To support generation of single cell datasets for one or more brain regions relevant to opioid use disorder and persistent HIV infection. If fully successful, this project will generate 1. A cellular parts list for selected NIDA-relevant brain regions, 2. Reveal how cell types within these brain regions differ from one another with respect to gene expression, 3. Reveal how cell types within these brain regions are altered by chronic opioid exposure providing potential novel therapeutic targets for opioid addiction, 4.