Exercise can make you smarter by helping to slow down and even turn around the physical decay of the brain. Writing in the New York Times Sunday magazine, Gretchen Reynolds (who writes the NYT’s Well blog) reviews some recent scientific studies exploring why walking, running, swimming and the like are good for your health and for your head.
Reynolds points out that the “brain, like all muscles and organs, is a tissue, and its function declines with underuse and age.” From our late 20s on, we lose about 1 percent of the volume of our hippocampus (which is associated with memory and certain types of learning) a year. In the 1990s, scientists discovered that adult human brains do generate new neurons and that exercise helps the brain to generate larger amounts of neurons. But just having more new neurons doesn’t alone increase intellect, Reynolds writes: For such to happen, the new brain cells have to join a neural network. Researchers found that, when mice were running, their brains “readily wired many new neurons into the neural network”; they observed the same when the mice were using their cognitive skills for such tasks as exploring new environments.
Another study cited by Reynolds also uses mice. Under psychology professor Justin S. Rhodes of the Beckman Institute for Advanced Science and Technology at the University of Illinois, researchers divided the mice into four groups:
One group lived in a world of sensual and gustatory plenty, dining on nuts, fruits and cheeses, their food occasionally dusted with cinnamon, all of it washed down with variously flavored waters. Their “beds” were colorful plastic igloos occupying one corner of the cage. Neon-hued balls, plastic tunnels, nibble-able blocks, mirrors and seesaws filled other parts of the cage. Group 2 had access to all of these pleasures, plus they had small disc-shaped running wheels in their cages. A third group’s cages held no embellishments, and they received standard, dull kibble. And the fourth group’s homes contained the running wheels but no other toys or treats.
The scientists had injected the mice with a substance that enabled them to track changes in their brain structure. Both groups of mice that had running wheels in their cages performed better on cognitive tests than the mice who did not and had healthier brains as a whole.
Scientists could hardly conduct such an experiment on humans due to ethical issues which are equally present in research using animal subjects — Rhodes’s study suggests that it is essential to provide mice in such situations with cognitive stimulation and to enable them to exercise. Exercise fosters an increase in the production of brain-derived neurotropic factor, or B.D.N.F., which “strengthens cells and axons, fortifies the connections among neurons and sparks neurogenesis.” Scientists can’t directly study similar effects in human brains, but they have found that B.D.N.F. levels are higher after people work out.
The exercise need not be all-out exhausting. In another study of 120 older men and women, some were assigned walking or stretching as exercise. Those who walked had larger hippocampi after a year.
Teachers (and parnets) know that physical activity and exercise can be key to helping students calm and focus better in the classroom. But the other benefit to exercise — and a compelling reason to preserve and promote physical education for elementary and secondary school students — is that it can help students do better in their academics. Even more, it can help all of us keep brains and bodies healthy in another affirmation of the ancient dictum, mens sana in corpore sano.
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