News reports of research into memory April 2005
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April 2005
Zinc supplements improved cognitive performance in adolescents
Seventh graders given 20 mg zinc, five days per week, for 10 to
12 weeks showed improvement in cognitive performance, responding
more quickly and accurately on memory tasks and with more sustained
attention, than classmates who received no additional zinc. Those
who received only 10mg a day did not improve their performance.
Previous studies have linked zinc nutrition to motor, cognitive and
psychosocial function in very young children and adults, but this is
the first study of its effect in adolescents. Adolescents are at
particular risk of zinc deficiency, because they are undergoing
rapid growth and often have poor eating habits. Red meats, fish and
grains are good sources of zinc.
The findings were presented at Experimental Biology 2005, as part of
the scientific sessions of the American Society of Nutritional
Sciences.
http://www.eurekalert.org/pub_releases/2005-04/foas-zsi032005.php
Less cognitive impairment seen in women taking raloxifene
Raloxifene modulates the activity of the hormone estrogen and is
one of the most widely prescribed drugs for the treatment of
osteoporosis. A 3-year worldwide clinical trial involving 7705
postmenopausal women with osteoporosis found that those taking 120mg
of raloxifene had a 33% less chance of developing mild cognitive
impairment. There was no cognitive benefit from a 60mg dose. Note
that, of the 5386 women participating in the cognitive part of this
trial, only 3.4% had mild cognitive impairment, and 1% had dementia.
The finding was published in the April 2005 issue of the
American Journal of Psychiatry.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/uoc--lci040605.php
Review finds bypass surgery free of long-term brain effects for most
A broad retrospective review of the effects of coronary artery
bypass surgery on cognitive functions concludes that, although the
research confirms the existence of mild deficits in the period up to
three months after surgery, the procedure itself probably does not
cause late or permanent neurological effects. Rather, they argue,
the late cognitive declines seen in some long-term studies are for
most people likely associated with progression of underlying
conditions such as cerebrovascular disease. However, this is not
true for all. The exceptions might include older patients and those
with risk factors for cerebrovascular disease or a history of
stroke.
The review was published online April 25 in the
Annals of Neurology.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/jws-dsb042105.php
Antioxidant-rich diets reduce brain damage from stroke in rats
A new rat study suggests antioxidant-rich fruits and vegetables
may limit brain damage from stroke and other neurological disorders.
The study built upon previous research showing that diets enriched
with blueberries, spinach or spirulina reversed normal age-related
declines in memory and learning in old rats, and found that the same
diet significantly reduced brain cell loss and improved recovery of
movement in rats who had an ischemic stroke induced. The size of the
stroke in the rats fed blueberry or spinach supplements was half
that seen in the brains of untreated rats. Rats fed
spirulina-enriched diets had stroke lesions 75% smaller than their
untreated counterparts.
The study appears in the May issue of
Experimental Neurology.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/uosf-adr041205.php
No strong evidence linking mercury levels with worse cognitive performance in older adults
We are encouraged to eat fish for its health benefits, but there
has been some concern about mercury levels. Now the first study of
mercury and cognitive function in 1140 urban U.S. adults between the
ages of 50 and 70 years has found that blood mercury levels were not
consistently associated with adverse performance on a broad range of
tests of cognitive function. Most of the large number of tests
showed no correlation with mercury and there was a lack of
consistency of mercury effects in different aspects of brain
function.
The study was published in the April 20 issue of the
Journal of the American Medical Association.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/jhub-mla041505.php
http://www.eurekalert.org/pub_releases/2005-04/jaaj-nse041405.php
Ginkgo may improve executive function in MS patients
A study of 39 MS patients found that those receiving ginkgo
biloba were about 13% faster on a Stroop test (measures a person's
ability to pay attention and to sort conflicting information). Such
a difference would be comparable to differences in scores between
healthy people ages 30 to 39 and those ages 50 to 59. The benefit
appeared to be greatest for those who had certain problems with the
Stroop test.
