NYTimes: "Lobes of Steel" - neurogenesis as a product of exercise
- From: Florida <demeter547opine@xxxxxxxxx>
- Date: Wed, 22 Aug 2007 14:15:03 -0700
The New York Times
http://www.nytimes.com/2007/08/19/sports/playmagazine/0819play-brain.html?em&ex=1187928000&en=b71402a4ddd06aa3&ei=5087%0A
August 19, 2007
Phys Ed
Lobes of Steel
By GRETCHEN REYNOLDS
The Morris water maze is the rodent equivalent of an I.Q. test: mice
are placed in a tank filled with water dyed an opaque color. Beneath a
small area of the surface is a platform, which the mice can't see.
Despite what you've heard about rodents and sinking ships, mice hate
water; those that blunder upon the platform climb onto it immediately.
Scientists have long agreed that a mouse's spatial memory can be
inferred by how quickly the animal finds its way in subsequent
dunkings. A "smart" mouse remembers the platform and swims right to
it.
In the late 1990s, one group of mice at the Salk Institute for
Biological Studies, near San Diego, blew away the others in the Morris
maze. The difference between the smart mice and those that floundered?
Exercise. The brainy mice had running wheels in their cages, and the
others didn't.
Scientists have suspected for decades that exercise, particularly
regular aerobic exercise, can affect the brain. But they could only
speculate as to how. Now an expanding body of research shows that
exercise can improve the performance of the brain by boosting memory
and cognitive processing speed. Exercise can, in fact, create a
stronger, faster brain.
This theory emerged from those mouse studies at the Salk Institute.
After conducting maze tests, the neuroscientist Fred H. Gage and his
colleagues examined brain samples from the mice. Conventional wisdom
had long held that animal (and human) brains weren't malleable: after
a brief window early in life, the brain could no longer grow or renew
itself. The supply of neurons - the brain cells that enable us to
think - was believed to be fixed almost from birth. As the cells died
through aging, mental function declined. The damage couldn't be staved
off or repaired.
Gage's mice proved otherwise. Before being euthanized, the animals had
been injected with a chemical compound that incorporates itself into
actively dividing cells. During autopsy, those cells could be
identified by using a dye. Gage and his team presumed they wouldn't
find such cells in the mice's brain tissue, but to their astonishment,
they did. Up until the point of death, the mice were creating fresh
neurons. Their brains were regenerating themselves.
All of the mice showed this vivid proof of what's known as
"neurogenesis," or the creation of new neurons. But the brains of the
athletic mice in particular showed many more. These mice, the ones
that scampered on running wheels, were producing two to three times as
many new neurons as the mice that didn't exercise.
But did neurogenesis also happen in the human brain? To find out, Gage
and his colleagues had obtained brain tissue from deceased cancer
patients who had donated their bodies to research. While still living,
these people were injected with the same type of compound used on
Gage's mice. (Pathologists were hoping to learn more about how quickly
the patients' tumor cells were growing.) When Gage dyed their brain
samples, he again saw new neurons. Like the mice, the humans showed
evidence of neurogenesis.
Gage's discovery hit the world of neurological research like a
thunderclap. Since then, scientists have been finding more evidence
that the human brain is not only capable of renewing itself but that
exercise speeds the process.
"We've always known that our brains control our behavior," Gage says,
"but not that our behavior could control and change the structure of
our brains."
[....]
(The preceding is about half the article)
.
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