Of Mice & Men — And Women

Scientists love to work with mice or rats — laboratory rats, not the creepy kind found in alleys. They can take a bunch of the little guys, put one group in a high activity environment with lots of exercise and another group in a sedentary environment where they just eat and sleep.

After a few weeks or months they dissect them and examine what’s happened to their brains based on which environment they were in. What they find is that there’s more going on with the active guys than those in the sedentary environment — by a lot.

To be sure that what they learn applies to us, all they have to do is find human volunteers who are either willing to do lots of exercise or just sit — finding those is not all that hard. But then, they need to do a bit of brain dissection. Where did those volunteers go?

As mentioned earlier, the Beckman Institute at the University of Illinois is one of the laboratories generating lots of research on exercise and the brain. Bill Greenough’s pioneering studies on the effects of exercise and environmental stimulation on rats was done there.

In the following section we’ll discuss two areas of the brain: dentate gyrus, which is a section of the hippocampus that contributes to new memories, and olfactory bulb, the section involved with the perception of odors.

Worth Reading Twice

Art Kramer, director of the Beckman Institute, said, “Both the animal and human research is pretty solid with respect to the fitness effect on brain structure, brain function, neurochemistry, learning, memory and cognition.” This is from a paper, “The Science of the Brain: A Beckman Perspective” by Steve McGaughey, May 2007. Beckman is the source of many of the studies that examine fitness training effects on human brain structure and function.

Stanley J. Colcombe and others at the University of Illinois reported on fifty-nine healthy but sedentary volunteers, age sixty to seventy-nine. For six months half of them did aerobic exercise and the other half did toning and stretching.

Using MRIs they reported: “Significant increases in brain volume in both gray and white matter regions were found as a function of fitness training for the older adults who participated in the aerobic fitness but not for the older adults who participated in the stretching and toning.”

After six months of aerobic exercise that group had the brain volume of people three years younger. They reversed brain loss.

Their conclusion: “These results suggest a strong biological basis for the role of aerobic fitness in maintaining and enhancing central nervous system health and cognitive functioning in older adults.”

Another study at UCLA of ninety-four people in their seventies showed that obese people have eight percent less brain tissue that those of normal weight. Their brains looked sixteen years older than the brains of lean participants.

Justin Rhodes, also at the University of Illinois, said, “We know that there are areas of the brain that continuously generate new neurons throughout adulthood and one of those areas is the dentate gyrus section of the hippocampus. It turns out that exercise produces a tremendous increase in the number of new neurons that are found in that area.”

Research has shown new neurons in the dentate gyrus and in the olfactory bulb. Art Kramer said, “Every other area of the brain is highly debatable, but these two areas are not debatable. And those neurons are born as a function of exercise.”

Art Kramer added: “Actually, although neurogenesis occurs in developed organisms in both the dentate gyrus of the hippocampus and the olfactory bulb — thus far only exercise-related neurogenesis has been found in the hippocampus.”