While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the current issue of Science, Nikolaus Rajewsky and his team at the Berlin Institute of Medical Systems Biology (BIMSB) of the Max Delbrück Center for Molecular Medicine in the Helmholtz Association (MDC), as well as other collaborators within the MDC and Charité, present data that—for the first time—link a circular RNA to brain function.