氯胺酮-美托咪定全身麻醉伴随皮层电生理活动在高与低复杂状态间的交替
Ketamine-Medetomidine General Anesthesia Occurs With Alternation of Cortical Electrophysiological Activity Between High and Low Complex States
AI总结：
本研究通过分析非人灵长类ECoG记录，发现氯胺酮-美托咪定麻醉期间皮层活动复杂性在局部波动并在全局尺度上于高、低复杂状态间交替，为麻醉机制提供了新证据。
摘要：
已知麻醉剂能够引起皮层电生理活动的一系列改变，例如特征性模式的出现、统计特性的变化以及神经记录动态行为的改变。许多方法可用于监测这些变化，其中复杂度指标已被证明能够区分涉及不同意识水平的状态。人们普遍认为麻醉药物可以在不同水平和时间尺度上干扰神经活动，既能在局部引起改变，也能在整个皮层建立的空间-时间模式上引起改变。然而，皮层活动复杂性的这些变化究竟如何发生仍不清楚，且仍需要实验证据。为此，我们分析了一只非人灵长类动物在氯胺酮-美托咪定麻醉诱导过程中的ECoG记录数据库。MDR-ECoG技术提供了具有高时间分辨率和空间分辨率且覆盖皮层表面广泛区域的皮层活动记录。采用排列熵和分形维数来评估神经时间序列的复杂性。结果发现，在清醒状态下皮层活动的复杂性相对恒定。向无意识状态的转变发生得相对较快；首次显著变化大约需要30至40秒。在麻醉期间，复杂性在局部水平上呈现相当大的变化，并似乎没有明确周期地波动。皮层在全局尺度上动态地交替于高和低复杂状态之间。本研究提供了麻醉剂对神经活动和皮层动力学影响的新证据，有助于从回路、通路和全局脑功能方面阐明麻醉机制。
英文摘要：
Anesthetic agents are known to induce a range of alterations in cortical electrophysiological activity, such as the rise of signature patterns, changes in statistical properties, and altered dynamic behavior of neural records. Plenty of methods can be used to monitor these changes, among them complexity metrics demonstrated to have the power to discriminate states involving distinct levels of awareness. There is a consensus that anesthetic drugs can interfere with neural activities at different levels and time scales, being able to induce alterations both locally and in the spatiotemporal patterns established throughout the whole cortex. However, it is still unclear how such changes in the complexity of cortical activity are supposed to occur, and experimental evidence is still needed. For this purpose, we have analyzed an ECoG records database of a Ketamine-Medetomidine anesthetic induction in a non-human primate subject. The MDR-ECoG technique provided records of cortical activity with both high temporal and spatial resolution allied with extensive coverage of the cortical surface. The Permutation Entropy and the Fractal Dimension were employed to evaluate the complexity of the neural time series. It was found that the complexity of cortical activity was relatively constant during awakened conditions. The transition to unconsciousness occurred relatively fast; it required about 30 to 40 seconds for the first remarkable changes to take place. During anesthesia, the complexity assumed considerable variation at local levels and fluctuated apparently without a defined period. The cortex dynamically alternated between high and low complex states on a global scale. This study provides novel evidence of the effects of anesthetics on neural activity and cortical dynamics, contributing to the elucidation of anesthetic mechanisms in terms of circuits, pathways, and global brain functioning.
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