The purpose of this FOA is to provide resources for integrated development of experimental, analytic and theoretical capabilities for large-scale analysis of neural systems and circuits. We seek applications for exploratory 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. Studies should incorporate rich information on cell-types, on circuit functionality and connectivity, and should be performed in conjunction with sophisticated analysis of 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 theoretical frameworks in preparation for a future competition for large scale awards.