amnesia

n. Memory disorder. Different types of amnesia are distinguished. A major distinction in amnesia has been established between specific and nonspecific amnesia. Specific amnesia refers to amnesia for certain particular types of information (e.g., for verbal information), whereas the ability to memorize other types of information (e.g., spatial information) is well preserved. Nonspecific amnesia refers to a memory disorder for every type of information. Patients with amnesia may have difficulty in retaining new information (anterograde amnesia) and/or recalling previously stored information (retrograde amnesia). In general, specific amnesias are observed in cases of cortical damage, whereas nonspecific amnesias are more frequently found in cases of damage in the so- called brain memory system, in particular the mesial structures of the temporal lobe; for instance, damage in the hippocampus, mammillary bodies, and some thalamic nuclei is associated with significant amnesia. Amnesia due to damage in the mammillary bodies and some thalamic nuclei is also called diencephalic amnesia and may be associated with confabulation. Damage in the hippocampus is not associated with confabulation and represents a type of amnesia unrelated to other defects in cognition.   - AA

►See also ALCOHOL AMNESIC DISORDER, ANTEROGRADE AMNESIA, MEMORY, RETROGRADE AMNESIA, and SOURCE AMNESIA