RT Journal Article
SR Electronic
T1 Variations in vibrissal geometry across the rat mystacial pad: base diameter, medulla, and taper
JF Journal of Neurophysiology
JO J Neurophysiol
FD American Physiological Society
DO 10.1152/jn.00054.2016
A1 Belli, Hayley
A1 Yang, Anne En-Tzu
A1 Bresee, Chris
A1 Hartmann, Mitra J. Z.
YR 2016
UL http://jn.physiology.org/content/early/2016/11/18/jn.00054.2016.abstract
AB Many rodents tactually sense the world through active motions of their vibrissae (whiskers), which are regularly arranged in rows and columns (arcs) on the face. The present study quantifies several geometric parameters of rat whiskers that determine the tactile information acquired. Findings include: 1) A meta-analysis of seven studies shows that whisker base diameter varies with arc length, with a surprisingly strong dependence on the whisker's row position within the array. 2) The length of the whisker medulla varies linearly with whisker length, and the medulla's base diameter varies linearly with whisker base diameter. 3) Two parameters are required to characterize whisker "taper": radius ratio (base radius divided by tip radius) and radius slope (the difference between base and tip radius, divided by arc length). A meta-analysis of five studies shows that radius ratio exhibits large variability due to variations in tip radius, while radius slope varies systematically across the array. 4) To within the resolution of the present study, radius slope does not differ between the proximal and distal segments of the whisker, where "proximal" is defined by the presence of the medulla. 5) Radius slope of the medulla is offset by a constant value from radius slope of the proximal portion of the whisker. We conclude with equations for all geometric parameters as functions of row and column position. In a companion paper we discuss some implications of these geometric results for vibrissal-based tactile sensing.