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A year adds up to big brain changes
By Laura Sanders
Neuroscientists have confirmed what any
kid knows: Third grade changes everything. Compared with kids just out of second grade, recent third-grade graduates
use their brains in an entirely different
way when solving math problems, a study
in an upcoming NeuroImage finds.
“I think this is really fascinating,” says
cognitive neuroscientist Daniel Ansari
of the University of Western Ontario in
London, Canada. “Anybody who doesn’t
believe that development is important
needs to read this paper, because it
really shows how dynamically the brain
changes as we learn.”
Cognitive neuroscientist Vinod
Menon of the Stanford University School
of Medicine and his colleagues recruited
90 children, ages 7 to 9, who had just
completed either second or third grade.
The youngsters calculated easy ( 3 + 1 =
4) or more complex ( 8 + 5 = 13) addition
problems while Menon and his team
scanned the children’s brains
using functional MRI.
Overall, second-graders’
brains tackled the easy and
hard problems about the
same way. But third-graders’
brains responded very differently to the easy and the hard
questions.
Third-graders showed
heightened activity in a brain region
important for working memory, which
keeps relevant info handy. Studies of older
children have found that this region, the
left dorsolateral prefrontal cortex, grows
less active with age while doing math, so
the new results may reflect an age-specific
approach to math that later gives way to
something else, the authors suggest.
Connections between the dorsolateral
prefrontal region and regions in the back
of the brain, some of which are involved
in vision, were also stronger in the third-graders as they crunched numbers, the
team found.
It’s not clear whether math classes
caused the differences. Nor-
mal development may cause
some of the changes, but
training and skill acquisition
probably play a role, too, says
developmental psychologist
Ann Dowker of the Univer-
sity of Oxford in England.
Ansari says that research-
ers need to figure out what
these changes in the brain actually
mean. “School changes your brain,
but what do we do with that?” he says.
“That’s the next big question.” So
far, scientists don’t know whether
the changes correlate with stronger
math performance, particular kinds
of math training or how good a child
will be at math in the future.
“School
changes
your brain,
but what
do we do
with that?”
DANIEL ANSARI
Breast cancer
drug passes test
By Nathan Seppa
A drug that inhibits the manufacture
of estrogen can lower the likelihood of
breast cancer among healthy women
whom doctors consider at risk of developing the disease. The drug, called
exemestane, may offer a preventive
approach to combating the malignancy,
researchers reported June 4 at a cancer
meeting in Chicago and online in the
New England Journal of Medicine.
Two drugs, tamoxifen and raloxifene,
have previously been shown to lessen
breast cancer risk when taken as preventives. Those drugs hamper the
pro-growth effects of the hormone estrogen, which is implicated in most breast
cancers. But while tamoxifen is commonly
used as a treatment for breast cancer, few
cancer-free women take it as a preventive
even if they are deemed at risk.
Exemestane, a different kind of drug
called an aromatase inhibitor, lessens
the amount of estrogen made in the body.
In the new study, scientists enrolled
4,560 postmenopausal women at risk of
breast cancer because of age, abnormal
breast-cell growth or other factors. The
researchers randomly assigned roughly
half to get exemestane and half a placebo
pill. After a median follow-up of 35
months, 11 invasive breast cancers had
appeared in the exemestane group
compared with 32 among the placebo
recipients. Invasive breast cancer is
dangerous because it spreads within the
breast and is prone to jumping to nearby
lymph nodes or to other organs.
The results suggest that taking an aromatase inhibitor such as exemestane
reduces a woman’s risk of developing
invasive breast cancer by 65 percent, says
study coauthor Paul Goss, a physician at
Harvard Medical School in Boston.
While that rate indicates a substantial
lessening of risk, the absolute annual incidence of breast cancers in each group was
less than 1 percent. Hot flashes, sweating,
fatigue and insomnia were slightly more
common among women on exemestane,
but women in both groups rated their
overall quality of life similarly.
The findings “support the use of
exemestane as an option for risk reduction
in postmenopausal women at high risk
for breast cancer,” say Nancy Davidson
and Thomas Kensler of the University
of Pittsburgh, writing in a New England
Journal of Medicine editorial. Exemestane is marketed as Aromasin by its maker
Pfizer, which funded the study.
