Task engagement differentially drives hippocampal and neocortical neural codes

Sensory inputs are progressively transformed into internal representations of the environment along the cortical hierarchy. How does the behavioral relevance of these inputs affect this encoding? Using two-photon calcium imaging in mice navigating virtual-reality environments, we found that visual cortex maintained high sensory discrimination regardless of behavioural engagement, whereas the hippocampal dentate gyrus required active navigation for effective discrimination. These findings suggest that sensory cortices act as general-purpose sensory discriminators, while the hippocampus filters information based on task relevance.