News reports of research into memory August 2003

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August 2003

You may not be able to recall it, but it influences you anyway

“Forgetting” doesn’t mean the memory is erased from your brain. “Forgotten” information may in fact influence you more than it would if it hadn’t been forgotten — because you’re unaware of the influence. This somewhat alarming possibility has been raised by a recent study in which college students studied lists of nonfamous and famous names. Some participants were told to remember the nonfamous names, while the others were told to forget them. Later, both groups were asked to judge whether or not a name was famous from a mixed list of famous and nonfamous names. Those who were told to forget misidentified more nonfamous names as famous than those who had been told to remember.
Such a judgment is of course made on the basis of the familiarity of the name. It is exposure to an item that affects its familiarity – not whether or not you consciously remember it. By telling the participants to “forget” what they’d seen, the experimenters were removing the participants’ awareness of the source of the familiarity, not the familiarity itself.
The study appeared in the Journal of Experimental Psychology: Learning, Memory, and Cognition. Full reference
http://www.apa.org/monitor/study.html

Amphetamines and cocaine can damage the brain’s ability to learn from new experiences

A rat study suggests that amphetamines and cocaine can damage the brain’s ability to learn from new experiences. Rats were given either amphetamine, cocaine, or saline for 20 days, and then half were moved to new cages containing multiple levels with ramps, bridges, and a climbing chain; tunnels; and toys that were rearranged once a week to encourage continued exploration of the environment. After three and a half months, the rats who received saline solutions and had lived in a stimulating environment had a greater number of neuronal connections than those who remained in their usual environment. Rats given either amphetamines or cocaine, however, did not respond to the complex environment with a similar growth in neuronal connection.
The report was published online by the Proceedings of the National Academy of Sciences. Full reference
http://www.eurekalert.org/pub_releases/2003-08/niod-aoc082503.php

Sage improves memory

Sage has long had a reputation for improving memory and concentration. Now, clinical trials with healthy, young adults (aged between 18 and 37) have found that those who had taken sage oil capsules performed significantly better in a word recall test. Sage is being investigated as a potential treatment for Alzheimer's Disease after earlier research found that it inhibits an enzyme called acetylcholinesterase (AChE) which breaks down the chemical messenger acetylcholine (reduced in those with Alzheimers').
The results of the study were published in the June issue of Pharmacology, Biochemistry and Behaviour. Full reference
http://www.eurekalert.org/pub_releases/2003-08/uonu-sim082703.php

Failing recall not an inevitable consequence of aging

New research suggests age-related cognitive decay may not be inevitable. Tests of 36 adults with an average age of 75 years found that about one out of four had managed to avoid memory decline. Those adults who still had high frontal lobe function had memory skills “every bit as sharp as a group of college students in their early 20s." (But note that most of those older adults who participated were highly educated – some were retired academics). The study also found that this frontal lobe decline so common in older adults is associated with an increased susceptibility to false memories – hence the difficulty often experienced by older people in recalling whether they took a scheduled dose of medication.
The research was presented on August 8 at the American Psychological Association meeting in Toronto.
http://www.eurekalert.org/pub_releases/2003-08/wuis-fmf080703.php

Creatine boosts working memory and general intelligence

New research has found that taking creatine, a compound found in muscle tissue, as a dietary supplement can give a significant boost to both working memory and general intelligence. 45 young adult vegetarians participated in the study (vegetarians or vegans were chosen as meat-eaters obtain a variable level of creatine from meat). Those having creatine were given 5g a day, a level previously shown to increase brain creatine levels, and comparable to that taken to boost sports fitness. In a backward digit span test (subject has to repeat in reverse order progressively longer verbal random number sequences), those on creatine improved from a number length of about 7 to an average of 8.5 digits. They also did significantly better in an intelligence test involving completion of pattern sequences.
Creatine may however affect regulation of blood sugar levels (and is therefore particularly dangerous for diabetics). It also has an unpleasant effect on your body odor.
The work will be published on 22 October 2003 in the Royal Society Proceedings B. Full reference
http://www.eurekalert.org/pub_releases/2003-08/rs-byb081103.php

Alcohol's benefits for cognition may be overstated

Some studies (that receive a lot of media attention) have suggested that moderate alcohol drinking may have beneficial effects on the heart or the brain. Other studies have found no effect, or a negative one. Now a new study may provide an answer to the conflicting results. Using data from the Wisconsin Longitudinal Study, which has followed more than 10,000 men and women who graduated from Wisconsin high schools in 1957, researchers in 1992 asked the participants about their drinking habits. It was found that men who consumed low levels of alcohol in 1992 had higher scores on the abstract reasoning test than those who drank either more or less. However, when earlier cognitive ability (measured in high school) was taken into account, the difference between non-drinkers and those who had one drink a day disappeared. With the women, both non-drinkers and heavy drinkers had lower scores at age 53 than moderate drinkers. But when adolescent cognitive ability was taken into account, these differences disappeared. Participants will be re-examined next year, when they’re about 65.
The study was reported in the July issue of Alcoholism: Clinical and Experimental Research. Full reference
http://www.eurekalert.org/pub_releases/2003-08/cfta-abo082103.php

Selective erasure of memories one step closer

It is now believed that memories become “labile” (able to be changed) every time they are reactivated. If so, it would seem that we could, by re-activating a memory, “erase” it – even though the memory is very old. Researchers have, however, had mixed success in achieving this. A new report suggests why. Any memory is made up of a number of different associations, but only one association will be “dominant” (will determine our reaction). It is this dominant association that is susceptible to change, and thus, to erasure.(background article on consolidation and re-consolidation)
The results of the study were published in the August 22 issue of Science. Full reference
http://www.eurekalert.org/pub_releases/2003-08/wi-npg082003.php

Key brain link in associative learning directly observed

Rat studies have now shown that the amygdala supports the formation of new associations by changing nerve cell firing patterns in a different but connected part of the brain. In earlier studies, the researchers had demonstrated that nerve cells in the amygdala and the orbitofrontal cortex changed their firing patterns to reflect new associations between cues and outcomes. In this later study, they examined how changes in neural activity in amygdala might be supporting changes in the orbitofrontal cortex. Rats were first deprived of water, then repeatedly given either desirable drinking water, laced with sugar, or undesirable drinking water, laced with quinine. The associations then learned would show up in the orbitofrontal cortex when the rats smelled the odor cue. The same activation patterns did not however, show up in those rats who had their amygdala chemically lesioned (although these rats still learned to avoid the undesirable drinking water). Specifically, although lesioned rats had neurons in the orbitofrontal cortex that were responsive to the odor cues, they did not have neurons that were responsive in anticipation of the predicted outcome. The responsive neurons were also less associative, more responsive to the identity of the cue rather than the association betwen odor and consequence.
The study was published in the August 28 issue of Neuron. Full reference
http://www.eurekalert.org/pub_releases/2003-08/jhu-kbl082803.php

Mouse study suggests new approach to reducing age-related cognitive decline

Young and old mice learned that a particular tone was associated with a mild electric footshock. When the tone was immediately followed by a shock, both young and aged mice easily remembered the association on the following day. When the tone was separated from the shock by several seconds, the old mice were strongly impaired in comparison to the young mice. The researchers found highly elevated levels of a calcium-activated potassium channel, the so-called SK3 channel, in the hippocampus of old, but not of young mice. When the researchers selectively downregulated SK3 channels in the hippocampus of aged mice, the impairment in learning and memory was prevented. This suggests a new approach to treating age-related memory decline.
The results were published as a Brief Communication in the September issue of Nature Neuroscience. Full reference
http://tinyurl.com/nm3r

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