This paper reviews the current knowledge about the mechanisms of anesthesia-induced alteration of consciousness. It is now evident that hypnotic anesthetic agents have specific brain targets whose function is hierarchically altered in a dose-dependent manner. Higher order networks, thought to be involved in mental content generation, as well as sub-cortical networks involved in thalamic activity regulation seems to be affected first by increasing concentrations of hypnotic agents that enhance inhibitory neurotransmission. Lower order sensory networks are preserved, including thalamo-cortical connectivity into those networks, even at concentrations that suppress responsiveness, but cross-modal sensory interactions are inhibited. Thalamo-cortical connectivity into the consciousness networks decreases with increasing concentrations of those agents, and is transformed into an anti-correlated activity between the thalamus and the cortex for the deepest levels of sedation, when the subject is non responsive. Future will tell us whether these brain function alterations are also observed with hypnotic agents that mainly inhibit excitatory neurotransmission. The link between the observations made using fMRI and the identified biochemical targets of hypnotic anesthetic agents still remains to be identified.

中文翻译：

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使用功能磁共振成像（fMRI）在全身麻醉过程中意识的神经相关性。

本文综述了有关麻醉诱导的意识改变机制的最新知识。现在很明显，催眠麻醉剂具有特定的大脑目标，其功能以剂量依赖的方式进行分层改变。被认为与精神内容产生有关的高阶网络以及与丘脑活动调节有关的皮层下网络似乎首先受到增强抑制神经传递抑制作用的催眠药浓度的影响。较低级别的感觉网络得以保留，包括进入这些网络的丘脑-皮质连接性，即使在抑制反应性的浓度下也是如此，但是跨模式的感觉相互作用受到抑制。随着这些媒介物浓度的增加，进入意识网络的丘脑-皮质连接性降低，当受试者无反应时，可转化为丘脑和皮质之间的抗相关活性，以达到最深的镇静作用。未来将告诉我们，是否还可以使用主要抑制兴奋性神经传递的催眠药来观察这些脑功能的改变。使用fMRI进行的观察与已确定的催眠麻醉药生化目标之间的联系仍有待确定。