College of Health Professions, Medical University of South Carolina, 77 President St., MSC700, Charleston, SC, 29425-571, USA.
Ralph H. Johnson Veterans Affairs Medical Center, Charleston, SC, USA.
Sci Rep. 2020 Jul 22;10(1):12197. doi: 10.1038/s41598-020-69052-5.
During human walking, step width is predicted by mediolateral motion of the pelvis, a relationship that can be attributed to a combination of passive body dynamics and active sensorimotor control. The purpose of the present study was to investigate whether humans modulate the active control of step width in response to a novel mechanical environment. Participants were repeatedly exposed to a force-field that either assisted or perturbed the normal relationship between pelvis motion and step width, separated by washout periods to detect the presence of potential after-effects. As intended, force-field assistance directly strengthened the relationship between pelvis displacement and step width. This relationship remained strengthened with repeated exposure to assistance, and returned to baseline afterward, providing minimal evidence for assistance-driven changes in active control. In contrast, force-field perturbations directly weakened the relationship between pelvis motion and step width. Repeated exposure to perturbations diminished this negative direct effect, and produced larger positive after-effects once the perturbations ceased. These results demonstrate that targeted perturbations can cause humans to adjust the active control that contributes to fluctuations in step width.
在人类行走过程中，步幅由骨盆的横向运动来预测，这种关系可以归因于被动的身体动力学和主动的感觉运动控制的组合。本研究的目的是调查人类是否会根据新的机械环境来调节主动控制步幅的方式。参与者反复暴露于一种力场中，该力场辅助或干扰了骨盆运动和步幅之间的正常关系，并用洗脱期来检测潜在的后效。如预期的那样，力场辅助直接加强了骨盆位移和步幅之间的关系。这种关系在反复接受辅助后仍然保持加强，随后又恢复到基线水平，几乎没有证据表明主动控制受到辅助的驱动而发生了变化。相比之下，力场干扰直接削弱了骨盆运动和步幅之间的关系。反复暴露于干扰会减小这种负向直接效应，并在干扰停止后产生更大的正向后效。这些结果表明，有针对性的干扰可以使人类调整主动控制，从而影响步幅的波动。
