Decision making is a problem that every living organism continually faces. Our laboratory studies the neurobiological principles of how brains make decisions. We view decisions as the elementary units of behavior from which more complex behaviors are assembled. Yet even simple decisions involve the integration of sensory and memory information with emotional and motivation attributes requiring the concerted action of millions of neurons across brain regions. Therefore we take an integrative approach centered around rodent behavioral tasks that allow us to systematically manipulate sensory stimuli, reward expectation and uncertainty. We conduct simultaneous recordings of large populations of neurons in behaving rats coupled with pharmacology and lesion studies. Given the complexity of animal behavior and the dynamics of neural networks producing it, our studies require quantitative analysis and we also make regular use of theoretical models to guide and sharpen the neurobiological questions. Future plans include adapting molecular tools for use in behaving animals to monitor and manipulate genetically identified circuit elements.