補足運動野に対する経頭蓋直流電流陰極刺激が先行随伴性姿勢調節に及ぼす影響 [in Japanese] The effects of cathodal transcranial direct current stimulation of the supplementary motor area on the function of anticipatory postural adjustments [in Japanese]
Access this Article
主動作筋の活動に先行して姿勢調節筋群が放電開始する現象は, 先行随伴性姿勢調節 (APAs) と呼ばれ, 補足運動野 (SMA) がその生成に関与すると考えられている。本研究では, SMAに対する経頭蓋直流電流陰極刺激 (陰極tDCS) が, APAsの機能に影響を及ぼすか否かを検討した。健常被験者11名が, 自己ペースで右上肢を急速拳上する課題を重心動揺計上で行い, この時の右三角筋と右大腿二頭筋の活動を表面筋電図で記録した。左側M1 (Cz上) とSMAに陰極tDCS (2 mAで15分間) 及び疑似刺激を行い, 刺激前後における両筋の放電開始時間差 (ΔEMG onset) の変化を比較した。陰極tDCS後におけるΔEMG onsetの有意な短縮はSMA刺激時にのみ認められた。APAsの生成にはSMAが重要な役割を果たし, また陰極tDCSはSMAの予測的姿勢調節機能を抑制し得ることが示唆された。
Although SMA is thought to contribute to the generation of anticipatory postural adjustments (APAs), which act to stabilize supporting body segments prior to movement, its precise role remains unclear. Non-invasive brain stimulation, such as transcranial direct current stimulation (tDCS), over the primary motor cortex (M1) has been shown to modulate cortical excitability, thereby influencing motor behavior and learning. However, only a few studies have reported that application of tDCS over the SMA changes the excitability of the M1 and motor learning process. This study was performed to elucidate whether cathodal tDCS applied over the SMA modifies the function of APAs. Cathodal tDCS and sham tDCS (2 mA) were applied over the SMA or left of the leg area of the M1 of 11 healthy subjects for 15 min. Subjects performed the task of self-paced rapid shoulder flexion on before, immediately after, and 15 min after tDCS. Electromyographic (EMG) activity was recorded from the deltoid anterior (DEL_A), as the prime mover muscle, and biceps femoris (BF), as the postural muscle during tasks. Latency differences (ΔEMG onset) with the two types of stimuli were calculated by subtracting the EMG burst onset of the BF from that of the DEL_A. Following cathodal tDCS over the SMA, the ΔEMG onset was significantly shortened compared to after sham tDCS, while tDCS over the M1 did not produce any significant effect. These results suggest that the SMA may play a critical role in the generation of voluntary movement accompanied by APAs. Cathodal tDCS could have beneficial method to investigate the function of the SMA in virtual lesion studies.
- Japanese Journal of Clinical Neurophysiology
Japanese Journal of Clinical Neurophysiology 41(4), 202-208, 2013
Japanese Society of Clinical Neurophysiology