Whisking asymmetry signals motor preparation and the behavioral state of mice

Abstract

A central function of the brain is to plan, predict and imagine the effect of movement in a dynamically changing environment. Here we show that in mice head fixed in a plus-maze, floating on air, and trained to pick lanes based on visual stimuli, the asymmetric movement and position of whiskers on the two sides of the face signals whether the animal is moving, turning, expecting reward or licking. We show that 1) we can decode and predict the behavioral state of the animal based on this asymmetry, 2) that tactile input from whiskers indicates little about the behavioral state, and 3) that movement of the nose correlates with asymmetry, indicating that facial expression of the mouse is itself correlated with behavioral state. Amazingly, the movement of whiskers - a behavior that is not instructed or necessary in the task--informs an observer about what a mouse is doing in the maze. Thus, these mobile tactile sensors reflect a behavioral and movement-preparation state of the mouse.