Functional MRI of the immediate impact of transcranial magnetic stimulation on cortical and subcortical motor circuits
Functional MRI of the immediate impact of transcranial magnetic stimulation on cortical and subcortical motor circuits
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DOI：
10.1111/j.1460-9568.2004.03277.x
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发表时间：
2004-04-01
影响因子：
3.4
通讯作者：
Frahm, J
中科院分区：
文献类型：
--
作者：
Bestmann, S;Baudewig, J;Frahm, J
最近的研究表明，经颅磁刺激（TMS）的皮质效应可能不会局限于刺激部位，而是扩散到其他远距离区域。使用回波平面成像与血氧水平依赖（BOLD）对比度在3特斯拉，我们测量了MRI信号的变化，在高频（3.125 Hz）重复TMS（rTMS）的左侧感觉运动皮层（M1/S1）的强度高于和低于主动运动阈值在健康人的皮质和皮质下运动区。TMS脉冲的阈下和阈下性质通过同时对手部肌肉进行肌电图监测来证实。阈上rTMS激活了包括M1/S1、辅助运动区、背侧运动前区、扣带运动区、壳核和丘脑在内的初级和次级皮质运动区网络。阈下rTMS在刺激的M1/S1中没有引起MRI可检测的活动，但在其他方面导致了与阈上刺激相似的激活模式，尽管强度降低。此外，我们观察到听觉系统内的激活，包括横回和上级颞回，下丘和内侧膝状体核。目前的研究结果支持的概念，即从诱发运动的再传入反馈代表的主导输入的运动系统通过M1在阈上刺激。远离阈下刺激部位的运动区的BOLD MRI变化可能源于M1/S1中诱导的兴奋性变化引起的突触传递改变。它们反映了rTMS将局部和远程大脑区域作为皮层和皮层下网络的紧密连接成分的能力。
Recent studies indicate that the cortical effects of transcranial magnetic stimulation (TMS) may not be localized to the site of stimulation, but spread to other distant areas. Using echo-planar imaging with blood-oxygenation-level-dependent (BOLD) contrast at 3 Tesla, we measured MRI signal changes in cortical and subcortical motor regions during high-frequency (3.125 Hz) repetitive TMS (rTMS) of the left sensorimotor cortex (M1/S1) at intensities above and below the active motor threshold in healthy humans. The supra- and subthreshold nature of the TMS pulses was confirmed by simultaneous electromyographic monitoring of a hand muscle. Suprathreshold rTMS activated a network of primary and secondary cortical motor regions including M1/S1, supplementary motor area, dorsal premotor cortex, cingulate motor area, the putamen and thalamus. Subthreshold rTMS elicited no MRI-detectable activity in the stimulated M1/S1, but otherwise led to a similar activation pattern as obtained for suprathreshold stimulation though at reduced intensity. In addition, we observed activations within the auditory system, including the transverse and superior temporal gyrus, inferior colliculus and medial geniculate nucleus. The present findings support the notion that re-afferent feedback from evoked movements represents the dominant input to the motor system via M1 during suprathreshold stimulation. The BOLD MRI changes in motor areas distant from the site of subthreshold stimulation are likely to originate from altered synaptic transmissions due to induced excitability changes in M1/S1. They reflect the capability of rTMS to target both local and remote brain regions as tightly connected constituents of a cortical and subcortical network.