The Development of Direction Selectivity in Visual Cortex

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DESCRIPTION (provided by applicant): Both the perception of moving objects and the visual guidance of eye movements require that cortical circuits generate an accurate neural representation of moving objects in the visual scene. This process is critically dependent on cortical neurons that respond selectively to the direction of moving stimuli. The goal of the proposed research is to continue our inquiry into the role of visual experience in the development of direction selective responses in ferret primary visual cortex. Work during the previous period of support demonstrated that experience plays a unique and essential role in the early maturation of direction selective cortical responses. If visual experience is withheld for the 2 weeks following eye opening, direction selective responses fail to emerge, and are not recovered by subsequent visual experience. The proposed experiments extend this line of inquiry to address four questions. (1) Does experience with moving visual stimuli serve as an instructive cue for the construction of direction selective cortical responses? (2) What role do innate neuronal tuning properties play in the experience dependent emergence of direction selective responses? (3) What contribution do changes in cortical layer 4 circuits and cortical layer 2/3 circuits make to the experience dependent emergence of direction selective responses? (4) Is the emergence of direction selective responses accompanied by direction-specific alterations in the arrangement of anatomical connections? These experiments employ state of the art functional imaging techniques in a novel experimental paradigm that permits us to monitor the impact of visual experience on developing cortical circuits in vivo. These experiments will contribute to a better understanding of deficits in motion perception that are common in developmental disorders, and more broadly, they will provide new insights into the mechanisms by which experience shapes cortical circuit development.