Separating cognitive and motor processes in the behaving mouse.

The cognitive processes supporting complex animal behavior are closely associated with ubiquitous movements responsible for our posture, facial expressions, ability to actively sample our sensory environments, and other central processes. These movements are strongly related to neural activity across much of the brain, making it challenging to dissociate the neural dynamics that support cognitive processes from those supporting movements when they are highly correlated in time. Of critical importance is whether the dynamics supporting cognitive processes and related movements are separable, or if they are both driven by common neural mechanisms. Here, we demonstrate how the separability of cognitive and motor processes can be assessed, and, when separable, how each component can be isolated. We establish a novel two-context behavioral task in mice that involves multiple cognitive processes and show that commonly observed dynamics taken to support cognitive processes are strongly contaminated by movements. When cognitive and motor components are isolated using our analytical approach, we find that they exhibit distinct dynamical trajectories. Further, properly accounting for movement revealed that separate populations of cells encode cognitive and motor variables, in contrast to the 'mixed selectivity' reported by prior work. Accurately isolating the dynamics associated with particular cognitive and motor processes will be essential for developing conceptual and computational models of neural circuit function and evaluating the function of the cell types of which neural circuits are composed.