College of LAS « Illinois

Psychology

Exercise Boosts Brainpower

Physical exercise even has benefits over certain mental exercise.

Rhodes

If you want to do your mind a favor and boost your ability to learn, a gym might be as good a place to start as a library. After all, University of Illinois research shows that exercise is not just good for the lungs, legs, and arms. It’s also good for the brain.

In fact, regular physical exercise may do more to improve general brain function than certain mind exercises, says Justin Rhodes, U of I psychology professor with the Beckman Institute for Advanced Science and Technology.

“We’ve shown that exercise seems to improve your general cognitive abilities,” Rhodes says. “The question is how it does that.”

Rhodes’s work has shed some light on this question, for his research with mice has shown that regular exercise can increase the number of neurons in the brain’s hippocampus by two to five times. It also helps existing neurons to survive, causing the hippocampus to grow larger. The hippocampus, a critical part of the brain for memory and learning, is where important sensory information first comes together from various regions of the brain.

“Physical activity seems to engage this structure directly in proportion with the intensity of the activity,” he says. “If you walk sluggishly, you get a little benefit. If you run, you get more.”

In addition to boosting the number of neurons in the hippocampus, Illinois research found that blood vessel density also increased in the dentate gyrus region of the hippocampus. This makes sense because exercise stimulates the heart rate and blood flow throughout the body, including the brain.

“So the only thing that mattered for growing neurons was running,” he says.

However, Rhodes stresses that his research does not mean that environmental enrichment has no benefit for the brain, even if it doesn’t increase neurons in the hippocampus. He says landmark research by William Greenough, Illinois psychology professor emeritus, has long shown that environmental enrichment improves learning in a variety of tasks; it also enhances plasticity (changes in neural pathways) in the motor cortex and cerebellum.

In Rhodes’s study, mice that had an increase in neurons also performed significantly better in cognitive learning tests. But was the increase in neurons in the hippocampus responsible for this improved cognitive ability, or was something else coming into play?

To find out, Illinois researchers used irradiation to prevent the brain’s hippocampus from growing new neurons, even when the mice exercised. Sure enough, without the increase in neurons, researchers no longer saw benefits in spatial navigation learning. They are now trying to confirm this link between increased neurons and improved learning in a follow-up study with genetically modified mice.

Mice saw benefits after a month of exercising, but Rhodes says other Illinois research has shown that the cognitive benefits of exercise in humans can take about six months of exercise three times per week. Illinois is known for its extensive research on the impacts of exercise, and human studies confirm the benefits of exercise shown by mouse studies.

According to Rhodes, “When you double or triple the number of new neurons and you grow a structure in the brain that is well known to play a role in learning and memory, positive things can happen.”

 

Rhodes’s team studied four groups of mice, which make ideal research models because they are genetically and physiologically similar to humans.

  • One group was placed in a “sensory exciting” environment with numerous toys, as well as exposure to many types of sounds, colors, textures, and tastes. However, these mice did not have an exercise wheel.
  • A second group had both an exercise wheel and the sensory-enriched environment.
  • A third group had an exercise wheel, but did not have a sensory-enriched environment.
  • The final group had no exercise wheel and no additional sensory stimulation.

Researchers discovered that the increase in neuron numbers was found only in the two groups of mice with running wheels, even those without a sensory-enriched environment.

Summer 2013
By Doug Peterson