Aware beside an unconscious patient, not the inverse! On the necessity of knowing how anesthesia modulates consciousness

One of the magic's of general anesthesia is the reversible modulation of consciousness. The past 20 years have seen important progress in the understanding of consciousness physiology, and its alteration by hypnotic anesthetic agents. However, this knowledge is sparsely spread among anesthesiology practitioners. One of the reasons is that the new concepts underlying brain functioning are far from their usual basic science background, and are not necessarily easy to catch. In this narrative review, the aim is to make these current concepts within reach, including brain connectivity, network laws, and theories on consciousness. The hypotheses on how anesthetic agents interfere with brain function are also described, from their initial biochemical targets to interactions with sleep/wake regulating systems and consciousness networks. The importance of the topic to anesthesiologists is underlined, and the questions that still remain to be solved are listed..