General indices to characterize the electrical response of the cerebral cortex to TMS
General indices to characterize the electrical response of the cerebral cortex to TMS
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DOI：
10.1016/j.neuroimage.2009.09.026
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发表时间：
2010-01-15
期刊：
影响因子：
5.7
通讯作者：
Massimini, Marcello
中科院分区：
文献类型：
--
作者：
Casali, Adenauer G.;Casarotto, Silvia;Massimini, Marcello
经颅磁刺激（TMS）与同步高密度脑电图（HD-EEG）相结合，代表了一种测量人类皮层兴奋性和连通性的直接方法。然而，TMS诱发电位的分析，分类和解释受到阻碍，缺乏先验知识的生理效应的TMS和缺乏一个既定的数据分析框架。在这里，我们实施了一个标准化的，数据驱动的程序来表征的电响应的大脑皮层TMS通过三个综合指标：显着电流密度（SCD），锁相（PL）和显着电流散射（SCS）。SCD总结了由TMS诱导的所有显著电流的幅度，PL反映了TMS重置正在进行的皮层振荡的相位的能力，而SCS测量显著激活的源与刺激部位的平均距离。这些指数旨在捕捉大脑反应的不同方面，从全局皮层兴奋性到全局皮层连接性。我们分析了5名健康受试者的Brodmann 19区TMS的EEG反应。SCID、PL和SCS的空间分布和时间过程揭示了兴奋性和连通性的可重复性概况，其特征在于在TMS诱导的电场为50 V/m附近的局部激活阈值，以及TMS诱发的激活从枕叶到同侧额叶区域的选择性传播，在70- 80 V/m处达到最大值。这些一般指数可用于表征TMS对任何皮层区域的影响，并定量评估生理和病理条件下的皮层兴奋性和连通性。(C)2009 Elsevier Inc. All rights reserved.
Transcranial magnetic stimulation (TMS) combined with simultaneous high-density electroencephalography (hd-EEG) represents a straightforward way to gauge cortical excitability and connectivity in humans. However, the analysis, classification and interpretation of TMS-evoked potentials are hampered by scarce a priori knowledge about the physiological effect of TMS and by lack of an established data analysis framework. Here, we implemented a standardized, data-driven procedure to characterize the electrical response of the cerebral cortex to TMS by means of three synthetic indices: significant current density (SCD), phase-locking (PL) and significant current scattering (SCS). SCD sums up the amplitude of all significant currents induced by TMS, PL reflects the ability of TMS to reset the phase of ongoing cortical oscillations, while SCS measures the average distance of significantly activated sources from the site of stimulation. These indices are aimed at capturing different aspects of brain responsiveness, ranging from global cortical excitability towards global cortical connectivity. We analyzed the EEG responses to TMS of Brodmann's area 19 at increasing intensities in five healthy subjects. The spatial distribution and time course of SCID, PL and SCS revealed a reproducible profile of excitability and connectivity, characterized by a local activation threshold around a TMS-induced electric field of 50 V/m and by a selective propagation of TMS-evoked activation from occipital to ipsilateral frontal areas that reached a maximum at 70-100 ms. These general indices may be used to characterize the effects of TMS on any cortical area and to quantitatively evaluate Cortical excitability and connectivity in physiological and pathological conditions. (C) 2009 Elsevier Inc. All rights reserved.