section_path: Medical uses
section_name: Medical uses
paragraph_text: Medical uses
  
  The purpose of anesthesia can be distilled down to three basic goals or endpoints:
  
  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 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.
  
  To achieve the goals of anesthesia, drugs act on different but interconnected parts of the nervous system. Hypnosis, for instance, is generated through actions on the nuclei in the brain and is similar to the activation of sleep. The effect is to make people less aware and less reactive to noxious stimuli.
  
  Loss of memory (amnesia) is created by action of drugs on multiple (but specific) regions of the brain. Memories are created as either declarative or non-declarative memories in several stages (short-term, long-term, long-lasting) the strength of which is determined by the strength of connections between neurons termed synaptic plasticity. 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.
  
  Nevertheless, a person can 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 ". It is not known whether animals dream while under general anesthesia.