When interacting with the environment we depend on our perception of the world around us. Visual perception relies on information flow from the eye to the visual cortex, where it is relayed and transformed via a series of cortical processing stages. Most research so far has focused on feedforward processing of visual information. However, it is increasingly obvious that perception crucially depends on how sensory input is interpreted in the context of an animal’s behavioural state, goals and actions. These non-sensory signals may be relayed by prominent long-range projections from higher-order cortical and thalamic areas, whose contribution to vision remains largely unexplored. Recent advances in imaging techniques and genetic tools for visualizing and manipulating neuronal activity enable us for the first time to study directly what information is conveyed through these major alternative visual pathways in the behaving animal and how they influence the processing of feedforward sensory information to allow us to actively perceive and interpret the environment.Using state-of-the-art methodology combining in vivo imaging, electrophysiology, animal behaviour, virtual reality, genetic tools and targeted optogenetics using advanced optics, we will determine the functional role of (i) cortical feedback and (ii) higher-order thalamic signals during cortical processing of visual information in the behaving mouse. Specifically, we will investigate what information these projections convey to the visual cortex in anaesthetized and awake mice, whether they provide signals mediating the increased saliency of behaviourally relevant stimuli, and whether they enable the integration of sensory and motor information during locomotion and navigation. Together, the proposed work will answer fundamental questions about the role of these important but poorly understood visual pathways in active processing of visual input as animals interact with their environment.