Yamamoto Shunpei, Miyaguchi Shota, Ogawa Takuma, Inukai Yasuto, Otsuru Naofumi, Onishi Hideaki
Graduate School, Niigata University of Health and Welfare, Niigata, Japan.
Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan.
Front Behav Neurosci. 2024 Apr 29;18:1378059. doi: 10.3389/fnbeh.2024.1378059. eCollection 2024.
Transcranial alternating current stimulation (tACS) is a noninvasive method for brain stimulation that artificially modulates oscillatory brain activity in the cortical region directly beneath the electrodes by applying a weak alternating current. Beta (β) oscillatory activity in the supplementary motor area (SMA) is involved in motor planning and maintenance, whereas gamma (γ) oscillatory activity is involved in the updating of motor plans. However, the effect of applying tACS to the SMA on motor learning has not yet been investigated. This study assessed the effects of applying tACS to the SMA on motor learning. Forty-two right-handed healthy adults (age 20.6 ± 0.5 years, 24 men and 18 women) were included. Motor learning was assessed using a visuomotor tracking task with pinch tension of the right thumb and right forefinger. Each trial lasted 60 s, and the error rates were measured. Conductive rubber electrodes were attached to the SMA and the left shoulder for tACS. Stimulation was applied at an intensity of 1.0 mA and frequencies of 70 and 20 Hz in the γ-tACS and β-tACS treatment groups, respectively. The sham group was only administered a fade-in/out. The visuomotor tracking task was performed for 10 trials before tACS and 10 trials after tACS. Two trials were conducted on the following day to determine motor skill retention. The average deviation measured during 60 s was considered the error value. Pre-stimulation learning rate was calculated as the change in error rate. Post-stimulation learning rate and retention rate were calculated as the change in error rate after stimulation and on the day after stimulation, respectively. In both the stimulation groups, differences in pre-stimulation learning, post-stimulation learning, and retention rates were not significant. However, in the γ-tACS group, baseline performance and pre-stimulation learning rate were positively correlated with post-stimulation learning rate. Therefore, applying γ-tACS to the SMA can increase post-stimulation learning rate in participants exhibiting low baseline performance and high pre-stimulation learning rate. Our findings suggest that motor learning can be effectively enhanced by applying γ-tACS to the SMA based on an individual's motor and learning abilities.
经颅交流电刺激（tACS）是一种用于脑刺激的非侵入性方法，通过施加微弱的交流电来人工调节电极正下方皮质区域的脑振荡活动。辅助运动区（SMA）中的β振荡活动参与运动计划和维持，而γ振荡活动参与运动计划的更新。然而，将tACS应用于SMA对运动学习的影响尚未得到研究。本研究评估了将tACS应用于SMA对运动学习的影响。纳入了42名右利手健康成年人（年龄20.6±0.5岁，男性24名，女性18名）。使用右手拇指和右手食指捏力的视觉运动跟踪任务评估运动学习。每个试验持续60秒，并测量错误率。将导电橡胶电极连接到SMA和左肩用于tACS。γ-tACS和β-tACS治疗组分别以1.0 mA的强度和70 Hz和20 Hz的频率施加刺激。假刺激组仅进行渐强/渐弱处理。在tACS之前进行10次视觉运动跟踪任务试验，tACS之后进行10次试验。在接下来的一天进行两次试验以确定运动技能的保持情况。将60秒内测量的平均偏差视为误差值。刺激前学习率计算为错误率的变化。刺激后学习率和保持率分别计算为刺激后和刺激后一天错误率的变化。在两个刺激组中，刺激前学习、刺激后学习和保持率的差异均不显著。然而，在γ-tACS组中，基线表现和刺激前学习率与刺激后学习率呈正相关。因此，对基线表现低且刺激前学习率高的参与者，将γ-tACS应用于SMA可提高刺激后学习率。我们的研究结果表明，根据个体的运动和学习能力，将γ-tACS应用于SMA可有效增强运动学习。
