaction between multiple brain areas. The recall of a specific memory can be triggered by contextual information and relies on the interaction between the hippocampus (HIP) and the prefrontal cortex (PFC). It has been shown that the synchronization of HIP-PFC theta oscillations is enhanced during the resolution of contextual/spatial working memory tasks. However, little is known about how the HIP and PFC are coordinated during a contextual-guided recall of an episodic-like memory. To address this, we performed electrophysiological recordings in behaving rats during the retrieval phase of the object-in-context memory task (OIC). We observed an increase in HIP-PFC LFP coherence in the theta range when animals explore contextually mismatched objects. We also analyzed the activity of PFC neurons during the OIC test. Interestingly, 50% of PFC cells showed firing rate modulations during the test with respect to their baseline activity (25% responded to object exploration and 25% to non-object exploration periods). In addition, 25% of PFC neurons were phase-locked to the hippocampal theta rhythm. Altogether, these results suggest that HIP-PFC functional connectivity in the theta band is differentially modulated depending on the contextual congruence of the presented stimuli. In addition, PFC neurons encode different types of information that may be necessary for the OIC resolution.