The Interplay of Hippocampus, Medial Prefrontal Cortex and Thalamic Nucleus Reuniens in Spatial Learning and Memory

The interplay of the hippocampus (HPC), medial prefrontal cortex (mPFC), and nucleus reuniens (NR) is crucial for spatial learning and memory. This coordination relies on oscillatory synchrony, particularly of the theta rhythm, which organize neural activity across brain circuits to support memory functions. Theta coherence between the HPC and mPFC increases during decision-making in reward-based spatial memory tasks, such as a T-maze. The NR plays a key role in facilitating this coordination, and its inactivation impairs working memory, leading to reduced choice accuracy. To further explore the role of this network in encoding and retrieval of spatial memory, this study analyzes simultaneous recordings of neurons and local field potentials in HPC, mPFC, and NR during reward-based learning in a multiple T-maze. The results show that these regions synchronize at decision points during learning, and preliminary analyses suggest that spatial selectivity of individual neurons increases during retrieval compared to learning. Future work will focus on understanding how oscillatory synchronization drives the stabilization of single-neuron spatial maps. Altogether, this study reinforces the importance of HPC-mPFC synchronization during learning and supports the hypothesis that NR facilitates this coordination to ensure effective memory encoding and consolidation.