amnesia

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Related to amnestic: amnesia, amnesiac, amnestic disorder, amnestic syndrome

amnesia

(ămnē`zhə), [Gr.,=forgetfulness], condition characterized by loss of memorymemory,
in psychology, the storing of learned information, and the ability to recall that which has been stored. It has been hypothesized that three processes occur in remembering: perception and registering of a stimulus; temporary maintenance of the perception, or short-term
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 for long or short intervals of time. It may be caused by injury, shock, senility, severe illness, or mental disease. Some cases of amnesia involve the unconscious suppression of a painful experience and everything remindful of it including the individual's identity (see defense mechanismdefense mechanism,
in psychoanalysis, any of a variety of unconscious personality reactions which the ego uses to protect the conscious mind from threatening feelings and perceptions.
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). Retrograde amnesia is loss of memory of events just preceding temporary loss of consciousness, as from head injury; it is evidence that memory proceeds in two stages, short term and long term. One form of the condition known as tropic amnesia, or coast memory, affecting white men in the tropics, is probably a variety of hysteriahysteria
, in psychology, a disorder commonly known today as conversion disorder, in which a psychological conflict is converted into a bodily disturbance. It is distinguished from hypochondria by the fact that its sufferers do not generally confuse their condition with real,
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. Aphasiaaphasia
, language disturbance caused by a lesion of the brain, making an individual partially or totally impaired in his ability to speak, write, or comprehend the meaning of spoken or written words.
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 of the amnesic variety is caused by an organic brain condition and is not to be confused with other forms of amnesia. To cure amnesia, attempts are made to establish associationsassociation,
in psychology, a connection between different sensations, feelings, or ideas by virtue of their previous occurrence together in experience. The concept of association entered contemporary psychology through the empiricist philosophers John Locke, George Berkeley,
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 with the past by suggestion, and hypnotismhypnotism
[Gr.,=putting to sleep], to induce an altered state of consciousness characterized by deep relaxation and heightened suggestibility. The term was originally coined by James Braid in 1842 to describe a phenomenon previously known as animal magnetism or mesmerism (see
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 is sometimes employed.

Amnesia

A significant but relatively selective inability to remember. Amnesia can be characterized along two dimensions with respect to its onset: an inability to remember events that occurred after the onset of amnesia is referred to as anterograde amnesia, and a deficit in remembering events that occurred prior to the onset of amnesia is referred to as retrograde amnesia. Amnesia can be due to a variety of causes and can be classified according to whether the cause is primarily neurological or psychological in origin. Neurological amnesias are the result of brain dysfunction and can be transient or permanent. They are usually characterized by a severe anterograde amnesia and a relatively less severe retrograde amnesia. Transient amnesias are temporary memory disturbances and can range in duration from hours to months, depending on the cause and severity. They can be caused by epilepsy, head injury, and electroconvulsive therapy (most frequently used for the treatment of depression). In cases of transient global amnesia, an extensive amnesia that is usually sudden in onset and resolves within a day, the cause is still not known, although many believe that it is vascular in origin.

Permanent amnesia usually occurs following brain damage to either the diencephalons or the medial temporal lobe. Amnesia resulting from impairment to the medial temporal lobe can occur following anoxia, cerebrovascular accidents, head injury, and viral infections to the brain. The primary structures involved in the processing of memory within the medial temporal lobe are the hippocampus and the amygdala. One of the most common causes of diencephalic amnesia is Wernicke-Korsakoff syndrome, a disorder caused by a thiamine deficiency, usually related to chronic alcoholism.

Memory impairment that is not associated with brain damage is referred to as functional amnesia. Functional amnesia can be classified according to whether the amnesia is nonpathological or pathological. Nonpathological functional amnesia is a normal memory loss for events occurring during infancy and early childhood, sleep, hypnosis, and anesthesia. Pathological functional amnesia is an abnormal memory loss found in cases of functional retrograde amnesia and multiple personality. In contrast to neurological amnesia, pathological functional amnesia is usually associated with more severe retrograde than anterograde amnesia. See Brain, Memory

amnesia

[am′nēzh·ə]
(medicine)
The pathological loss or impairment of memory brought about by psychogenic or physiological disturbances.

amnesia

a defect in memory, esp one resulting from pathological cause, such as brain damage or hysteria
References in periodicals archive ?
Doctors can now administer rapidly acting intravenous amnestic agents--physicians jokingly refer to one medication that has a slightly whitish color in solution as "milk of amnesia"--that inhibit the brain's ability to encode memories.
By sorting the HRS subjects who have the [epsilon] 4 gene into subtypes of impairment identified in Petersen's and Smith's work, the Cornell researchers were able to show a significant correlation between the [epsilon] 4 gene and risk of the Alzheimer's precondition, known as amnestic MCI (or a-MCI).
Delirium, Dementia, Amnestic and Other Cognitive Disorders.
Such treatment is expected to delay the serial progression of amnestic cognitive impairment and to reduce significantly the incidence of Alzheimer's disease in the developed world.
11C PiB and structural MRI provide complementary information in imaging of Alzheimer's disease and amnestic mild cognitive impairment.
Their topics include a comparative analysis of structural brain magnetic resonance imaging (MRI) in the diagnosis of AD, diffusion tensor imaging in AD and mild cognitive impairment, changes in para-hippocampal white matter integrity in amnestic mild and cognitive impairment as seen with diffusion tensor imaging, pinpointing synaptic loss caused by AD with functional MRI, amyloid imaging in aging and dementia to test the amyloid hypothesis in vivo, and applications of neuroimaging to disease-modification trials in AD.
The ANOVA test indicates no statistically significant difference in the amnestic heterosexism scores across incongruence categories.
3,5,11) This variability undoubtedly is determined by whether the patient (1) has preexisting antibodies from a prior exposure to the drug, (2) needs to mount an amnestic response because a previously made antibody has fallen below clinically significant levels, or (3) has never before been exposed to the drug and must undergo primary alloimmunization.
The research team compared participants with amnestic MCI to individuals with AD and determined that the people with this type of MCI had impaired memory but that other elements of cognitive function were not affected.
Neuropathologic features of amnestic mild cognitive impairment.
Jacques Derrida (1930-2004) is cleverly approached by way of the 2001 movie Memento in which the amnestic character must resort to writing all the events of his life down on small scraps of paper.