The hippocampus (HPC) and the medial prefrontal cortex (mPFC) are two structures crucial for effective decision-making, and it has been shown that these two structure communicate when spatial working memory (WM) recall is necessary in rats. The hippocampal system is critical for episodic memory, and is especially important in the acquisition and retrieval of spatial information, while the mPFC’s major function is to form and store representations of events and contexts, so that in the future, the most appropriate behavioral response is used in a given context. We will be investigating the correlation between a rat’s behavior and neural activity in the mPFC and the HPC simultaneously to better understand the detailed interaction between these two structures. Rats are trained on a task where they must switch between two types of spatial learning strategies while on the maze to obtain a food reward. While the rat performs the task, we will monitor neural activity in the HPC and mPFC as well as the rat’s behavior. Past research has shown that identification of a certain deliberative behavior can be determined by looking at hippocampal oscillatory data. We predict there will be a correlation between this deliberative behavior made by the rat and an identifiable pattern in hippocampal-prefrontal engagement. We also expect to observe the two structures align their activity as the rat learns to switch from one strategy to the other, giving insight into the involvement of the hippocampal-prefrontal network in learning and decision-making. Understanding the neural mechanism employed in memory-guided decision-making has tremendous implications for the field of medicine, as disadvantageous decision-making and impaired volitional control are characteristic of many mental health disorders, such as addiction, eating disorders, depression, and anxiety disorders.

The medial prefrontal cortex (mPFC) and hippocampus (HPC) are critical structures in a network that supports spatial working memory and flexible decision making in rats. The HPC has traditionally been implicated in episodic and spatial memory, while the mPFC has been studied for roles in working memory, response inhibition, outcome evaluation, and implementation of task rules and strategies. Flexible decision making is often tested via reversal learning (RL) paradigms in rats, monkeys, and humans. However, many studies have suggested that the mPFC is not necessary for RL, and fewer studies have shown that the mPFC is crucial for specific types of RL. We elucidate the role of the mPFC in spatial RL by optogenetically disrupting the mPFC during specific task phases, or epochs, of a spatial RL task. We also perform the same epoch-specific optogenetic disruption of the mPFC during a probabilistic reversal learning (PRL) task, which is compared to RL performance data to investigate how probabilistic contingencies recruit the mPFC differentially compared to absolute contingencies. In both experiments we analyze metrics such as choice accuracy, perseverative and regressive errors, and trials per reversal. Our data suggest that RL performance is only impaired when the mPFC is disrupted during the choice epoch of our task, while mPFC disruption during any epoch of the PRL task results in performance deficits. This suggests that the mPFC is involved in decision making processes and maintenance of probabilistic reward contingencies. This study contributes to knowledge about the mPFC in reward-guided decision making and can give insight into how impaired behavioral flexibility is caused by mPFC dysfunction, which is implicated in neurological disorders including depression, schizophrenia, and others.