Translating spatial maps into goal-directed actions in the hippocampal-accumbens circuit

Our ability to navigate flexibly needs more than a map of where we are. The brain must also decide where to go next. The hippocampus encodes where we are, yet how these signals turn into goal-directed choices is still unclear. Theoretical models suggest that the nucleus accumbens (NAc) combines hippocampal maps with rewards to build spatial value maps that guide movement, yet this has never been tested experimentally. I propose this system guides navigation by continuously sampling from the spatial value map during hippocampal theta sweeps. The project has three aims. First, I will perform Neuropixel recordings in mice to test whether hippocampal CA1 encodes predictive spatial maps while NAc computes spatial value maps during flexible navigation. Second, I will optogenetically silence CA1-NAc projections to determine if hippocampal inputs are necessary for NAc value coding and navigation. Third, I will test whether NAc evaluates hippocampal theta sweeps and whether disrupting theta timing impairs value-guided actions. Overall, this research will provide mechanistic accounts of how spatial predictions become goal-directed actions and generate a large-scale dataset that will accelerate discoveries across navigation and decision-making research.