Integrating multiple incoming messages simultaneously and discriminating 'meaningful' signals from spontaneous neural activity represent central problems to the nervous system. One mechanism by which signal integration and signal-to-noise resolution are achieved is the formation of temporal coincidence circuits by interacting transduction pathways. Signal integration via temporal coincidence detection is exemplified most readily by the way in which neural adenylate cyclases are regulated. This review will discuss the role of adenylate cyclases as coincidence detectors in the nervous system with special focus on adenylate cyclase type III, an isoenzyme that is found in large quantities in olfactory receptor neurons. The notion that olfactory transduction might also utilize an adenylate-cyclase-mediated temporal coincidence circuit strengthens the idea that signal integration via temporal-coincidence pathways is a universal feature of all neural adenylate cyclases.