Lee Kyoung-Hyun, Baksh Asheeba, Bryant Alyssa, McGowan Mollie, McMillan Ryan, Chong Raymond K
Center for Sport Science in Gwangju, Gwangju Sports Council, Gwangju, South Korea.
Department of Physical Therapy, Augusta University, Augusta, GA, United States.
Front Hum Neurosci. 2017 Oct 23;11:480. doi: 10.3389/fnhum.2017.00480. eCollection 2017.
Orientation of posture relative to the environment depends on the contributions from the somatosensory, vestibular, and visual systems mixed in varying proportions to produce a sensorimotor set. Here, we probed the sensorimotor set composition using a postural adaptation task in which healthy adults stood on an inclined surface for 3 min. Upon returning to a horizontal surface, participants displayed a range of postural orientations - from an aftereffect that consisted of a large forward postural lean to an upright stance with little or no aftereffect. It has been hypothesized that the post-incline postural change depends on each individual's sensorimotor set: whether the set was dominated by the somatosensory or vestibular system: Somatosensory dominance would cause the lean aftereffect whereas vestibular dominance should steer stance posture toward upright orientation. We investigated the individuals who displayed somatosensory dominance by manipulating their attention to spatial orientation. We introduced a distraction condition in which subjects concurrently performed a difficult arithmetic subtraction task. This manipulation altered the time course of their post-incline aftereffect. When not distracted, participants returned to upright stance within the 3-min period. However, they continued leaning forward when distracted. These results suggest that the mechanism of sensorimotor set adaptation to inclined stance comprises at least two components. The first component reflects the dominant contribution from the somatosensory system. Since the postural lean was observed among these subjects even when they were not distracted, it suggests that the aftereffect is difficult to overcome. The second component includes a covert attentional component which manifests as the dissipation of the aftereffect and the return of posture to upright orientation.
相对于环境的姿势定向取决于体感、前庭和视觉系统以不同比例混合产生的感觉运动集合的作用。在此，我们使用姿势适应任务来探究感觉运动集合的组成，在该任务中，健康成年人站在倾斜表面上3分钟。回到水平表面后，参与者表现出一系列姿势定向——从由大幅度向前姿势倾斜组成的后效应到几乎没有后效应或没有后效应的直立姿势。据推测，倾斜后姿势变化取决于每个人的感觉运动集合：该集合是由体感系统还是前庭系统主导：体感主导会导致倾斜后效应，而前庭主导应使姿势朝向直立方向。我们通过操纵他们对空间定向的注意力来研究表现出体感主导的个体。我们引入了一种分心条件，即受试者同时进行一项困难的算术任务。这种操纵改变了他们倾斜后效应的时间进程。不分心时，参与者在3分钟内恢复到直立姿势。然而，分心时他们继续向前倾斜。这些结果表明，感觉运动集合适应倾斜姿势的机制至少包括两个组成部分。第一个组成部分反映了体感系统的主要作用。由于即使在这些受试者不分心时也观察到姿势倾斜，这表明后效应难以克服。第二个组成部分包括一个隐蔽的注意力成分，表现为后效应的消散和姿势恢复到直立方向。
