A training program and research proposal have been designed to prepare the applicant for a career as an independent researcher and to investigate the microcircuitry of the superficial layers of striate cortex involved in the processing of sensory information and the generation of cortical projections to higher areas of visual processing. In the first phase of the 5 year program, the applicant will attend selected didactic courses, learn the techniques of in vivo and in vitro intracellular neuronal injection and associated receptive field recordings needed for localization in vivo, neuronal cell culture, histo- and immunohistochemistry, and electron microscopy. The research study will also be initiated in this phase and completed in phase II. The study proposal is designed to characterize the distribution of various inputs onto particular cell classes in superficial layers of the visual cortex, including those from thalamus, layer 4, laterally within the superficial layers and from other cortical areas. The experiments will be performed in vivo and in a brain slice preparation, and will involve a number of tracers and histochemical stairs. The study investigates hypotheses of cortical information processing in the superficial layers of cat and monkey striate cortex and in recurrent loops between blob and interblob cells in V1 and the stripes of V2. These studies may also contribute to the understanding of where different components of visual sensory information (e.g., form and color) are first integrated in the visual cortex. In future studies of the normal and diseased human cortex the principles of cortical connectivity may provide information about the disease process.