Feeding, sleeping or sex require opportune times that combine information gathered by multiple brain regions and are differentially gated. How does the brain weigh myriad stimuli to shape a behavioral output? To determine how such a large neural network functions, it is essential to influence the activity of a subpopulation of neurons and observe both physiological and behavioral responses simultaneously. Using genetic tools that allow precise control of neural activity in combination with in vivo electrophysiology and behavioral assays, we are discovering circuits that regulate homeostatic behaviors such as feeding or thermoregulation in mice. Furthermore, innovating and improving tools to manipulate molecular, biochemical or electrical characteristics of specific cell types is crucial in leading new discoveries. To this end, we seek opportunities to create techniques to alter the biology of a single protein or a network of cells in a predictable manner to uncover their role in whole organisms.