Biomechanical models for radial distance determination by the rat vibrissal system
Biomechanical models for radial distance determination by the rat vibrissal system
复制标题
DOI：
10.1152/jn.00707.2006
复制
发表时间：
2007-10-01
影响因子：
2.5
通讯作者：
Hartmann, Mitra J. Z.
中科院分区：
文献类型：
--
作者：
Birdwell, J. Alexander;Solomon, Joseph H.;Hartmann, Mitra J. Z.
老鼠利用胡须的主动、有节奏的运动来获取有关三维物体特征的触觉信息。沿着胡须的长度没有受体；因此，所有触觉信息都必须通过机械方式转回到胡须基部的受体。这就提出了一个问题：老鼠如何确定物体沿胡须的径向接触位置？我们开发了两个互补的生物力学模型，表明大鼠可以通过监测胡须基部的力矩变化率（或等效的曲率变化率）来确定径向物体距离。第一个模型用于探索锥度和固有胡须曲率对胡须变形的影响，并用于预测真实大鼠胡须在不同径向距离偏转期间的形状。预测的形状与实验测量结果非常吻合。第二个模型描述了径向物体距离与锥形、固有弯曲晶须底部的力矩变化率之间的关系。总之，这些模型可以解释最近的记录，这些记录显示一些三叉神经节（Vg）神经元编码的径向距离更近，放电率更高。这些模型还表明，需要在晶须底部的四个且仅四个物理变量——角位置、角速度、力矩和力矩变化率——来描述晶须的动态。我们在不断发展的假设的背景下解释这些结果，即 Vg 中的神经反应可以使用包含这四个变量组合的状态编码方案来表示。
Rats use active, rhythmic movements of their whiskers to acquire tactile information about three-dimensional object features. There are no receptors along the length of the whisker; therefore all tactile information must be mechanically transduced back to receptors at the whisker base. This raises the question: how might the rat determine the radial contact position of an object along the whisker? We developed two complementary biomechanical models that show that the rat could determine radial object distance by monitoring the rate of change of moment ( or equivalently, the rate of change of curvature) at the whisker base. The first model is used to explore the effects of taper and inherent whisker curvature on whisker deformation and used to predict the shapes of real rat whiskers during deflections at different radial distances. Predicted shapes closely matched experimental measurements. The second model describes the relationship between radial object distance and the rate of change of moment at the base of a tapered, inherently curved whisker. Together, these models can account for recent recordings showing that some trigeminal ganglion (Vg) neurons encode closer radial distances with increased firing rates. The models also suggest that four and only four physical variables at the whisker base - angular position, angular velocity, moment, and rate of change of moment - are needed to describe the dynamic state of a whisker. We interpret these results in the context of our evolving hypothesis that neural responses in Vg can be represented using a state-encoding scheme that includes combinations of these four variables.