Amnesia is a deficit in memory caused by brain damage, disease, or psychological trauma. Amnesia can also be caused temporarily by the use of various sedatives and hypnotic drugs. Memory may be lost entirely or partially due to the degree of damage inflicted. There are two main types of amnesia: retrograde amnesia and anterograde amnesia. Retrograde amnesia is the inability to retrieve information obtained before a certain date, usually the date of accident or operation. In some cases, memory loss may 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 short-term stores to long-term stores. People with this type of amnesia can not remember things for long periods of time. These two types are not mutually exclusive; both can occur together.
Case studies also show that amnesia is usually associated with damage to the medial temporal lobes. In addition, the specific area of ​​the hippocampus (CA1 region) is involved with memory. Research also shows that when the diencephalon area is damaged, amnesia can occur. Recent studies show a correlation between RbAp48 protein deficiency and memory loss. Scientists can find that mice with defective memory have lower levels of RbAp48 protein than normal healthy mice. In people suffering from amnesia, the ability to remember information immediately is still preserved, and they may still be able to form new memories. However, a severe reduction in the ability to learn new material and retrieve old information can be observed. Patient can learn new procedural knowledge. In addition, priming (both perceptual and conceptual) can help amnesiacs in non-declarative fresh knowledge learning. Amnesia patients also retain substantial intellectual, linguistic, and social skills despite major disruptions in the ability to remember specific information encountered in earlier learning episodes. The term is derived from Greek, which means 'forgetfulness'; from? - (a -) , meaning 'without', and ?????? (mnesis) , which means 'memory'.
Video Amnesia
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Acquisition of new memory
Patients with amnesia can learn new information, especially non-declarative knowledge. However, some patients with solid anterograde amnesia do not remember episodes in which they studied or observed previous information.
Declarative information
Some patients with anterograde amnesia can still obtain some semantic information, although it may be more difficult and may remain somewhat unrelated to more general knowledge. H.M. can accurately draw a floor plan of the place where he lived after surgery, although he has not lived there for years. The reason patients can not form new episodic memories is likely because the CA1 region of the hippocampus is a lesion, and thus the hippocampus can not make connections to the cortex. After ischemic episodes after surgery, MRI patients R.B. shows his hippocampus intact except for specific lesions confined to pyramidal CA1 cells.
Non-declarative information
Some retrograde and anterograde amnesics are capable of non-declarative memory, including implicit learning and procedural learning. For example, some patients showed an increase in pseudorandom sequence experiments as healthy people. Therefore, procedural learning can proceed independently of the brain system required for declarative memory. According to the fMRI study, procedural memory acquisitions activate basal ganglia, premotor cortex and additional motor areas, areas that are not normally associated with the formation of declarative memories. This type of dissociation between declarative and procedural memory can also be found in patients with diencephalic amnesia such as Korsakoff syndrome. Other examples are shown by some patients, such as K.C. and H.M, which suffered temporal medial damage and anterograde amnesia, still have a perceptual priming. The patients succeeded in the word fragment completion test.
Maps Amnesia
Cause
There are three general categories in which amnesia can be obtained by a person. The three categories are head trauma (eg head injury), traumatic events (eg, seeing something that destroys the mind), or physical deficiency (eg, hippocampal atrophy). The majority of amnesia and related memory problems come from the first two categories because this is more common and the third can be considered as the first subcategory.
- Head trauma is a very wide range because it deals with any kind of injury or active action to the brain that may cause amnesia. Retrograde and anterograde abnormalities are more commonly seen from such events, a precise example of the cause being both electric shock treatments, which will cause both to be briefly for the receiving patient.
- Traumatic events are more subjective. What is traumatic depends on what that person finds to be traumatic. Regardless, a traumatic event is an event in which something so sad happens that the mind chooses to forget rather than face stress. A common example of amnesia caused by a traumatic event is dissociative amnesia, which occurs when the person forgets the event that is very disturbing to them. An example is someone who forgets a fatal car accident and involves their loved one.
- Physical deficiency is different from head trauma because physical deficiency is more leaning to passive physical problems.
Many forms of amnesia improve themselves without being treated. However, there are several ways to overcome memory loss if that is not the case. One of these ways is cognitive or occupational therapy. In therapy, amnesia will develop their memory abilities and try to recover some of what has been lost by discovering which techniques help to retrieve memories or create a new fetch path. This may also include strategies for organizing information to remember it more easily and to improve understanding of long conversations.
