AGE AND COGNITIVE FUNCTION

Age and Cognitive Function

Age and Cognitive Function

Age-related declines in memory do occur and are of real concern to many older people. Yet one of the most striking aspects of the experimental literature is that age-related memory changes are extremely variable. It appears that some aspects of memory are well maintained as we age, while others are more vulnerable to the effects of aging.

Short term memory refers to the holding of information in the conscious awareness for a short period of time. Long term memory refers to material which is removed from conscious awareness but which is retrievable after longer periods of time. The main effects of aging have shown to take place in long term memory (Winocur, COCR 938, Program 4). A concept closely related to short term memory is working memory which, however, refers to the more complex attention capacity for simultaneously storing and processing the information needed during cognitive performances. However, although short term memory is well preserved, working memory is strongly affected by aging. This dissociation has been explained in terms of the long-term memory component involved in working memory. According to Baddeley¡¦s model, working memory comprises multiple components: the central executive, and two support systems (articulatory loop and visuospatial sketchpad) for the temporary maintenance of information. It has been suggested that central executive resources undergo a specific decrease, whereas the storage capacities remain unaffected by aging.

Explicit memory accounts for the conscious recollection of facts and information acquired through learning. Procedural memory and implicit memory describes memory involved with learned skills or modifiable cognitive operations which is not expressed by conscious recollection, but rather through modified performance.

Episodic memory refers to memory for autobiographical events related to particular temporal contexts. Ordinary memory tests of free recall, cued recall and recognition involve this type of memory. Semantic memory includes general knowledge about the world not associated with specific learning situations. The age differences in episodic memory are obvious, whereas in semantic memory they appear only if tasks, in addition to memory also involve conceptual or inferential processing.

A reduction in working memory processing, which is dependent on the frontal lobes, is the crucial factor for age-related changes not only in memory but in various other cognitive domains. Later, studies have emphasized reduction in processing speed as the general factor behind various cognitive decrements. Close functional associations appear to exist between working memory, and episodic memory, which may explain the more pronounced age-related decline in all of these systems in comparison to semantic memory.

The description of the neurobiology of learning and memory varies depending on the level of biological organization in observation. At the basic level, memory is dependent on the function of individual neurons. Initial memory storage involves the changes in the strength of synaptic connections. Longer-term memory storage, however, involves growth of new synaptic connections between neurons. The most crucial neurotransmitter for these modulatory effects is acetylcholine. Various changes which occur at the cellular level of brain function during aging affect these basic and modulatory ...