The modular organization of the cortex refers to subsets of highly interconnected nodes, sharing specific cytoarchitectural and dynamical properties. These properties condition the level of excitability of local pools of neurons. In this study, we described TMS evoked potentials (TEP) input–output properties to provide new insights into regional cortical excitability. We combined robotized TMS with EEG to disentangle region‐specific TEP from threshold to saturation and describe their oscillatory contents. Twenty‐two young healthy participants received robotized TMS pulses over the right primary motor cortex (M1), the right dorsolateral prefrontal cortex (DLPFC) and the right superior occipital lobe (SOL) at five stimulation intensities (40, 60, 80, 100, and 120% resting motor threshold) and one short‐interval intracortical inhibition condition during EEG recordings. Ten additional subjects underwent the same experiment with a realistic sham TMS procedure. The results revealed interregional differences in the TEPs input–output functions as well as in the responses to paired‐pulse conditioning protocols, when considering early local components (<80 ms). Each intensity in the three regions was associated with complex patterns of oscillatory activities. The quality of the regression of TEPs over stimulation intensity was used to derive a new readout for cortical excitability and dynamical properties, revealing lower excitability in the DLPFC, followed by SOL and M1. The realistic sham experiment confirmed that these early local components were not contaminated by multisensory stimulations. This study provides an entirely new analytic framework to characterize input–output relations throughout the cortex, paving the way to a more accurate definition of local cortical excitability.

中文翻译：

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使用经颅磁刺激和脑电图耦合通过输入输出特性探测区域皮质兴奋性。

皮层的模块化组织是指高度互连的节点的子集，共享特定的细胞结构和动力学特性。这些特性决定了局部神经元池的兴奋性水平。在这项研究中，我们描述了 TMS 诱发电位 (TEP) 输入输出特性，为区域皮质兴奋性提供新的见解。我们将机器人 TMS 与 EEG 结合起来，将区域特异性 TEP 从阈值到饱和状态解开，并描述其振荡内容。22 名年轻健康参与者在右侧初级运动皮层 (M1)、右侧背外侧前额叶皮层 (DLPFC) 和右侧枕上叶 (SOL) 上接受了五种刺激强度（40、60、80、100、和 120% 静息运动阈值）以及脑电图记录期间的一种短间隔皮质内抑制条件。另外 10 名受试者也通过真实的假 TMS 程序进行了相同的实验。结果揭示了在考虑早期局部成分（<80 ms）时，TEP 输入输出函数以及对成对脉冲调节协议的响应存在区域间差异。这三个区域的每个强度都与复杂的振荡活动模式相关。TEP 对刺激强度的回归质量用于导出皮质兴奋性和动力学特性的新读数，揭示了 DLPFC 的兴奋性较低，其次是 SOL 和 M1。真实的假实验证实，这些早期的局部成分没有受到多感官刺激的污染。这项研究提供了一个全新的分析框架来表征整个皮层的输入输出关系，为更准确地定义局部皮层兴奋性铺平了道路。