Quantifying brain dynamics during anesthesia is an important challenge for understanding the neurophysiological mechanisms of anesthetic drug effect. Several single channel Electroencephalogram (EEG) indices have been proposed for monitoring anesthetic drug effect. The most commonly used single channel commercial index is the Bispectral index (BIS). However, this monitor has shown some drawbacks. In this study, a nonlinear functional connectivity measure named Standardized Permutation Mutual Information (SPMI) is proposed to describe communication between two-channel EEG signals at frontal and temporal brain regions during a controlled propofol-induced anesthesia and recovery design from eight subjects. The SPMI index has higher correlation with estimated propofol effect-site concentration and has better ability to distinguish three anesthetic states of patient than the other functional connectivity indexes (cross-correlation, coherence, phase analysis) and also the BIS index. Moreover, the SPMI index has a faster reaction to the effect of drug concentration, less variability at the consciousness state and better robustness to noise than BIS.

中文翻译：

---

通过麻醉过程中的标准化置换互信息，脑电信号的额颞功能连通性。

量化麻醉期间的脑动力是理解麻醉药物作用的神经生理机制的重要挑战。已经提出了几种单通道脑电图（EEG）指数来监测麻醉药的作用。最常用的单通道商业索引是双光谱索引（BIS）。但是，此监视器显示出一些缺点。在这项研究中，提出了一种非线性功能连通性度量，称为标准化置换互信息（SPMI），用于描述异丙酚诱导的麻醉和八名受试者的恢复设计期间额叶和颞叶大脑区域的两通道EEG信号之间的通信。SPMI指数与估计的异丙酚作用部位浓度具有更高的相关性，并且比其他功能连通性指数（互相关，相干性，相位分析）和BIS指数具有更好的区分患者三种麻醉状态的能力。此外，与BIS相比，SPMI指数对药物浓度的影响具有更快的反应，意识状态下的变异性较小，并且对噪声的鲁棒性更好。