Amnesia

Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, it would be impossible for language, relationships, or personal identity to develop. Memory loss is usually described as forgetfulness or amnesia.

Memory is often understood as an informational processing system with explicit and implicit functioning that is made up of a sensory processor, short-term (or working) memory, and long-term memory. This can be related to the neuron.The sensory processor allows information from the outside world to be sensed in the form of chemical and physical stimuli and attended to various levels of focus and intent. Working memory serves as an encoding and retrieval processor. Information in the form of stimuli is encoded in accordance with explicit or implicit functions by the working memory processor. The working memory also retrieves information from previously stored material. Finally, the function of long-term memory is to store through various categorical models or systems.

Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prevention of pain), paralysis (muscle relaxation), amnesia (loss of memory), and unconsciousness. An individual under the effects of anesthetic drugs is referred to as being anesthetized.

Anesthesia enables the painless performance of procedures that would otherwise require physical restraint in a non-anesthetized individual, or would otherwise be technically unfeasible. Three broad categories of anesthesia exist:

XIII ("Thirteen") is a Belgian graphic novel series about an amnesiac who seeks to discover his past. It was created by writer Jean Van Hamme and artist William Vance. It is currently being written by Yves Sente and Youri Jigounov. The storyline of the first five volumes was adapted into a video game in 2003, also titled XIII, with a remake being released in 2020. A Canadian television film based on the series, XIII: The Conspiracy, was released in 2008. It was followed in 2011 by two seasons of a TV series, each 13 episodes, called XIII: The Series.

General anaesthetics (or anesthetics) are often defined as compounds that induce a loss of consciousness in humans or loss of righting reflex in animals. Clinical definitions are also extended to include an induced coma that causes lack of awareness to painful stimuli, sufficient to facilitate surgical applications in clinical and veterinary practice. General anaesthetics do not act as analgesics and should also not be confused with sedatives. General anaesthetics are a structurally diverse group of compounds whose mechanisms encompass multiple biological targets involved in the control of neuronal pathways. The precise workings are the subject of some debate and ongoing research.

General anesthetics elicit a state of general anesthesia. It remains somewhat controversial regarding how this state should be defined. General anesthetics, however, typically elicit several key reversible effects: immobility, analgesia, amnesia, unconsciousness, and reduced autonomic responsiveness to noxious stimuli.

Ketamine is a cyclohexanone-derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. Ketamine exists as its two enantiomers, S- (esketamine) and R- (arketamine), and has antidepressant action likely involving other mechanisms in addition to NMDA antagonism.

At anesthetic doses, ketamine induces a state of dissociative anesthesia, a trance-like state providing pain relief, sedation, and amnesia. Its distinguishing features as an anesthestic are preserved breathing and airway reflexes, stimulated heart function with increased blood pressure, and moderate bronchodilation. As an anesthetic, it is used especially in trauma, emergency, and pediatric cases. At lower, sub-anesthetic doses, it is used as a treatment for pain and treatment-resistant depression.

Diazepam, sold under the brand name Valium among others, is a medication of the benzodiazepine family that acts as an anxiolytic. It is used to treat a range of conditions, including anxiety, seizures, alcohol withdrawal syndrome, muscle spasms, insomnia, and restless legs syndrome. It may also be used to cause memory loss during certain medical procedures. It can be taken orally (by mouth), as a suppository inserted into the rectum, intramuscularly (injected into muscle), intravenously (injection into a vein) or used as a nasal spray. When injected intravenously, effects begin in one to five minutes and last up to an hour. When taken by mouth, effects begin after 15 to 60 minutes.

Common side effects include sleepiness and trouble with coordination. Serious side effects are rare. They include increased risk of suicide, decreased breathing, and a paradoxical increased risk of seizures if used too frequently in those with epilepsy. Occasionally, excitement or agitation may occur. Long-term use can result in tolerance, dependence, and withdrawal symptoms on dose reduction. Abrupt stopping after long-term use can be potentially dangerous. After stopping, cognitive problems may persist for six months or longer. It is not recommended during pregnancy or breastfeeding. Its mechanism of action works by increasing the effect of the neurotransmitter gamma-aminobutyric acid (GABA).

