A new study has uncovered the existence of specialized neurons that regulate anxiety, a mental disorder affecting more than 30 million Americans.
Named as "anxiety cells," these neurons are located in the area of the brain that has long been linked to anxious behavior, the hippocampus.
In a mice experiment, a group of researchers from California and New York observed that when the rodents were exposed to provoking conditions, such cells were activated. They also figured out how to control the neurons using a beam of light, a discovery that could lead to a more effective treatment for the disorder.
"If we can learn enough, we can develop the tools to turn on and off the key players that regulate anxiety in people," says Joshua Gordon, director of the National Institute of Mental Health which funded the study.
Locating The Brain's Center For Anxiety
To study anxiety in mice, the animals were placed inside a maze with paths that led to open spaces. Their brain cell activity was then monitored as they navigated through the course. Researchers noticed that whenever a rodent ends up in an open space and begins to feel anxiety, certain neurons at the bottom of their hippocampus "fire up."
In a paper published Jan. 31 in Neuron, they report that this activity may not directly cause anxiousness but it appeared to be responsible for regulating the behavior. Through optogenetics, a new technique that alters specific cells using a beam of light, the group toned down such activity to determine its effect on the animals.
As the level of activity was reduced, the mice started to become less anxious and more adventures. They explored the maze without fearing its open spaces. However, this behavior changed when the level was increased. They felt more anxious and therefore, refused to move inside the maze at all.
Searching For Better Anxiety Treatment
Mazen Kheirbek of the University of California in San Francisco and one of the paper's authors stressed that their findings are simply as "one brick in a big wall." According to Kheirbek, there are more factors at play to induce the behavior besides these anxiety cells. They could only be a portion of an "extended circuit" that allows the rodent's brain to process anxiety-related information.
Still, this discovery is still considered as a tremendous step forward in the pursuit of a better anxiety treatment.
"Now that we've found these cells in the hippocampus, it opens up new areas for exploring treatment ideas that we didn't know existed before," says lead author Jessica Jimenez of Columbia University.
The presence of anxiety cells in the human brain is still a theory, though it is highly possible because of the similarities it shares with that of a mouse.