Is effect of transcranial direct current stimulation on visuomotor coordination dependent on task difficulty?
Yong Hyun Kwon1, Kyung Woo Kang2, Sung Min Son3, Na Kyung Lee2
1 Department of Physical Therapy, Yeungnam University College,170, Daemyung-dong, Namgu, Daegu, 705-703, Republic of Korea
2 Department of Physical Therapy, College of Rehabilitation Science, Daegu University, 15, Jilyang, Gyeongsan-si, Kyeongbuk, 712-714, Republic of Korea
3 Department of Physical Therapy, College of Health Science, Cheongju University, 298 Daeseong-ro, Cheongwon-gu, Cheongju-si, Chungbuk 363-764, Republic of Korea
Na Kyung Lee
Department of Physical Therapy, College of Rehabilitation Science, Daegu University, 15, Jilyang, Gyeongsan-si, Kyeongbuk, 712-714
Republic of Korea
Source of Support: This work was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning, No. 2012R1A1B4003477., Conflict of Interest: None
Transcranial direct current stimulation (tDCS), an emerging technique for non-invasive brain stimulation, is increasingly used to induce changes in cortical excitability and modulate motor behavior, especially for upper limbs. The purpose of this study was to investigate the effects of tDCS of the primary motor cortex on visuomotor coordination based on three levels of task difficulty in healthy subjects. Thirty-eight healthy participants underwent real tDCS or sham tDCS. Using a single-blind, sham-controlled crossover design, tDCS was applied to the primary motor cortex. For real tDCS conditions, tDCS intensity was 1 mA while stimulation was applied for 15 minutes. For the sham tDCS, electrodes were placed in the same position, but the stimulator was turned off after 5 seconds. Visuomotor tracking task, consisting of three levels (levels 1, 2, 3) of difficulty with higher level indicating greater difficulty, was performed before and after tDCS application. At level 2, real tDCS of the primary motor cortex improved the accurate index compared to the sham tDCS. However, at levels 1 and 3, the accurate index was not significantly increased after real tDCS compared to the sham tDCS. These findings suggest that tasks of moderate difficulty may improve visuomotor coordination in healthy subjects when tDCS is applied compared with easier or more difficult tasks.