Lobes of Steel

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

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.

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