Project Summary/Abstract- Core C The in vitro Electrophysiology Core (Core C) will provide services for in vitro electrophysiological studies using novel tools such as optogenetics, designer receptors exclusively activated by designer drugs (DREADDs) and in vitro GCaMP6 calcium imaging. We will prepare brain slices, conduct patch-clamp recordings, optimize the protocols for the optogenetic and chemogenetic experiments, perform Ca2+ imaging studies in in vitro slices, and conduct channelrhodopsin2 (ChR2)-assisted circuit mapping (CRACM). The Core will also perform histology of the recorded slices, and analyze the associated data. Project 1 (Saper), Project 2 (Scammell), Project 3 (Fuller) and Project 4 (Vanderhost and Dymecki) will use this Core facility. These projects are not equipped to conduct in vitro electrophysiology recordings and there are no institutional resources that can provide this service. The Projects will benefit from the expertise and shared resources of the Core.