Cognitive experience alters cortical involvement in goal-directed navigation

Neural activity in the mammalian cortex has been studied extensively during decision tasks, and recent work aims to identify under what conditions cortex is actually necessary for these tasks. We studied whether cognitive experience, beyond sensory or motor learning, affects cortical involvement in goal-directed navigation. To this aim, we first trained different cohorts of mice on either a simple goal-directed navigation task (“simple task”), or one of two complex tasks involving delay periods (“delay task”) or rule reversals (“switching task”) in virtual reality. After task learning, we optogenetically inhibited various cortical areas on a subset of trials while mice performed a given task to assess the necessity of each area for task performance. We found overall minor cortical necessity for the simple task, but large necessity of cortical association areas (specifically of posterior parietal cortex and retrosplenial cortex) for each complex task. We then permanently transitioned mic...