Scientists have discovered not just the physical location of anxiety in the brain, but they’re engineering ways to treat it at the source.
Anxiety plays an important role in our everyday life. Essentially it is designed to keep us safe from harm; so when we are in an environment that feels threatening or unsafe, anxiety is the catalyst for our avoidance behaviours to kick in. However, if threats begin to become overestimated in our brain, then this is where anxiety can become problematic.
So, in a bid to better understand these incidences of anxiety, the clever folks at Columbia University Irving Medical Centre (CUIMC) and the University of California, San Francisco (UCSF) examined how healthy anxiety is processed in the brains of mice.
They did this by inserting a miniature microscope into the brains of the mice, and then as the mice moved around a custom-built enclosure, they recorded the activity of these hundreds of cells within the hippocampus.
The mice were provided with enclosed spaces (in which they typically feel safe and protected, and are therefore without anxiety), as well as elevated, open spaces (where they tend to feel vulnerable and therefore highly anxious).
What the researchers noticed was that whenever the animals were in the open, anxiety-provoking spaces, specific cells in the central part of the hippocampus were fired. And the more anxious they became, the more intense the activity in the cells became.
The researchers found that the output of these cells was linked to the hypothalamus, which is the part of the brain that helps control behaviours associated with anxiety (in humans this includes the release of stress hormones, avoidance and increased heart rate).
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Researchers then experimented by turning the anxiety cells on and off through the use of a technique called “optogenetics”, which shines dedicated light beams onto the cells, to impact the level of activity of these anxiety neurons. What they discovered was that these cells directly controlled the anxiety behaviours of the mice. So even if the mice were in the safe, enclosed surrounds, when the anxiety cells were activated the animals elicited fear-related behaviours; and conversely, when the cells were suppressed, the mice showed no signs of fear or anxiety when entering the open, elevated spaces.
“We wanted to understand where the emotional information that goes into the feeling of anxiety is encoded within the brain,” explained Dr Mazen Kheirbek, PhD, an assistant professor of psychiatry and a member of the research team. Of the findings, Kheirbek added, “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.”
“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,” said researcher Jessica Jimenez.
Obviously, the next step is to confirm that these anxiety cells exist and function similarly in humans. There is a known likeness between mice and human brains so the possibility is high, which would then expand the potential for developing new, highly effective treatments for anxiety disorders.