Mace, Jackson2020-09-212020-09-212020-05https://udspace.udel.edu/handle/19716/27721The medial prefrontal cortex (mPFC), dorsal hippocampus (dHPC), and nucleus reuniens (Re) of the midline thalamus have been demonstrated to be necessary for spatial working memory (SWM). Previous studies have implicated the mPFC-HPC interactions as crucial for supporting accurate SWM performance. Past work has also revealed the Re as a key component for mediating these mPFC-dHPC interactions during a SWM task. However, little work has described how this circuit contributes to the three core components of SWM: memory encoding, memory maintenance, and memory retrieval. With previous evidence that began to understand how the outputs from the Re contribute to memory encoding as opposed to memory maintenance and retrieval, this new study examines the inputs from the mPFC and dHPC to the Re. We used optogenetic suppression techniques to selectively perturb pathways from the mPFC and dHPC to the Re. We also utilized a delayed non-match to position task to parse apart SWM into its three core components. We demonstrated that disrupting synaptic projections from the dHPC to the Re in rats disrupted their ability to encode memories. We determined that suppressing synaptic projections from the mPFC to the Re in rats disturbed their ability to encode and retrieve memories. These findings highlight the Re as a vital component for coordinating mPFC-dHPC interactions during memory encoding. The results also show that Re-mPFC interactions are critical for memory retrieval. Altogether, this study will establish a better understanding of the neural circuitry underlying SWM, enabling doctors to better address working memory deficits in humans that are associated with many neurological disorders.neuroscience, memory, nucleus reuniens pathwayThesis