To guide memory-based behavioural decisions, the hippocampus needs to discriminate between distinct sensory environments. Before reaching the hippocampus, sensory information is initially processed in sensory cortices. We hypothesised that primary sensory cortices provide a faithful representation of the sensory environment to distributed brain regions, whereas the hippocampus produces a cognitive map weighted according to the behavioural relevance of sensory inputs. To test this hypothesis, we aimed to determine how complex sensory stimuli differentially depend on the behavioural context in the primary visual cortex (V1), CA1 and the dentate gyrus (DG). We performed two-photon calcium imaging from head-fixed mice navigating in a linear virtual-reality track. Mice were exposed to alternating environments by changing visual textures along the virtual corridor. During active navigation, movements in the virtual environment were controlled by the animal motion on a running wheel. By contrast, in a passive open-loop condition, the visual scene was uncoupled from animal locomotion. In all regions during active navigation, we found that single neurons showed preferential firing for one environment or another, and that a decoder trained on the activity from all neurons could predict which environment was being explored. During passive exposure, neuronal activity in V1 maintained a high discrimination while it dropped to chance in the hippocampus. We concluded that task engagement is therefore necessary for neuronal discrimination in the hippocampus but not in V1, suggesting that primary sensory cortices serve as robust general-purpose discriminators of sensory information, while the hippocampus selectively discriminates behaviourally relevant inputs.