Factors That Influence a Shift in Memory Networks During Spatial Learning in Rats

What is influencing the consistent oscillatory activity between brain regions, that describes their communication as they cooperate and compete to produce a behavioral output, during spatial learning? We analyzed local field potentials (LFPs) in the hippocampus, striatum, and prefrontal cortex (PFC) of rats forced to learn either a place (spatial cue) or response (egocentric navigation) strategy on a T-maze. Additionally, we analyze the impacts of stress on that oscillatory activity. We observed two distinct patterns of firing between the hippocampus and striatum: one with in-phase theta communication and high coherence, and one with out-phase theta communication and low coherence between these regions. We saw these patterns of communication were consistent within individual rats, regardless of the strategy forced. There was a potential, but inconclusive, relationship between stress and patterns of communication between the hippocampus and striatum. However, we observed that the PFC has distinct patterns of firing with the hippocampus and striatum that are associated with different hippocampal-striatal communication. These data suggest that rats have consistent interindividual differences in firing patterns between the hippocampus and striatum, and the PFC may mediate the communication between those regions to influence the final behavioral output. Future studies should look into the directionality of communication of signaling between the hippocampus, striatum, and PFC. Additionally, a future study should look directly at the impacts of stress on brain activity and communication.