News reports of research into memory April 2007
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April 2007
Sleep reinforces the temporal sequence in memory
Following on from research showing long-term memory is
consolidated during sleep through the replaying of recently encoded
experiences, a study has found that the particular order in which
they were experienced is also strengthened, probably by a replay of
the experiences in "forward" direction. The study involved students
being asked to learn triplets of words presented one after the
other. Those whose recall of the order of the words was tested after
sleep showed better recall, but only when they were asked to
reproduce the learned words in forward direction.
The paper appeared in the April 18 issue of
PLoS ONE.
Full reference
http://www.eurekalert.org/pub_releases/2007-04/plos-set041707.php
Sleep protects against interference
A study involving 48 people (aged 18—30) found that those who
learned 20 pairs of words at 9pm and were tested at 9am the
following morning, after a night’s sleep, performed better than
those who learned them at 9am and were tested at 9pm of the same
day. Moreover, for those who were given a second list of word pairs
to remember just before testing, where the first word in each pair
was the same as on the earlier list, the advantage of sleep was
dramatically better. For those who experienced the interference
manipulation, those in the sleep group recalled 12% more word pairs
than the wake group, but with interference, the recall rate was 44%
higher for the sleep group.
The findings were presented by Dr Jeffrey Ellenbogen at the American
Academy of Neurology’s 59th Annual Meeting in Boston, April 28 – May
5, 2007.
http://www.eurekalert.org/pub_releases/2007-04/aaon-ssy040307.php
Sleeping helps us put facts together
And in yet another sleep study, researchers found evidence that
sleep also helps us see the big picture. The study involved 56
students who were shown oval images of colorful abstract patterns
nicknamed "Fabergé eggs." Participants were first shown a
combination of five pairs of the eggs, all of which were given
ratings. The students were given 30 minutes to learn which shape
rated higher and so should be chosen over another shape. They were
not told the hidden connection that linked all five pairs together.
They were then tested either after 20 minutes, after 12 hours, or
after 24 hours. Half of those in the 12-hour group slept before the
test, the other half did not. The 20-minute group performed the
worst, showing no evidence of seeing the pattern. Those who had
longer before being tested were much more likely to show signs of
inferential judgment (75% vs 52%), and for the most distant (and
difficult) inferential judgment, the students who had had periods of
sleep in between learning and testing significantly outperformed
those who hadn’t slept (93% vs 69%). The researchers are interested
in exploring whether meditation can provide a similar benefit.
The findings appeared online April 20 in the Early Edition of the
Proceedings of the National Academy of Sciences.
Full reference
http://www.physorg.com/news98376198.html
http://www.eurekalert.org/pub_releases/2007-04/bidm-tut042007.php
Does migraine protect your memory?
A long-running study involving 1,448 women, of whom 204 had
migraine, has found that, while women with migraine performed worse
on cognitive tests at the beginning of the study, their performance
declined 17% less over 12 years than women without migraine. The
benefit was restricted to women over 50 who experience migraine with
aura. It’s possible that some medications for migraine may have a
protective effect, but the researchers did account for this
possibility and the medications showed no indication of a
significant protective effect. It is possible that women with
migraine may change their diet or behavior in some way that might
improve cognition. It’s also possible that there is some underlying
biological mechanism, such as changes in blood vessels or underlying
differences in brain activity.
The findings were published in the April 24 issue of
Neurology.
Full reference
http://www.eurekalert.org/pub_releases/2007-04/aaon-dmp041707.php
Seeing red worsens test performance
Perhaps because teachers usually mark in red pen, resulting in a
lot of red on a page indicating a lot of mistakes, a study has found
that seeing the color red before a test results in worse
performance. Although the effect isn’t huge, it does appear
consistently in different contexts. In one experiment, students were
given a quiz that had a number in either red or green on the corner,
while in another, students saw a glimpse of red, green, or grey on
the cover of an IQ test. Those who saw red got fewer answers right
on average. The researchers suggest the color produces anxiety. Red
is of course also associated with danger, and with stopping.
The paper was published in the February edition of the Journal
of Experimental Psychology.
Full reference
http://www.sciencentral.com/articles/view.htm3?article_id=218392927
Research explains how lead exposure produces learning deficits
A rat study has shown how exposure to lead during brain
development produces learning deficits — by reducing
neurogenesis, and by altering the normal development of newly
born neurons in the
hippocampus.
Dendrites
(branches from neurons that make the connections with other neurons)
were shorter and twisted in lead-exposed rats.
The study is published in the March 30 issue of
Neuroscience.
