Early and late components of feed-forward postural adjustments to predictable perturbations.
Early and late components of feed-forward postural adjustments to predictable perturbations.
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DOI：
10.1016/j.clinph.2011.09.014
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发表时间：
2012-05
期刊：
影响因子：
--
通讯作者：
Aruin AS
中科院分区：
文献类型：
--
作者：
Krishnan V;Latash ML;Aruin AS
目的是调查两种类型的前馈姿态调整与可预测的外部扰动的准备。九名受试者脚趾朝上或脚趾朝下站在楔形物上，同时钟摆撞击他们的肩膀。在不受控制的流形假设的框架内分析了腿部和躯干肌肉的肌电图。在撞击前400-500 ms观察到早期姿势调整（EPA），在撞击前100-150 ms观察到预期姿势调整（APA）。EPA和APA也出现在肌肉模式的时间曲线中，代表肌肉群的激活水平呈线性缩放。通过在试验中对肌肉模式幅度进行共变调整来稳定压力偏移中心。这些多肌肉协同作用的指数显示两个下降（预期协同作用调整，ASA），之前EPA和阿帕在每个主题。这两种情况下的结果是一致的。结果表明，前馈姿态调整代表了一系列的两种现象，EPA和APA。每一个都是在ASA之前，降低了在EPA和APA期间要调整的变量的稳定性。研究结果符合一个层次的计划与协同的少到多的映射在每一个层次的基础上，所指的身体配置假设。结果表明，复杂的姿势准备行动。潜在的，他们有影响的当前策略的康复神经运动障碍患者的特点是受损的姿势控制。
The purpose was to investigate two types of feed-forward postural adjustments associated with preparation to predictable external perturbations. Nine subjects stood on a wedge, toes-up or toes-down while a pendulum impacted their shoulders. EMGs of leg and trunk muscles were analyzed within the framework of the uncontrolled manifold hypothesis. Early postural adjustments (EPAs) were seen 400–500 ms and anticipatory postural adjustments (APAs), 100–150 ms prior to the impact. EPAs and APAs were also seen in the time profiles of muscle modes representing muscle groups with linear scaling of the activation levels. Center of pressure shifts were stabilized by co-varied adjustments in muscle mode magnitudes across trials. The index of these multi-muscle synergies showed two drops (anticipatory synergy adjustments, ASAs), prior to EPA and APA in each subject. The findings were consistent between the two conditions. The results show that feed-forward postural adjustments represent a sequence of two phenomena, EPAs and APAs. Each of those is preceded by ASAs that reduce stability of a variable that is to be adjusted during the EPAs and APAs. The findings fit a hierarchical scheme with synergic few-to-many mappings at each level of the hierarchy based on the referent body configuration hypothesis. The results show the complexity of the postural preparation to action. Potentially, they have implications for the current strategies of rehabilitation of patients with neuro-motor disorders characterized by impaired postural control.
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2
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