Orofacial Movements: Individuality and Stereotypy When Mice Move a Single Whisker to Touch.

A key function of the brain is to move the body through a rich, complex environment. When rodents engage with their environment, they move their whiskers as they extract tactile information. Even though the study of whisking has a long history, the details of individual whisker movements bilaterally, of nose movement, of stereotypy and variability in an active whisking to touch behavior are unknown. Here we trained five head-fixed male and 11 female mice in a go-cue task to move a whisker to touch a sensor. Our analysis of orofacial movements shows that mice specifically control movement of the whisker they use to touch and that as they move their whiskers, they move their nose and apply forces on the head post in a manner that reflects the behavioral epoch, i.e., whether go-cue triggered movement had begun or a whisker was touching the sensor. Importantly, mice control the setpoint, amplitude, and frequency of movement of whiskers bilaterally and individually. Additionally, even though mice achieved the goal of the task-to touch the sensor within 2 s-how they coordinated movement of the nose and forces on head post with movement of individual whiskers was stereotyped and related to the distance they needed to move a whisker to touch the sensor. Our work shows how stereotyped mouse behavior can be, and it emphasizes both the level of fine motor control mice can exert over individual whiskers and the extent of facial movements in a goal-directed whisking-to-touch task.