Systematic evaluation of the impact of stimulation intensity on neuroplastic after-effects induced by transcranial direct current stimulation
Systematic evaluation of the impact of stimulation intensity on neuroplastic after-effects induced by transcranial direct current stimulation
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DOI：
10.1113/jp272738
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发表时间：
2017-02-01
影响因子：
5.5
通讯作者：
Nitsche, Michael A.
中科院分区：
文献类型：
--
作者：
Jamil, Asif;Batsikadze, Giorgi;Nitsche, Michael A.
当代非侵入性神经调节技术，如经颅直流电刺激（tDCS），已显示出在临床环境中恢复皮质生理学损伤以及调节健康人群认知能力方面的潜力。然而，tDCS的神经可塑性后效高度依赖于刺激参数，持续时间相对较短，并且个体之间不均匀。本研究系统地研究了0.5和2.0mA之间的电流强度对左侧初级运动皮层（M1）可塑性的影响，以及个体水平的协变量对解释个体间变异性的影响。将38名健康受试者分为阳极和阴极tDCS组。在单独的会话中研究了五种DC强度（假手术，0.5，1.0，1.5和2.0mA）。采用经颅磁刺激（TMS）技术，在tDCS前和tDCS后15 min至2h的10个时间点记录25个运动诱发电位（MEP）。重复测量方差分析表明，阳极和阴极tDCS的强度的主要影响。对于阳极tDCS，所有活动强度均导致与假手术相当的易化效应，而对于阴极tDCS，仅1.0 mA导致持续的兴奋性降低。为评估个体内变异性而进行的另一项实验显示，1.0 mA阳极tDCS的可靠性总体良好（前30分钟内ICC（2，1）=0.74）。辨别个体间变异性来源的事后分析证实了先前的发现，其中个体TMS SI1mV（1mV MEP振幅的刺激强度）敏感性与1.0mA阳极tDCS对兴奋性的影响呈负相关。因此，我们的研究提供了关于阳极和阴极tDCS的非线性强度依赖性神经可塑性后效的程度的进一步见解。
Contemporary non-invasive neuromodulatory techniques, such as transcranial direct current stimulation (tDCS), have shown promising potential in both restituting impairments in cortical physiology in clinical settings, as well as modulating cognitive abilities in the healthy population. However, neuroplastic after-effects of tDCS are highly dependent on stimulation parameters, relatively short lasting, and not expectedly uniform between individuals. The present study systematically investigates the full range of current intensity between 0.5 and 2.0mA on left primary motor cortex (M1) plasticity, as well as the impact of individual-level covariates on explaining inter-individual variability. Thirty-eight healthy subjects were divided into groups of anodal and cathodal tDCS. Five DC intensities (sham, 0.5, 1.0, 1.5 and 2.0mA) were investigated in separate sessions. Using transcranial magnetic stimulation (TMS), 25 motor-evoked potentials (MEPs) were recorded before, and 10 time points up to 2h following 15min of tDCS. Repeated-measures ANOVAs indicated a main effect of intensity for both anodal and cathodal tDCS. With anodal tDCS, all active intensities resulted in equivalent facilitatory effects relative to sham while for cathodal tDCS, only 1.0mA resulted in sustained excitability diminution. An additional experiment conducted to assess intra-individual variability revealed generally good reliability of 1.0mA anodal tDCS (ICC(2,1)=0.74 over the first 30min). A post hoc analysis to discern sources of inter-individual variability confirmed a previous finding in which individual TMS SI1mV (stimulus intensity for 1mV MEP amplitude) sensitivity correlated negatively with 1.0mA anodal tDCS effects on excitability. Our study thus provides further insights on the extent of non-linear intensity-dependent neuroplastic after-effects of anodal and cathodal tDCS.