News reports of research into memory February 2002
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February 2002
Older adults show two kinds of
cognitive-processing deficits: under-recruitment, where appropriate
areas of the brain are less likely to be utilised without specific
instruction, and non-selective recruitment, where non-relevant
regions of the brain are more likely to be used. A recent imaging
study confirmed that older adults were less likely than younger ones
to use the critical frontal regions when performing a memory task,
and more likely to use cortical regions that are not as useful.
However, when subjects were given specific strategy instructions,
the older adults showed increased activity in the frontal regions,
and their remembering improved. Even with this support however,
older adults still showed a greater tendency to use brain regions
that were not useful.
The report appeared in the February 28 issue of
Neuron. Full
reference
http://www.eurekalert.org/pub_releases/2002-02/hhmi-tci021302.php
http://www.eurekalert.org/pub_releases/2002-02/wuis-bis021402.php
Two recent studies investigating the effect of pre-natal exposure
to cocaine in rats suggest that children
exposed to cocaine while in the womb may have permanent changes to
the part of the brain that helps control attention and memory,
leading to learning deficits and symptoms that are very much like
attention deficit hyperactivity disorder.
The studies appeared in Behavioural Brain
Research and Neuropsychopharmacology.
Full references
http://www.eurekalert.org/pub_releases/2002-02/yu-ucd021802.php
After only a month, older
rats fed two chemicals normally found in the body's cells and
available as dietary supplements — acetyl-L-carnitine and an
antioxidant, alpha-lipoic acid — performed better on memory tests,
and had noticeably more energy (on a par with a “middle-aged” rat).
It is thought that these chemicals act on the mitochondria, the
“power-houses” of the cells. Mitochondria are increasingly being
implicated as especially vulnerable to the aging process. Carnitine
is a natural compound produced in the cell and obtained in the diet
through meats and vegetables. It has been shown to improve balance
and short-term memory in human. Lipoic acid is found in green, leafy
vegetables.
The University of California has patented use of the combination of
the two supplements to rejuvenate cells. Human clinical trials are
currently underway.
Three reports appeared in the February 19 issue of the
Proceedings of the National Academy of Sciences.
Full references
http://www.eurekalert.org/pub_releases/2002-02/uoc--dsm021502.php
http://www.eurekalert.org/pub_releases/2002-02/osu-crr021902.php
Elevated temperatures within 8-10 hours after
surgery are often seen in patients who have undergone coronary
bypass surgery. This has not however been regarded as anything other
than a nuisance. Many bypass patients also suffer measurable
cognitive decline. A new study reports on a relationship between
these fevers and cognitive decline six weeks following surgery.
Patients who suffered the highest post-operative temperatures also
suffered the highest amount of cognitive decline.
The study was published in the February 1 issue of
Stroke. Full
reference
http://www.eurekalert.org/pub_releases/2002-01/dumc-fia012802.php
Following studies indicating that
new neurons are generated in the adult
mammalian hippocampus, this study demonstrates that these newly
generated cells do mature into functional neurons.
The report appeared in the 28 February issue of
Nature.
Full reference
http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v415/n6875/abs/4151030a_fs.html
(registration required)
Humans are widely considered to have a
disproportionately large frontal cortex compared to other animals,
and the disparity in cognitive capabilities is partly attributed to
this difference. However, a comparison of the relative size of the
frontal cortex in humans versus other great apes reveals that human
frontal cortices are not disproportionately large in comparison to
those of the great apes. The authors suggest that the human
advantage may be due to differences in individual cortical areas and
to a richer interconnectivity, rather than an overall size
difference.
The report was published in Nature
Neuroscience.
Full reference
http://www.nature.com/cgi-taf/DynaPage.taf?file=/neuro/journal/v5/n3/abs/nn814.html
(registration required)
A study into the brains of songbirds found that birds living in
large groups have more new neurons and
probably a better memory than those living alone. Does this have
relevance for humans? We don't know yet, but it has been observed
that social animals such as elephants tend to have better memories
than loners.
The study will be published in the journal
Behavioural Brain Research. A report appeared in the February
23 issue of New Scientist.
www.newscientist.com
http://www.eurekalert.org/pub_releases/2002-02/ns-lil022002.php
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