Project Summary Heavy episodic drinking results in disrupted patterns of neural signaling that place an individual at increased risk for developing an alcohol use disorder. Serotonin (5-hydroxytryptamine, 5-HT) systems, originating in the dorsal raphe nucleus (DR), are highly alcohol sensitive and dysregulated by excessive drinking. DR 5-HT systems are remarkably complex and form a network of distinct yet overlapping efferent pathways. These subsystems, which collateralize cortically or subcortically, may regulate specific aspects of alcohol reward and aversion. Ongoing work in our lab is focused on characterizing a DR 5-HT projection to the orbitofrontal cortex (OFC) and determining its role in binge-like alcohol consumption. In this supplement, the candidate proposes to build upon ongoing work from the existing parent grant to assess a subcortical DR 5-HT projection to the central nucleus of the amygdala (CeA). In Aim 1 the candidate will map DR 5-HT inputs to the CeA, characterize their topography, and quantify their overlap with DR 5-HT cortical inputs. In Aim 2, she will evaluate the role of this pathway in modulating binge-like alcohol drinking using chemogenetics. The project outlined in this supplement is a non-redundant and logical extension of the parent grant that will provide the candidate with training in stereotaxic surgery, chemogenetics, anatomical tracing, confocal microscopy, and quantitative immunohistochemistry. This new skillset will add to the applicant’s existing strong behavioral background and provide her with a solid foundation in neuroscience techniques. The candidate’s goal is to continue her research efforts and education by obtaining a PhD in Neuroscience. Thus, mentorship at this stage will focus on increasing her scientific repertoire along with her oral and written communication skills. Emphasis will be placed on the candidate generating two first-author publications from the proposed work and presenting her research at several scientific conferences. The tailored mentoring plan and project proposed in this award will provide the candidate with the support she needs to reach her goal of acceptance into a PhD program in Neuroscience.