Instruct: Given a question, retrieve documents that can help answer the question.
Query: Is amnesia real?
Amnesia is a deficit in memory caused by brain damage, disease, or psychological trauma.[1] Amnesia can also be caused temporarily by the use of various sedatives and hypnotic drugs. The memory can be either wholly or partially lost due to the extent of damage that was caused.[2] There are two main types of amnesia: retrograde amnesia and anterograde amnesia. Retrograde amnesia is the inability to retrieve information that was acquired before a particular date, usually the date of an accident or operation.[3] In some cases the memory loss can extend back decades, while in others the person may lose only a few months of memory. Anterograde amnesia is the inability to transfer new information from the short-term store into the long-term store. People with this type of amnesia cannot remember things for long periods of time. These two types are not mutually exclusive; both can occur simultaneously.
 is the series protagonist. He suffers amnesia and adopted the addressed name on a letter found in his possession when he washed ashore. He lives with the Misugi family and does all of the household chores. Using the belt, Shouichi can transform into , an ancient and powerful warrior whose abilities are constantly evolving. As the series progressed, he discovers the reason behind his amnesia and that his real name is Tetsuya Sawaki. He has a Honda VTR1000F, which turns into the when he transforms.
Alzheimer's disease (AD), which is known to be associated with frontal lobe dysfunction, is implicated as a cause of source amnesia. In laboratory conditions, one study found source monitoring to be so poor that the AD participants were correctly performing source memory attributions at approximately chance. This lack of ability to attribute the source of memories is likely related to AD patients' deficits in reality monitoring. Reality monitoring, the process of distinguishing whether information originated from an external or an internal source, relies on judgement processes to examine the qualitative characteristics of the information in order to determine if the information was real or imagined. It appears that it is this process that is experiencing the dysfunction, which causes mild confabulation in some AD patients, as well as being related to the source amnesia experienced in some individuals with AD.
All people experience selective amnesia in their lives, and this selective amnesia may allow individuals to use their attention more effectively. In these studies, selective amnesia is defined as the phenomena experienced when a participant pays attention to the information given but then almost immediately forgets it. Rodrigues (2011) conducted a study in which participants were put into pairs and each pair was given five minutes to interact with an assigned stimuli. The participants’ actions and speech were recorded during this time. After the five minutes were completed, the experimenter questioned the participants about why the participants made certain decisions or said certain things. Rodrigues found that inattention blindness, attention capture, and selective amnesia all played a role in the participant’s overall accuracy. Thus, even though most other forms of amnesia are harmful, selective amnesia may play a practical, and even helpful, role in our lives.
Psychogenic amnesia is defined by the presence of retrograde amnesia (the inability to retrieve stored memories leading up to the onset of amnesia), and an absence of anterograde amnesia (the inability to form new long term memories). Access to episodic memory can be impeded, while the degree of impairment to short term memory, semantic memory and procedural memory is thought to vary among cases. If other memory processes are affected, they are usually much less severely affected than retrograde autobiographical memory, which is taken as the hallmark of psychogenic amnesia. However the wide variability of memory impairment among cases of psychogenic amnesia raises questions as to its true neuropsychological criteria, as despite intense study of a wide range of cases there is little consensus of which memory deficits are specific to psychogenic amnesia.
Spontaneous amnesia has also been difficult to determine as research bias has been found to influence in many cases. In one study participants were put into two groups; one was to receive amnesic instructions and half were not given the instructions. The next day the groups were reversed. Results showed that there was little spontaneous amnesia across all participants, leading to doubts towards the actual occurrence of amnesia. It was later found that those more susceptible to hypnosis were more susceptible to suggested post-hypnotic amnesia and not spontaneous amnesia. These results suggest that spontaneous amnesia is less common than suggested amnesia and that when high results of spontaneous amnesia are recorded, some incidences may be false.
Retrograde amnesia is typically the result of physical or psychological trauma which manifests itself as the inability to remember information preceding the traumatic event. It is usually accompanied by some type of anterograde amnesia, or inability to acquire new knowledge. Focal retrograde amnesia (FRA), sometimes known as functional amnesia, refers to the presence of retrograde amnesia while knowledge acquisition remains intact (no anterograde amnesia). Memory for how to use objects and perform skills (implicit memory) may remain intact while specific knowledge of personal events or previously learned facts (explicit memory) become inaccessible or lost. Amnesia can result from a number of different causes, including encephalitis, severe traumatic brain injury, vitamin B deficiency as seen in Korsakoff's Syndrome, and psychotic episodes, or by witnessing an emotionally traumatic event (Dissociative amnesia). Dysfunction of the temporal and frontal lobes have been observed in many cases of focal retrograde amnesia, whether metabolic or the result of lesions. However, this evidence only appears to correlate with the symptoms of retrograde amnesia as cases have been observed where patients suffering from minor concussions, showing no visible brain damage, develop FRA. It has been suggested that FRA could represent a variety of different disorders, cognitive deficits, or conditions that result in disproportionate loss of explicit memory, hence Disproportionate Retrograde Amnesia.
