News reports of research into memory June 2008

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June 2008

Remedial instruction can close gap between good, poor readers

A brain imaging study of poor readers has found that 100 hours of remedial instruction not only improved the skills of struggling readers, but also changed the way their brains activated when they comprehended written sentences. 25 fifth-graders who were poor readers worked in groups of three for an hour a day with a reading "personal trainer," a teacher specialized in administering a remedial reading program. The training included both word decoding exercises in which students were asked to recognize the word in its written form and tasks in using reading comprehension strategies. Brain scans while the children were reading revealed that the parietotemporal region — responsible for decoding the sounds of written language and assembling them into words and phrases that make up a sentence — was significantly less activated among the poor readers than in the control group. The increases in activation seen as a result of training were still evident, and even greater, a year later.
Although dyslexia is generally thought of as caused by difficulties in the visual perception of letters, leading to confusions between letters like "p" and "d", such difficulties occur in only about 10% of the cases. Most commonly, the problem lies in relating the visual form of a letter to its sound.
The findings are available online in the August issue of Neuropsychologia. Full reference
http://www.eurekalert.org/pub_releases/2008-06/cmu-cmb061108.php

Morningness a predictor of better grades in college

A survey of 824 undergraduate students has found that those who were evening types had lower average grades than those who were morning types.
The finding was presented at SLEEP 2008, the 22nd Annual Meeting of the Associated Professional Sleep Societies (APSS).
http://www.eurekalert.org/pub_releases/2008-06/aaos-map050708.php

Diabetic seniors may experience memory declines after eating high-fat food

Growing evidence links diabetes to cognitive impairment. Now a small study of 16 adults (aged 50 years and older) with type 2 diabetes compared their cognitive performance on three separate occasions, fifteen minutes after consuming different meals. One meal consisted of high fat products – a danish pastry, cheddar cheese and yogurt with added whipped cream; the second meal was only water; and the third was the high-fat meal plus high doses of vitamins C (1000 mg) and E (800 IU) tablets. Researchers found that vitamin supplementation consistently improved recall scores relative to the meal alone, while those who ate the high fat meal without vitamin supplements showed significantly more forgetfulness of words and paragraph information in immediate and time delay recall tests. Those on water meal and meal with vitamins showed similar levels in cognitive performance. The finding indicates not only that diabetics can temporarily further worsen already underlying memory problems associated with the disease by consuming unhealthy meals, but also that this can be remedied by taking high doses of antioxidant vitamins C and E with the meal, suggesting that the effect of high-fat foods is to cause oxidative stress. However, this is hardly a recommended course of action, and the real importance of this finding is that it emphasizes the need for diabetics to consume healthy foods high in antioxidants, like fruits and vegetables. Of course, this is a very small study, and further replication is needed.
The study was published in the July issue of Nutrition Research. Full reference
http://www.eurekalert.org/pub_releases/2008-06/bcfg-swt062408.php

Memory loss linked to sleep apnea

Sleep apnea occurs when a blocked airway repeatedly halts the sleeper's breathing, resulting in loud bursts of snoring and chronic daytime fatigue. Memory loss and difficulty focusing are also common complaints. While sleep loss is a common cause for such impairment, memory problems continue despite treatment for the sleep disorder, implying a long-lasting brain injury. Now a new imaging study has found significant tissue loss in brain regions that help store memory (mammillary bodies). It’s hypothesized that repeated drops in oxygen might be the cause, but further research is needed.
The report appeared in the June 27 edition of Neuroscience Letters. Full reference
http://www.eurekalert.org/pub_releases/2008-06/uoc--mll060608.php

Midlife smokers may have worse memory than non-smokers

Data from the very large Whitehall II study has found that those who smoked were more likely to be in the lowest 20% for cognitive performance compared with those who had never smoked. Those who reported being ex-smokers at the beginning of the study were 30% less likely than smokers to have poor vocabulary and low verbal frequency scores, showing that recovery is likely if smoking is stopped. The study also found a higher risk of death as well as non-participation in cognitive tests among smokers, suggesting the association between smoking and cognition may have been under-estimated.
The report was published in the June 9 issue of Archives of Internal Medicine. Full reference
http://www.eurekalert.org/pub_releases/2008-06/jaaj-msm060508.php

Drinking Concord grape juice may improve memory in older adults

A small pilot study, involving only 12 older adults with early memory decline, has found that those who drank Concord grape juice daily for a 12-week period showed significant improvement in list learning compared to those taking a placebo, and trends suggested improved short-term retention and spatial memory.
The results were presented at the 38th annual scientific meeting of the American Aging Society in Boulder, Colo., May 30-June 2, 2008.
http://www.eurekalert.org/pub_releases/2008-06/w-dpc060208.php

