Decision and navigation in mouse parietal cortex
Posterior parietal cortex (PPC) has been implicated in navigation, in the control of body movement, and in visually-guided decisions. Seeking to relate these views, we measured activity in populations of PPC neurons while mice performed a virtual navigation task driven by visual decisions. We found that PPC neurons are selective for specific combinations of the animals spatial position and heading angle. This selectivity closely predicted both the activity of individual PPC neurons, and the arrangement of their collective firing patterns in choice-selective sequences. These sequences reflected the influence on PPC of the animals navigation trajectory. An alternative model in which PPC activity encoded position and decision performed more poorly, and a model with all three variables barely outperformed the simple position-heading model. Alternative models based on visual or motor variables were inferior. We conclude that when mice use vision to choose their trajectories, a large fraction of parietal cortex activity can be predicted from simple attributes such as spatial position and heading.