Teasing apart the roles and responsibilities of each cell — and using that knowledge to build a complete picture of larger brain circuits, areas or regions — is a herculean challenge, one that cannot be accomplished through traditional imaging methods alone. Flow Cytometry is a powerful technique that enables scientists to rapidly identify and analyze key physical and chemical properties of individual cells, at rates of up to 20,000 cells per second. Cells of interest can be physically separated from the population for further study even if the unique cells are present in a concentration as little as one in a million. The information we glean from these analyses is critical to understanding how individual cells function in a healthy brain, as well as how these cells change when their normal function is disrupted in disease.