Retrograde amnesia (RA) is the loss of memory access to events that occur, or information learned, before an injury or illness. This tends to negatively impact episodic, autobiographic, and declarative memories while usually keeping the procedural memory intact without difficulty learning new knowledge. RA can be assessed temporarily or more permanently based on the severity of the cause and is usually consistent with Ribot's Law: where subjects are more likely to lose memories closer to traumatic incidents than to further memories. The type of forgotten information can be very specific, such as one event, or more commonly, resembling generic amnesia. This is not to be confused with anterograde amnesia, which is associated with the inability to form new memories after the onset of injury or disease.
Video Retrograde amnesia
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The most commonly affected areas are associated with episodic and declarative memories such as the hippocampus, the diencephalon, and the temporal lobes.
- The sealed hippocampus deals mostly with memory consolidation, where information from working memory and short-term memory is encoded to long-term storage for upcoming retrieval. Amnesic patients with hippocampal damage are able to demonstrate an undisturbed level of semantic memory, despite episodic memory loss, as it spares from the parahippocampal cortex. In other words, retrograde retroactively "knows" information or skills, but can not "remember" how they do it.
- The role of diencephalon and its surroundings in memory is not well understood. However, this structure seems to be involved in episodic memory memories.
- The temporal lobes are essential for semantic and factual memory processing. In addition to helping consolidate memory with the hippocampus, the temporal lobes are essential for semantic memory. Damage to this area of ​​the brain can lead to organizational disturbance and categorization of verbal material, language comprehension disorder, and long-term memory impairment. The right frontal lobe is essential for retrieval of episodic information, while the left frontal region is more active for semantic information retrieval. [56] Lesions in the right hemisphere and right frontal lobes result in disturbed memories of non-verbal material, such as music and pictures. The difficulty in studying this brain region extends to its task in understanding, naming objects, verbal memory, and other language functions.
Brain plasticity has helped explain the process of restoring brain damage caused by retrograde amnesia, in which neuro structures use different neural pathways to avoid damaged areas while still performing their tasks. Thus, the brain can learn to be independent of the hippocampal disorder, but only to some extent. For example, older memories are consolidated over time and in various brain structures, including the Wernicke and neocortex areas, making retrieval through alternative pathways possible.
Maps Retrograde amnesia
Types of retrograde amnesia
As mentioned earlier, RA generally results from damage to areas of the brain most closely related to episodic and declarative memories, including autobiographical information. In extreme cases, individuals may actually forget who they are. Generally, this is a more severe type of amnesia known as global or general amnesia. However, memory loss can also be selective or categorical, manifested by a person's inability to remember events related to specific incidents or topics. Patients also differ within the RA period (how long they can not remember information) and the time period of what was forgotten (past time frames for information not available).
Temporally sorted retrograde amnesia
In retrospectful amnesia amnesia, the victim eventually recovered most of the memory after the onset of RA. This suggests that hippocampal formation is only used in systematic consolidation for a while, and a short period of time, until long-term consolidation occurs in other brain structures. Here, the fact that damage to the hippocampal formation can ultimately overcome the RA suggests that other brain structures are capable of taking over work from non-functioning areas. RA can also develop and worsen memory memory, as in the case of Korsakoff syndrome and Alzheimer's disease, due to the nature of the damage caused by the disease. The extent to which different patients recover from RA differs in time (some take several days while others are decades) and content (some will only remember certain specific examples while others are more).
Focal, isolated, and pure retrograde amnesia
These terms are used to describe the pure form of RA, in the absence of anterograde amnesia (AA). In addition, Focal RA in particular, has also been used to describe the situation of RA where there is a lack of physical deficits that can be observed as well. This can be described as a psychogenic form of amnesia with mild anterograde and retrograde retina. A case study DH reveals that the patient can not provide personal or public information, but no parahippocampal or entorhinal damage is found. Individuals with focal brain damage have minimal RA.
Isolated RA is associated with a visible thalamic lesion. Consistent with other RA forms, isolated forms are characterized by an inability to recall past information.
Pure retrograde amnesia (PRA) refers to a behavioral syndrome characterized by an inability to retrieve remote information in the face of normal ability to learn new information, without ecological or other psychometric evidence of cognitive impairment. It should not be confused with brief periods of peritraumatic amnesia common to minor head trauma. The pure retrograde amorphous findings have helped to form the dissociation between the mechanisms for RA and AA. Several studies have found many causes of PRA such as vascular disease, head injuries ranging from mild to severe, encephalitis, as well as purely psychological and etiological conditions that can not be identified as a whole. Most people who suffer from PRA can function normally and learn new information and are therefore not rearranged in life. [57] (Lucchelli, Muggia, & amp; Spinnler, 1998).
