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Anaesthesia => Amnesia => Memory
Memory
INTRODUCTION
Memory (psychology), process of storing and retrieving information in the brain. The process is central to learning and thinking.
Memory has no one anatomical location. However, damage to highly specific brain areas, such as the mammiliary bodies owing to a condition known as Korsakoff's syndrome, which is caused by severe alcoholism, prevents acquisition of new memories. Dementia results when widespread cortical damage occurs, commonly owing to problems in blood supply, or to Alzheimer's disease.
Research suggests some aspects of memory are associated with particular cortical areas: sounds and words with the temporal lobes, sight with the visual cortex, patterns with the parietal lobes, and faces with the frontal lobes. However, memory of an event relies on widespread regions of the brain, working together to create a gestalt, a whole. Thus, memory is stored as separate sense modalities that have to be put together anew each time.
Perceptions first occupy an immediate, iconic memory, then move to short-term memory, from which some transfer to long-term stores. Recall is often connected to the feelings that accompanied the event-dull events are hard to remember, life-changing ones are easy.
Animal studies indicate that structures in the brain's limbic system have different memory functions. For example, one circuit of neurons through the hippocampus and thalamus may be involved in spatial memories, whereas another, through the amygdala and thalamus, may be involved in emotional memories. Research also suggests that "skill" memories, like playing music, are stored differently from intellectual memories.
TYPES OF MEMORY
Four different types of remembering are ordinarily distinguished by psychologists: recollection, recall, recognition, and relearning. Recollection involves the reconstruction of events or facts on the basis of partial cues, which serve as reminders; recall is the active and unaided remembering of something from the past; recognition is the ability to correctly identify previously encountered perceptions or internal experiences as familiar; relearning may show evidence of the effects of memory. Material that is familiar is often easier to learn a second time than it would be if it were unfamiliar, suggesting this is a different type of memory.
In general, memories are less clear and detailed than perceptions, but occasionally a remembered image is complete in every detail. This phenomenon, known as eidetic memory, is usually found in children, who sometimes project the image so completely that they can spell out an entire page of writing in an unfamiliar language that they have seen for a short time.
FORGETTING
The course of forgetting over time has been studied extensively by psychologists. Most often, rapid forgetting occurs at first, followed by a slower rate of loss. Improvement in the amount of material retained, however, can be achieved by practising active recall during learning, periodically reviewing the material, and overlearning-that is, relearning the material beyond the point of bare mastery. This process relates memory ability to comprehension.
Four traditional explanations of forgetting have been provided. One is that memory traces fade naturally over time as a result of organic processes occurring in the brain, although little evidence for this notion exists. A second is that memories become systematically distorted or modified over time. A third is that new learning often interferes with or replaces old learning. Finally, some forgetting may be motivated by emotional needs and wishes-as when unpleasant childhood experiences are repressed or denied. These can be "re-memorized" under hypnosis or in psychotherapy.
Mnemonics is a mechanical technique devised to improve memory. It involves the use of associations and various devices to remember particular facts, coding them in more than one sense to make recall easier; for instance, remembering a shopping list by linking the items into a story or visualizing the items along a street, or linking words and numbers with action and location, as actors tend to do.
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