RACHEL MARTIN, HOST:
Scientists have identified specific brain cells that appear to control anxiety in mice. This could have implications for treating people with debilitating anxiety. Here's NPR's Jon Hamilton.
JON HAMILTON, BYLINE: There's a part of the brain that plays a key role in anxiety. It's called the hippocampus, and scientists wanted to learn more about precisely what the hippocampus is doing. So a team that included Mazen Kheirbek of the University of California, San Francisco studied the brains of mice. Kheirbek says they're great for this kind of experiment because they lead anxious lives.
MAZEN KHEIRBEK: Mice tend to be afraid of open places. So, for example, if you have a mouse in your apartment, the mouse will kind of run along the walls and won't really enter into the center of the room.
HAMILTON: To mimic that situation in the lab, the team put mice in a maze in which some pathways lead to scary, open spaces. Then they monitored the activity of brain cells at the very bottom of the hippocampus.
KHEIRBEK: And what we found is that these cells became more active whenever the animal went into an area that kind of elicits anxiety in these animals.
HAMILTON: That didn't prove the cells were causing anxious behavior though, so the team found a way to control the activity of these cells. Kheirbek says they wanted to answer a simple question.
KHEIRBEK: If we basically turned down this activity, will the animals become less anxious? And what we found is that they did become less anxious. They actually tended to want to explore the open arms of the maze even more so.
HAMILTON: When the researchers dialed up the activity, the mice got more anxious and didn't want to explore at all. But Kheirbek says there's a lot more to anxiety than just these cells in the hippocampus.
KHEIRBEK: These cells are probably just one part of an extended circuit by which the animal learns about anxiety-related information.
HAMILTON: For example, the cells communicate with another brain area that tells mice when to avoid something dangerous. Kheirbek says other parts of the anxiety circuit might detect dangerous odors or sounds. The team published their findings in the journal Neuron. And Joshua Gordon, who directs the National Institute of Mental Health, says it's an important advance.
JOSHUA GORDON: You can think of this paper as one brick in a big wall.
HAMILTON: Gordon says scientists are finding and assembling other bricks in the anxiety wall at a rapid pace. And they need to, he says, because nearly 1 in 5 adults in the U.S. suffers from an anxiety disorder, like out of control worrying, panic attacks or social phobia.
GORDON: Anxiety disorders are incredibly prevalent. They hit in the prime working years of life, and our treatments are, at best, partially efficacious.
HAMILTON: Gordon says treatments that specifically target the anxiety circuit should work better.
GORDON: If we can learn enough, we can develop the tools to turn on and off the key players that regulate anxiety in people.
HAMILTON: Gordon says that's why his institute is funding a wide range of research on anxiety, including the work that led to this new study.
Jon Hamilton, NPR News.
(SOUNDBITE OF HYAKKEI'S "PAVEMENT ALONG THE GINKGO TREES")
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