Full reference
http://www.eurekalert.org/pub_releases/2007-04/jhub-reh040307.php
Low dose aspirin does not protect women against cognitive decline
Evidence that aspirin and other anti-inflammatory drugs may
protect against dementia has been inconclusive. Now a large,
long-running study involving 6,377 women aged 65 years or more, over
ten years, has found that those who took low dose aspirin (100 mg on
alternate days) performed at similar levels to a placebo group on
cognitive tests. However, there was evidence of benefit in one very
specific area of cognition: category fluency.
The results appeared in the May issue of the
British Medical Journal.
Full reference
Full text is available at
http://tinyurl.com/25kzxf
http://www.eurekalert.org/pub_releases/2007-04/bmj-lda042607.php
Gender differences in the brain
Results from an extremely large internet survey looking at
sex-linked cognitive abilities, personality traits, interests,
sexual attitudes and behavior, as well as physical traits, has found
that cognitive abilities decline with age more steeply in men than
in women. This effect is independent of sexual orientation.
Differences in specific cognitive abilities were also found that did
depend on sexual orientation as well as gender. Men scored higher
than women on tests of mental rotation and the ability to judge line
angles, whereas women scored higher than men on tests of object
location memory and word fluency. However, homosexual men's
visual-spatial abilities were, on average, lower than those of
heterosexual men, and lesbian women's visual-spatial abilities were
higher than those of heterosexual women.
Key findings for the survey were reported in several papers in the
April issue of the Archives of Sexual Behavior.
Full reference
Full reference
Full reference
http://www.sciencedaily.com/releases/2007/05/070507113352.php
Sex and prenatal hormones affect cognitive performance
A study involving rhesus macaque monkeys has found that the
tendency to use landmarks for navigation is typical only of females.
In a situation where they had to navigate an open area to locate
highly valued food items in goal boxes, gender or prenatal treatment
did not affect how well the monkeys did when both spatial and marker
cues were available. When landmarks directly indicated the correct
locations but spatial information was unreliable, females performed
better than males. Moreover, males whose testosterone exposure had
been blocked early in gestation were more able to use the landmarks
to navigate than normal males.
The finding was reported in the April issue of
Hormones and Behavior.
Full reference
http://www.sciencedaily.com/releases/2007/04/070413102051.htm
http://www.eurekalert.org/pub_releases/2007-04/eu-sap041207.php
Monkeys can reflect on their thoughts
A study involving two rhesus macaque monkeys has shown that a
monkey can reflect on its own thoughts and assess its performance.
The experiment trained the monkeys to play a video game that tested
their ability to remember a particular photograph while also
allowing them to make a large or a small bet on how likely they were
to be right. The monkeys could also request hints for problems that
would otherwise have to be solved by trial and error. Not only did
the results provide clear evidence of their ability to engage in
metacognition, but the study also points to a means of testing
nonverbal humans, such an infants and autistic children.
The study appeared in the January issue of
Psychological Science.
Full reference
http://www.eurekalert.org/pub_releases/2007-04/afps-mat042007.php
Brain's speech site revisited and revised
The brains of the two patients that caused the 19th
century anatomist Paul Broca to locate the speech center in a region
of the brain now known as
Broca’s area
have been preserved, and recently they were reinspected using modern
scanning techniques. The study found that both patients’ lesions
extended significantly into medial regions of the brain, in addition
to the surface lesions observed by Broca, and also revealed
inconsistencies between the area originally identified by Broca and
what is now called Broca's area.
The study appeared online ahead of print April 2 in
Brain.
Full reference
http://www.nature.com/news/2007/070423/full/446956b.html
http://www.nature.com/nature/journal/v446/n7139/full/446956b.html
How memory networks are formed
We know that memories are encoded in a network of neurons, but
how do the neurons “decide” which ones to connect to? A mouse study
reveals that the level of a protein called
CREB is critical in this decision. The findings suggest a
competitive model in which eligible neurons
are selected to participate in a memory trace as a function
of their relative CREB activity at the time of learning.
The findings were reported in the April 20 edition of
Science.
Full reference
http://www.physorg.com/news96213299.html
http://www.eurekalert.org/pub_releases/2007-04/uoc--uru041707.php
Mutation improves memory, may lead to memory-enhancing pill
A mouse study investigating a gene that normally increases levels
of a natural memory-blocking protein has found that carriers of a
defective version of this gene showed improved performance in memory
tests, while animals treated with a small molecule that increased
the memory-blocker's concentration showed signs of memory
impairment. These findings point to a potential target for the
development of a drug to treat memory loss.
The findings were reported in the April 6 issue of
Cell.
Full reference
http://www.physorg.com/news94994494.html
http://www.eurekalert.org/pub_releases/2007-04/cp-mim033007.php
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