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News reports of research into memory July 2002

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July 2002

Evidence is mounting that sleep helps information processing and learning. A new study has showed that subjects performing a visual task (reporting the horizontal or vertical orientation of three diagonal bars against a background of horizontal bars in the corner of a computer screen) got worse over the course of four daily practice sessions. However, allowing subjects a 30-minute nap after the second session prevented any further deterioration, and a 1-hour nap actually boosted performance in the third and fourth sessions back to morning levels. It appears that the fatigue is limited to the brain visual system circuits involved in the task. When the image was switched to a different right corner of the computer screen on the fourth practice session, subjects performed about as well as they did in the first session -- or after a short nap. Recordings of brain activity reveal that the 1-hour naps contained more than four times as much deep, or slow wave sleep and rapid eye movement (REM) sleep than the half-hour naps.
The study was reported in the July 1 issue of Nature Neuroscience. Full reference
http://www.eurekalert.org/pub_releases/2002-07/niom-np070102.php

People taught a simple motor sequence (to type a sequence of keys on a computer keyboard as quickly and accurately as possible) practised it for 12 minutes and were then re-tested 12 hours later. Those who practised in the morning and tested later that same day improved their performance by about 2%. Those trained in the evening and re-tested after a good night's sleep, however, improved by about 20%. The amount of improvement was directly correlated with the amount of Stage 2 (a stage of non-rapid eye movement or NREM) sleep experienced, particularly late in the night. "This is the part of a good night's sleep that many people will cut short by getting up early in the morning."
The study appeared in the July 3 issue of Neuron. Full reference
http://www.eurekalert.org/pub_releases/2002-07/hms-pmp070102.php

Two new animal studies add to the growing body of evidence that certain fruits and vegetables may slow down or reverse age-related cognitive decline. In the first study, older rats fed a diet rich in spinach for six weeks learned a simple association faster than those fed regular rat food. The second study compared three different foods - one group of older rats ate a diet supplemented by spirulina (high in antioxidants), another was fed a daily ration of apple (moderate in antioxidant activity),and the third was given a cucumber-enriched diet (low in antioxidants). Those fed either spirulina-or apple-enriched diets for two weeks demonstrated improved neuron function, and a suppression of inflammatory substances in the brain. Indeed, spirulina reversed the impairment in adrenergic neural function normally associated with aging. There was no improvement in rats fed a diet supplemented with cucumber. The best fruits and vegetables for antioxidant activity are generally the most colorful.
Both reports appeared in the July 15 issue of the Journal of Neuroscience. Full reference 2
http://www.eurekalert.org/pub_releases/2002-07/uosf-adi071002.php

More support for a link between cardiopulmonary bypass surgery and cognitive impairment comes from a new study. In particular, it seems, that attention may be most affected. The study also found evidence of longer-lasting cognitive decline than previously thought. Bypass patients also demonstrated poorer cognitive performance before the surgery, and it is now being suggested that it may be the disease itself that is the major problem, rather than the surgery itself. This is consistent with recent research connecting cardiovascular risk factors with risk factors for cognitive decline.
The study appeared in the July issue of Neuropsychology. Full reference http://www.eurekalert.org/pub_releases/2002-07/apa-lci070802.php
Full text available at http://www.apa.org/journals/neu/press_releases/july_2002/neu163411.html )

A new brain imaging study reveals gender differences in the encoding of emotional memories. We have long known that women are better at remembering emotional memories, now we can see that the sexes tend to encode emotional experiences in different parts of the brain. In women, it seems that evaluation of emotional experience and encoding of the memory is much more tightly integrated.
The report appeared in the August 6 issue of Proceedings of the National Academy of Sciences. Full reference
http://www.newscientist.com/news/news.jsp?id=ns99992576

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