Courtine Grégoire, Schieppati Marco
Sezione di Fisiologia Umana, Dipartimento di Medicina Sperimentale, Università di Pavia, and Centro Studi Attività Motorie, Fondazione Salvatore Maugeri (Istituto di Ricovero e Cura a Carattere Scientifico), Istituto Scientifico di Pavia, Pavia, Italy.
J Neurophysiol. 2004 Apr;91(4):1524-35. doi: 10.1152/jn.00817.2003. Epub 2003 Dec 10.
We tested the hypothesis that common principles govern the production of the locomotor patterns for both straight-ahead and curved walking. Whole body movement recordings showed that continuous curved walking implies substantial, limb-specific changes in numerous gait descriptors. Principal component analysis (PCA) was used to uncover the spatiotemporal structure of coordination among lower limb segments. PCA revealed that the same kinematic law accounted for the coordination among lower limb segments during both straight-ahead and curved walking, in both the frontal and sagittal planes: turn-related changes in the complex behavior of the inner and outer limbs were captured in limb-specific adaptive tuning of coordination patterns. PCA was also performed on a data set including all elevation angles of limb segments and trunk, thus encompassing 13 degrees of freedom. The results showed that both straight-ahead and curved walking were low dimensional, given that 3 principal components accounted for more than 90% of data variance. Furthermore, the time course of the principal components was unchanged by curved walking, thereby indicating invariant coordination patterns among all body segments during straight-ahead and curved walking. Nevertheless, limb- and turn-dependent tuning of the coordination patterns encoded the adaptations of the limb kinematics to the actual direction of the walking body. Absence of vision had no significant effect on the intersegmental coordination during either straight-ahead or curved walking. Our findings indicate that kinematic laws, probably emerging from the interaction of spinal neural networks and mechanical oscillators, subserve the production of both straight-ahead and curved walking. During locomotion, the descending command tunes basic spinal networks so as to produce the changes in amplitude and phase relationships of the spinal output, sufficient to achieve the body turn.
我们检验了这样一个假设，即共同的原理支配着直线行走和转弯行走时运动模式的产生。全身运动记录表明，持续的转弯行走意味着众多步态描述指标中肢体特异性的显著变化。主成分分析（PCA）被用于揭示下肢各节段间协调的时空结构。PCA显示，在直线行走和转弯行走过程中，无论在额面还是矢状面，相同的运动学规律都能解释下肢各节段间的协调：内外侧肢体复杂行为中与转弯相关的变化在协调模式的肢体特异性适应性调整中得以体现。我们还对一个包含肢体节段和躯干所有仰角的数据集进行了PCA分析，从而涵盖13个自由度。结果表明，直线行走和转弯行走都是低维度的，因为3个主成分解释了超过90%的数据方差。此外，转弯行走并未改变主成分的时间进程，从而表明在直线行走和转弯行走过程中，所有身体节段间的协调模式是不变的。然而，协调模式的肢体和转弯依赖性调整编码了肢体运动学对行走身体实际方向的适应性变化。在直线行走或转弯行走过程中，视觉缺失对节段间协调没有显著影响。我们的研究结果表明，运动学规律可能源于脊髓神经网络和机械振荡器的相互作用，它有助于直线行走和转弯行走的产生。在运动过程中，下行指令调节基本的脊髓网络，从而产生脊髓输出的幅度和相位关系变化，足以实现身体转弯。
