http://www.biosciencetechnology.com/news/2014/08/scientists-discover-brain-area-responsible-exercise-motivation?et_cid=4111840&
Scientists at Seattle Children’s Research Institute have discovered an area of the brain that could control a person’s motivation to exercise and participate in other rewarding activities – potentially leading to improved treatments for depression.
Dr. Eric Turner, a principal investigator in Seattle Children’s
Research Institute’s Center for Integrative Brain Research, together
with lead author Dr. Yun-Wei (Toni) Hsu, have discovered that a tiny
region of the brain – the dorsal medial habenula– controls the desire to
exercise in mice. The structure of the habenula is similar in humans
and rodents and these basic functions in mood regulation and motivation
are likely to be the same across species.
Exercise is one of the most effective non-pharmacological therapies
for depression. Determining that such a specific area of the brain may
be responsible for motivation to exercise could help researchers develop
more targeted, effective treatments for depression.
“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.”
Turner’s study, titled “Role of the Dorsal Medial Habenula in the
Regulation of Voluntary Activity, Motor Function, Hedonic State, and
Primary Reinforcement,” was published by the Journal of Neuroscience
and funded by the National Institute of Mental Health and National
Institute on Drug Abuse. The study used mouse models that were
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. Turner’s genetically engineered mice also
lost their preference for sweetened drinking water.
“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 turning one of two
response wheels with their paws. 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.
Past studies have attributed many different functions to the
habenula, but technology was not advanced enough to determine roles of
the various subsections of this area of the brain, including the dorsal
medial habenula.
“Traditional methods of stimulation could not isolate this part of
the brain,” Turner said. “But cutting-edge technology at Seattle
Children’s Research Institute makes discoveries like this possible.”
As a professor in the University of Washington Department of
Psychiatry and Behavioral Sciences, Turner treats depression and hopes
this research will make a difference in the lives of future patients.
“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.”
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