Interactions Between Limb and Environmental Mechanics Influence Stretch Reflex Sensitivity in the Human Arm
Interactions Between Limb and Environmental Mechanics Influence Stretch Reflex Sensitivity in the Human Arm
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DOI：
10.1152/jn.00679.2009
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发表时间：
2010-01-01
影响因子：
2.5
通讯作者：
Perreault, Eric J.
中科院分区：
文献类型：
--
作者：
Krutky, Matthew A.;Ravichandran, Vengateswaran J.;Perreault, Eric J.
Krutky MA、Ravichandran VJ、Trumbower RD、Perreault EJ。肢体和环境力学之间的相互作用会影响人类手臂的牵张反射敏感性。 J Neurophysiol 103: 429-440, 2010。首次发表于 2009 年 11 月 11 日； doi：10.1152/jn.00679.2009。牵张反射有助于手臂阻抗，较长潜伏期的牵张反射在与顺从或不稳定的环境相互作用时表现出更高的敏感性。这种增加的灵敏度与调节臂阻抗以补偿环境稳定性下降是一致的，但这种调节的特异性还有待研究。许多任务（例如工具使用）会损害手臂沿特定方向的稳定性，而针对这些方向调整的牵张反射可以提供一种有效的机制，以适合任务的方式调节手臂阻抗。为了有效，这种调整不仅应该适应环境的机械特性，还应该适应与手臂相关的特性，手臂也具有定向特定的机械特性。本研究的目的是研究在与挑战手臂稳定性的机械环境相互作用期间牵张反射调节的特异性。测试环境不稳定，具有负刚度弹簧的特性。这些与每个受试者的最大端点刚度方向对齐或正交。我们的结果表明，在扰动开始的 50-100 毫秒内引起的反射优先增加，特别是沿着不稳定环境的方向施加的扰动。仅当环境不稳定性的大小超过沿同一方向的端点刚度时，才会出现这种增加。这些结果与根据环境机械特性（相对于人臂的机械特性）调整的任务特定反射调制一致。他们展示了一种高度适应性的非自愿机制，可用于沿特定方向调节肢体阻抗。
Krutky MA, Ravichandran VJ, Trumbower RD, Perreault EJ. Interactions between limb and environmental mechanics influence stretch reflex sensitivity in the human arm. J Neurophysiol 103: 429-440, 2010. First published November 11, 2009; doi: 10.1152/jn.00679.2009. Stretch reflexes contribute to arm impedance and longer-latency stretch reflexes exhibit increased sensitivity during interactions with compliant or unstable environments. This increased sensitivity is consistent with a regulation of arm impedance to compensate for decreased stability of the environment, but the specificity of this modulation has yet to be investigated. Many tasks, such as tool use, compromise arm stability along specific directions, and stretch reflexes tuned to those directions could present an efficient mechanism for regulating arm impedance in a task-appropriate manner. To be effective, such tuning should adapt not only to the mechanical properties of the environment but to those properties in relation to the arm, which also has directionally specific mechanical properties. The purpose of this study was to investigate the specificity of stretch reflex modulation during interactions with mechanical environments that challenge arm stability. The tested environments were unstable, having the characteristics of a negative stiffness spring. These were either aligned or orthogonal to the direction of maximal endpoint stiffness for each subject. Our results demonstrate preferential increases in reflexes, elicited within 50-100 ms of perturbation onset, to perturbations applied specifically along the direction of the destabilizing environments. This increase occurred only when the magnitude of the environmental instability exceeded endpoint stiffness along the same direction. These results are consistent with task-specific reflex modulation tuned to the mechanical properties of the environment relative to those of the human arm. They demonstrate a highly adaptable, involuntary mechanism that may be used to modulate limb impedance along specific directions.