How far we’ve come. In the 1930s, Sigmund Freud asked his depression stricken patients to lie down on a couch. Now, a new study shows, the better cure may be to get off the couch and run it off.
The search for a non-pharmacological mental health treatment has been fine-tuned by scientists at Seattle Children’s Research Institute (SCRI). Researchers there have discovered a specific area of the brain that might eventually be targeted in an attempt to treat depression.
Dr. Eric Turner, a principal investigator in the Institute’s Center for Integrative Brain Research, together with lead author Dr. Yun-Wei (Toni) Hsu, discovered that a tiny region of the brain – called the dorsal medial habenula – controls the motivation in mice to exercise and participate in other physically rewarding activities.
The abstract of the team’s study was recently published in the Journal of Neuroscience.
“Changes in physical activity and the inability to enjoy rewarding or pleasurable experiences are two hallmarks of major depression,” Turner said. “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.”
Funded by the National Institute of Mental Health and the National Institute on Drug Abuse, the study used mouse models genetically engineered to block signals from the dorsal medial habenula. In the first part of the study, Turner’s team collaborated with Dr. Horacio de la Iglesia, a professor in University of Washington’s Department of Biology, to show that compared to typical mice, who love to run in their exercise wheels, the genetically engineered mice were lethargic and ran far less.
“Without a functioning dorsal medial habenula, the mice became couch potatoes,” Turner said. “They were physically capable of running but appeared unmotivated to do it.”
In a second group of mice, Turner’s team activated the dorsal medial habenula using optogenetics – a precise laser technology developed in collaboration with the Allen Institute for Brain Science. The mice could “choose” to activate this area of the brain by manipulating response wheels with their paws. Results showed the mice strongly preferred turning the wheel that stimulated the dorsal medial habenula, demonstrating that this area of the brain is tied to rewarding behavior.
Hope for humans? It’s possible: the basic structure of the habenula is similar in humans and rodents. Basic triggers for mood regulation and motivation are likely to be the same across species.
Bottom line: Exercise could be a big key to treating depression and associated conditions. And Turner is hopeful.
“Working in mental health can be frustrating,” Turner said. “We have not made a lot of progress in developing new treatments. I hope the more we can learn about how the brain functions the more we can help people with all kinds of mental illness.”
Journal source: The Journal of Neuroscience, 20 August 2014, 34(34): 11366-11384; doi: 10.1523/JNEUROSCI.1861-14.2014