Hasan Z
Department of Movement Sciences, University of Illinois at Chicago, Mail Code 898, 1919 W. Taylor Street, Room 447, Chicago, IL 60612, USA.
J Mot Behav. 2005 Nov;37(6):484-93. doi: 10.3200/JMBR.37.6.484-493.
From among the diverse meanings of stability, the one the author adopts here is that the effects of a perturbation are opposed, and therefore small effects remain small. Except in linear systems, however, instability need not lead to unbounded motion and may actually be desirable when maneuverability is important. Moreover, properties of nerves, muscles, and tendons present serious challenges to stabilization. A review of observations from the motor control literature reveals that responses to perturbations in many common situations assist rather than resist the perturbation and are therefore presumably destabilizing. The observations encompass situations of position maintenance as well as impending or ongoing movement. The author proposes that the motor control system responds to a sudden perturbation by a pattern of muscle activity that mimics an accustomed voluntary movement, oblivious of stability considerations. What prevents runaway motion in the face of short-term instability appears to be voluntary intervention.
在稳定性的多种含义中，作者在此采用的是这样一种含义：扰动的影响会受到抵制，因此小的影响仍然很小。然而，除了线性系统外，不稳定性不一定会导致无界运动，并且在机动性很重要时，不稳定性实际上可能是可取的。此外，神经、肌肉和肌腱的特性给稳定化带来了严峻挑战。对运动控制文献中的观察结果进行回顾后发现，在许多常见情况下，对扰动的反应是协助而非抵制扰动，因此大概是会破坏稳定性的。这些观察结果涵盖了位置维持以及即将发生或正在进行的运动的情况。作者提出，运动控制系统会通过模仿习惯性自主运动的肌肉活动模式来应对突然的扰动，而忽略稳定性因素。面对短期不稳定性时，防止运动失控的似乎是自主干预。
