The purpose of this FOA is to promote the integration of experimental, analytic, and theoretical capabilities for large-scale analysis of neural systems and circuits. This FOA seeks applications for exploratory research studies that use new and emerging methods for large scale recording and manipulation of neural circuits across multiple brain regions. Applications should propose to elucidate the contributions of dynamic circuit activity to a specific behavioral or neural system. Applications should seek to understand circuits of the central nervous system by systematically controlling stimuli and/or behavior while actively recording and/or manipulating relevant dynamic patterns of neural activity and by measuring the resulting behaviors and/or perceptions. Studies should incorporate rich information on cell-types, on circuit functionality and connectivity, and should be performed in conjunction with sophisticated analysis of complex, ethologically relevant behaviors. Applications should propose teams of investigators that seek to cross boundaries of interdisciplinary collaboration by bridging fields and linking theory and data analysis to experimental design. Exploratory studies supported by this FOA are intended to develop experimental capabilities and quantitative, theoretical frameworks in preparation for a future competition for larger-scale, multi-component, Team-Research Circuit Programs (U19) awards.