Another real life problem with RA is malingering, which is conceived as the rational output of a neurologically normal brain aiming at the surreptitious achievement of a well identified gain. Since it is common for people who have committed a crime to report having RA for that specific event in order to avoid their punishment, the legal system has pushed for the creation of a standardized test of amnesia. However, since most cases differ in onset, duration, and content forgotten, this task has shown to be a rather complex one.
The cause of the fugue state is related to dissociative amnesia, ("DSM-IV Codes 300.12") which has several other subtypes: selective amnesia, generalised amnesia, continuous amnesia, and systematised amnesia, in addition to the subtype "dissociative fugue".
Petersen notices that this Edwardes has a peculiar phobia about sets of parallel lines against a white background. She also soon realizes, by comparing handwriting, that this man is not the real Edwardes, but an impostor. He confides to her that he has killed the real Edwardes and has taken his place. He suffers from massive amnesia and does not know who he is. Petersen believes he is innocent and that he is suffering from a guilt complex. He disappears overnight, leaving a note for her. At the same time, it becomes public knowledge that the supposed Edwardes is an impostor, and that the real Edwardes is missing and may have been murdered.
Petersen manages to track him down and starts to use her psychoanalytic training to break his amnesia and find out what really happened. Pursued by the police, Petersen and the impostor (calling himself John Brown) travel by train to Rochester, New York, where they stay with Dr. Alexander Brulov (Michael Chekhov), Petersen's former mentor.
He appeared in "I, Normo" where he had amnesia courtesy of the Black Falcon. With Alan's help, he regained his memory, but mistook Alan for the real Black Falcon and gave him amnesia. With his full suit on, he resembles Optimus Prime from Transformers.
For most of the 19th century, investigators reported that post-hypnotic amnesia only occurred spontaneously as scientific knowledge regarding this form of amnesia was minimal. Spontaneous post-hypnotic amnesia represents a slight memory impairment that results as a consequence of being put under hypnosis or being tested. This form of amnesia can also be experienced across susceptibility groups, but to a much lesser extent and magnitude to suggested post-hypnotic amnesia.
Semantic amnesia is a type of amnesia that affects semantic memory and is primarily manifested through difficulties with language use and acquisition, recall of facts and general knowledge. A patient with semantic amnesia would have damage to the temporal lobe.
Drug-induced amnesia is amnesia caused by drugs. Amnesia may be therapeutic for medical treatment or for medical procedures, or it may be a side-effect of a drug, such as alcohol, or certain medications for psychiatric disorders, such as benzodiazepines.
Neurological cause of psychogenic amnesia is controversial. Even in cases of organic amnesia, where there is lesion or structural damage to the brain, caution must still be taken in defining causation, as only damage to areas of the brain crucial to memory processing is it possible to result in memory impairment. Organic causes of amnesia can be difficult to detect, and often both organic cause and psychological triggers can be entangled. Failure to find an organic cause may result in the diagnosis that the amnesia is psychological, however it is possible that some organic causes may fall below a threshold of detection, while other neurological ails are thought to be unequivocally organic (such as a migraine) even though no functional damage is evident. Possible malingering must also be taken into account. Some researchers have cautioned against psychogenic amnesia becoming a 'wastebasket' diagnosis when organic amnesia is not apparent. Other researchers have hastened to defend the notion of psychogenic amnesia and its right not to be dismissed as a clinical disorder. Diagnoses of psychogenic amnesia have dropped since agreement in the field of transient global amnesia, suggesting some over diagnosis at least. Speculation also exists about psychogenic amnesia due to its similarities with 'pure retrograde amnesia', as both share similar retrograde loss of memory. Also, although no functional damage or brain lesions are evident in the case of pure retrograde amnesia, unlike psychogenic amnesia it is not thought that purely psychological or 'psychogenic triggers' are relevant to pure retrograde amnesia. Psychological triggers such as emotional stress are common in everyday life, yet pure retrograde amnesia is considered very rare. Also the potential for organic damage to fall below threshold of being identified does not necessarily mean it is not present, and it is highly likely that both psychological factors and organic cause exist in pure retrograde amnesia.
Post-hypnotic amnesia is the inability in hypnotic subjects to recall events that took place while under hypnosis. This can be achieved by giving individuals a suggestion during hypnosis to forget certain material that they have learned either before or during hypnosis. Individuals who are experiencing post-hypnotic amnesia cannot have their memories recovered once put back under hypnosis and is therefore not state dependent. Nevertheless, memories may return when presented with a pre-arranged cue. This makes post-hypnotic amnesia similar to psychogenic amnesia as it disrupts the retrieval process of memory. It has been suggested that inconsistencies in methodologies used to study post-hypnotic amnesia cause varying results.
