playthink

From researchers at Princeton University: Running by yourself could be bad for your brain. Or at least, not as good as running with a group.

According to an article in the journal Nature Neuroscience, as reported by the BBC, exercise can have “negative effects on activity in the brain… Running is known to increase levels of stress hormone corticosterone, which can reduce the creation of new brain cells - a process known as neurogenesis.”

But wait, right?! Isn’t exercise good for the brain? Doesn’t physical activity promote neurogenesis?

Here’s where things can get a bit complicated.

Yes, exercise “has been found to increase spatial awareness and to boost communication between neurons.”

But… Only (or at least, especially) if exercise is done with others. Or if done for a really long time. Here’s the rundown on this study (no pun intended):

The researchers at Princeton looked at rats that ran in groups and rats that ran in social isolation. In both groups, “running caused similar elevations of the stress hormone, which can impair neuron generation.”

However, “running was found to increase neuron generation when rats were housed in groups. In rats that ran in social isolation, neurogenesis was suppressed.”

So even though running increased stress on the brain, which can impair neuron generation, group running “increase[d] spatial awareness and boost[ed] communication between neurons.” Running is stressful for the brain, but the social aspect of group running produced more good things for the brain than it hurts.

The rats that ran in isolation, however, experienced no such gain. “Only animals that ran alone were vulnerable to its negative influence. They also had higher levels of the hormone compared to group runners.”

So running alone could be bad for the brain. Unless…

Unless you go for a really long run. “When isolated rats ran for a long time, they did see the same benefits as their short-term runner peers [who ran in groups] - but only when they had been running for a much longer period.”

The Princeton research team was led by Dr. Elizabeth Gould. In their article, “Social isolation delays the positive effects of running on adult neurogenesis” (aka “The Stress of Running Alone” article), in the journal Nature Neuroscience, she explained, “In the absence of social interaction, a normally beneficial experience can exert a potentially deleterious influence on the brain.”

So what to do? Grab a friend and hit the trails. Or, if going solo, go long. Real long.

Fascinating research. It’s enough to make you…

Play, think…
J.R. Atwood

Here’s a long excerpt from “Lobes of Steel,” a fascinating story by Gretchen Reynolds in the NYT that (1) explores the relationship between exercise and neurogenesis and (2) explains how engaging in physical fitness might have as many benefits for your brain as it does for your body:

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.

Gage’s mice proved otherwise. Before being euthanized, the animals had been injected with a chemical compound that incorporates itself into actively dividing cells. During autopsy, those cells could be identified by using a dye. Gage and his team presumed they wouldn’t find such cells in the mice’s brain tissue, but to their astonishment, they did. Up until the point of death, the mice were creating fresh neurons. Their brains were regenerating themselves.

All of the mice showed this vivid proof of what’s known as “neurogenesis,” or the creation of new neurons. But the brains of the athletic mice in particular showed many more. These mice, the ones that scampered on running wheels, were producing two to three times as many new neurons as the mice that didn’t exercise.

But did neurogenesis also happen in the human brain? To find out, Gage and his colleagues had obtained brain tissue from deceased cancer patients who had donated their bodies to research. While still living, these people were injected with the same type of compound used on Gage’s mice. (Pathologists were hoping to learn more about how quickly the patients’ tumor cells were growing.) When Gage dyed their brain samples, he again saw new neurons. Like the mice, the humans showed evidence of neurogenesis.

Gage’s discovery hit the world of neurological research like a thunderclap. Since then, scientists have been finding more evidence that the human brain is not only capable of renewing itself but that exercise speeds the process.

This spring, neuroscientists at Columbia University in New York City published a study in which a group of men and women, ranging in age from 21 to 45, began working out for one hour four times a week. After 12 weeks, the test subjects, predictably, became more fit. Their VO2 max, the standard measure of how much oxygen a person takes in while exercising, rose significantly.

But something else happened as a result of all those workouts: blood flowed at a much higher volume to a part of the brain responsible for neurogenesis. Functional M.R.I.’s showed that a portion of each person’s hippocampus received almost twice the blood volume as it did before. Scientists suspect that the blood pumping into that part of the brain was helping to produce fresh neurons.

Rather than send students who struggle academically to the principal’s office or to a learning specialist, maybe teachers should send them out on a run with the PE class for a few laps around the baseball and football fields.

Play, think…
J.R. Atwood