The long term goal of proposal is the development and testing of new optical technology for photochemical control of neuronal function. The caged neurotransmitters developed we have previously made have been widely used by many research groups around the world. An important feature of our work is that we have forged long-term collaborative relationships with noted physiologists. These interactions have been vital the development of useful and important caged compounds as it is the biological problems that define the probes. In this proposal we seek to address several major gaps in the area of optical chemical methods that are used for photochemical probing of neuronal function. Namely: multi-color photoactuation is not a standard technique; caged compounds are not designed for 2-photon excitation a priori. Photoreversible drugs for ?next generation? (opto)pharmacology; genetically targeted photoswitchable, subunit specific probes to control behavior. The overall goal of this proposal is to develop new photochemical tools that allow optical control of a wide variety neuronal signaling processes in vitro and in vivo.