Shiva Tania, Misiaszek John E
Department of Occupational Therapy, Faculty of Rehabilitation Medicine, University of Alberta, 2-64 Corbett Hall, Edmonton, AB, T6G 2G4, Canada.
Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada.
Exp Brain Res. 2018 Feb;236(2):563-576. doi: 10.1007/s00221-017-5151-9. Epub 2017 Dec 15.
The first exposure of a rapid displacement of a light touch reference induces an inappropriate balance corrective response during standing in a proportion of participants that is extinguished with repeated exposures. We hypothesized that if the spatial touch reference was critical to performing of a task the evoked response would be more consistently expressed across participants and observed with repeated exposures to the disturbance. To test this, 20 participants received either forward (N = 10) or backward right-touch displacements at right-heel strike during motorized treadmill walking without visual feedback. Electromyographic recordings from four arm, four leg and one neck muscle were sampled along with joint kinematic and step cycle data. Rapid displacement of the touch surface elicited responses in all 20 participants. However, the frequency of first trial responses was not different from what was observed during standing. In contrast, responses were observed in all participants with subsequent trials. None of the participants tripped or stumbled as a result of the touch perturbations; however, the step cycle duration was consistently shorter following the first forward-touch displacement. A post-experiment questionnaire revealed that many participants often perceived the touch plate displacement as a disturbance to the treadmill belt speed, suggesting the disturbance was occasionally misinterpreted. The activation of ankle muscles following the unexpected slip of a touch reference during walking suggests that tactile information from the finger is a relevant sensory cue for the regulation and control of stepping and stability.
在一部分参与者中，当轻触参考点快速位移时，首次暴露会在站立过程中引发不适当的平衡纠正反应，而这种反应会随着重复暴露而消失。我们推测，如果空间触觉参考对于执行任务至关重要，那么诱发反应在参与者之间会更一致地表现出来，并且在反复暴露于干扰时也能观察到。为了验证这一点，20名参与者在无视觉反馈的电动跑步机行走过程中，在右足跟触地时接受向前（N = 10）或向后的右触摸位移。采集了来自四块手臂肌肉、四块腿部肌肉和一块颈部肌肉的肌电图记录，以及关节运动学和步周期数据。触摸表面的快速位移在所有20名参与者中都引发了反应。然而，首次试验反应的频率与站立时观察到的频率没有差异。相比之下，在随后的试验中，所有参与者都出现了反应。没有参与者因触摸扰动而绊倒或踉跄；然而，在第一次向前触摸位移后，步周期持续时间始终较短。实验后的问卷调查显示，许多参与者经常将触摸板的位移视为对跑步机皮带速度的干扰，这表明这种干扰偶尔会被误解。行走过程中触摸参考点意外滑动后踝关节肌肉的激活表明，来自手指的触觉信息是调节和控制步幅及稳定性的相关感觉线索。
