Independent effects of learning and attentional switching on neural responses in mouse primary visual cortex
The response selectivity of cortical neurons can increase for behaviourally relevant stimuli both across days as animals learn a novel stimulus-reward association, and across minutes or seconds when animals transiently attend to sensory stimuli. Both of these phenomena can lead to an enhanced ability of downstream brain regions to discriminate relevant stimuli. However, while learning and attention can increase selectivity in the same cortical region, it is not known whether they rely on the same neural mechanisms. In addition, changes to cortical networks with experience or attention involve complex interactions between multiple excitatory and inhibitory cell classes. Understanding these processes thus requires the simultaneous measurement of activity from multiple identified cell classes. We studied how responses of neuronal populations in layer 2/3 of primary visual cortex (V1) evolve as mice learn to discriminate two visual patterns, and subsequently as the same mice perform an attention switching task. We obtained simultaneously detected parvalbumin (PV), somatostatin (SOM) and vasoactive intestinal peptide (VIP) interneuronal activity using two-photon calcium imaging of neural populations and post-hoc immunostaining. Learning and attention-switching differentially affected the responses and interactions between different cell classes. We suggest that there are distinct mechanisms underlying the increased discriminability of relevant sensory stimuli across longer and shorter time scales.