Encoding of body state in whisker-related somatosensory cortex of freely moving mice

Sensory systems have evolved to solve computational challenges that animals face during behavior in their natural environments. To illuminate how the sensory cortex operates under such conditions, we investigated the function of neurons in the whisker-related somatosensory cortex (wS1) of freely moving mice engaged in tactile exploratory behavior. By recording neural activity from wS1 while tracking the mouse's head/body in 3D, we found that wS1 neurons are substantially modulated by body state (configuration of the mouse's head and spine), even in the absence of whisker afferent input. Most neurons were modulated by multiple dimensions of body state, with the most prominently encoded ones being the pitch angle of the head to the body and locomotion speed. Overall, our data suggest that sensory cortical pathways contain a rich representation of body state at their earliest stages and that the brain mechanisms of sensation are fundamentally integrated with such states.