Two normal-light cameras (SpeedCam MiniVis) operating at thesame frequency and synchronized to the X-ray system were usedto record the movements of mystacial vibrissae. One camera was installed dorso-frontally, approximately perpendicular to the planeof the face, to document the fore-and-aft motion of the vibrissae(Fig. 1C; see also supplementary video file V). The second camerawas installed laterally to record the vertical and longitudinal excur-sions of the vibrissae relative to the forepaw. A third high-speedcamera (Photron FastCam; Photron, Tokyo, Japan) was placed infront of the treadmill to document the spatial relationship betweenvibrissae and forepaw in a transversal direction