Despite the success in technology development in neuroscience, there currently lacks a method to directly link activity, connectivity, and molecular identity of individual neurons in a functional circuit at the single cell resolution. Here, Drs. Cai, Cui, and teams aim to use coMAAP, a method that combines Brainbow AAV labeling, calcium imaging, innovative sample preparation, and light-sheet microscopy, to acquire correlative optical mapping of activity, anatomy, and molecular identity of the same neurons in the same animal. After optimizing and validating the coMAAP experimental paradigm, they plan to utilize coMAAP to uncover the heterogenous neuronal populations that are activated in the mouse ventral tegmental area during arousal. Improved understanding of the cellular and circuitry components could accelerate the identification of specific neuronal targets in psychiatric disorders.