The pure form of RA is rare because most cases of RA occur simultaneously with AA. The famous example is the patient ML . The patient's MRI shows damage to the right ventral frontal cortex and underlying white matter, including the uncolic fasciculus, a group of fibers previously thought to mediate the retrieval of specific events from one's personal past.
Cause
A causal explanation of retrograde amnesia is still under investigation.
The three main models used to explain RA assume that the hippocampus is one of the main areas of the brain used in memory consolidation. During consolidation, the hippocampus acts as an intermediary tool that quickly stores new information until it is transferred to the neocortex for the long term. The temporal lobe, which holds the hippocampus, entorhinal, perirhinal and parahippocampal cortex, has a reciprocal relationship with the neocortex. A temporal temporal lobe is required when consolidating new information; because learning becomes stronger, the neocortex becomes more independent of the temporal lobes.
Studies in specific cases show how certain areas of the hippocampus are associated with the severity of RA. Damage can be confined to the CA1 field of the hippocampus, causing very limited RA for about 1 to 2 years. Wider damage is limited to the hippocampus causing temporary assessed amnesia for 15 to 25 years. Other studies have also shown that large medial temporal lobe lesions, extending laterally to include other regions, produce a wider RA, spanning 40 to 50 years. These findings suggest that RA density becomes more severe and long-term as the damage extends beyond the hippocampus to surrounding structures.
The underlying cause of RA does not always cause RA. It may even be in some cases both mock and unconscious processes being played.
Traumatic brain injury (TBI) or post-traumatic amnesia
Traumatic brain injury (TBI), also known as post-traumatic amnesia, occurs from external forces causing structural damage to the brain, such as a sharp blow to the head, diffuse axonal injury, or childhood brain damage (eg, shaken baby syndrome). In the case of sudden rapid acceleration, the brain continues to move in the skull, damaging the brain tissue while crashing into the internal bulge.
TBI varies according to the impact of external forces, the location of structural damage, and the severity of damage ranging from mild to severe. Retrograde amnesia can be one of the many consequences of brain injury but it is important to note that it is not always the result of TBI. Examples of subgroups of people who are frequently exposed to TBI are individuals involved in high-contact sports. Research on football players a closer look at some implications for their high-contact activity. Experiencing a consistent head injury may have an impact on memory nerve consolidation.
Specific cases, such as the ML patients, support evidence that a heavy blow to the head can lead to RA. In this specific case an isolated RA attack occurs after a severe head injury. Brain damage does not affect a person's ability to form new memories. Therefore, the idea that certain parts of the retrograde memory independently of anterograde is supported. Usually, there is a very gradual recovery, however, the period of solid amnesia immediately before the trauma usually continues.
Traumatic event
RA can occur without anatomical damage to the brain, has no observable neurobiological basis. Primarily referred to as psychogenic amnesia or psychogenic fugue, it often occurs because of the traumatic situations that they want to avoid consciously or unconsciously through intrapsychic conflict or subconscious repression. The onset of psychogenic amnesia can be global (ie, individuals forget all history) or a particular situation (ie, the individual can not retrieve the memory of a particular situation).
Persons experiencing psychogenic amnesia have impaired episodic memory, wandering and traveling instances, and acceptance of new identities as a result of inaccessible memories associated with previous identities.
Recent research has begun to investigate the effects of stress and situations that trigger fear with the onset of RA. Long-term potentiation (LTP) is a process in which there is signal transmission between neurons after the activation of neurons, which has been known to play a strong role in the hippocampus in learning and memory. General changes in the hippocampus have been found to be associated with stress and LTP induced. The similarities support the idea that stress variations can play a role in generating new memories and the incidence of RA for other memories. Also, the amygdala plays an important role in memory and can be affected by emotional stimulation, generating RA.
Certain case studies, such as 'AMN', support evidence of traumatic experiences as a reasonable cause of RA. AMN escaped from a small fire in his home, did not breathe in smoke, and did not suffer brain damage. Surprisingly, the next day, he can not recall knowledge based on autobiography. This case shows that RA can occur without structural brain damage.
After a traumatic head injury, emotional disturbance can occur at three different levels: neurological, reactionary, and long-term disorders. Neurological disorders can alter emotional responses and motivations. Reaction disorders also affect emotional responses and motivations, but they reflect failure to cope with environmental demands. Someone with this may withdraw from the environment in which they are placed because they no longer know how to handle cognitive resources.
Lack of nutrition
RA has been found among alcohol-dependent patients with Korsakoff syndrome. Korsakoff syndrome patients suffer from retrograde amnesia due to thiamine deficiency (vitamin B1 deficiency). Also, chronic alcohol use disorders are associated with a decrease in the volume of the left and right hippocampus.
