In rats, anxiety is not in the head. It can begin in the heart

When you are stressed and anxious, you may feel your heart racing. Is your heart racing that you fear? Is your racing heart itself contributing to your anxiety? Both could be true, a new study in mice suggests.

By artificially increasing the heart rates of the mice, the scientists were able to increase anxiety-like behavior – which the team then calmed down by turning off a part of the brain. Study in the month of March 9 published natureshows that in high-risk contexts the heart rate can go to the head and increase anxiety. The findings could provide a new angle for studying and potentially treating anxiety disorders.

The idea of ​​contributing bodily sensations to movements in the brain goes back at least to one of the founders of psychology, William James, says Karl Deisseroth, a neuroscientist at Stanford University. In James’s 1890 book Principles of Psychologyto propose that the emotion follows what the body experiences. “Let us repent because we cry, we are angry because we strike, we fear because we tremble,” James wrote.

The brain is certainly capable of sensing internal body signals, a phenomenon called interoception. However, whether these sensations – such as the racing heart – can contribute to movement, it is difficult to prove, Anna Beyeler, a neuroscientist at the French National Institute of Health and Medical Research in Bordeaux. He studied brain circuitry related to movement and wrote a commentary on the new study but was not involved in the research. “I’m sure many people thought of doing these experiments, but no one really had the tools,” he said.

Deisseroth spent his life developing those tools. He is one of the physicists who developed optogenetics—a technique that uses viruses to modify the genes of specific cells in response to light.SN: 6/18/21; SN: 1/15/10). Scientists can use a light flip switch to activate or suppress the activity of those cells.

In the new study, Deisseroth and colleagues placed the light of a small garment over the heart of a mouse engineered to change the animal’s heart rate. When the light was off, the mouse’s heart beats about 600 times per minute. But when the ball turned on the light that flashed at 900 beats per minute, the pulsing pulsation of the mouse followed suit. “It’s a nice reasonable acceleration; [one a mouse] at a time when stress or fear would occur,” explains Deisseroth.

The mice, when they felt their hearts racing, made similar gestures; In dangerous situations – such as in open areas where a muscle would be a meal – rats have sunk into the walls and are hiding in darker corners. When the bar was pressed for water, which could sometimes be coupled with a mild shock, the rats with their heartburns were still uncontrollably pressed. But the rats, with racing hearts, decided to be thirsty instead.

“Everyone was waiting, but it was the first time it was shown,” Beyeler says.

The researchers also examined the animals’ brains to find areas that could be enhanced by processing. One of the most important signs said that Deisseroth came from the back island.SN: 4/25/16). “The island was interesting because it’s very connected to the interoceptive environment,” he explains. “When we saw this sign, [our] the matter is certainly tiring.”

Using several optogenetics, the team reduced activity in the posterior insula, which reduced the mice’s anxiety-related behavior. The hearts of the animals were still poured out, but they behaved regularly, staying in the open places of the blunderbusses and rushing to the water without fear.

A lot of people are very excited about the work, says Wen Chen, branch chief of basic medical research for complementary and integrative health at the National Center for Complementary and Integrative Health in Bethesda, Md. “Any meeting I’m going to go to, in the next couple of days, everyone brought up this paper,” said Chen, who was not involved in the research.

The next step, says Deisseroth, is to look at other parts of the body that affect anxiety. Sometimes we feel it in our stomach, or we feel it in our neck or shoulder, he says. Using optogenetics to tense the muscles, or give away butterflies in the tummy, reveals other ways that fearful or anxiety-producing behaviors are produced.

Understanding the connection between the heart and the head is ultimately a factor in how doctors treat panic and anxiety, Beyeler says. But the journey between the lab and the clinic is much more convoluted than heart-to-head.