Brain Plasticity Laboratory, Department of Physical Therapy, College of Applied Health Sciences, University of Illinois, Chicago, IL,USA.
Graduate Program in Rehabilitation Science, College of Applied Health Sciences, University of Illinois, Chicago, IL,USA.
Motor Control. 2023 May 8;27(4):751-764. doi: 10.1123/mc.2022-0105. Print 2023 Oct 1.
Transcranial direct current stimulation (tDCS) has been demonstrated to facilitate motor performance in healthy individuals; however, results are variable. The neuromodulatory effects of tDCS during visuomotor tasks may be influenced by extrinsic visual feedback. However, this interaction between tDCS and visual feedback has not been explored for the lower limb. Hence, our objective was to explore if tDCS over the primary lower limb motor cortex differentially facilitates motor performance based on the availability of visual feedback.
Twenty-two neurotypical adults performed ankle plantarflexion and dorsiflexion movements while tracking a sinusoidal target. Spatiotemporal, spatial, and temporal error were calculated between the ankle position and target. Participants attended two sessions, a week apart, with (Stim) and without (No-Stim) anodal tDCS. Sessions were divided into two blocks containing randomized visual feedback conditions: full, no, and blindfold. During Stim sessions, the first block included the application of tDCS to the lower limb M1.
Spatiotemporal and spatial error increased as feedback faded (p < .001). A two-way repeated-measures analysis of variance showed a significant interaction between tDCS and visual feedback (p < .05) on spatiotemporal error. Post hoc analyses revealed a significant improvement in spatiotemporal error when visual feedback was absent (p < .01). Spatial and temporal errors were not significantly affected by stimulation or visual feedback.
Our results suggest that tDCS enhances spatiotemporal ankle motor performance only when visual feedback is not available. These findings indicate that visual feedback may play an important role in demonstrating the effectiveness of tDCS.
经颅直流电刺激（tDCS）已被证明能促进健康个体的运动表现；然而，结果是可变的。tDCS 在视动任务中的神经调节作用可能受到外在视觉反馈的影响。然而，tDCS 和视觉反馈之间的这种相互作用尚未在下肢中得到探索。因此，我们的目的是探索 tDCS 是否会根据视觉反馈的可用性，对初级下肢运动皮层产生不同的促进运动表现的效果。
22 名神经正常的成年人在跟踪正弦波目标的同时进行踝关节跖屈和背屈运动。踝关节位置和目标之间的时空、空间和时间误差。参与者参加了两个相隔一周的会议，一个是有（Stim）和一个没有（No-Stim）阳极 tDCS。会议分为两个包含随机视觉反馈条件的块：全、无和蒙眼。在 Stim 会议期间，第一块包括 tDCS 应用于下肢 M1。
随着反馈的减弱，时空和空间误差增加（p<0.001）。双向重复测量方差分析显示 tDCS 和视觉反馈之间存在显著的交互作用（p<0.05）时空误差。事后分析显示，在没有视觉反馈的情况下，时空误差显著改善（p<0.01）。空间和时间误差不受刺激或视觉反馈的显著影响。
我们的结果表明，只有在没有视觉反馈的情况下，tDCS 才能增强时空踝关节运动表现。这些发现表明，视觉反馈可能在展示 tDCS 的有效性方面发挥重要作用。
