Neuroscientists have identified that the receptor IL-1R1 plays a critical role in enabling neurons to directly communicate with the immune system. The new study provides the most detailed mapping of neuronal IL-1R1 (nIL-1R1) expression in the mouse brain, clarifying prior inconsistencies. Researchers were able to tag neuronal populations that express nIL-1R1 using a clever cell tagging approach, offering new insights into the functional roles of this receptor in the central nervous system (CNS).