Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, China; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, China.
Department of Anesthesiology, Huashan Hospital, Fudan University, Shanghai 200040, China.
Clin Neurophysiol. 2022 Oct;142:209-219. doi: 10.1016/j.clinph.2022.08.003. Epub 2022 Aug 19.
General anesthesia might disrupt neuronal network communications measured by functional connectivity (FC; undirected connectivity) and directional information flow (directed connectivity). We sought to characterize the state-dependent effects of propofol on cortico-cortical undirected and directed FC.
We collected 256-channel high-density EEGs from 14 patients undergoing surgery while awake (AWA) or in propofol-induced moderate sedation (SED) or loss of consciousness (LOC) states. Using source-space EEG, we estimated neuronal oscillatory activity for 68 cortical regions of interest. FC was analyzed using the weighted phase lag index. Directed connectivity was computed using directed phase transfer entropy (dPTE) as a measure of information flow in the bilateral prefrontal, frontal, parietal, and occipital areas.
FC strength evidently reduced during LOC compared with those during the AWA and SED states. The dPTE analysis showed significant propofol-induced changes in directed connectivity. In the alpha band, the prefrontal-to-frontal information flow was significantly stronger in the AWA than in the SED (p = 0.033) and LOC states (p = 0.033). The parietal-to-frontal dPTE was significantly weaker during LOC than during the AWA (p = 0.033) and SED states (p = 0.007). Finally, a loss of occipital-to-frontal connectivity occurred during LOC but not the AWA state (p = 0.001). In the beta band, the dominant occipital-to-frontal direction of information flow in the AWA state was gradually converted to a frontal-to-occipital direction during LOC.
Propofol-induced unconsciousness is marked by a decrease in FC and posterior-to-anterior (feedforward) directed connectivity, which may be useful as a measure to discriminate different conscious states caused by propofol administration.
The study demonstrates that propofol produces state-dependent effects on cortico-cortical undirected and directed FC, supporting the idea that propofol induces loss of consciousness may through disrupting network interactions and cortical coordination.
全身麻醉可能会通过功能连接（无向连接）和定向信息流（有向连接）来破坏神经元网络通信。我们试图描述丙泊酚对皮质间无向和有向功能连接的状态依赖性影响。
我们从 14 名接受手术的患者中收集了清醒（AWA）、丙泊酚诱导中度镇静（SED）或意识丧失（LOC）状态下的 256 通道高密度 EEG。使用源空间 EEG，我们估计了 68 个皮质感兴趣区的神经元振荡活动。使用加权相位滞后指数分析 FC。使用有向相位转移熵（dPTE）作为双侧前额叶、额叶、顶叶和枕叶区域信息流的度量来计算有向连接。
与 AWA 和 SED 状态相比，LOC 期间 FC 强度明显降低。dPTE 分析显示有向连接受到丙泊酚诱导的显著变化。在 alpha 波段，前额叶到额叶的信息流在 AWA 状态下明显强于 SED（p=0.033）和 LOC 状态（p=0.033）。LOC 状态下，顶叶到额叶的 dPTE 明显弱于 AWA（p=0.033）和 SED 状态（p=0.007）。最后，LOC 状态下出现了枕叶到额叶连接的丢失，但 AWA 状态下没有（p=0.001）。在 beta 波段，AWA 状态下主导的枕叶到额叶信息流的方向在 LOC 状态下逐渐转变为额叶到枕叶的方向。
丙泊酚诱导的无意识状态以 FC 和后到前（前馈）有向连接的减少为特征，这可能是区分丙泊酚给药引起的不同意识状态的有用指标。
该研究表明，丙泊酚对皮质间无向和有向 FC 产生状态依赖性影响，支持丙泊酚诱导意识丧失可能通过破坏网络相互作用和皮质协调的观点。