Low levels of good cholesterol linked to memory loss, dementia risk

Previous research has focused on total or LDL cholesterol levels because they are proven risk factors for cardiovascular disease, but data from the Whitehall II study has found that low levels of high-density lipoproteins (HDL) — the "good" cholesterol — in middle age were associated with a significantly greater risk of memory loss by age 60. Total cholesterol and triglycerides did not show a link with memory decline. To raise HDL and lower LDL cholesterol, the American Heart Association recommends exercising regularly; eliminating trans fats from the diet; reducing the intake of all fats, especially saturated fats; and consuming monounsaturated fats, such as olive, canola and peanut oils. (for more advice on cholesterol see www.americanheart.org/cholesterol)
The report appeared online June 30 in Arteriosclerosis, Thrombosis and Vascular Biology. Full reference
http://www.eurekalert.org/pub_releases/2008-06/aha-llo062708.php

Mixed feelings not remembered as well as happy or sad ones

A series of studies that tested participants' emotions when they faced scenarios such as taking tests and moving, events that are typically associated with mixed emotions, has found that the intensity of mixed emotions tends to be underestimated when recalling the experience. This underestimation increases over time, to the point that people sometimes don't remember having felt ambivalent at all. This is more likely among those who are uncomfortable feeling mixed emotions. Interestingly, Asian Americans in the study did not exhibit the same degree of memory decline for mixed emotions as Anglo-Americans did.
The findings appeared in the August issue of the Journal of Consumer Research. Full reference
http://www.eurekalert.org/pub_releases/2008-06/uocp-mfn062508.php

Long-term cannabis users may have structural brain abnormalities

An imaging study of 15 men who smoked more than five cannabis joints daily for more than 10 years has found that, compared with individuals who were not cannabis users, the heavy cannabis users tended to have a smaller hippocampus and amygdala. They also performed significantly worse on verbal learning, but this didn’t correlate with regional brain volumes.
The report appeared in the June issue of Archives of General Psychiatry. Full reference
http://www.eurekalert.org/pub_releases/2008-06/usmc-usr061208.php

How Ritalin works to focus attention

Ritalin has been widely used for decades to treat attention deficit hyperactivity disorder (ADHD), but until now the mechanism of how it works hasn’t been well understood. Now a rat study has found that Ritalin, in low doses, fine-tunes the functioning of neurons in the prefrontal cortex, and has little effect elsewhere in the brain. It appears that Ritalin dramatically increases the sensitivity of neurons in the prefrontal cortex to signals coming from the hippocampus. However, in higher doses, prefrontal neurons stopped responding to incoming information, impairing cognition. Low doses also reinforced coordinated activity of neurons, and weakened activity that wasn't well coordinated. All of this suggests that Ritalin strengthens dominant and important signals within the prefrontal cortex, while lessening weaker signals that may act as distractors.
The report was published online June 30 in Biological Psychiatry. Full reference
http://www.eurekalert.org/pub_releases/2008-06/uow-suh062408.php

Great apes think ahead

Another nail in the coffin of an attribute unique to humans — a series of experiments involving two chimpanzees and an orangutan has provided conclusive evidence that apes can plan for their future needs just as humans can – by using self-control (the suppression of immediate drives in favor of delayed rewards) and mental time travel (the ability to imagine future events). Shown a hose and how to use it to extract fruit soup, the animals were then tempted with their favorite fruit alongside the hose to test their ability to suppress the choice of the immediate reward (favorite fruit) in favor of a tool (the hose) that would lead to a larger reward 70 minutes later on (the fruit soup). The apes chose the hose more frequently than their favorite fruit. Given a choice of three novel tools, the apes chose the useful tool more often and took it to the reward room later on, where they used it appropriately, demonstrating that they selected the tool based on its functional properties. One of the decisive experiments excluded associative learning (previously claimed as a possible explanation for similar behaviors).
The findings were published online 14 June in Animal Cognition. Full reference
http://www.eurekalert.org/pub_releases/2008-06/s-gat061808.php

Complex synapses drove brain evolution

Research into the evolution of human intelligence has concentrated on the large size of the human brain, and the number of neurons. It has been thought that the connections between neurons — synapses — are similar in most animals, and it is the increase in number of synapses that’s important. But now a study has looked at the molecular composition of synapses across species, and has found dramatic differences in the numbers of proteins. Of 600 proteins found in mammalian synapses, only 50% were also found in invertebrate synapses, and about 25% in single-cell animals (which don't have a brain). This suggests that the proteins found in single-cell animals represent the ancient or 'protosynapse' involved with simple behaviors, which were then dramatically added to when multicellular animals emerged, some billion years ago, and then dramatically added to again with the appearance of vertebrates, perhaps 500 million years ago. This expansion in proteins that occurred in vertebrates provided a pool of proteins that were used for making different parts of the brain into the specialised regions such as cortex, cerebellum and spinal cord.
The report was published online 8 June in Nature Neuroscience. Full reference
http://www.eurekalert.org/pub_releases/2008-06/wtsi-oot060508.php

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