Editing Anesthesia (section)

== Medical uses ==
<!--see Talk page on endpoints.  Discussed with expert; author of Miller's anesthesiology-->
The purpose of anesthesia can be distilled down to three basic goals or endpoints:<ref name="Miller 2010">{{Cite book|title=Miller's Anesthesia | edition = Seventh| vauthors = Miller RD |publisher=Churchill Livingstone Elsevier|year=2010|isbn=978-0-443-06959-8| veditors = Erikson LI, Fleisher LA, Wiener-Kronish JP, Young WL |location=US}}</ref>{{rp|236}}
* [[hypnotic|hypnosis]] (a temporary loss of [[consciousness]] and with it a loss of [[memory]].  In a pharmacological context, the word hypnosis usually has this technical meaning, in contrast to its more familiar lay or psychological meaning of an altered state of consciousness not necessarily caused by drugs—see [[hypnosis]]).
* [[analgesia]] (lack of sensation which also blunts [[Autonomic nervous system|autonomic reflexes]])
* [[Muscle relaxant|muscle relaxation]]

Different types of anesthesia affect the endpoints differently. [[Regional anesthesia]], for instance, affects analgesia; [[benzodiazepine]]-type sedatives (used for sedation, or "[[twilight anesthesia]]") favor [[amnesia]]; and [[general anesthesia|general anesthetics]] can affect all of the endpoints.  The goal of anesthesia is to achieve the endpoints required for the given surgical procedure with the least risk to the subject.
[[File:Operating room anesthetic station.jpg|thumb|right|The anesthetic area of an operating room]]
To achieve the goals of anesthesia, drugs act on different but interconnected parts of the nervous system. [[hypnotic|Hypnosis]], for instance, is generated through actions on the [[Nucleus (neuroanatomy)|nuclei in the brain]] and is similar to the activation of [[sleep]].  The effect is to make people less [[awareness|aware]] and less reactive to [[noxious stimulus|noxious stimuli]].<ref name="Miller 2010" />{{rp|245}}

Loss of [[memory]] ([[amnesia]]) is created by action of drugs on multiple (but specific) regions of the brain.  Memories are created as either [[Declarative memory|declarative]] or [[Procedural memory|non-declarative]] memories in several stages ([[Short-term memory|short-term]], [[Long-term memory|long-term]], [[Working memory|long-lasting]]) the strength of which is determined by the strength of connections between neurons termed [[synaptic plasticity]].<ref name="Miller 2010" />{{rp|246}} Each anesthetic produces amnesia through unique effects on memory formation at variable doses. [[Inhalational anesthetics]] will reliably produce amnesia through general suppression of the nuclei at doses below those required for loss of consciousness. Drugs like [[midazolam]] produce amnesia through different pathways by blocking the formation of long-term memories.<ref name="Miller 2010" />{{rp|249}}

Nevertheless, a person can [[dreams|dream]] under anesthesia or are conscious of the procedure despite giving no indication of this during it.  An estimated 22% of people do [[dream]] under [[general anesthesia]], and one or two cases in a thousand have some consciousness, termed "[[anesthesia awareness]]".<ref name="Miller 2010" />{{rp|253}} It is not known whether animals dream while under general anesthesia.