Distinct Response Selectivity Changes in the Primary Visual and Parietal Cortex during Visual Discrimination Learning.

When animals learn the behavioral relevance of sensory features, response selectivity in primary sensory areas increases for those features. However, the effect of learning on neuronal activity in higher-level areas associated with decision-making in the parietal cortex, compared with primary sensory cortex, is not yet known. We used two-photon calcium imaging to determine how learning modifies neural representations in the primary visual cortex (V1) and posterior parietal cortex (PPC) in a visual go/no-go orientation discrimination task in male and female mice. We found that behavior improvements after learning were associated with increased neuronal selectivity in both V1 and PPC. The increased selectivity in PPC was mainly driven by neurons preferring the rewarded go stimulus, while neurons in V1 increased their selectivity for both the rewarded go and unrewarded no-go stimulus. Furthermore, feature preference was robust in V1 neurons but reorganized in PPC after learning. Finally, feature preference after learning was preserved across contexts in V1 but not in PPC, where many neurons switched their preference to the rewarded feature during active task engagement. Our results demonstrate that learning a visually guided discrimination task increased information about relevant sensory features through distinct changes in the bottom and top levels of the visual cortical hierarchy. Visual cortex neurons encode visual features with increased reliability but with preserved feature preferences after learning, while parietal neurons reorganize their feature preferences in a task-dependent manner.