Does Running on a Treadmill Enhance Brain Plasticity?

Aerobic exercise may enhance motor skill learning via changes in the midbrain.

Posted May 09, 2020

Do you need a new source of motivation to get you off the couch and exercising more during COVID-19 quarantines? If so, consider this:

 Wikimedia/Life Science Databases (LSDB)
Midbrain in red.
Source: Wikimedia/Life Science Databases (LSDB)

New research (Li & Spitzer, 2020) from the University of California San Diego suggests that running on a treadmill—or doing any type of sustained aerobic exercise regularly—may increase brain plasticity and enhance motor skill acquisition.

This paper, "Exercise Enhances Motor Skill Learning by Neurotransmitter Switching in the Adult Midbrain," was published on May 4 in Nature Communications.

Although this study was conducted in mice, the research findings may apply to all mammalian brains, including those of humans. "[Our] study provides new insight into how we get good at things that require motor skills and provides information about how these skills are actually learned," co-author Nicholas Spitzer, director of UCSD's Kavli Institute for Brain and Mind (KIBM), said in a recent news release.

For decades, I've been trying to solve a complex riddle involving the midbrain's role in coordinating fine-tuned motor skills and creating Flow states. In my mind's eye, I view the midbrain as a bridge that connects both hemispheres of the cerebrum with both hemispheres of the cerebellum (Latin for "little brain").

Photo and illustration by Christopher Bergland (circa 2009)
Source: Photo and illustration by Christopher Bergland (circa 2009)

In 2009, I drew this rudimentary brain map (above) with multi-colored highlighters and Sharpie pens to illustrate my hypothesis that a superfluid state of Flow is more likely to occur during an athletic performance when all four brain hemispheres work together with frictionless synchronization.

In elite-level sports and everyday life, fine-tuned motor coordination relies on the midbrain. Why? The midbrain regulates motor coordination by integrating activity between the basal ganglia, cerebellum, and motor cortex. (See "Superfluidity and the Synergy of Your Four Brain Hemispheres")

Why Would Sustained Running Enhance Motor Skill Learning? 

For their recent study, Hui-quan Li and Nicholas Spitzer compared adult mice that voluntarily ran on an exercise wheel with a control group of mice that didn't have access to a running wheel. Li and Spitzer found that mice who exercised regularly for seven days were able to learn new complex motor skills (e.g., crossing a narrow balance beam or staying on a spinning "rotarod") more quickly than mice in the non-exercise group. 

"In comparison to mice without running wheels, mice that ran for one week demonstrated enhanced learning of motor skills, mastering an accelerating rotarod more rapidly and accommodating to balance beams more quickly," the authors wrote. 

Li and Spitzer's study on how sustained aerobic exercise affects the midbrain in mice found that running on an exercise wheel causes neurotransmitters in a region of the midbrain called the pedunculopontine nucleus to switch from acetylcholine (ACh) to gamma-aminobutyric acid (GABA).

The latest findings (2020) by Li and Spitzer suggest that sustained aerobic exercise causes neurotransmitter switching in the midbrain from ACh to GABA. This exercise-induced conversion of excitatory cholinergic neurons to inhibitory GABAergic neurons in the midbrain appears to enhance motor skill learning. As the authors explain:

"Aerobic physical exercise promotes the ability to acquire new motor skills and serves as a therapy for many motor disorders, but its basis of action is not well understood. Running is a natural motor activity for mice and generates plasticity in multiple brain regions. We find that mice that have run on a wheel for a week have an enhanced ability to acquire motor skill on the rotarod and balance beam."

Before this study, Li and Spitzer hypothesized that running might induce neurotransmitter switching in midbrain circuitry that is key to motor skill learning. Neurotransmitter switching is a newly appreciated form of plasticity in the adult mammalian brain that refers to a neuron's ability to change its transmitter identity in response to sustained stimuli. Neurotransmitter switching dramatically changes how neurons function.

Pixabay
Source: Pixabay

"For people who would like to enhance their motor skill learning, it may be useful to do some exercise to promote this form of plasticity to benefit the brain," Li said in the news release. "For example, if you hope to learn and enjoy challenging sports such as surfing or rock climbing when we're no longer sheltering at home, it can be good to routinely run on a treadmill."

In future studies, Nick Spitzer and his team at KIBM plan to investigate ways to deliberately trigger neurotransmitter switching without sustained aerobic exercise. "With an understanding of this mechanism comes the opportunity to manipulate and to harness it for further beneficial purposes," he concluded. 

References

Hui-quan Li and Nicholas C. Spitzer. "Exercise Enhances Motor Skill Learning by Neurotransmitter Switching in the Adult Midbrain" Nature Communications (First published: May 04, 2020) DOI: 10.1038/s41467-020-16053-7