Kim Heegoo, Lee Gihyoun, Lee Jungsoo, Kim Yun-Hee
Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute, Samsung Medical Center, Seoul, Republic of Korea.
Department of Health Sciences and Technology, Samsung Advanced Institute for Health Science & Technology (SAIHST), Sungkyunkwan University, Seoul, Republic of Korea.
Front Neurosci. 2023 Jun 2;17:1189420. doi: 10.3389/fnins.2023.1189420. eCollection 2023.
Motor learning is a key component of stroke neurorehabilitation. High-definition transcranial direct current stimulation (HD-tDCS) was recently developed as a tDCS technique that increases the accuracy of current delivery to the brain using arrays of small electrodes. The purpose of this study was to investigate whether HD-tDCS alters learning-related cortical activation and functional connectivity in stroke patients using functional near-infrared spectroscopy (fNIRS).
Using a sham-controlled crossover study design, 16 chronic stroke patients were randomly assigned to one of two intervention conditions. Both groups performed the sequential finger tapping task (SFTT) on five consecutive days, either with (a) real HD-tDCS or (b) with sham HD-tDCS. HD-tDCS (1 mA for 20 min, 4 × 1) was administered to C3 or C4 (according to lesion side). fNIRS signals were measured during the SFTT with the affected hand before (baseline) and after each intervention using fNIRS measurement system. Cortical activation and functional connectivity of NIRS signals were analyzed using a statistical parametric mapping open-source software package (NIRS-SPM), II.
In the real HD-tDCS condition, oxyHb concentration increased significantly in the ipsilesional primary motor cortex (M1). Connectivity between the ipsilesional M1 and the premotor cortex (PM) was noticeably strengthened after real HD-tDCS compared with baseline. Motor performance also significantly improved, as shown in response time during the SFTT. In the sham HD-tDCS condition, functional connectivity between contralesional M1 and sensory cortex was enhanced compared with baseline. There was tendency toward improvement in SFTT response time, but without significance.
The results of this study indicated that HD-tDCS could modulate learning-related cortical activity and functional connectivity within motor networks to enhance motor learning performance. HD-tDCS can be used as an additional tool for enhancing motor learning during hand rehabilitation for chronic stroke patients.
运动学习是中风神经康复的关键组成部分。高清经颅直流电刺激（HD-tDCS）是最近开发的一种经颅直流电刺激技术，它使用小电极阵列提高了电流输送到大脑的准确性。本研究的目的是使用功能近红外光谱（fNIRS）研究HD-tDCS是否会改变中风患者与学习相关的皮质激活和功能连接。
采用假对照交叉研究设计，将16例慢性中风患者随机分配到两种干预条件之一。两组均连续五天执行顺序手指敲击任务（SFTT），一组接受（a）真实HD-tDCS，另一组接受（b）假HD-tDCS。HD-tDCS（1 mA，持续20分钟，4×1）施加于C3或C4（根据病变侧）。在每次干预之前（基线）和之后，使用fNIRS测量系统在受影响手执行SFTT期间测量fNIRS信号。使用统计参数映射开源软件包（NIRS-SPM）分析NIRS信号的皮质激活和功能连接。
在真实HD-tDCS条件下，患侧初级运动皮层（M1）的氧合血红蛋白浓度显著增加。与基线相比，真实HD-tDCS后患侧M1与运动前皮层（PM）之间的连接明显增强。运动表现也显著改善，如SFTT期间的反应时间所示。在假HD-tDCS条件下，与基线相比，对侧M1与感觉皮层之间的功能连接增强。SFTT反应时间有改善趋势，但无显著性差异。
本研究结果表明，HD-tDCS可以调节运动网络内与学习相关的皮质活动和功能连接，以提高运动学习表现。HD-tDCS可作为慢性中风患者手部康复期间增强运动学习的辅助工具。
