Adaptation of postural orientation to changes in surface inclination
Adaptation of postural orientation to changes in surface inclination
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DOI：
10.1007/s00221-006-0715-0
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发表时间：
2007-03-01
影响因子：
2
通讯作者：
Horak, Fay B.
中科院分区：
文献类型：
--
作者：
Kluzik, JoAnn;Peterka, Robert J.;Horak, Fay B.
我们先前表明，站在倾斜表面上会导致许多健康的、蒙眼的受试者在返回到站在水平表面上时产生倾斜的后效（Kluzik等人，Exp Brain Res 162：474-489，2005）。倾斜的方向取决于先前表面倾斜的方向，总是在保持身体和支撑表面之间的相对对准的方向上。例如，受试者站在脚趾朝上的斜面上后身体前倾。在本研究中，我们调查了表面倾斜的幅度如何影响姿势性肌肉活动，关节位置，身体部分的方向，以及身体的质量中心（CoM）和脚的压力中心（CoP）的位置之前，期间和之后的主题站在倾斜的表面。我们问，精益后效应的机制是否涉及局部姿势变量的调节，如踝关节的位置或肌肉活动的水平，或者，该机制是否涉及全局，全身姿势变量的调节，只能由多感官处理，如躯干的方向或身体的CoM。在一个实验中，我们发现，脚趾向上表面倾斜的幅度在2.5度和10度之间变化，对躯干和头部的倾斜后方向有系统的、线性的影响，但并没有系统地影响腿部的倾斜后方向、踝关节的位置、EMG活动的水平或CoP的位置。在第二个实验中，我们发现，在后倾斜期防止腿部倾斜并不能消除上身的倾斜。这些发现表明：（1）身体与支撑表面的关系是中枢神经系统对姿势定向的内部表征的重要参考，姿势定向受到适应性修改;（2）倾斜后效应的适应机制作用于全局、全身姿势变量水平。
We previously showed that standing on an inclined surface resulted in an after-effect of leaning in many healthy, blindfolded subjects when they returned to standing on a horizontal surface (Kluzik et al. in Exp Brain Res 162:474-489, 2005). The direction of leaning depended on the direction of prior surface inclination, always in a direction that preserved the relative alignment between the body and the support surface. For example, subjects leaned forward after they stood on a toes-up-inclined surface. In the present study, we investigated how the amplitude of surface inclination affected postural muscle activity, joint position, body segment orientation, and body center of mass (CoM) and foot center of pressure (CoP) locations before, during, and after subjects stood on an inclined surface. We asked whether the mechanism that underlies the lean after-effect involves regulation of local postural variables, such as the position of the ankle joint or the level of muscle activity, or whether instead, the mechanism involves regulation of global, whole-body postural variables that can only be determined by multisensory processing, such as orientation of the trunk or the body's CoM. In one experiment, we found that varying the amplitude of a toes-up surface inclination between 2.5 degrees and 10 degrees had a systematic, linear, effect on the post-incline orientation of the trunk and head, but did not systematically affect the post-incline orientation of the legs, position of the ankle joint, the level of EMG activity, or the location of the CoP. In a second experiment, we found that preventing the legs from leaning in the post-incline period did not abolish leaning of the upper body. These findings suggest that (1) the body-to-support-surface relationship is an important reference for the CNS internal representation of postural orientation which is subject to adaptive modification and (2) the adaptive mechanism underlying the post-incline after-effect of leaning acts at the level of global, whole-body postural variables.