Where does anxiety come from?

A new study has shown that it seems to be controlled by a group of cells in the hippocampus and they could be regulated using light

Where does anxiety come from?

I woke up in the middle of the night, at 1:22 a.m. according to my cell phone. The numbness of my left arm and leg made me intensely worry, so I leap from my bed to the bathroom to check out everything was right. With no mirror, I had not any external sign that I was neither well nor bad. I thought that numbness was a clear indicator that I was having a severe attack or a stroke. At that moment, I thought that I could stop breathing and fall dead any minute.

I started breathing heavily, while I washed my hands and checked myself up in the dim light of the bathroom. Not convinced, I got out of the bathroom and lit the light of my bedroom. I still could not see anything out of order. I felt my so far 26 year-long life to be near the end. However, the only thing that end and the only attack I was experiencing was an anxiety attack. That is how you can feel when having one - that is, actually, the description of the last attack I had, less than 24 hours before writing this article.

Human brain is programmed to feel anxiety and, until recently, scientists did not have a clear idea of how it happened. According to a recent study, called “Anxiety cells in a hippocampal-hypothalamic circuit”, there is a group of cells in the hippocampus that controls anxiety and can be regulated with a beam of light.

The aim of the study, published by Neuron magazine, was to understand where emotional information about anxiety feelings is codified in the brain. For finding an answer, the scientists Rene Hen y Mazen Kheirbek used calcium-imaging technique, designed to show calcium status in an isolated cell, as well as in tissues.

They inserted miniature microscopes in the brains of laboratory mice to record activity of the cells in hippocampus, while the animals moved through circuits designed by them. Some of the paths led to open and elevated spaces, which induce anxiety in mice, due to the increased vulnerability to predators.

As they reached those spaces, researchers observed cells in the area called ventral CA1 (vCA1) activating and the more anxious the rodent was, the more activity they observed. The researchers decided to call those “anxiety cells” because they only activate when the animal is anxious, exposed to places known to be frightening for them, according to Rene Hen, from Columbia University.

The investigators traced the outputs of the cells to the hypothalamus, brain region that regulates the hormones responsible for controlling emotions. These results could be extrapolated to human neurobiology, given it functions in the same manner. Researchers hypothesize that anxiety cells could be present in human brains as well.

Therapeutic implications

Having discovered these cells implies that possibilities are open for exploring new treatments for this condition. Even more, it has already been discovered how to control them to the extent of changing the animal’s observable behavior.

Using a technique called optogenetics to shine a beam of light onto these cells, researchers were able to silence their activity and induce confident and anxiety-free behavior in the mice.

The scientists were able to do the opposite. Changing the light settings, they could enhance anxiety cells activity even in spaces that the animals considered safe. They concluded that these cells could be part of a larger circuit involved in learning about anxiety-related information. Investigators affirm is enough motivation to conduct another study of other neural cells.

The next step is to identify if the same control switch regulates human anxiety, as they think it does. If so, it would open a new research lead about new ways to treat anxiety conditions. This condition affect 7,3% of global population and ranges from 5,3% in African cultures to 10,4% in Anglo-European ones. According to a systematic review of other studies in the matter, published between 1980 and 2009, due to gender, ethnicity, age, conflicts, and economic status, anxiety could be as high as 28,3%.

 

Latin American Post | Andrés Felipe Ropero
Copy edited by Marcela Peñaloza

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