The study was presented at the American Academy of Neurology's 57th
Annual Meeting in Miami Beach, Fla.
http://www.eurekalert.org/pub_releases/2005-04/ohs-osf042705.php
Chemical in clear plastics can impair learning
A rat study has found that low doses of the environmental
contaminant bisphenol–A (BPA), widely used to make many plastics
found in food storage containers (including feeding bottles for
infants), inhibit estrogen–induction of synaptic connections in the
hippocampus, suggesting implications for children's learning
ability. Also, when the ability to make estrogen is impaired, as in
old age, exposure to BPA could adversely affect hippocampal function
and contribute to age–related neurodegenerative diseases such as
Alzheimer's disease, in which hippocampal function is impaired. The
doses were below the current U.S. Environmental Protection Agency
reference daily limit for human exposure.
The study was available online 24 February in
Environmental Health Perspectives.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/yu-cpi041205.php
People can learn motor skills by watching
Sure we learn by doing, but we also learn by watching. Recent
imaging studies have shown that when we observe the actions of
others, we activate the same neural circuitry responsible for
planning and executing our own actions. Now a new study has
demonstrated that such observation can actually facilitate motor
learning. This occurred even when observers were distracted by
another task (doing arithmetic) while watching, indicating that the
process does not require conscious awareness. However, although
there was no sign of muscle activity during the observation, the
beneficial effects of observing were significantly reduced when the
subjects were asked to perform unrelated arm movements during
observation.
The study appeared in the April 7 issue of
Neuron.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/cp-pcl040105.php
Psychological reasoning begins earlier than had been thought
According to conventional wisdom, babies don't begin to develop
sophisticated psychological reasoning about people until they are
about 4 years old. A study of 15-month-olds proves otherwise. The
study used a non-verbal approach, for obvious reasons, and the
researchers suggest earlier studies that found 3 year olds unable to
reason about what others believe used verbal tasks that were overly
complex for the young children.
The findings were published in the April 8 issue of
Science.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/uoia-prb041405.php
New insight into brain and speech promises help for learning disabilities
Following a new understanding of the nature of certain language
dysfunctions, researchers have devised a new non-invasive diagnostic
tool called BioMAP that can quickly identify children with a subset
of learning disabilities that results from a dysfunction in the way
the brainstem encodes certain basic sounds of speech. Such children
accounted for nearly a third of the language-disordered children the
researchers studied. BioMAP measures whether a child's nervous
system can accurately translate a sound wave into a brain wave. If
it cannot, the affected individual demonstrates problems in
discriminating speech sounds that interfere with normal learning.
Once identified, children with these problems will be able to
improve their speech discrimination skills through auditory
training.
The report appeared in the April issue of
Trends in Neurosciences.
Full reference
http://www.eurekalert.org/pub_releases/2005-04/nu-nii040405.php
"Neural cliques" create memories
Typically, brain activity is measured in one or a few neurons at
a time. But memory depends on the actions of large sets of neurons.
Now a new study has simultaneously recorded the electrical activity
of up to 260 individual neurons of the mouse
hippocampus in three conditions. Each episode produced different
brain activity patterns and identified basic coding units in the
hippocampus, “neural cliques”, that respond to the different
stimuli. The individual neurons within neural cliques exhibit
"collective cospiking" dynamics that allow the neural clique to
overcome the response variability of its members and to achieve
encoding robustness. These neural cliques provide a plausible neural
basis of memory formation.
The study was published in the April 26 issue of the
Proceedings of the National Academy of Sciences (USA).
Full reference
http://www.eurekalert.org/pub_releases/2005-04/potn-phf041105.php
Louder neurons form more connections
A study of tiny, see-through zebrafish has provided new insight
into how the developing brain chooses which connections to keep.
During development, neurons reach out to form many connections, some
of which will remain, while others don’t. The study found the
decision was based on how “loud” they were — that is, which
connections had the most activity compared to other, neighboring
connections. The finding could help to explain how early experiences
guide brain development.
The study was published in the April 21 issue of
Nature . Full
reference
http://www.eurekalert.org/pub_releases/2005-04/sumc-lnf041805.php
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