The foveal visual representation of the primate superior colliculus

Processing of foveal retinal input is important not only for high quality visual scene analysis, but also for ensuring precise, albeit tiny, gaze shifts during high acuity visual tasks. The representations of foveal retinal input in primate lateral geniculate nucleus and early visual cortices have been characterized. However, how such representations translate into precise eye movements remains unclear. Here we document functional and structural properties of the foveal visual representation of midbrain superior colliculus. We show that superior colliculus, classically associated with extra-foveal spatial representations needed for gaze shifts, is highly sensitive to visual input impinging on the fovea. Superior colliculus also represents such input in an orderly and very specific manner, and it magnifies representation of foveal images in neural tissue as much as primary visual cortex does. Primate superior colliculus contains a high-fidelity visual representation, with large foveal magnification, perfectly suited for active visuomotor control and perception.