In neurology, anterograde amnesia is the inability to create new memories after an event that caused amnesia, leading to a partial or complete inability to recall the recent past, while long-term memories from before the event remain intact. This is in contrast to retrograde amnesia, where memories created prior to the event are lost while new memories can still be created. Both can occur together in the same patient. To a large degree, anterograde amnesia remains a mysterious ailment because the precise mechanism of storing memories is not yet well understood, although it is known that the regions of the brain involved are certain sites in the temporal cortex, especially in the hippocampus and nearby subcortical regions.

Korsakoff syndrome (KS) is a disorder of the central nervous system characterized by amnesia, deficits in explicit memory, and confabulation. This neurological disorder is caused by a deficiency of thiamine (vitamin B₁) in the brain, and it is typically associated with and exacerbated by the prolonged, excessive ingestion of alcohol. Korsakoff syndrome is often accompanied by Wernicke encephalopathy; this combination is called Wernicke–Korsakoff syndrome.

Korsakoff syndrome is named after Sergei Korsakoff, the Russian neuropsychiatrist who described it during the late 19th century.

Dissociatives, colloquially dissos, are a subclass of hallucinogens that distort perception of sight and sound and produce feelings of detachment – dissociation – from the environment and/or self. Although many kinds of drugs are capable of such an effect, dissociatives are unique in that they do so in such a way that they produce hallucinogenic effects, which may include dissociation, a general decrease in sensory experience, hallucinations, dream-like states or anesthesia.

Despite most dissociatives' main mechanism of action being tied to NMDA receptor antagonism, some of these substances, which are nonselective in action and affect the dopamine and/or opioid systems, may be capable of inducing more direct and repeatable euphoria or symptoms which are more akin to the effects of typical "hard drugs" or common drugs of abuse. This is likely why dissociatives are considered to be addictive with a fair to moderate potential for abuse, unlike psychedelics. Despite some dissociatives, such as phencyclidine (PCP) possessing stimulating properties, most dissociatives seem to have a general depressant effect and can produce sedation, respiratory depression, nausea, disorientation, analgesia, anesthesia, ataxia, cognitive and memory impairment as well as amnesia.

The Outsider is the name of three characters appearing in American comic books published by DC Comics. The first is an evil persona that Alfred Pennyworth assumes after nearly dying and becoming amnesiac. The second, Michael Desai, is an Indian metahuman and businessman introduced during the Flashpoint storyline. The third is Alfred's Earth-Three counterpart.

Dissociative fugue (/fjuːɡ/ FYOOG), previously referred to as a fugue state or psychogenic fugue, is a rare psychiatric condition characterized by reversible amnesia regarding one's identity, often accompanied by unexpected travel or wandering. In some cases, individuals may assume a new identity and be unable to recall personal information from before the onset of symptoms. It is classified as a mental and behavioral disorder and is variously categorized as a dissociative disorder, a conversion disorder, or a somatic symptom disorder. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), dissociative fugue is a subset of dissociative amnesia.

Recovery from a fugue state typically results in the restoration of prior memories, and additional treatment is generally unnecessary. Episodes are not considered dissociative fugue if attributable to psychotropic substances, physical trauma, general medical conditions, or disorders such as dissociative identity disorder, delirium, or dementia. Dissociative fugue is often triggered by prolonged traumatic experiences and is most frequently associated with individuals who experienced childhood sexual abuse, during which they developed dissociative amnesia to suppress memories of the abuse.

XIII is a first-person shooter video game, loosely based on the first five volumes of the 1984 Belgian graphic novel series of the same name. Developed and published by Ubisoft, it was released in November 2003 for Microsoft Windows, PlayStation 2, and GameCube; an Xbox version of the game, released at the same time, was developed by Southend Interactive, while an OS X version was developed by Zonic, published by Feral Interactive, and released in June 2004.

Designed with a comic book-style, cel-shaded presentation, the game incorporates single-player and multiplayer game modes. The game's main story focuses on a confused and amnesic man who searches for his identity after being found stranded on a beach. He slowly finds himself caught up in a conspiracy by a group who aims to overthrow the government. The protagonist assassinated the President of the United States, and is wanted by the FBI.