Scientists from the Seattle Children’s Research Institute have discovered a tiny area of the brain that could control our moviation to exercise and do other rewarding activities.
Their research revealed that a small region, known as the dorsal medial habenula, controls the desire to exercise in mice. Because the structure of the habenula brain region is very similar in humans and rodents, the scientists believe this section may play the same role in humans, and could be the key to new treatments for depression.
To identify the pathways involved in motivating exercise, the researchers studied mice that were genetically engineered to block signals from their dorsal medial habenula. Compared to regular mice, who love to run on their wheels, these engineered mice were lazy and ran far less.
“Without a functioning dorsal medial habenula, the mice became couch potatoes,” said Eric Turner, a neuroscientist and one of the lead researchers, in a press release. “They were physically capable of running but appeared unmotivated to do it.” The mice also lost their preference for sweetened drinking water.
The team then gave a second group of mice the choice of turning one of two response wheels with their paws - one of the wheels would result in their dorsal medial habenula being activated by lasers. The researchers found that the mice strongly preferred turning the wheel that stimulated their dorsal medial habenula, showing that this area of the brain is linked to rewarding behaviour. Their results have been published in the Journal of Neuroscience.
In the past, scientists have attributed many different functions to the habenula, but until now technology hasn’t been advanced enough to look at the various roles of the subsections of this area of the brain. Turner is now hoping that the region will have a similar function in humans, and that it will help them to better understand depression and mental health and develop new treatments.
Exercise is already known to be good for depression, but the problem is, people with depression aren’t usually interested in being active. “Changes in physical activity and the inability to enjoy rewarding or pleasurable experiences are two hallmarks of major depression,” said Turner.
“But 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.”