What moves when mice move a single whisker to touch? Individuality and stereotypy in behavior

Abstract

AbstractA key function of the brain is to move the body through a rich, complex environment. When rodents engage their environment, they move their whiskers as they extract tactile information. Even though the study of whisking has a long history, the details of what mice move when they move a whisker actively to touch are still unknown. Here we trained head fixed mice in a simple go-cue task to move a whisker on one side of the face to touch a sensor and tracked facial movements. Our analysis shows that mice specifically control the 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. Importantly, mice controlled 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 seconds -- how they did so, how they coordinated movement of the nose and forces on head post with movement of individual whiskers was stereotyped, specific 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.