[Top] [All Lists]

[CQ-Contest] Be a better contester: EXERCISE (Really!)

To: cq-contest@contesting.com
Subject: [CQ-Contest] Be a better contester: EXERCISE (Really!)
From: kr2q@optonline.net
Date: Sun, 19 Aug 2007 13:08:51 +0000 (GMT)
List-post: <mailto:cq-contest@contesting.com>
 New York TimesAugust 19, 2007Phys EdLobes of SteelBy GRETCHEN REYNOLDSThe 
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 human brain is extremely difficult to 
study, especially when a person is still alive. Without euthanizing their 
subjects, the closest that researchers can get to seeing what goes on in there 
is through a functional M.R.I. machine, which measures the size and shape of 
the brain and, unlike a standard M.R.I. machine, tracks blood flow and 
electrical activity.This spring, neuroscientists at Columbia University in New 
York City published a study in which a group of men and women, ranging in age 
from 21 to 45, began working out for one hour four times a week. After 12 
weeks, the test subjects, predictably, became more fit. Their VO2 max, the 
standard measure of how much oxygen a person takes in while exercising, rose 
significantly.But something else happened as a result of all those workouts: 
blood flowed at a much higher volume to a part of the brain responsible for 
neurogenesis. Functional M.R.I.’s showed that a portion of each person’s 
hippocampus received almost twice the blood volume as it did before. Scientists 
suspect that the blood pumping into that part of the brain was helping to 
produce fresh neurons.The hippocampus plays a large role in how mammals create 
and process memories; it also plays a role in cognition. If your hippocampus is 
damaged, you most likely have trouble learning facts and forming new memories. 
Age plays a factor, too. As you get older, your brain gets smaller, and one of 
the areas most prone to this shrinkage is the hippocampus. (This can start 
depressingly early, in your 30’s.) Many neurologists believe that the loss of 
neurons in the hippocampus may be a primary cause of the cognitive decay 
associated with aging. A number of studies have shown that people with 
Alzheimer’s and other forms of dementia tend to have smaller-than-normal 
hippocampi.The Columbia study suggests that shrinkage to parts of the 
hippocampus can be slowed via exercise. The subjects showed significant 
improvements in memory, as measured by a word-recall test. Those with the 
biggest increases in VO2 max had the best scores of all.“It’s reasonable to 
infer, though we’re not yet certain, that neurogenesis was happening in the 
people’s hippocampi,” says Scott A. Small, an associate professor of neurology 
at Columbia and the senior author of the study, “and that working out was 
driving the neurogenesis.”Other recent studies support this theory. At the 
University of Illinois at Urbana- Champaign, a group of elderly sedentary 
people were assigned to either an aerobic exercise program or a regimen of 
stretching. (The aerobic group walked for at least one hour three times a 
week.) After six months, their brains were scanned using an M.R.I. Those who 
had been doing aerobic exercise showed significant growth in several areas of 
the brain. These results raise the hope that the human brain has the capacity 
not only to produce new cells but also to add new blood vessels and strengthen 
neural connections, allowing young neurons to integrate themselves into the 
wider neural network. “The current findings are the first, to our knowledge, to 
confirm the benefits of exercise training on brain volume in aging humans,” the 
authors concluded.And the benefits aren’t limited to adults. Other University 
of Illinois scientists have studied school-age children and found that those 
who have a higher level of aerobic fitness processed information more 
efficiently; they were quicker on a battery of computerized flashcard tests. 
The researchers also found that higher levels of aerobic fitness corresponded 
to better standardized test scores among a set of Illinois public school 
students. The scientists next plan to study how students’ scores change as 
their fitness improves.What is it about exercise that prompts the brain to 
remake itself? Different scientists have pet theories. One popular hypothesis 
credits insulin-like growth factor 1, a protein that circulates in the blood 
and is produced in greater amounts in response to exercise. IGF-1 has trouble 
entering the brain — it stops at what’s called the “blood-brain barrier” — but 
exercise is thought to help it to do so, possibly sparking neurogenesis.Other 
researchers are looking at the role of serotonin, a hormone that influences 
mood. Exercise speeds the brain’s production of serotonin, which could, in 
turn, prompt new neurons to grow. Abnormally low levels of serotonin have been 
associated with clinical depression, as has a strikingly shrunken hippocampus. 
Many antidepressant medications, like Prozac, increase the effectiveness of 
serotonin. Interestingly, these drugs take three to four weeks to begin working 
— about the same time required for new neurons to form and mature. Part of the 
reason these drugs are effective, then, could be that they’re increasing 
neurogenesis. “Just as exercise does,”Gage says.Gage, by the way, exercises 
just about every day, as do most colleagues in his field. Scott Small at 
Columbia, for instance , likes nothing better than a strenuous game of tennis. 
“As a neurologist,” he explains, “I constantly get asked at cocktail parties 
what someone can do to protect their mental functioning. I tell them, ‘Put down 
that glass and go for a run.’ ” .This Is Your Brain on Something Other Than 
ExerciseThe human brain undergoes neurogenesis — the creation of new cells — 
throughout a person’s life, although the amount depends on a variety of 
factors, not just exercise.MARIJUANA: We just report the data; we don’t endorse 
it. A 2005 study on rats found that stimulation of the brain’s receptors for 
marijuana increased neurogenesis.ALCOHOL: A 2005 study found that mice that 
swallowed a moderate amount of ethanol showed more neurogenesis than 
teetotalers. Other studies on mice have suggested that heavier drinking can be 
damaging to the brain.SOCIABILITY: One study suggests that rats that live alone 
and have access to a run ning wheel experience less neurogenesis than those 
that have access to a running wheel and live in group housing. So go ahead and 
join that singles running club you’ve been avoiding.DIET: A diet high in 
saturated fat and sugar sharply diminishes the brain’s production of the 
proteins and nerve-growth factors necessary for neurogenesis. Exercise may 
mitigate that effect somewhat.STRESS: Mice that are subjected to uncontrollable 
stress (like electric shock) suffer substantial deterioration in their ability 
to produce new neurons.CHOCOLATE: In a study published this year, an ingredient 
in cocoa, epicatechin, was shown to improve spatial memory in mice, especially 
among those that exercised. Epicatechin can also be found in grapes, 
blueberries and black tea. “I plan to start ingesting more epicatechin,” says 
Henriette van Praag, a neuroscientist at the Salk Institute, “as soon as I 
can’t find my car keys anymore.” G.R.Copyright 2007 The New York Times Company
CQ-Contest mailing list

<Prev in Thread] Current Thread [Next in Thread>
  • [CQ-Contest] Be a better contester: EXERCISE (Really!), kr2q <=