Department of Mechanical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208, USA.
Philos Trans R Soc Lond B Biol Sci. 2011 Nov 12;366(1581):3049-57. doi: 10.1098/rstb.2011.0166.
Rats rhythmically tap and brush their vibrissae (whiskers) against objects to tactually explore the environment. To extract a complex feature such as the contour of an object, the rat must at least implicitly estimate radial object distance, that is, the distance from the base of the vibrissa to the point of object contact. Radial object distance cannot be directly measured, however, because there are no mechanoreceptors along the vibrissa. Instead, the mechanical signals generated by the vibrissa's interaction with the environment must be transmitted to mechanoreceptors near the vibrissa base. The first part of this paper surveys the different mechanical methods by which the rat could determine radial object distance. Two novel methods are highlighted: one based on measurement of bending moment and axial force at the vibrissa base, and a second based on measurement of how far the vibrissa rotates beyond initial contact. The second part of the paper discusses the application of Weber's law to two methods for radial distance determination. In both cases, Weber's law predicts that the rat will have greatest sensing resolution close to the vibrissa tip. These predictions could be tested with behavioural experiments that measure the perceptual acuity of the rat.
老鼠有节奏地轻敲和刷动它们的触须（胡须）以触觉方式探索环境。为了提取物体的复杂特征，例如物体的轮廓，老鼠必须至少隐式估计径向物体距离，即从触须根部到物体接触点的距离。然而，由于触须上没有机械感受器，因此无法直接测量径向物体距离。相反，触须与环境相互作用产生的机械信号必须传递到触须根部附近的机械感受器。本文的第一部分调查了老鼠确定径向物体距离的不同机械方法。重点介绍了两种新方法：一种基于测量触须根部的弯矩和轴向力，另一种基于测量触须超出初始接触后旋转的距离。本文的第二部分讨论了韦伯定律在两种径向距离确定方法中的应用。在这两种情况下，韦伯定律预测老鼠在触须尖端附近的感知分辨率最高。这些预测可以通过测量老鼠感知锐度的行为实验来检验。
