Inter-individual variability in cortical excitability and motor network connectivity following multiple blocks of rTMS.
Inter-individual variability in cortical excitability and motor network connectivity following multiple blocks of rTMS.
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DOI：
10.1016/j.neuroimage.2015.06.004
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发表时间：
2015-09
期刊：
影响因子：
5.7
通讯作者：
Grefkes C
中科院分区：
文献类型：
--
作者：
Nettekoven C;Volz LJ;Leimbach M;Pool EM;Rehme AK;Eickhoff SB;Fink GR;Grefkes C
对非侵入性神经调节方案的反应性显示出高度的个体差异，其原因仍然知之甚少。我们在这里测试了间歇性脉冲刺激（iTBS）——一种有效的重复性经颅磁刺激（rTMS）方案，以增加皮质兴奋性——的反应是否取决于皮质运动系统的网络特性。我们进一步研究了对iTBS的反应性是否具有剂量依赖性。为此，我们在16名健康受试者中采用假刺激控制的单盲受试者设计测试，研究iTBS后遗症与(i)运动诱发电位（MEPs）和（ii）静息状态功能连接（rsFC）的关系。在每个疗程中，应用3块iTBS，间隔15分钟。我们发现，与反应者相比，无反应者（在一次iTBS阻断后MEP未增加≥10%的受试者）在刺激前受刺激的初级运动皮层（M1）和运动前区域之间的rsFC更强。然而，只有应答者组显示rsFC和mep增加，而大多数无应答者在所有三个iTBS块后仍接近基线水平。重要的是，在两组中仍然存在很大的差异。我们的数据表明，局部水平对iTBS的反应性（即M1兴奋性）取决于受刺激区域的介入前网络连通性。值得注意的是，增加iTBS剂量并没有使无反应者变成反应者。较高水平的干预前连通性排除了对iTBS的反应，这一发现可能反映了系统层面上对iTBS无反应的天花板效应。
The responsiveness to non-invasive neuromodulation protocols shows high inter-individual variability, the reasons of which remain poorly understood. We here tested whether the response to intermittent theta-burst stimulation (iTBS) – an effective repetitive transcranial magnetic stimulation (rTMS) protocol for increasing cortical excitability – depends on network properties of the cortical motor system. We furthermore investigated whether the responsiveness to iTBS is dose-dependent. To this end, we used a sham-stimulation controlled, single-blinded within-subject design testing for the relationship between iTBS aftereffects and (i) motor-evoked potentials (MEPs) as well as (ii) resting-state functional connectivity (rsFC) in 16 healthy subjects. In each session, three blocks of iTBS were applied, separated by 15 min. We found that non-responders (subjects not showing an MEP increase of ≥10% after one iTBS block) featured stronger rsFC between the stimulated primary motor cortex (M1) and premotor areas before stimulation compared to responders. However, only the group of responders showed increases in rsFC and MEPs, while most non-responders remained close to baseline levels after all three blocks of iTBS. Importantly, there was still a large amount of variability in both groups. Our data suggest that responsiveness to iTBS at the local level (i.e., M1 excitability) depends upon the pre-interventional network connectivity of the stimulated region. Of note, increasing iTBS dose did not turn non-responders into responders. The finding that higher levels of pre-interventional connectivity precluded a response to iTBS could reflect a ceiling effect underlying non-responsiveness to iTBS at the systems level.
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影响因子：
5.7
作者：
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