This patient's routine diet consists mostly of intake of hard alcohol, which lacks the necessary nutrients for healthy development and maintenance. Therefore, after a long period of consuming alcohol, these people have memory difficulties and eventually suffer from RA. However, some of the disadvantages of using Korsakoff patients to study RA are the progressive nature of disease and unknown time of onset.
Infection
Infections that cross the blood-brain barrier can cause brain damage (encephalitis), sometimes resulting in RA. In the case of 'SS' patients, infection causes retrograde or isolated retrograde amnesia where there is an absence or limited AA. The brain scan shows abnormalities in the medial bilateral temporal lobe, including two thirds of the hippocampal formation and the posterior portion of the amygdala.
Surgery
Henry Molaison suffers from epilepsy that develops and worsens by the late twenties. The severity of his condition led him to undergo surgery in an attempt to prevent his seizures. Unfortunately, due to a lack of known neurological knowledge, the Molaison surgeon lifts his medial bilateral temporal lobe, causing deep AA and RA. Discarded brain structures include the hippocampus, the amygdala, and the parahippocampal gyrus, now called the medial temporal lobe temporal memory. HM is one of the most studied memory cases to date and commenced the examination of neurological structures in relation to memory.
Other patients suffering from RA due to surgery are 'P.B.' and 'F.C.' which has a unilateral elimination of the medial area in the left temporal lobe.
Controlled induction
RA that has been clinically induced has been achieved using various forms of electrical induction.
- Electroconvulsive therapy (ECT), used as a depression therapy, can cause memory impairment. The tests indicate that information days and weeks before ECT can be permanently lost. The results of this study also show that the severity of RA is more extreme in bilateral ECT cases than unilateral ECT. Disorders can also be more intense if ECT is given repeatedly (simulating a sine wave) as opposed to one pulse (short pulse stimulation).
- Electroconvulsive stings (ECS): Research in this field has been advanced using animals as subjects. The researchers induced RA in mice, for example, by administering ECS ​​treatments daily. This is done to better understand RA.
Diagnosis and care
Test for retrograde amnesia
As mentioned earlier, RA can affect people's memories in different degrees, but tests are needed to help determine whether a person has RA. Some tests exist, for example, testing factual knowledge such as known public events. The problem with this form of testing is that people are generally different in their knowledge of the subject. Another way to test a person is through autobiographical knowledge using the Autobiographical Memory Interview (AMI), which consists of relatives' names, personal information, and employment history. This information can help determine whether a person is experiencing RA and the memory level is affected. However, due to the nature of the information being tested, it is often difficult to verify the accuracy of memorable memories, especially if they are from a distant past. Some researchers have found that the lapse of time after head injury does not seem to be a problem. The effect of memory loss is the same no matter how long after from injury.
Brain abnormality can be measured using magnetic resonance imaging (MRI), computed tomography scan (CT) and electroencephalography (EEG), which can provide detailed information about specific brain structures. In many cases, the autopsy helps identify the affected brain region and the extent of damage that causes RA once the patient has died.
There are several important aspects for patients who remain unaffected by RA. In many patients, their personality remains the same. Also, semantic memory, that is, general knowledge of the world, is usually unaffected. However, episodic memory, which refers to a person's life experience, is disrupted.
Another real-life problem with RA is pretending to be sick, which is understood as a neurological normal rational brain output leading to the tacit achievement of well-identified advantages. Since it is common for people who have committed crimes to report having an RA for such special events to avoid their punishment, the legal system has encouraged the creation of standard amnesia tests. However, since most cases are different in onset, duration, and content is forgotten, this task has proven to be a bit complicated.
Spontaneous recovery
When a person suffers from RA, their memories can not be recovered from just being told of their personal experiences and their identity. These are called reminder effects or reminder treatments. The reminder effect consists of re-exposing the patient to past personal information, which can not reverse RA. Thus, reminding patients details about their lives has no scientific bearing to restore memory. Fortunately, memory can and usually recovers because of spontaneous recovery and plasticity.
Case study
Because the researchers are interested in examining the effects of disturbed areas of the brain and experimenting for a further understanding of the unaffected and normal brain, many individuals with brain damage voluntarily undergo countless tests to advance our scientific knowledge of the human brain. For example, Henry Molaison (HM) is someone with significant brain damage and participates in many neurological studies. In addition, he is also the most tested person in the field of neuropsychology. All participating living people are referred to in the literature using only their initials to protect privacy.
Each case of RA has caused different symptoms and durations, in which some patients have shown an inability to describe future plans, whether in the near future (eg, this afternoon) or in the distant future (eg, next summer) due to their disability to consolidate memories. Furthermore, researchers also found that some patients could identify themselves and loved ones in the photo, but could not determine the time or place of the photo taken. It has also been found that patients with RA differ greatly from the general population in remembering past events.
