SMRs and AMRs

Wednesday, July 07, 2010

Phys Ed: Your Brain on Exercise

By GRETCHEN REYNOLDS
NYT

What goes on inside your brain when you exercise? That question has preoccupied a growing number of scientists in recent years, as well as many of us who exercise. In the late 1990s, Dr. Fred Gage and his colleagues at the Laboratory of Genetics at the Salk Institute in San Diego elegantly proved that human and animal brains produce new brain cells (a process called neurogenesis) and that exercise increases neurogenesis. The brains of mice and rats that were allowed to run on wheels pulsed with vigorous, newly born neurons, and those animals then breezed through mazes and other tests of rodent I.Q., showing that neurogenesis improves thinking.

But how, exactly, exercise affects the staggeringly intricate workings of the brain at a cellular level has remained largely mysterious. A number of new studies, though, including work published this month by Mr. Gage and his colleagues, have begun to tease out the specific mechanisms and, in the process, raised new questions about just how exercise remolds the brain.

Some of the most reverberant recent studies were performed at Northwestern University’s Feinberg School of Medicine in Chicago. There, scientists have been manipulating the levels of bone-morphogenetic protein or BMP in the brains of laboratory mice. BMP, which is found in tissues throughout the body, affects cellular development in various ways, some of them deleterious. In the brain, BMP has been found to contribute to the control of stem cell divisions. Your brain, you will be pleased to learn, is packed with adult stem cells, which, given the right impetus, divide and differentiate into either additional stem cells or baby neurons. As we age, these stem cells tend to become less responsive. They don’t divide as readily and can slump into a kind of cellular sleep. It’s BMP that acts as the soporific, says Dr. Jack Kessler, the chairman of neurology at Northwestern and senior author of many of the recent studies. The more active BMP and its various signals are in your brain, the more inactive your stem cells become and the less neurogenesis you undergo. Your brain grows slower, less nimble, older.

(More here.)

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