PROJECT SUMMARY Complex decision-making often encompasses both cognitive and affective components. Cognitive and affective processes engage distinct but interacting systems in the brain, and both systems are effected by stress, a prevalent problem in modern society and a well-known risk factor for psychiatric disorders. Human brain imaging studies suggest a network of brain regions as the potential interface between cognitive and affective processing, particularly the medial prefrontal cortex (mPFC), the anterior insular cortex (aIC), and midbrain dopamine (DA) regions such as the ventral tegmental area (VTA). However, these studies lack causality tests at the neural circuit level. Comparative neuroanatomy and developmental genetics have identified in mice evolutionarily related mPFC, aIC, and DA regions. The structure and function of these regions are also disturbed by stress. These findings open the venue to use mouse as a model species for causal studies of the fundamental functions of these brain regions with precise circuit manipulation tools. Our overall goal is to elucidate the fronto-insular circuit mechanisms underlying cognitive-affective interactions during decision-making and the impact of stress on such mechanisms in mice. Our proposal is based on published literature and preliminary data showing: 1) mPFC, aIC and VTA are engaged in cognitive and affective decision-making; 2) mPFC and aIC are directly connected and both receive DA inputs from VTA; 3) stress affects mPFC and aIC neurons as well as DA release in these areas; 4) DA modulates mPFC and aIC activity and decision-making. By combining projection-specific viral labeling of neural circuits with in vivo imaging/electrophysiology and optogenetic/pharmacogenetic manipulations, we will test the central hypothesis that mPFC-aIC interaction is crucial for decision-making, which is disrupted by chronic stress but rescuable via DA modulation. Specifically, in Aim 1, we will determine the function of mPFC-aIC connections during decision-making in the attentional set-shifting test. In Aim 2, we will examine how stress affects mPFC-aIC connectivity and function. In Aim 3, we will define impact of stress on DA modulation of mPFC and aIC function, and explore the possibility to rescuing decision-making by selectively restore DA modulation in mPFC or aIC in stressed mice. The successful outcomes of this project will not only provide fundamental knowledge about the circuit mechanisms underlying higher brain functions, but also point out potential therapeutic targets for alleviating the detrimental effects of stress and psychiatric illnesses.