Some examples of cases are:
- After a head injury, AB should review the personal information. Many AB customs also change.
- Patients CD , reported disorientation of place and time after the wound and reviewed the previously learned information and activities (eg, using a razor).
- EF was examined and found very confused about social norms (eg appropriate clothing outside his home). EF shows memory loss from personal experience (eg, childhood), and impaired ability to recognize his wife and parents.
- JG were the first patients recorded to have isolated RA.
- GH , mother and wife, underwent surgery in August 2002. When GH woke up after surgery, he believed it was May 1989. Because of his amnesia, GH had great difficulty in him. social environment, overwhelmed by relationships with others.
- DH , instructors and husbands with learning disabilities, suffering from a closed head injury. He showed no sign of normal memory loss but he could not remember anything before the accident.
- CDA is a 20-year-old man who fell and suffered head trauma after being unconscious for less than an hour. She has lost her identity and a limited retrograde deficit on an autobiographical event 5 years before the trauma. He often shows signs of spontaneous and sometimes incoherent spontaneous speech. When he saw his family and friends, he was surprised at how old they were because he remembered them from 5 years earlier. The case also included amnesia for procedural skills such as fear of shaving or driving, which was eventually overcome. There are no psychological, neuropsychological, or brain damage problems. His memory recovery is progressive and spontaneous, in which after several months of amnesia is limited to two years before the trauma. This is a classic case of PRA. [57]
- GC is a 38-year-old accountant found in a town square who can not remember anything about him and does not know where he is and how he got there. She is finally able to remember basic information about herself and her family, but can not recall emotionally related autobiographical events related to the last 7 years of her life. Within 3-4 days, it is determined that the autobiographical amnesia is clear and highly selective for a professional event, as he can remember everything unrelated to his work. Eventually it was discovered that the work had created severe emotional and anxiety pressure due to the extreme hours that triggered a sudden fugue state. He can finally recover most of his memories minus one work event in which he has stolen money from the company. This is a classic case of psychogenic amnesia. [57]
- AF is a 15 year old boy who hits his head and loses consciousness. He can not remember anything but can play a song on the piano, indicating that his procedural memory is still intact. He gradually recovers some memories within the first 2-3 days but has an autobiographical amnesia as well as significant memory loss for well-known public facts and events for 2 years before injury. [57]
While it may seem that people living with brain damage have great difficulty resuming the usual everyday aspects, they can still achieve many accomplishments. People with RA are able to lead normal lives. For example, KC is a person who has many functional aspects intact; normal intelligence, unaffected perceptual and linguistic skills, short-term memory, social skills, and reasoning ability. All these things are necessary in everyday life and contribute to a normal life. KC is also fully capable of doing script activity (eg, Making reservations or changing a flat tire). In addition, patients HC successfully graduate from high school and continue to post-secondary studies, a clear achievement despite the circumstances. DH re-learns his childhood memories from his parents and can retell the stories, but can not remember specifically than what he has been told.
Other forms of amnesia
Other forms of amnesia exist and may be confusing with RA. For example, anterograde amnesia (AA) is the inability to learn new information. This explains the problem of encoding, storing, or retrieving information that can be used in the future. It is important to note that both of these conditions can, and often both occur in the same patient simultaneously, but are separate forms of amnesia.
RA can also be an inherent aspect of another form of amnesia, which is temporary global amnesia (TGA). TGA is a sudden attack of AA and RA caused by a traumatic event, but it lasts only briefly, usually lasting only 4 to 8 hours. TGA is very difficult to learn because of the patient's rapid recovery. This form of amnesia, like AA, remains distinct from RA.
Post-traumatic amnesia (PTA) is a state of confusion that occurs immediately after a traumatic brain injury in which an injured person is disorienting and can not recall events that occurred after an injury.
Psychogenic amnesia, or dissociative amnesia, is a memory disorder characterized by sudden retrograde autobiographical memory loss, said to occur for a period ranging from hour to year.
See also
- Amnesia
- Anterograde amnesia
- Dissociative amnesia
- Jab Tak Hai Jaan - Bollywood movies show RA briefly to someone
- Samantha Who? - American comedy-drama television show about retrograde amnesia
- Inferno - A novel by Dan Brown. The main character, Robert Langdon, shows RA
- Scott Bolzan - One of the most severe cases of retrograde amnesia on record
- "Oath: The True Event Inspiring Movies" by Kim Carpenter and Krickitt Carpenter
- Golden Time (novel series) - Japanese light novel, where the main character suffers from RA.
References
External links
- Journal of Neuroscience
- Jonathan Overfeld's weird case of The State We're In radio show
Source of the article : Wikipedia
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