Lucas Pinto, Kanaka Rajan, Brian DePasquale, Stephan Thiberge, David W Tank, Carlos D Brody. Task-dependent changes in the large-scale dynamics and necessity of cortical regions.

A central question in the neuroscience of decision making is to what extent computations are distributed or localized in specific brain areas. Work done in primates has generally found that the neural correlates of decision making are widespread across many cortical areas, but inactivation studies in rodents have suggested highly localized decision-making processes in a small subset of areas. However, beyond differences in model species and experimental approaches, these two bodies of literature differ in terms of task complexity, which tends to be higher in primate studies. In this paper, we set out to test the hypothesis that the degree to which decision-making computations are distributed depends on the underlying cognitive demands of the tasks. We trained mice on three different virtual reality navigation tasks, happening in the same virtual maze but with varying degrees of task complexity. We then performed systematic optogenetic mapping and wide-field calcium imaging across the dorsal cortex as mice performed these tasks. Our results suggest that tasks with higher cognitive demands engage more distributed cortical circuits, with more independent computations across different cortical regions. More generally, they suggest that changes in the underlying computations result in a reorganization of whole-cortical dynamics.