News reports of research into memory December 2005

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December 2005

Lifestyle changes improve seniors’ memory surprisingly quickly

A small 14-day study found that those following a memory improvement plan that included memory training, a healthy diet, physical exercise, and stress reduction, showed a 5% decrease in brain metabolism in the dorsal lateral prefrontal region of the brain (involved in working memory) suggesting they were using their brain more efficiently. This change in activity was reflected in better performance on a cognitive measure controlled by this brain region, and participants reported that they felt their memory had improved. The memory training involved doing brainteasers, crossword puzzles and memory exercises. Diet involved eating 5 small meals daily (to prevent fluctuations in blood glucose levels) that were rich in omega-3 fats, low-glycemic index carbohydrates (e.g., whole grains) and antioxidants. Physical exercise involved brisk walking and stretching, and stress reduction involved stretching and relaxation exercises.
The study was presented at the American College of Neuropsychopharmacology's Annual Meeting on December 11-15, in Hawaii.
http://www.eurekalert.org/pub_releases/2005-12/g-nsf121205.php

Uncontrolled high blood pressure means more cognitive problems in old age

A study involving a subset of men (average age 67 years) in the VA Normative Aging Study has found that those men with uncontrolled hypertension performed significantly worse on tests of verbal fluency and short-term memory. Those whose hypertension was controlled did as well as those with normal blood pressure. In the United States, hypertension affects 60% of adults age 60 and older, and a high proportion of these are untreated or inadequately treated.
The study appeared in the November issue of Neuropsychology. Full reference
Full text is available at http://www.apa.org/journals/releases/neu196770.pdf
http://www.eurekalert.org/pub_releases/2005-12/apa-uhb113005.php

Brain size does matter, but differently for men and women

A study involving the intelligence testing of 100 neurologically normal, terminally ill volunteers, who agreed that their brains be measured after death, found that a bigger brain size is correlated with higher intelligence in certain areas, but there are differences between women and men. Verbal intelligence was clearly correlated with brain size, accounting for 36% of the verbal IQ score, for women and right-handed men — but not for left-handed men. Spatial intelligence was also correlated with brain size in women, but much less strongly, while it was not related at all to brain size in men. It may be that the size or structure of specific brain regions is related to spatial intelligence in men. Brain size decreased with age in men over the age span of 25 to 80 years, suggesting that the well-documented decline in visuospatial intelligence with age is related, at least in right-handed men, to the decrease in cerebral volume with age. However age hardly affected brain size in women.
The study was published in the December issue of Brain. Full reference
http://www.sciencedaily.com/releases/2005/12/051223123116.htm

Brain enlargement may be characteristic of autism

Comparison of 164 children with autism and 214 control children (all younger than 3 years) has found significant enlargement in the volume of the cerebral cortex, in both white and grey matter, and generalized throughout the cortex. Head circumference was not significantly different at birth — an increased rate of growth occurred from around 12 months.
The study appeared in the December issue of Archives of General Psychiatry. Full reference
http://www.eurekalert.org/pub_releases/2005-12/jaaj-bem120105.php

More light shed on memory retrieval

A new technique has confirmed the idea that when we retrieve memories we try to reinstate our original mindset, when we formed the memory. As you search for memories of a particular event, your brain state progressively comes to resemble the state it was in when you initially experienced the event, as one memory triggers another. They also found patterns of brain activity for specific categories, such as faces, started to emerge approximately five seconds before subjects recalled items from that category — suggesting that participants were bringing to mind the general properties of the images in order to cue for specific details. The technique also enabled researchers to predict with reasonable accuracy what items participants would successfully recall.
The findings were detailed in the December 23 issue of Science. Full reference
http://www.eurekalert.org/pub_releases/2005-12/pu-rdn122205.php
http://www.eurekalert.org/pub_releases/2005-12/uop-rkw121905.php

How new neurons are integrated in the adult brain

Now that we accept that new neurons can indeed be created in adult brains, the question becomes: how are these new neurons integrated into existing networks? Mouse experiments have now found that a brain chemical called GABA is critical. Normally, GABA inhibits neuronal signals, but it turns out that with new neurons, GABA has a different effect: it excites them, and prepares them for integration into the adult brain. Thus a constant flood of GABA is needed initially; the flood then shifts to a more targeted pulse that gives the new neuron specific connections that communicate using GABA; finally, the neuron receives connections that communicate via another chemical, glutamate. The neuron is now ready to function as an adult neuron, and will respond to glutamate and GABA as it should. It’s hoped the discovery will help efforts to increase neuron regeneration in the brain or to make transplanted stem cells form connections more efficiently.
The discovery is described in the December 11 advance online section of Nature. Full reference
http://www.eurekalert.org/pub_releases/2005-12/jhmi-nnt122205.php

Neuron growth in adult brain

A few years ago, we were surprised by news that new neurons could be created in the adult brain. However, it’s remained a tenet that adult neurons don’t grow — this because researchers have found no sign that any structural remodelling takes place in an adult brain. Now a mouse study using new techniques has revealed that dramatic restructuring occurs in the less-known, less-accessible inhibitory interneurons. Dendrites (the branched projections of a nerve cell that conducts electrical stimulation to the cell body) show sometimes dramatic growth, and this growth is tied to use, supporting the idea that the more we use our minds, the better they will be. The finding also offers new hope that one day it may be possible to grow new cells to replace ones damaged by disease or spinal cord injury.
The finding was reported in the December 27 issue of Public Library of Science (PLoS) Biology. Full reference
Full text available at http://biology.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pbio.0040042
http://www.eurekalert.org/pub_releases/2005-12/miot-mrf122205.php
http://www.eurekalert.org/pub_releases/2005-12/plos-anw122205.php

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