Brain+and+Exercise+2

Taken from [] New York Times, April 18, 2012 How Exercise Could Lead to a Better Brain

So, last year a team of researchers led by Justin S. Rhodes, a psychology professor at the Beckman Institute for Advanced Science and Technology at the University of Illinois, gathered four groups of mice and set them into four distinct living arrangements. 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.

All the animals completed a series of cognitive tests at the start of the study and were injected with a substance that allows scientists to track changes in their brain structures. Then they ran, played or, if their environment was unenriched, lolled about in their cages for several months. Afterward, Rhodes’s team put the mice through the same cognitive tests and examined brain tissues. It turned out that the toys and tastes, no matter how stimulating, had not improved the animals’ brains.

“Only one thing had mattered,” Rhodes says, “and that’s whether they had a running wheel.” Animals that exercised, whether or not they had any other enrichments in their cages, had healthier brains and performed significantly better on cognitive tests than the other mice. Animals that didn’t run, no matter how enriched their world was otherwise, did not improve their brainpower in the complex, lasting ways that Rhodes’s team was studying. “They loved the toys,” Rhodes says, and the mice rarely ventured into the empty, quieter portions of their cages. But unless they also exercised, they did not become smarter.

Why would exercise build brainpower in ways that thinking might not? The brain, like all muscles and organs, is a tissue, and its function declines with underuse and age. Beginning in our late 20s, most of us will lose about 1 percent annually of the volume of the hippocampus, a key portion of the brain related to memory and certain types of learning. Exercise though seems to slow or reverse the brain’s physical decay, much as it does with muscles. Although scientists thought until recently that humans were born with a certain number of brain cells and would never generate more, they now know better. In the 1990s, using a technique that marks newborn cells, researchers determined during autopsies that adult human brains contained quite a few new neurons. Fresh cells were especially prevalent in the hippocampus, indicating that neurogenesis — or the creation of new brain cells — was primarily occurring there. Even more heartening, scientists found that exercise jump-starts neurogenesis. Mice and rats that ran for a few weeks generally had about twice as many new neurons in their hippocampi as sedentary animals. Their brains, like other muscles, were bulking up.