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颞叶癫痫患者海马CA3和内嗅皮层网络的癫痫尖波对theta节律抑制作用的量化评估

葛曼玲^*, 郭俊丹, 陈盛华, 张吉昌, 付晓璇, 陈玉民

河北工业大学电磁场与磁性材料省部共建国家重点实验室，电气工程学院，天津 300130

摘要

海马CA3和内嗅皮层(entorhinal cortex, EC)网络是海马认知功能和颞叶癫痫研究的关键回路之一，尖波对海马网络theta (4~8 Hz)节律抑制作用的研究有利于揭示癫痫对认知功能影响的机制。以往，在网络层面上，该抑制作用常借助脑片来实现定量评估。本文旨在建立依赖于脑深度局部场电位评估癫痫尖波对theta节律抑制作用的方法。从4位术前处于快速眼球运动(rapid eyes movement, REM)睡眠下的颞叶癫痫患者皮质电极记录中择取发作间期有散发性尖波(sporadic spikes, SSs)脑电和两个相邻SSs间无尖波暂态期脑电，尖波分别只在CA3、只在EC、或在CA3和EC同步出现，应用Gabor小波和Hilbert变换计算尖波前后和无尖波暂态期theta能量，并计算无尖波暂态期theta节律的断裂程度。结果显示：(1)尖波可瞬时降低theta能量，CA3和EC同步尖波时下降最为剧烈，抑制作用最强；(2)无尖波暂态期theta能量下降，出现theta节律消失，造成节律断裂，表明抑制作用在持续，且断裂程度与尖波附近抑制作用一致；(3) 3例患者无尖波暂态期theta能量水平降低程度与尖波附近抑制作用一致，而1例不一致。本文结果提示，SSs可对theta节律产生瞬时、直接的抑制作用，该抑制作用可在无尖波暂态期持续，并可由theta节律断裂程度反映。该工作首次应用局部场电位证明了癫痫尖波对theta节律抑制作用可通过无尖波时脑电节律的断裂程度来评估，为利用脑电衡量癫痫尖波抑制作用提供了量化分析方法。

关键词： CA3和EC网络; 癫痫尖波 ; theta节律 ; 时频能量

分类号：Q4

Quantitative evaluation of inhibitory effects of epileptic spikes on theta rhythms in the network of hippocampal CA3 and entorhinal cortex in patients with temporal lobe epilepsy

GE Man-Ling^*, GUO Jun-Dan, CHEN Sheng-Hua, ZHANG Ji-Chang, FU Xiao-Xuan, CHEN Yu-Min

The Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability, Department of Electrical Engineering, Hebei University of Technology, Tianjin 300130, China

Abstract

Epileptic spike is an indicator of hyper-excitability and hyper-synchrony in the neural networks. The inhibitory effects of spikes on theta rhythms (4–8 Hz) might be helpful to understand the mechanism of epileptic damage on the cognitive functions. To quantitatively evaluate the inhibitory effects of spikes on theta rhythms, intracerebral electroencephalogram (EEG) recordings with both sporadic spikes (SSs) and spike-free transient period between adjacent spikes were selected in 4 patients in the status of rapid eyes movement (REM) sleep with temporal lobe epilepsy (TLE) under the pre-surgical monitoring. The electrodes of hippocampal CA3 and entorhinal cortex (EC) were employed, since CA3 and EC built up one of key loops to investigate cognition and epilepsy. These SSs occurred only in CA3, only in EC, or in both CA3 and EC synchronously. Theta power was respectively estimated around SSs and during the spike-free transient period by Gabor wavelet transform and Hilbert transform. The intermittent extent was then estimated to represent for the loss of theta rhythms during the spike-free transient period. The following findings were obtained: (1) The prominent rhythms were in theta frequency band; (2) The spikes could transiently reduce theta power, and the inhibitory effect was severer around SSs in both CA3 and EC synchronously than that around either SSs only in EC or SSs only in CA3; (3) During the spike-free transient period, theta rhythms were interrupted with the intermittent theta rhythms left and theta power level continued dropping, implying the inhibitory effect was sustained. Additionally, the intermittent extent of theta rhythms was converged to the inhibitory extent around SSs; (4) The average theta power level during the spike-free transient period might not be in line with the inhibitory extent of theta rhythms around SSs. It was concluded that the SSs had negative effects on theta rhythms transiently and directly, the inhibitory effects aroused by SSs sustained during the spike-free transient period and were directly related to the intermittent extent. It was indicated that the loss of theta rhythms might qualify exactly the sustained inhibitory effects on theta rhythms aroused by spikes in EEG. The work provided an argumentation about the relationship between the transient negative impact of interictal spike and the loss of theta rhythms during spike-free activity for the first time, offered an intuitive methodology to estimate the inhibitory effect of spikes by EEG, and might be helpful to the analysis of EEG rhythms based on local field potentials (LFPs) in deep brain.

Key words: network of CA3 and entorhinal cortex; sporadic spikes ; theta rhythm ; time-frequency energy

收稿日期：2016-06-14　　录用日期：2016-10-21

通讯作者：葛曼玲　　E-mail: mlgeliliangao@126.com

引用本文：

葛曼玲, 郭俊丹, 陈盛华, 张吉昌, 付晓璇, 陈玉民. 颞叶癫痫患者海马CA3和内嗅皮层网络的癫痫尖波对theta节律抑制作用的量化评估[J]. 生理学报 2017; 69 (1): 77-88.

GE Man-Ling, GUO Jun-Dan, CHEN Sheng-Hua, ZHANG Ji-Chang, FU Xiao-Xuan, CHEN Yu-Min. Quantitative evaluation of inhibitory effects of epileptic spikes on theta rhythms in the network of hippocampal CA3 and entorhinal cortex in patients with temporal lobe epilepsy. Acta Physiol Sin 2017; 69 (1): 77-88 (in Chinese with English abstract).