与年轻人相比,老年人在步行过程中的皮质脊髓驱动减少,但目前尚不清楚这种减少可能会如何损害一个人调整步进的能力,特别是在视觉运动适应期间。我们假设与年龄相关的皮质脊髓驱动的变化可以预测老年人在视觉扰动下的步长和步长时间调整与年轻人相比的差异。健康的年轻人(n=21;年龄18-33岁)和老年人(n=20;年龄68-80岁)通过跑步机任务进行测试,结合脚的位置和脚步目标的实时视觉反馈。适应期间,一侧的视觉运动增益降低,导致脚光标和脚步目标在屏幕的那一侧移动较慢(即,分裂视觉运动适应)。通过β-γ频段(15-45Hz)的肌电图信号之间的相干性来量化皮质脊髓驱动。结果表明,1)老年人适应行走过程中的视觉运动扰动,与年轻人相比,误差不对称性的降低相似;2)然而,老年人在步长时间对称性上表现出适应性降低,尽管在步长不对称方面表现出与年轻成年人相似的适应;3)步长时间不对称的总体变化较小,与在视觉运动分裂适应过程中慢腿的皮质脊髓向胫骨前的驱动减少相关.这些发现表明,皮质脊髓驱动的变化可能会影响老年人对视觉挑战的步数控制。这对于在不同环境中行走或处理意外情况时的安全导航可能很重要。
Corticospinal drive during walking is reduced in older adults compared with young adults, but it is not clear how this decrease might compromise one\'s ability to adjust stepping, particularly during
visuomotor adaptation. We hypothesize that age-related changes in corticospinal drive could predict differences in older adults\' step length and step time adjustments in response to visual perturbations compared with younger adults. Healthy young (n = 21; age 18-33 yr) and older adults (n = 20; age 68-80 yr) were tested with a treadmill task, incorporating visual feedback of the foot position and stepping targets in real-time. During adaptation, the
visuomotor gain was reduced on one side, causing the foot cursor and step targets to move slower on that side of the screen (i.e., split-
visuomotor adaptation). Corticospinal drive was quantified by coherence between electromyographic signals in the beta-gamma frequency band (15-45 Hz). The results showed that 1) older adults adapted to
visuomotor perturbations during walking, with a similar reduction in error asymmetry compared with younger adults; 2) however, older adults showed reduced adaptation in step time symmetry, despite demonstrating similar adaptation in step length asymmetry compared with younger adults; and 3) smaller overall changes in step time asymmetry was associated with reduced corticospinal drive to the tibialis anterior in the slow leg during split-
visuomotor adaptation. These findings suggest that changes in corticospinal drive may affect older adults\' control of step timing in response to visual challenges. This could be important for safe navigation when walking in different environments or dealing with unexpected circumstances.NEW & NOTEWORTHY Corticospinal input is essential for visually guided walking, especially when the walking pattern must be modified to accurately step on safe locations. Age-related changes in corticospinal drive are associated with inflexible step time, which necessitates different locomotor adaptation strategies in older adults.