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Seattle Scientists Find Brain Area Linked To Motivation To Exercise

Kaytee Rlek
Mice without a functioning dorsal medial habenula didn't feel like running in their wheels.

Seattle scientists have zeroed in on a part of the brain that seems to have an interesting job: motivating the brain’s owner to exercise. The findings could have implications for understanding depression.

The dorsal medial habenula is a little structure tucked inside the brain, above the brainstem. Psychiatrist Eric Turner of Seattle Children’s Research Institute knew it had something to do with regulating mood, but not a lot more.

“People asked me, 'Well, what does it do?' And I actually didn’t know. And when I looked it up I found that very little is known about this area of the brain,” he said.

One way to find out what something does is to take it away and see what happens, so Turner and his collaborators, including Toni Hsu of Seattle Children's and Horacio de la Iglesia of the University of Washington, genetically engineered mice with habenulae that don’t work very well. The mice would eat and walk around pretty normally, but there was also a glaring difference.

“Anyone who’s had a pet hamster or gerbil or mouse knows that rodents love to runin a running wheel. They like exercise,” said Turner. “But [the altered mice] just had a greatly reduced desire to run in the wheel. They ran much, much less.”

Turner said those mice had turned into couch potatoes. And there was another difference: While most mice given a choice between sugar water and regular water will choose the sweet stuff, the altered mice just didn’t care.

Turner said the lack of motivation to exercise or even seek pleasure is a good model for depression. Depression probably doesn’t originate from just one brain area, Turner said, but likely emerges from multiple centers and systems. The new findings seem to point to a new “node in the depression pathway.” And since the habenula looks very similar in mice and people, it might be a something doctors can figure out how to tweak.

The findings are published in the Journal of Neuroscience.

Gabriel Spitzer is a former KNKX reporter, producer and host who covered science and health and worked on the show Sound Effect.