Influences of current direction on 1 Hz motor cortex rTMS

IF 3.7 3区医学 Q2 NEUROSCIENCES

Brain Research Bulletin Pub Date : 2025-07-27 DOI:10.1016/j.brainresbull.2025.111484

Carolina Kanig , Mirja Osnabruegge , Florian Schwitzgebel , Wolfgang Mack , Martin Schecklmann , Stefan Schoisswohl

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引用次数: 0

Abstract

Objective

Neuromodulatory changes induced by repetitive transcranial magnetic stimulation (rTMS) are highly variable and lack replicability. Amongst many influencing factors, the current direction of the stimulation is known to affect rTMS aftereffects. In this study, we investigated the influence of current direction on cortical and peripheral markers of motor cortex plasticity as induced by 1 Hz rTMS as well as the correlation of cortical and peripheral markers. Additionally, we investigated possible confounding variables.

Methods

Twenty-five healthy subjects received 2000 pulses of 1 Hz rTMS at 110 % resting motor threshold intensity over the left motor hotspot inducing anterior-posterior – posterior-anterior (AP-PA) and posterior-anterior – anterior-posterior (PA-AP) current directions in the brain. Motor evoked potentials (MEPs) and transcranial evoked potentials (TEPs) before and after rTMS were assessed with single pulses. Coil placement was ensured by a neuronavigated robot-assisted setup.

Results

In sum, 1 Hz rTMS resulted in higher amplitudes of MEPs and TEP components N15, N45 and P60 and a reduced amplitude of N100, whereby the induced PA-AP current direction in the brain elicited higher effects. MEP and TEP N15 latency were prolonged and N100 shortened after rTMS. PA-AP current direction elicited stronger changes in latency for MEPs and N15. N45 and MEP correlated in the PA-AP pre rTMS condition with negligible effect size.

Conclusions

Our findings of facilitatory pre-to-post rTMS changes are in contrast to preliminary assumptions that 1 Hz rTMS acts inhibitory. However, since high variability and low reliability of rTMS aftereffects are prominent in the current literature, these results shed light that potential influencing factors need to be better reported, controlled and investigated. We suggest to further investigate effects of stimulation intensity and tiredness of subjects on rTMS. We were able to replicate current direction effects which strengthens the hypothesis of activation of different sets of neurons.

查看原文本刊更多论文

电流方向对1Hz运动皮层rTMS的影响。

目的：重复经颅磁刺激（rTMS）引起的神经调节变化多变性强，缺乏可重复性。在许多影响因素中，刺激的当前方向已知会影响rTMS的后效。在本研究中，我们研究了电流方向对1Hz rTMS诱导的运动皮层可塑性皮层和外周标记的影响，以及皮层和外周标记的相关性。此外，我们调查了可能的混杂变量。方法：25名健康受试者在左侧运动热点处以110%静息运动阈值强度接受1Hz rTMS，诱导大脑前-后-后-前-前-前（AP-PA）和后-前-后（PA-AP）电流方向。采用单脉冲法测定rTMS前后的运动诱发电位（MEPs）和经颅诱发电位（TEPs）。线圈的放置由神经导航机器人辅助设置确保。结果：综上所述，1Hz rTMS使MEPs和TEP成分N15、N45和P60的幅值升高，N100的幅值降低，表明脑内PA-AP电流方向的诱导作用增强。rTMS后MEP和TEP N15潜伏期延长，N100潜伏期缩短。PA-AP电流方向引起的MEPs和N15潜伏期变化较强。在PA-AP预tms条件下，N45与MEP呈显著相关，但效应大小可忽略不计。结论：我们的研究结果促进了rTMS前后的变化，这与最初假设的1Hz rTMS的抑制作用形成了对比。然而，由于目前文献中rTMS后效的高变异性和低可靠性突出，这些结果提示需要更好地报道、控制和研究潜在的影响因素。我们建议进一步研究刺激强度和受试者疲劳程度对rTMS的影响。我们能够复制电流方向效应，这加强了不同神经元组激活的假设。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Brain Research Bulletin 医学-神经科学

CiteScore

6.90

自引率

2.60%

发文量

253

审稿时长

67 days

期刊介绍： The Brain Research Bulletin (BRB) aims to publish novel work that advances our knowledge of molecular and cellular mechanisms that underlie neural network properties associated with behavior, cognition and other brain functions during neurodevelopment and in the adult. Although clinical research is out of the Journal''s scope, the BRB also aims to publish translation research that provides insight into biological mechanisms and processes associated with neurodegeneration mechanisms, neurological diseases and neuropsychiatric disorders. The Journal is especially interested in research using novel methodologies, such as optogenetics, multielectrode array recordings and life imaging in wild-type and genetically-modified animal models, with the goal to advance our understanding of how neurons, glia and networks function in vivo.