Exercise, Motivation, and the Brain

A team at Seattle Children’s Research Institute, looking for answers about depression, learned something new that could make a difference to childhood obesity, specifically, an exciting revelation about motivation and mood regulation.

Principal investigator Dr. Eric Turner, who works with the Institute’s Center for Integrative Brain Research, is also a professor of Psychiatry and Behavioral Sciences at the University of Washington. The study’s lead author is Dr. Yun-Wei Hsu, and the publisher is the Journal of Neuroscience. The research was funded by the National Institute on Drug Abuse and the National Institute of Mental Health.

The area of interest is a part of the brain that seems to control the desire for physical activity, along with the ability to enjoy other activities that a well-functioning person recognizes as rewarding.

Depression Catch-22

A person suffering from major depression does not find enjoyment in much of anything, and the impulse to go out and run a few laps is definitely not operative in the midst of depression. This is particularly unfortunate because exercise can alleviate depression, and is in fact a recognized nonpharmacological therapy for the condition. The Catch-22 is that a person can’t benefit from physical activity if she or he is too depressed to engage in it. Dr. Turner is quoted as saying:

The brain pathways responsible for exercise motivation have not been well understood. Now, we can seek ways to manipulate activity within this specific area of the brain without impacting the rest of the brain’s activity.

What area of the brain is it? A tiny region called the the dorsal medial habenula. The hope is that by identifying it, a first step has been made toward developing more accurately targeted and thus more effective treatment for depression. Rodents and humans are similar in many ways, so knowing more about the habenula of a rodent is quite useful.

Two Stages

Normally, lab mice spend a lot of time running on their exercise wheels with every indication of enjoyment. They also relish drinking sweetened water when it is available. These traits are easily observable. But how do scientists know what kind of mood a rodent is in, and what motivates it to do what it does? A mouse that has no interest in running on the wheel or sipping sugar water obviously suffers from some impairment of its ability to have a good time. The first part of the study scrutinized mice that had been genetically engineered so that signals from the dorsal medial habenula were blocked, and their behavior was as lethargic, unmotivated, and couch-potatoish as that of depressed humans.

The second part of the elaborate experiment is best understood by reading the original report. The description of the very advanced technology employed to find these results is fascinating. The study convinced the researchers that the dorsal medial habenula is indeed intimately connected with rewarding behavior, and with mood regulation and motivation.

Benefits of Exercise

Hopefully at some point the knowledge gained here can be extrapolated and adapted to invent a new mode of therapy that can help morbidly obese young people turn their lives around. Childhood Obesity News has discussed the benefits of exercise before. On the most basic and obvious level, it burns calories, but this is just scratching the surface. For a refresher course in why physical activity is so essential, please review Neila Rey’s “50 Reasons to Exercise” poster. Shown in miniature on this page, it is available in full-size as a downloadable PDF file.

Your responses and feedback are welcome!

Source: “Area of brain responsible for exercise motivation discovered,” ScienceDaily.com, 08/20/14.
Image by Neila Rey.

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