Distinct functional classes of excitatory neurons in mouse V1 are differentially modulated by learning and task engagement

Learning can cause significant changes in neural responses to relevant stimuli, in addition to modulation due to task engagement. However, it is not known how different functional types of excitatory neurons contribute to these changes. To address this gap, we performed two-photon calcium imaging of excitatory neurons in layer 2/3 of mouse primary visual cortex before and after learning of a visual discrimination. We found that excitatory neurons show striking diversity in the temporal dynamics of their response to visual stimuli during the behavior, and based on this we classified them into transient, sustained, and suppressed groups. Notably, these functionally defined cell classes exhibit different visual stimulus selectivity and modulation by locomotion, and were differentially affected by training condition. In particular, we observed a decrease in the number of transient neurons responsive during behavior after learning, while both transient and sustained cells showed an increase in modulation due to task engagement after learning. The identification of functional diversity within the excitatory population, with distinct changes during learning and task engagement, provides insight into the cortical pathways that allow context-dependent neural representations.