Karabanov Anke Ninija, Shindo Keiichiro, Shindo Yuko, Raffin Estelle, Siebner Hartwig Roman
Danish Research Centre for Magnetic Resonance, Centre for Functional and Diagnostic Imaging and Research, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.
Department of Nutrition, Exercise and Sports, University of Copenhagen, Copenhagen, Denmark.
Front Hum Neurosci. 2021 Feb 25;15:639274. doi: 10.3389/fnhum.2021.639274. eCollection 2021.
Transcranial direct current stimulation (TDCS) targeting the primary motor hand area (M1-HAND) may induce lasting shifts in corticospinal excitability, but after-effects show substantial inter-individual variability. Functional magnetic resonance imaging (fMRI) can probe after-effects of TDCS on regional neural activity on a whole-brain level.
Using a double-blinded cross-over design, we investigated whether the individual change in corticospinal excitability after TDCS of M1-HAND is associated with changes in task-related regional activity in cortical motor areas.
Seventeen healthy volunteers (10 women) received 20 min of real (0.75 mA) or sham TDCS on separate days in randomized order. Real and sham TDCS used the classic bipolar set-up with the anode placed over right M1-HAND. Before and after each TDCS session, we recorded motor evoked potentials (MEP) from the relaxed left first dorsal interosseus muscle after single-pulse transcranial magnetic stimulation(TMS) of left M1-HAND and performed whole-brain fMRI at 3 Tesla while participants completed a visuomotor tracking task with their left hand. We also assessed the difference in MEP latency when applying anterior-posterior and latero-medial TMS pulses to the precentral hand knob (AP-LM MEP latency).
Real TDCS had no consistent aftereffects on mean MEP amplitude, task-related activity or motor performance. Individual changes in MEP amplitude, measured directly after real TDCS showed a positive linear relationship with individual changes in task-related activity in the supplementary motor area and AP-LM MEP latency.
Functional aftereffects of classical bipolar anodal TDCS of M1-HAND on the motor system vary substantially across individuals. Physiological features upstream from the primary motor cortex may determine how anodal TDCS changes corticospinal excitability.
经颅直流电刺激（TDCS）靶向初级运动手区（M1-HAND）可能会引起皮质脊髓兴奋性的持久变化，但后效应存在显著的个体差异。功能磁共振成像（fMRI）可以在全脑水平上探究TDCS对区域神经活动的后效应。
采用双盲交叉设计，我们研究了M1-HAND经TDCS后皮质脊髓兴奋性的个体变化是否与皮质运动区任务相关区域活动的变化有关。
17名健康志愿者（10名女性）在不同日期以随机顺序接受20分钟的真刺激（0.75 mA）或假TDCS。真刺激和假TDCS均采用经典的双极设置，阳极置于右侧M1-HAND上方。在每次TDCS疗程前后，我们在对左侧M1-HAND进行单脉冲经颅磁刺激（TMS）后，记录左侧第一背侧骨间肌放松状态下的运动诱发电位（MEP），并在参与者用左手完成视觉运动跟踪任务时，使用3特斯拉的设备进行全脑fMRI检查。我们还评估了在中央前回手部旋钮处施加前后和内外侧TMS脉冲时MEP潜伏期的差异（AP-LM MEP潜伏期）。
真TDCS对平均MEP振幅、任务相关活动或运动表现没有一致的后效应。真TDCS后直接测量的MEP振幅个体变化与辅助运动区任务相关活动的个体变化以及AP-LM MEP潜伏期呈正线性关系。
M1-HAND经典双极阳极TDCS对运动系统的功能后效应在个体间差异很大。初级运动皮层上游的生理特征可能决定阳极TDCS如何改变皮质脊髓兴奋性。
