This concept aims to continue a BRAIN Initiative program that supports technology development to probe cell- and circuit-specific processes in the brain (RFA-MH-19-136). Relating cognition and behavior of humans and other animals to the functions of specific brain cells and circuits is challenging. Progress in this effort has been limited in part by the complexity, scale, and speed of brain networks. The goal of this concept is to continue supporting research on new technologies for the analysis of brain cells and circuits with greater clarity, scalability, and precision. This work may enable further study of brain circuitry underlying behavior.