Stress\u2014Friend or Foe?
\nA little sharpens the mind and memory; too much shrivels the brain and makes you sick.<\/p>\n
The quote above captures the essence of the effects of stress on memory. In the following sections, we will examine in greater detail how the memory system functions and see exactly how stress disrupts the different functions.<\/p>\n
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Human Memory<\/p>\n
The Ebbinghaus experiment almost 150 years ago was the first real experiment on memory, in particular the remembering of trigrams (for example, DAX, LOC). All these had no meaning but were all distinct monosyllabic words. He measured the retention that he himself had of the words by counting the number of re-learns required to achieve perfect recall and recite them correctly. His results show that retention decreases over time, but the rate of forgetting slows down. He also looked at the effects of over learning and found that through over learning a higher score can be reached on his retention test.<\/p>\n
Scientists do not yet understand many things about human memory and many of the ideas and theories are still quite controversial. The following discussion emphasizes some of the more widely agreed upon ideas. For instance, most scientists agree that it is very useful to describe human memory as a set of stores, which are ‘places’ to put information, plus a set of processes that act on the stores.<\/p>\n
A very simple model might contain three different stores:<\/p>\n
\u2022 The Sensory Information Store (SIS);
\n\u2022 The Short-term Store (STS);
\n\u2022 The Long-term Store (LTS).<\/p>\n
and three processes:<\/p>\n
\u2022 Encoding (putting information into a store);
\n\u2022 Maintenance (keeping it ‘alive’);
\n\u2022 Retrieval (finding encoded information).<\/p>\n
Long-term Memory (Store)<\/p>\n
Long-term memory (LTM) was once thought of as a huge database where information was simply filed away in the same manner as a filing cabinet. LTM is often studied with normal people to assess its limits and characteristics. In order to determine the neural pathways to LTM, however, we must start with a brain that is damaged and then assess the deficiencies that the individual faces with respect to LTM. This deficiency may arise from an accident, pathology, or in the case of animal models, intentionally inflicted. Today,<\/p>\n
LTM in humans is believed to be partitioned into specialized modules:<\/p>\n
Research into the neurological basis of long-term memory generally involves studying those individuals who have had their brain structures altered in some way. Since it is considered unethical to knowingly induce brain damage on a human, researchers often use animal models to directly study cause-effect relationships.<\/p>\n
With equipment, such as, MRI, CAT, and PET scans, brain damage can be localized with more precision than previously possible. These tests, however, only reveal the biological and pathological nature of the brain trauma and not the functional characteristic of that affected region. In order to determine the function of a damaged region, researchers often have individuals, with a known damage to the brain, perform memory tasks which are thought to require the use of a certain type of long-term memory store.<\/p>\n
As an example, performance in real-time tracking in a task such as rotary pursuit is seen to improve in individuals who are unable to access other areas of the long-term memory. By determining what the individual can and cannot do with their damaged brain, researchers are able to infer what role a particular area of the brain plays in long-term memory.<\/p>\n","protected":false},"excerpt":{"rendered":"