Graduate School of Human Health Science, Tokyo Metropolitan University, Tokyo 116-8551, Japan.
Neurosci Lett. 2013 Jun 17;545:86-90. doi: 10.1016/j.neulet.2013.04.022. Epub 2013 Apr 27.
Transcranial direct current stimulation (tDCS) is a non-invasive technique that moderates cognitive and motor function. The effects of tDCS on cognitive and motor tasks vary among individuals. However, the source of the inter-individual variability remains unknown. The purpose of the present study was to examine whether the effect of bilateral tDCS on the performance of mental calculations differs among individuals according to the functional lateralization of parietal activity observed during a mental calculation task. Sixteen healthy subjects (11 males and five females, aged 20-23 years) participated. Laterality of parietal activity during a mental calculation task was evaluated using functional magnetic resonance imaging. Subjects also performed the mental calculation task pre-, during-, 30 min post-, and 60 min post-tDCS. Bilateral tDCS with the anode over the left parietal cortex and the cathode over the right parietal cortex shortened response times of the mental calculation task in subjects with left-hemispheric parietal lateralization, but not in subjects with bilateral parietal activation. This indicates that inter-individual variability in laterality of brain activity might be an important factor underlying the effect of bilateral tDCS. In conclusion, bilateral tDCS over the parietal cortex enhanced the performance of mental calculations in subjects with left-hemispheric parietal lateralization.
经颅直流电刺激（tDCS）是一种非侵入性技术，可以调节认知和运动功能。tDCS 对认知和运动任务的影响因人而异。然而，个体间变异性的来源尚不清楚。本研究旨在探讨在进行心算任务时观察到的顶叶活动的功能侧化是否会导致双侧 tDCS 对心算表现的影响因人而异。16 名健康受试者（11 名男性和 5 名女性，年龄 20-23 岁）参加了本研究。使用功能磁共振成像评估心算任务期间顶叶活动的偏侧性。受试者还在 tDCS 之前、期间、30 分钟后和 60 分钟后进行了心算任务。在左侧顶叶皮层放置阳极和右侧顶叶皮层放置阴极的双侧 tDCS 缩短了左侧顶叶偏侧化受试者的心算任务反应时间，但双侧顶叶激活的受试者则没有。这表明大脑活动偏侧性的个体间变异性可能是双侧 tDCS 效应的重要因素。总之，双侧顶叶皮层的 tDCS 增强了左侧顶叶偏侧化受试者的心算表现。
