The Mechanical Variables Underlying Object Localization along the Axis of the Whisker
The Mechanical Variables Underlying Object Localization along the Axis of the Whisker
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DOI：
10.1523/jneurosci.4316-12.2013
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发表时间：
2013-04-17
影响因子：
5.3
通讯作者：
Svoboda, Karel
中科院分区：
文献类型：
--
作者：
Pammer, Lorenz;O'Connor, Daniel H.;Svoboda, Karel
啮齿动物通过移动胡须来定位空间中的物体。在这里，我们使用心理物理学方法来证明，头部固定的小鼠可以沿着单个须的轴定位物体，径向尺寸，精度为一毫米。高速摄像使我们能够估计在晶须基部的力和弯矩，这是径向距离测量的基础。小鼠根据多次触摸判断径向物体位置。触摸次数（1-17次）和电极施加在晶须上的力（最大573 μ N；典型峰值振幅为100 μ N）在不同的试验中变化很大。我们通过改变物体在运动过程中的顺应性来控制将须状物压向毛囊两侧的弯矩和侧向力以及将须状物推入毛囊的轴向力。行为反应表明，小鼠使用多个变量（弯矩、轴向力、侧向力）来提取径向物体定位。晶须的力学特性表明，晶须的弯曲刚度随着与表面距离的增加而逐渐降低，超过5个数量级。结果表明，不同应力变量的相对幅值随物体径向距离的变化幅度较大。我们的数据表明，小鼠使用距离依赖的须力学来估计径向物体位置，使用的算法不依赖于须的精确控制，对须力的变化具有鲁棒性，并且与物体顺应性和物体运动无关。更一般地说，我们的数据表明，小鼠可以测量触觉感觉毛囊中的力的振幅。
Rodents move their whiskers to locate objects in space. Here we used psychophysical methods to show that head-fixed mice can localize objects along the axis of a single whisker, the radial dimension, with one-millimeter precision. High-speed videography allowed us to estimate the forces and bending moments at the base of the whisker, which underlie radial distance measurement. Mice judged radial object location based on multiple touches. Both the number of touches (1-17) and the forces exerted by the pole on the whisker (up to 573 mu N; typical peak amplitude, 100 mu N) varied greatly across trials. We manipulated the bending moment and lateral force pressing the whisker against the sides of the follicle and the axial force pushing the whisker into the follicle by varying the compliance of the object during behavior. The behavioral responses suggest that mice use multiple variables (bending moment, axial force, lateral force) to extract radial object localization. Characterization of whisker mechanics revealed that whisker bending stiffness decreases gradually with distance from the face over five orders of magnitude. As a result, the relative amplitudes of different stress variables change dramatically with radial object distance. Our data suggest that mice use distance-dependent whisker mechanics to estimate radial object location using an algorithm that does not rely on precise control of whisking, is robust to variability in whisker forces, and is independent of object compliance and object movement. More generally, our data imply that mice can measure the amplitudes of forces in the sensory follicles for tactile sensation.