PROJECT SUMMARY In order to forage effectively for food, the brain must integrate innate and learned information about the value of different food odors and use this information to select navigational motor programs. Although a great deal is known about how the brain computes the value of odor stimuli, how it uses this information to guide navigation remains mysterious. Here we propose to investigate the role of a conserved navigation center, the fan-shaped body (FB), in olfactory navigation. The FB receives a large number of inputs that are anatomically downstream of innate and learned olfactory processing centers. We have identified several lines labeling such inputs that respond to attractive odor and drive upwind orientation when activated. Here we will use whole-cell electrophysiology and imaging to investigate the representation of innate and learned odor value signals in FB input neurons. By combining these functional data with detailed connectomic information, we will generate quantitative models that relate sensory representations to anatomical connectivity. Next we will use both synchronous and asynchronous recordings to measure and model the relationship between FB neuron activity and navigational action selection. Finally, we will develop a new optogenetic plume assay that will allow us to determine the role of FB neurons in different aspects of odor plume navigation. Together these experiments and models will generate testable predictions about how the organization of central navigation circuits supports a critical goal-directed behavior, odor-guided food search.