Engineering Core-Abstract The goal of the Engineering Core is to enable our Team members to surmount their most challenging technological and engineering obstacles. There are many needs for engineering solutions in our proposal--from behavioral apparatus to optical and electrophysiological rigs, to software for data acquisition and analyses. Even the most technologically sophisticated of the research groups in our Team require special assistance with engineering problems in order to achieve our ambitious aims. In the Center for Brain Science at Harvard there is an existing Engineering Core that consists of (a) an integrated laboratory to design, prototype, iterate, and produce custom devices for neuroscience experiments and (b) an engineer-neuroscientist who solves the most challenging engineering problems in the user laboratories and trains young scientists to do this themselves. By adding a dedicated staff engineer, the Engineering Core will be able to support the team-based neuroscience research proposed here. The specific aims are to implement engineering solutions to problems faced by the Projects and other Cores. The Engineering Core will (a) design and build apparatuses to image rapidly swimming larval zebrafish; (b) build other apparatuses to quantitatively assay complex zebrafish behavior; (c) build rigs to record neural activity in larval zebrafish brains via calcium imaging; (d) fabricate rigs to record neural activity in larval Drosophila and rat; and modify software for data acquisition in many existing experimental apparatus, including microscopes.