An initial transient-state and reliable measures of corticospinal excitability in TMS studies
An initial transient-state and reliable measures of corticospinal excitability in TMS studies
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DOI：
10.1016/j.clinph.2009.02.164
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发表时间：
2009-05-01
影响因子：
4.7
通讯作者：
Brandt, S. A.
中科院分区：
文献类型：
--
作者：
Schmidt, S.;Cichy, R. M.;Brandt, S. A.
目的：本研究的目的是确定在经颅磁刺激（TMS）研究中，初始瞬态是否影响对皮质脊髓兴奋性的可靠估计。尽管肌肉诱发电位（MEP）振幅是皮质兴奋性的重要指标，但它们受到扫描到扫描变异性的严重限制。在这种情况下，有趣的是实验观察到，第一次MEP振幅可能比随后的反应大得多[Brasil-Neto JP， Cohen LG, Hallet M.运动后运动诱发电位下降所揭示的中枢疲劳]。[j]。这导致了一种假设，即兴奋性增加的初始瞬态影响MEP振幅衍生的皮质脊髓兴奋性估计。方法：为了解决这个问题，我们在有和没有导航脑刺激（NBS）和不同的tms线圈的情况下，对初级运动皮层的单脉冲MEP振幅进行了重复测量。重要的是，NBS允许对生理和生理变异性进行全面区分。结果：我们发现皮质脊髓兴奋性的估计值显著下降，并从对数正态分布状态过渡到正态分布状态，之后可以获得可靠的测量（英国标准协会）。结论：我们认为生理起源的初始瞬态影响皮质脊髓兴奋性的测量。意义：这对皮质兴奋性的研究具有重要意义。例如，它可以减少研究和小群体比较中的可变性。(C) 2009年国际临床神经生理学联合会。爱思唯尔爱尔兰有限公司出版。版权所有。
Objective: The objective of this Study was to determine if an initial transient state influences the acquisition of reliable estimates of corticospinal excitability in transcranial magnetic stimulation (TMS) studies. Whereas muscle evoked potential (MEP) amplitudes are an important index of cortical excitability, these are severely limited by sweep-to-sweep variability. Interesting in this context is the experimental observation that the first MEP amplitudes might be much larger than subsequent responses [Brasil-Neto JP, Cohen LG, Hallet M. Central fatigue as revealed by postexercise decrement of motor evoked potentials. Muscle Nerve 1994;17:713-9]. This led to the hypothesis that an initial transient-state of increased excitability affects MEP amplitude derived estimates of corticospinal excitability.Methods: To address this issue we acquired repeated measures of single pulse MEP amplitudes over the primary motor cortex with and without navigated brain stimulation (NBS) and with various TMS-coils. Importantly, NBS allows for the sweep-to-sweep differentiation of physical and physiological variability.Results: We found a significant decline in estimates of corticospinal excitability and a transition from log-Normal to Normal distributed state, after which reliable measures (British Standards Institute) could be acquired.Conclusions: We argue that an initial transient state of physiological origin influences measures of corticospinal excitability.Significance: This has important implications for investigations of cortical excitability. For example, it could reduce variability over studies and within small group comparisons. (C) 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.