Tiia Monto [creativecommons license] via Wikimedia CommonsThirst is the fundamental instinct to drink water in response to dehydration. Neurons in a specific brain region called the subfornical organ (SFO) are activated by dehydration, leading investigators at Columbia University (New York, NY) to suspect that this region is involved in thirst regulation. Yuki Oka, Mingyu Ze and Charles Zuker explored this notion using genetic and optogenetic engineering techniques in mice.