Liao Wei-Yeh, Hand Brodie J, Cirillo John, Sasaki Ryoki, Opie George M, Goldsworthy Mitchell R, Semmler John G
Discipline of Physiology, School of Biomedicine, University of Adelaide, Adelaide, Australia.
Graduate Course of Health and Social Services, Kanagawa University of Human Services, Yokosuka, Japan.
Eur J Neurosci. 2025 Feb;61(3):e70018. doi: 10.1111/ejn.70018.
Long-term potentiation (LTP)-like plasticity in primary motor cortex (M1) induced by intermittent theta burst stimulation (iTBS) can be enhanced by transcranial alternating current stimulation (tACS) at a gamma frequency of 70 Hz. Recent evidence suggests that there is some frequency specificity in the effects of tACS on motor function within the midgamma band (60-90 Hz). The purpose of this study was to examine the effect of different tACS frequencies within the gamma band on the neuroplastic response to iTBS. Seventeen healthy young adults performed four experimental sessions, where iTBS was combined with different tACS conditions (60, 75 and 90 Hz, sham) over M1 using a tACS-iTBS costimulation approach. Motor evoked potential (MEP) amplitude and short-interval intracortical inhibition (SICI) were assessed from a hand muscle before and after the intervention using transcranial magnetic stimulation with posterior-anterior (PA) and anterior-posterior (AP) coil orientations. Gamma tACS-iTBS costimulation increased PA and AP MEPs when gamma tACS was applied at 90 Hz, but not at 75 or 60 Hz, compared with sham tACS. PA and AP SICI was reduced by tACS-iTBS costimulation, but this was not influenced by gamma tACS frequency. Gamma tACS can increase LTP-like plasticity when combined with iTBS over M1, with the largest effect observed when tACS was applied at higher gamma frequencies. The functional relevance of targeting higher gamma frequencies within different brain areas and study populations remains to be determined.
间歇性θ波爆发刺激（iTBS）诱导的初级运动皮层（M1）中的长时程增强（LTP）样可塑性可通过70赫兹的γ频率经颅交流电刺激（tACS）得到增强。最近的证据表明，tACS对中γ频段（60 - 90赫兹）内运动功能的影响存在一定的频率特异性。本研究的目的是检验γ频段内不同tACS频率对iTBS神经可塑性反应的影响。17名健康年轻成年人进行了四个实验环节，采用tACS - iTBS联合刺激方法，在M1区域将iTBS与不同的tACS条件（60、75和90赫兹，假刺激）相结合。在干预前后，使用经颅磁刺激，通过前后（PA）和前 - 后（AP）线圈方向，对手部肌肉的运动诱发电位（MEP）幅度和短间隔皮质内抑制（SICI）进行评估。与假刺激tACS相比，当γ tACS以90赫兹施加时，γ tACS - iTBS联合刺激增加了PA和AP MEP，但在75或60赫兹时没有增加。tACS - iTBS联合刺激降低了PA和AP SICI，但这不受γ tACS频率的影响。当γ tACS与M1区域的iTBS联合使用时，可以增加LTP样可塑性，在较高γ频率施加tACS时观察到的效果最大。针对不同脑区和研究人群中较高γ频率的功能相关性仍有待确定。
