New York University, Department of Communicative Sciences and Disorders, New York, NY, USA.
New York University, Department of Communicative Sciences and Disorders, New York, NY, USA.
Cortex. 2019 Feb;111:274-285. doi: 10.1016/j.cortex.2018.11.014. Epub 2018 Nov 19.
There exists debate regarding the extent to which transcranial direct current stimulation (tDCS) can affect or enhance human behavior. Here, we examined a previously unexplored domain: speech motor learning. We investigated whether speech motor learning in unimpaired participants can be enhanced using a single-session tDCS experiment, and investigated whether the timing of tDCS relative to a behavioral task affected performance. Participants (N = 80) performed a twenty minute learning task with nonwords containing non-native consonant clusters (e.g., GDEEVOO), and were assigned to groups receiving either sham or active tDCS either immediately before or during the task. Both accuracy and properties of errors were examined throughout the course of the practice task, and then practice was compared to a retention period 30 min later (R1) and two days later (R2). For cluster and whole-(non)word accuracy measures, acquisition was observed for all groups during the practice session. Compared to the beginning of practice, the tDCS-Before group showed significantly greater improvement than both the sham group and the tDCS-During group at R1. An effect was also observed for vowel duration in errors (/gdivu/ → [gədivu]), with the tDCS-Before group showing significant shortening of vowel errors throughout practice. Overall, the findings suggest that tDCS can improve speech motor learning, and that the improvement may be greater when tDCS is applied immediately before practice, warranting further exploration of this new domain for tDCS research.
关于经颅直流电刺激(tDCS)在多大程度上可以影响或增强人类行为存在争议。在这里,我们研究了一个以前未被探索的领域:言语运动学习。我们调查了未受损参与者的言语运动学习是否可以通过单次 tDCS 实验来增强,并研究了 tDCS 相对于行为任务的时间安排是否会影响表现。参与者(N=80)进行了一项 20 分钟的非单词学习任务,其中包含非母语辅音群(例如,GDEEVOO),并被分配到接受假或真 tDCS 的组中,分别在任务之前或期间接受 tDCS。在整个练习过程中,我们检查了准确性和错误的特征,然后将练习与 30 分钟后的保留期(R1)和两天后的保留期(R2)进行比较。对于辅音群和整个(非)单词的准确性测量,所有组在练习期间都观察到了习得。与练习开始时相比,tDCS-Before 组在 R1 时比假刺激组和 tDCS-During 组显示出显著更大的改善。在错误中的元音时长 (/gdivu/→[gədivu]) 中也观察到了一种效果,tDCS-Before 组在整个练习过程中元音错误明显缩短。总的来说,这些发现表明 tDCS 可以改善言语运动学习,并且当 tDCS 在练习之前立即应用时,改善可能更大,值得进一步探索 tDCS 研究的这一新领域。