Meyer Kaspar
From the Institute of Anesthesiology, University Hospital, University of Zürich, Zürich, Switzerland, and the Brain and Creativity Institute, University of Southern California, Los Angeles, California.
Anesthesiology. 2015 Jun;122(6):1415-31. doi: 10.1097/ALN.0000000000000673.
Despite considerable progress in the identification of the molecular targets of general anesthetics, it remains unclear how these drugs affect the brain at the systems level to suppress consciousness. According to recent proposals, anesthetics may achieve this feat by interfering with corticocortical top-down processes, that is, by interrupting information flow from association to early sensory cortices. Such a view entails two immediate questions. First, at which anatomical site, and by virtue of which physiological mechanism, do anesthetics interfere with top-down signals? Second, why does a breakdown of top-down signaling cause unconsciousness? While an answer to the first question can be gleaned from emerging neurophysiological evidence on dendritic signaling in cortical pyramidal neurons, a response to the second is offered by increasingly popular theoretical frameworks that place the element of prediction at the heart of conscious perception.
尽管在确定全身麻醉药的分子靶点方面取得了相当大的进展，但这些药物如何在系统层面影响大脑以抑制意识仍不清楚。根据最近的提议，麻醉药可能通过干扰皮质-皮质自上而下的过程来实现这一壮举，也就是说，通过中断从联合皮质到早期感觉皮质的信息流。这种观点立即引发了两个问题。第一，麻醉药在哪个解剖部位以及凭借何种生理机制干扰自上而下的信号？第二，为什么自上而下信号的中断会导致意识丧失？虽然可以从关于皮质锥体细胞树突信号传导的新出现的神经生理学证据中找到第一个问题的答案，但越来越流行的理论框架为第二个问题提供了答案，这些理论框架将预测元素置于有意识感知的核心。
