The anxiety cells were found in the hippocampus region of the mouse brain. Photo by Rene Hen/Columbia University Irving Medical Center
Jan. 31 (UPI) -- Scientists have identified a new group of cells associated with the fight-or-flight response of mice. Researchers detailed their discovery of the so-called anxiety cells this week in the journal Neuron.
"We call these anxiety cells because they only fire when the animals are in places that are innately frightening to them," Rene Hen, a professor of psychiatry at Columbia University Irving Medical Center, said in a news release. "For a mouse, that's an open area where they're more exposed to predators, or an elevated platform."
Scientists have previously identified neural cells and pathways linked with fear and anxiety, but the newly discovered cells are the first shown to trigger anxiety under a variety of circumstances.
"This is exciting because it represents a direct, rapid pathway in the brain that lets animals respond to anxiety-provoking places without needing to go through the higher-order brain regions," said Mazen Kheirbek, an assistant professor of psychiatry at the University of California, San Francisco.
Mice are often used as models for humans in medical and science experiments because they share so many genetic and physiological traits. Though scientists have yet to find the same neural cells in humans, it's likely a similar group of anxiety cells exists in the human brain.
The discovery could pave the way for a new type of therapy -- one that curbs the activity of the anxiety cells.
Scientists were able to measure brain cell activity using a miniature microscope. As mice moved through their surroundings -- a mixture of safe, secluded spaces and riskier, exposed spaces -- scientists observed activity in different parts of the brain increasing and decreasing.
Researchers identified a group of cells that were more active any time a mouse moved into a more exposed position. The same cells were also most active when mice appeared visibly more anxious.
Scientists traced the brain activity to a group of cells in the hippocampus, a portion of the brain linked with anxiety responses in humans.
Anxiety, fear and worry are all natural responses that aid in survival. But the system can become overactive and less discerning. A better understanding of how healthy anxiety works can help scientists identify why the system malfunctions and how best to fix it.
"We wanted to understand where the emotional information that goes into the feeling of anxiety is encoded within the brain," said Kheirbek.
Scientists say their next step is to determine whether the biochemistry of the newfound anxiety cells are unique in any way.
"We're looking to see if these cells are different molecularly from other neurons," Hen said. "If there's a specific receptor on the cells that distinguishes them from their neighbors, it may be possible to produce a new drug to reduce anxiety."