Gilio Francesca, Iacovelli Elisa, Frasca Vittorio, Gabriele Maria, Giacomelli Elena, De Lena Carlo, Cipriani Anna Maria, Inghilleri Maurizio
Neurology and Neurophysiopathology Unit, S. Pertini, Rome, Italy.
Neurosci Lett. 2009 May 8;455(1):1-3. doi: 10.1016/j.neulet.2009.03.035. Epub 2009 Mar 16.
Repetitive transcranial magnetic stimulation (rTMS) delivered in short trains at 5Hz frequency and suprathreshold intensity over the primary motor cortex (M1) in healthy subjects facilitates the motor-evoked potential (MEP) amplitude by increasing cortical excitability through mechanisms resembling short-term synaptic plasticity. In this study, to investigate whether rTES acts through similar mechanisms we compared the effects of rTMS and repetitive transcranial electrical stimulation (rTES) (10 stimuli-trains, 5Hz frequency, suprathreshold intensity) delivered over the M1 on the MEP amplitude. Four healthy subjects were studied in two separate sessions in a relaxed condition. rTMS and anodal rTES were delivered in trains to the left M1 over the motor area for evoking a MEP in the right first dorsal interosseous muscle. Changes in MEP size and latency during the course of the rTMS and rTES trains were compared. The possible effects of muscle activation on MEP amplitude were evaluated, and the possible effects of cutaneous trigeminal fibre activation on corticospinal excitability were excluded in a control experiment testing the MEP amplitude before and after supraorbital nerve repetitive electrical stimulation. Repeated measures analysis of variance (ANOVA) showed that rTES and rTMS trains elicited similar amplitude first MEPs and a similar magnitude MEP amplitude facilitation during the trains. rTES elicited a first MEP with a shorter latency than rTMS, without significant changes during the course of the train of stimuli. The MEP elicited by single-pulse TES delivered during muscle contraction had a smaller amplitude than the last MEP in the rTES trains. Repetitive supraorbital nerve stimulation left the conditioned MEP unchanged. Our results suggest that 5 Hz-rTES delivered in short trains increases cortical excitability and does so by acting on the excitatory interneurones probably through mechanisms similar to those underlying the rTMS-induced MEP facilitation.
在健康受试者的初级运动皮层（M1）上，以5Hz频率和阈上强度进行短串重复经颅磁刺激（rTMS），通过类似于短期突触可塑性的机制增加皮层兴奋性，从而促进运动诱发电位（MEP）的幅度。在本研究中，为了探究重复经颅电刺激（rTES）是否通过类似机制起作用，我们比较了在M1上施加rTMS和重复经颅电刺激（rTES）（10个刺激串，5Hz频率，阈上强度）对MEP幅度的影响。在放松状态下，对4名健康受试者分两个独立时段进行研究。将rTMS和阳极rTES以串的形式施加于左侧M1的运动区，以诱发右侧第一背侧骨间肌的MEP。比较了rTMS和rTES串刺激过程中MEP大小和潜伏期的变化。评估了肌肉激活对MEP幅度的可能影响，并在眶上神经重复电刺激前后测试MEP幅度的对照实验中排除了皮肤三叉神经纤维激活对皮质脊髓兴奋性的可能影响。重复测量方差分析（ANOVA）表明，rTES和rTMS串刺激诱发的首个MEP幅度相似，且在刺激串期间MEP幅度促进程度相似。rTES诱发的首个MEP潜伏期比rTMS短，在刺激串过程中无显著变化。肌肉收缩期间单脉冲TES诱发的MEP幅度小于rTES串刺激中的最后一个MEP。重复眶上神经刺激使条件性MEP保持不变。我们的结果表明，短串施加的5Hz - rTES可增加皮层兴奋性，其作用机制可能是通过作用于兴奋性中间神经元，可能与rTMS诱导的MEP促进作用的机制相似。
