Diverse and complex muscle spindle afferent firing properties emerge from multiscale muscle mechanics.
Diverse and complex muscle spindle afferent firing properties emerge from multiscale muscle mechanics.
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DOI：
10.7554/elife.55177
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发表时间：
2020-12-28
期刊：
影响因子：
7.7
通讯作者：
Ting LH
中科院分区：
文献类型：
--
作者：
Blum KP;Campbell KS;Horslen BC;Nardelli P;Housley SN;Cope TC;Ting LH
尽管几十年的研究，我们缺乏一个机制框架，能够预测运动相关信号如何转化为实验观察到的肌肉纺锤体传入放电模式的多样性，特别是在自然行为中。在这里，一个生物物理模型证明了众所周知的哺乳动物肌肉纺锤体传入的放电特征——包括运动历史依赖性和肌肉拉伸速度的非线性缩放——来自肌肉收缩力学的第一原理。此外，肌肉纺锤体与肌肉肌腱动力学的机械相互作用揭示了运动指令对肌肉（α驱动）和肌肉纺锤体（γ驱动）的影响如何在主动肌肉收缩和肌肉拉伸期间引起高度可变和复杂的活动，这是无法简单解释的。根据神经力学条件，肌纺轴模型输出似乎“编码”了肌肉力、拉力、长度、刚度、速度和/或加速度的各个方面，为理解和预测健康和疾病中的本体感觉信号提供了一个可扩展的、多尺度的生物物理框架。
Despite decades of research, we lack a mechanistic framework capable of predicting how movement-related signals are transformed into the diversity of muscle spindle afferent firing patterns observed experimentally, particularly in naturalistic behaviors. Here, a biophysical model demonstrates that well-known firing characteristics of mammalian muscle spindle Ia afferents – including movement history dependence, and nonlinear scaling with muscle stretch velocity – emerge from first principles of muscle contractile mechanics. Further, mechanical interactions of the muscle spindle with muscle-tendon dynamics reveal how motor commands to the muscle (alpha drive) versus muscle spindle (gamma drive) can cause highly variable and complex activity during active muscle contraction and muscle stretch that defy simple explanation. Depending on the neuromechanical conditions, the muscle spindle model output appears to ‘encode’ aspects of muscle force, yank, length, stiffness, velocity, and/or acceleration, providing an extendable, multiscale, biophysical framework for understanding and predicting proprioceptive sensory signals in health and disease.