The mammalian cortex is an intricate, highly-organized neural circuit which processes sensory information and generates motor outputs that embody much of our behavior. It is likely that the local connectivity within cortical circuits is crucial to the computations performed. This proposal aims to explore how this connectivity is established during development in relation to visual processing. We will use multi-electrode recording along with quantitative models for receptive field characterization to determine how sensory encoding evolves during development. Further, by analyzing signals from simultaneously recorded neurons or other "optical probing" techniques, it should be possible to establish graphs of connectivity, and understand the properties of connected neurons. We will then apply these techniques to address the changes in both visual responses and connectivity resulting from monocular deprivation, which is an important model for activity dependent remodeling. In the end, this information will provide crucial tests and constraints for theoretical models of cortical development and information processing.