Department of Kinesiology, The Pennsylvania State University, 20, Recreation Building, University Park, PA 16802, USA.
Exp Brain Res. 2013 Mar;225(3):431-42. doi: 10.1007/s00221-012-3383-2. Epub 2013 Jan 4.
This study joined two approaches to motor control. The first approach comes from cognitive psychology and is based on the idea that goal postures and movements are chosen to satisfy task-specific constraints. The second approach comes from the principle of motor abundance and is based on the idea that control of apparently redundant systems is associated with the creation of multi-element synergies stabilizing important performance variables. The first approach has been tested by relying on psychophysical ratings of comfort. The second approach has been tested by estimating variance along different directions in the space of elemental variables such as joint postures. The two approaches were joined here. Standing subjects performed series of movements in which they brought a hand-held pointer to each of four targets oriented within a frontal plane, close to or far from the body. The subjects were asked to rate the comfort of the final postures, and the variance of their joint configurations during the steady state following pointing was quantified with respect to pointer endpoint position and pointer orientation. The subjects showed consistent patterns of comfort ratings among the targets, and all movements were characterized by multi-joint synergies stabilizing both pointer endpoint position and orientation. Contrary to what was expected, less comfortable postures had higher joint configuration variance than did more comfortable postures without major changes in the synergy indices. Multi-joint synergies stabilized the pointer position and orientation similarly across a range of comfortable/uncomfortable postures. The results are interpreted in terms conducive to the two theoretical frameworks underlying this work, one focusing on comfort ratings reflecting mean postures adopted for different targets and the other focusing on indices of joint configuration variance.
本研究结合了两种运动控制方法。第一种方法来自认知心理学，基于这样的理念：目标姿势和动作是为了满足特定任务的约束而选择的。第二种方法来自运动过剩原理，基于这样的理念：对明显冗余系统的控制与创建多要素协同作用以稳定重要性能变量有关。第一种方法通过依赖于舒适度的心理物理评级进行了测试。第二种方法通过估计基本变量空间（如关节姿势）中不同方向上的方差进行了测试。这里将这两种方法结合起来。站立的受试者进行了一系列运动，他们将手持指针指向位于正面平面内的四个目标，这些目标靠近或远离身体。受试者被要求对最终姿势的舒适度进行评分，并根据指针端点位置和指针方向量化它们在指向稳定状态下的关节配置的方差。受试者在目标之间表现出一致的舒适度评分模式，所有运动都表现出多关节协同作用，稳定了指针端点位置和方向。与预期相反，不太舒适的姿势比更舒适的姿势具有更高的关节配置方差，而协同指数没有发生重大变化。多关节协同作用在一系列舒适/不舒适姿势下以类似的方式稳定了指针位置和方向。结果根据这两项工作背后的两个理论框架进行了解释，一个框架侧重于反映针对不同目标采用的平均姿势的舒适度评分，另一个框架侧重于关节配置方差的指标。
