A fundamental goal in neuroscience research is to understand how neural activity links to observable behavior in humans and animals. To this end, I use a systems neuroscience approach of multi-level analysis that combines imaging of activity in neurons, across populations and circuits in vivo, and behavior studies in a translucent, genetically tractable animal system. In this talk, I will describe some of the techniques we use and the insights we have gained into a central vertebrate neural mechanism that transforms behavioral decisions.