Another coping mechanism is utilizing technological assistance, such as a personal digital device to keep track of daily tasks. Reminders can be set up for appointments, when to take medication, birthdays and other important events. Many images can also be stored to help amnesia remember the names of friends, family, and co-workers. Notebooks, wall calendars, pill reminders and photos of people and places are low-tech memory aids that can help too.
Although no drug is available to treat amnesia, the underlying medical conditions can be treated to improve memory. Such conditions include but are not limited to low thyroid function, liver or kidney disease, stroke, depression, bipolar disorder and blood clotting in the brain. Wernicke-Korsakoff syndrome involves thiamin deficiency and replaces this vitamin by consuming thiamin-rich foods such as whole-grain cereals, peas (peanuts and lentils), nuts, lean pork, and yeast. Treating alcoholism and preventing the use of alcohol and drugs can prevent further damage, but in many cases will not recover lost memory.
Although improvement occurs when patients receive certain treatments, there is still no actual cure for amnesia so far. The extent to which the patient recovers and how long the amnesia will continue depends on the type and severity of the lesion.
History
The French psychologist Theodule-Armand Ribot was one of the first scientists to study amnesia. He proposed the Ribot Law which states that there is a gradient of time in retrograde amnesia. The law follows the logical development of memory loss due to illness. First, a patient loses his memory recently, then personal memories, and finally intellectual memory. He implies that the most recent memory disappears first.
Case studies have played a major role in the discovery of amnesia and affected parts of the brain. Studies provide important insights on how amnesia affects the brain. The study also provides resource scientists to improve their knowledge of amnesia and insights about medicine or prevention. There are some very important case studies: Henry Molaison, R.B, and G.D.
Henry Molaison
Henry Molaison, formerly known as H.M., changed the way people think about memory. The case was first reported in a paper by William Beecher Scoville and Brenda Milner in 1957. He was a patient suffering from severe epilepsy who was associated with a bicycle accident at the age of nine. Doctors can not control their seizures with drugs, so Scoville's neurosurgeons try a new approach involving brain surgery. He raised his medial temporal lobe bilaterally by performing a temporal lobectomy. Epilepsinya improved, but Molaison lost the ability to form long-term memory (anterograde amnesia). He showed the ability of normal short-term memory. If he is given a list of words, he will forget it in about a minute. In fact, she will forget that she was even given a list in the first place. After Molaison stopped thinking about a list she could no longer remember from long-term memory. This gives evidence to researchers that short-term and long-term memory is actually two different processes. Although he forgot about the list, he can still learn things through his implicit memories. The psychologist will ask him to draw something on a piece of paper, but to see the paper using a mirror. Though he never remembers ever doing that task, he will improve after doing it repeatedly. It shows the psychologist that he is learning and remembering things unwittingly.
The study has been completed consistently throughout Molaison's life to discover more about amnesia. The researchers conducted a 14-year follow-up study at Molaison. They studied it for two weeks to learn more about his amnesia. After 14 years, Molaison still can not remember the things that have happened since the operation. However, he can still remember things that happened before the operation. The researchers also found that, when asked, Molaison could answer questions about national or international events, but he could not recall his own personal memories. After his death, Molaison donated his brain to science, where they could find areas of the brain that had lesions that caused amnesia. This case study provides important insights into the areas of the brain affected in anterograde amnesia, as well as how amnesia works.
Patient R.B.
Patient R.B. is a man who usually works until the age of 52 years. At the age of 50, he has been diagnosed with angina and had surgery for heart problems on two occasions. After an ischemic episode (blood reduction to the brain) caused by heart bypass surgery, RB indicates anterograde memory loss, but almost no retrograde memory loss, with the exception of a few years before surgery, and shows no signs of other cognitive impairment. Not until after his death, the researchers had a chance to examine his brain, when they found the wound confined to the CA1 section of the hippocampus. This case study led to important research involving the role of hippocampus and memory function.
Patient G.D.
Patient G.D. is a white man born in 1940 who served in the Navy. She was diagnosed with chronic renal failure and received hemodialysis treatment for the rest of her life. In 1983, he went to the hospital to choose elective parathyroidectomy. He also underwent a left thyroid lobectomy due to loss of blood in his left lobe. She began to experience heart problems due to surgery and became very agitated. Even five days after being released from the hospital, she could not remember what had happened to her. In addition to memory impairment, none of his cognitive processes seem to be affected. She does not want to be involved in many studies, but through her memory tests with doctors, they can confirm that her memory problems are present for 9.5 years until her death. After he died, his brain was donated to science, photographed, and preserved to be studied in the future.
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Source of the article : Wikipedia
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