Specialized brain cells in the hippocampus appear to control the fight or flight response of mice used in a new study. Researchers hope that the discovery of these neurons could pave way for better treatments that can target and reduce anxiety.
Anxiety disorders are the most common mental illness in the United States, afflicting 40 million adults or 18.1 percent of the nation's population per year. Those with anxiety orders are up to six times more likely to be hospitalized because of psychiatric disorders.
Currently available medications for anxiety disorders, however, have significant drawbacks. Benzodiazepine, the most common anti-anxiety medication, for instance, is highly addictive in that tolerance and dependence can develop when used for an extended period of time.
The discovery of the so-called anxiety cells may lead to the development of better treatments for anxiety.
Using miniature microscope, study researcher Rene Hen of the Columbia University Irving Medical Center and colleagues measured the brain cell activity of mice as they moved in their surroundings.
The researchers were then able to identify a group of cells that appear to be more active whenever a mouse moves into riskier and more exposed spaces. The same cells were also most active when the animals appeared more anxious.
Hen and colleagues called them "anxiety cells" because they only fire when the animals are in places where they are frightened, such as in open areas where the animals are more exposed to predators.
Researchers already identified neural cells and pathways associated with fear and anxiety, but the newly identified cells are the first that were observed to trigger anxiety under a range of circumstances. The firing of the anxiety cells sends signals to other parts of the brain that turn on anxious behaviors.
In the animals used in the study, the researchers found that these behaviors include fleeing to a safe zone or avoiding the dangerous area. This direct, rapid pathway in the brains allows animals to respond to anxiety-provoking places sans the need to go through higher-order brain regions.
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The findings, which were detailed in a study published in the journal Neuron on Wednesday, may eventually pave way to better treatments for anxiety disorders.
"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.","