Dose-Dependent Effects of Theta Burst rTMS on Cortical Excitability and Resting-State Connectivity of the Human Motor System
Dose-Dependent Effects of Theta Burst rTMS on Cortical Excitability and Resting-State Connectivity of the Human Motor System
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DOI：
10.1523/jneurosci.4993-13.2014
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发表时间：
2014-05-14
影响因子：
5.3
通讯作者：
Grefkes, Christian
中科院分区：
文献类型：
--
作者：
Nettekoven, Charlotte;Volz, Lukas J.;Grefkes, Christian
θ爆发刺激（TBS）是重复经颅磁刺激（rTMS）的一种特定方案，它能诱导皮质兴奋性发生变化，且这种变化在刺激结束后仍持续存在。然而，TBS诱导的后效应在不同受试者之间存在差异，并且到目前为止，这些后效应背后的机制仍知之甚少。因此，本研究的目的是探究增加间歇性TBS（iTBS）的脉冲数量是否（1）如通过运动诱发电位（MEPs）所测量的那样增加皮质兴奋性，以及（2）以剂量依赖的方式改变通过静息态功能磁共振成像（fMRI）所测量的功能连接性。16名健康人类受试者在初级运动皮质（M1刺激）和顶枕顶点（假刺激）接受了三个连续施加的、每个包含600脉冲的iTBS刺激组块，以测试iTBS对皮质兴奋性和功能连接性的剂量依赖效应（总共四个疗程）。与假刺激相比，在每个刺激组块后，M1上的iTBS使MEP振幅增加。尽管在M1刺激的第一个和第二个组块之间MEP振幅的增加没有差异，但我们观察到在三个组块（1800脉冲）后有显著增加。此外，iTBS增强了受刺激的M1与两个半球的运动前区之间的静息态功能连接性。在M1上施加1800脉冲的iTBS后，M1与同侧背侧运动前皮质之间的功能连接性进一步以剂量依赖的方式增加。然而，未检测到MEP振幅变化与功能连接性之间的相关性。总之，我们的数据表明，增加iTBS刺激组块的数量会在局部层面（皮质兴奋性）以及系统层面（功能连接性）产生剂量依赖效应，并且背侧运动前皮质 - M1连接性以剂量依赖的方式增强。
Theta burst stimulation (TBS), a specific protocol of repetitive transcranial magnetic stimulation (rTMS), induces changes in cortical excitability that last beyond stimulation. TBS-induced aftereffects, however, vary between subjects, and the mechanisms underlying these aftereffects to date remain poorly understood. Therefore, the purpose of this study was to investigate whether increasing the number of pulses of intermittent TBS (iTBS) (1) increases cortical excitability as measured by motor-evoked potentials (MEPs) and (2) alters functional connectivity measured using resting-state fMRI, in a dose-dependent manner. Sixteen healthy, human subjects received three serially applied iTBS blocks of 600 pulses over the primary motor cortex (M1 stimulation) and the parieto-occipital vertex (sham stimulation) to test for dose-dependent iTBS effects on cortical excitability and functional connectivity (four sessions in total). iTBS over M1 increased MEP amplitudes compared with sham stimulation after each stimulation block. Although the increase in MEP amplitudes did not differ between the first and second block of M1 stimulation, we observed a significant increase after three blocks (1800 pulses). Furthermore, iTBS enhanced resting-state functional connectivity between the stimulated M1 and premotor regions in both hemispheres. Functional connectivity between M1 and ipsilateral dorsal premotor cortex further increased dose-dependently after 1800 pulses of iTBS over M1. However, no correlation between changes in MEP amplitudes and functional connectivity was detected. In summary, our data show that increasing the number of iTBS stimulation blocks results in dose-dependent effects at the local level (cortical excitability) as well as at a systems level (functional connectivity) with a dose-dependent enhancement of dorsal premotor cortex-M1 connectivity.