Zimmerman discovered a new class of sensory signals that arise from the mouth, throat, and gut during ingestion and then converge in the brain to dynamically adjust the motivation to drink. This unexpected discovery revealed how drinking can quench thirst within seconds and how eating rapidly generates prandial thirst. Additionally, Zimmerman revealed the existence of a sensory system in the gastrointestinal tract that helps regulate drinking behavior by rapidly communicating the osmolarity of ingested fluids to the brain’s thirst circuit. Taken together, his work has transformed our understanding of how the brain regulates thirst and drinking behavior and introduced experimental approaches that are now commonly used.