Figure 5. Vibrissa Contact with a Smooth Surface.

A. Average intensity across all frames in a movie of an ex vivo vibrissa sweeping across glass (see Methods and Figure 1). Lighter regions of the image indicate positions of lower vibrissa velocity. An oscillatory pattern can be seen even though the vibrissa is not being obstructed by macroscopic features, suggesting the importance of frictional interactions. B. A track from an in vivo vibrissa during active surface contact with the smooth surface, every frame is shown (~0.3 msec period). Line-marking conventions as in Figure 3. C. Two tracks and line scans from vibrissae simultaneously contacting a smooth surface within a trial. These data correspond to Supplemental Movie S3. The data show that while robust oscillatory behavior was observed in one of the vibrissae during smooth surface contact, no detectable signal was present on a neighboring vibrissa, indicating the diversity of surface interactions. D. The mean frequency and standard deviations for all scanned vibrissae that showed significant micro-motions (N = 15) during smooth surface contact is plotted against 1/Length². See Figure 4 for legend descriptions.