额顶叶连接是一种非静态现象，在无意识状态下会发生特征性变化。
Fronto-parietal connectivity is a non-static phenomenon with characteristic changes during unconsciousness.
作者信息
Untergehrer Gisela, Jordan Denis, Kochs Eberhard F, Ilg Rüdiger, Schneider Gerhard
机构信息
Department of Anesthesiology, Helios Clinic Wuppertal, Witten/Herdecke University, Wuppertal, Germany ; Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
Department of Anesthesiology, Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
出版信息
PLoS One. 2014 Jan 27;9(1):e87498. doi: 10.1371/journal.pone.0087498. eCollection 2014.
BACKGROUND
It has been previously shown that loss of consciousness is associated with a breakdown of dominating fronto-parietal feedback connectivity as assessed by electroencephalogram (EEG) recordings. Structure and strength of network connectivity may change over time. Aim of the current study is to investigate cortico-cortical connectivity at different time intervals during consciousness and unconsciousness. For this purpose, EEG symbolic transfer entropy (STEn) was calculated to indicate cortico-cortical information transfer at different transfer times.
METHODS
The study was performed in 15 male volunteers. 29-channel EEG was recorded during consciousness and propofol-induced unconsciousness. EEG data were analyzed by STEn, which quantifies intensity and directionality of the mutual information flow between two EEG channels. STEn was computed over fronto-parietal channel pair combinations (10 s length, 0.5-45 Hz total bandwidth) to analyze changes of intercortical directional connectivity. Feedback (fronto → parietal) and feedforward (parieto → frontal) connectivity was calculated for transfer times from 25 ms to 250 ms in 5 ms steps. Transfer times leading to maximum directed interaction were identified to detect changes of cortical information transfer (directional connectivity) induced by unconsciousness (p<0.05).
RESULTS
The current analyses show that fronto-parietal connectivity is a non-static phenomenon. Maximum detected interaction occurs at decreased transfer times during propofol-induced unconsciousness (feedback interaction: 60 ms to 40 ms, p = 0.002; feedforward interaction: 65 ms to 45 ms, p = 0.001). Strength of maximum feedback interaction decreases during unconsciousness (p = 0.026), while no effect of propofol was observed on feedforward interaction. During both consciousness and unconsciousness, intensity of fronto-parietal interaction fluctuates with increasing transfer times.
CONCLUSION
Non-stationarity of directional connectivity may play a functional role for cortical network communication as it shows characteristic changes during propofol-induced unconsciousness.
背景
先前的研究表明，通过脑电图（EEG）记录评估，意识丧失与主导的额顶叶反馈连接性的破坏有关。网络连接的结构和强度可能随时间变化。本研究的目的是调查意识和无意识状态下不同时间间隔的皮质-皮质连接性。为此，计算了EEG符号转移熵（STEn）以指示不同转移时间的皮质-皮质信息传递。
方法
该研究在15名男性志愿者中进行。在意识状态和丙泊酚诱导的无意识状态下记录29通道EEG。通过STEn分析EEG数据，STEn量化两个EEG通道之间互信息流的强度和方向性。在额顶叶通道对组合上计算STEn（长度为10秒，总带宽为0.5 - 45Hz），以分析皮质间方向性连接的变化。以5毫秒步长计算从25毫秒到250毫秒转移时间的反馈（额→顶）和前馈（顶→额）连接性。确定导致最大定向相互作用的转移时间，以检测由无意识状态引起的皮质信息传递（方向性连接）的变化（p<0.05）。
结果
当前分析表明，额顶叶连接性是一种非静态现象。在丙泊酚诱导的无意识状态下，最大检测到的相互作用发生在转移时间减少时（反馈相互作用：从60毫秒到40毫秒，p = 0.002；前馈相互作用：从65毫秒到45毫秒，p = 0.001）。最大反馈相互作用的强度在无意识状态下降低（p = 0.026），而未观察到丙泊酚对前馈相互作用有影响。在意识和无意识状态下，额顶叶相互作用的强度均随转移时间增加而波动。
结论
方向性连接的非平稳性可能在皮质网络通信中发挥功能作用，因为它在丙泊酚诱导的无意识状态下表现出特征性变化。
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