Project Summary The use of in vivo imaging and modulation tools to study neural function in the visual system have the potential to deliver transformative scientific discoveries and advance translational science. In particular, calcium imaging and optogenetics provide cell-type specific resolution of the neural circuits involved in visual processing and behavior. Despite the major advances in technology, and the enthusiastic use of these tools in rodent and smaller animal models for basic neuroscience applications, these approaches have been incorporated relatively slowly in large-brain animal models that have neural and perceptual functions more similar to humans (e.g., non- human primates, ferrets, and others). Further, although these methods can provide significant advantages for translational studies, they are not commonly used in disease models for pre-clinical testing and optimization in the eye or brain. The slow implementation of these methods in both in the eye and in large brain animal models is largely due to the complexity of establishing the hardware and viral transfection parameters to consistently perform these experiments. Issues relating to, eye and respiratory movements that distort light delivery and recording, immune responses, anesthesia and limited signal to noise, particularly deep in tissue all play a role. Yet, these are common challenges faced by the in vivo imaging community that are readily overcome with shared expertise and new technical advances are continuously pushing back the boundaries of what is possible. This application proposes a 2.5 day symposium that brings together world-leading scientists, engineers, and clinicians from around the world to discuss major progress in cutting-edge neural imaging and modulation methods to study function in the visual system in vivo. A major goal of the conference is to promote in depth discussions and knowledge-transfer between investigators to implement ‘best practices’ for neural imaging and modulation of activity in the visual system. Moreover, we provide a set of career development workshops aimed at increasing diversity and representation in vision research. We have devised a strategic plan to attract scientists-in-training (graduate students and postdocs) to the conference. In particular, we have invited a great mix of established and junior faculty with strong record in mentoring, provided ample speaking opportunities at the conference to these young investigators, and will award a generous number of travel awards to these young scientists to attend the conference. Their participation will shape and implement the new path forward to making discoveries in the visual system using these cutting-edge tools.