Recognition amnesia equates to an impairment of an individual's recognition memory brought on by amnesia. As event-related potentials have been found to be sensitive to familiar stimuli in the absence of recognition impairments it has been suggested that individuals who report amnesia after hypnosis might not be experiencing post-amnesia recognition impairments. Instead, they may not be accurately describing their experience and confuse having amnesia for a lack of attention during encoding of tested stimuli.
There are two types of amnesia: retrograde amnesia (loss of memories that were formed shortly before the injury) and anterograde amnesia (problems with creating new memories after the injury has taken place). Both retrograde and anterograde forms may be referred to as PTA, or the term may be used to refer only to anterograde amnesia.
Amnesia is partial or complete loss of memory that goes beyond mere forgetting. Often it is temporary and involves only part of a person's experience. Amnesia is often caused by an injury to the brain, for instance after a blow to the head, and sometimes by psychological trauma. Anterograde amnesia is a failure to remember new experiences that occur after damage to the brain; retrograde amnesia is the loss of memories of events that occurred before a trauma or injury. For a memory to become permanent (consolidated), there must be a persistent change in the strength of connections between particular neurons in the brain. Anterograde amnesia can occur because this consolidation process is disrupted; retrograde amnesia can result either from damage to the site of memory storage or from a disruption in the mechanisms by which memories can be retrieved from their stores. Many specific types of amnesia are recognized, including:
The form of amnesia that is linked with recovered memories is dissociative amnesia (formerly known as psychogenic amnesia). This results from a psychological cause, not by direct damage to the brain, and is a loss of memory of significant personal information, usually about traumatic or extremely stressful events. Usually this is seen as a gap or gaps in recall for aspects of someone's life history, but with severe acute trauma, such as during wartime, there can be a sudden acute onset of symptoms.
A PlayStation 4 version was included in the "Amnesia Collection", released on 22 November 2016 via PlayStation Network, containing "Amnesia: The Dark Descent" and its expansion "Amnesia: Justine".
post-hypnotic amnesia is characterized as a "retrieval deficit", whereas other types of amnesia suffer from a "storage" deficit (e.g. Anterograde amnesia). post-hypnotic amnesia has been correlated with reduced cortical activity in the occipital and temporal cortex, while showing an increase in activation in the prefrontal cortex. It has been suggested that some of these areas are involved in the retrieval of long term episodic memories, while others are involved in inhibiting this retrieval. Various forms of functional amnesia have been suggested as the outcome of "retrieval abortion" and thus could be partially modeled using post-hypnotic amnesia (i.e. lower physical risk to the individual). For example, cases of post-hypnotic amnesia show strikingly similar cognitive and neurological characteristics to cases of functional amnesia. Previous fMRI studies indicate that individuals suffering from functional amnesia show reduced frontal lobe activity that could impair working memory and lexical tasks involving one's native language.
Suggested amnesia has been found to result in a more significant memory loss than spontaneous amnesia, regardless of the order of induction. On average, more individuals experience suggested amnesia and there appears to be a moderate effect across individuals of all levels of hypnotic susceptibility. Suggested post-hypnotic amnesia also involves a "temporary, retrieval-based dissociation between episodic and semantic memory". However, it is more common for highly hypnotizable individuals to remember less information than low hypnotizable individuals or controls while under suggested post-hypnotic amnesia.
Post-hypnotic recall amnesia refers to an individual's inability to recall, when in a normal conscious state, the events that occurred during hypnosis. Evidence for this type of post-hypnotic amnesia is seen in a typical research model testing where nonsense syllables, that were paired during hypnosis, are unable to be recalled post hypnotically when a suggestion for amnesia was given during hypnosis. Recall amnesia for word associations tend to be very high when done by post-hypnotic individuals, with some studies showing one hundred percent total recall amnesia. This amnesia can also be measured by asking individuals, after their hypnosis has been terminated, to describe what they have been doing since they first laid down on the couch for their hypnosis session. When using this method for experimental testing, the hypnosis session will typically involve several tests or activities that the subject will engage in. Recall amnesia can then be measured by the amount of accurate tasks and activities the subject is able to remember.
The atypical clinical syndrome of the memory disorder (as opposed to organic amnesia) is that a person with psychogenic amnesia is profoundly unable to remember personal information about themselves; there is a lack of conscious self-knowledge which affects even simple self-knowledge, such as who they are. Psychogenic amnesia is distinguished from organic amnesia in that it is supposed to result from a nonorganic cause; no structural brain damage or brain lesion should be evident but some form of psychological stress should precipitate the amnesia, however psychogenic amnesia as a memory disorder is controversial.
Hypnotic amnesia, or forgetting under hypnosis, appears to be similar to naturally occurring clinical amnesia. However, hypnotic amnesia is distinct from naturally occurring amnesia because forgotten memories can be restored through a hypnotist’s prearranged signal. Also, hypnotic amnesia is usually incomplete, meaning that the participants do not forget everything they were instructed to forget. Due to this trait, hypnosis can be used to research selective amnesia through studies that direct attention to the targets, or erased memories, of hypnotic amnesia.