Scientists Identify Cells in the Brain That Control Anxiety

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People plagued with the uncomfortable thoughts and sensations characteristic of anxiety disorders may have a small group of cells in the brain to blame, according to a new study. As NPR reports, a team of researchers has identified a class of brain cells that regulates anxiety levels in mice.

The paper, published in the journal Neuron, is based on experiments conducted on a group of lab mice. As is the case with human brains, the hippocampus in mouse brains is associated with fear and anxiety. But until now, researchers didn't know which neurons in the hippocampus were responsible for feelings of worry and impending danger.

To pinpoint the cells at work, scientists from Columbia University, the University of California, San Francisco, and other institutions placed mice in a maze with routes leading to open areas. Mice tend to feel anxious in spacious environments, so researchers monitored activity in the hippocampus when they entered these parts of the maze. What the researchers saw was a specialized group of cells lighting up when the mice entered spaces meant to provoke anxiety.

To test if anxiety was really the driving factor behind the response, they next used a technique called optogenetics to control these cells. When they lowered the cells' activity, the mice seemed to relax and wanted to explore the maze. But as they powered the cells back up, the mice grew scared and didn't venture too far from where they were.

Anxiety is an evolutionary mechanism everyone experiences from time to time, but for a growing portion of the population, anxiety levels are debilitating. Generalized anxiety disorder, social anxiety disorder, and panic disorder can stem from a combination of factors, but most experts agree that overactive brain chemistry plays a part. Previous studies have connected anxiety disorders to several parts of the brain, including the hippocampus, which governs memory as well as fear and worry.

By uncovering not just how the brain produces symptoms of anxiety but the individual cells behind them, scientists hope to get closer to a better treatment. There's more work to be done before that becomes a possibility. The anxiety cells in mice aren't necessarily a perfect indicator of which cells regulate anxiety in humans, and if a new treatment does eventually come from the discovery, it will be one of many options rather than a cure-all for every patient with the disorder.

[h/t NPR]

Why Is Pee Yellow?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asks. Do you have a question? Send it to why@mentalfloss.com.

Your body is kind of like a house. You bring things into your body by eating, drinking, and breathing. But just like the things we bring home to real houses, we don’t need every part of what we take in. So there are leftovers, or garbage. And if you let garbage sit around in your house or your body for too long, it gets gross and can make you sick. Your body takes out the garbage by peeing and pooping. These two things are part of your body’s excretory system (ECKS-krih-tore-eee SISS-tem), which is just a fancy way of saying “trash removal.” If your body is healthy, when you look in the toilet you should see brown poop and yellow pee.

Clear, light yellow pee is a sign that your excretory system and the rest of your body are working right. If your pee, or urine (YER-inn), is not see-through, that might mean you are sick. Dark yellow urine usually means that you aren’t drinking enough water. On the other hand, really pale or colorless pee can mean you might be drinking too much water! 

Your blood is filtered through two small organs called kidneys (KID-knees). Remember the garbage we talked about earlier? The chemicals called toxins (TOCK-sins) are like garbage in your blood. Your kidneys act like a net, catching the toxins and other leftovers and turning them into pee.

One part of your blood is called hemoglobin (HEE-moh-gloh-bin). This is what makes your blood red. Hemoglobin goes through a lot of changes as it passes through your body. When it reaches your kidneys, it turns yellow thanks to a chemical called urobilin (yer-ah-BY-lin). Urobilin is kind of like food coloring. The more water you add, the lighter it will be. That's why, if you see dark yellow pee in the toilet, it's time to ask your mom or dad for a cup of water. 

To learn more about pee, check out this article from Kids Health. 

Why Don’t We Fall Off the Earth?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asksHave a question? Send it to why@mentalfloss.com.

Do you know the saying “what goes up, must come down”? There’s a lot of truth to that. No matter how hard you hit that baseball or how high you get on the swings, you’re not going to make it into space (without a spaceship, of course). This is because of something called gravity (GRAV-it-ee). Gravity is the force that keeps you (and all your toys) from floating into space. 

The Earth’s gravity is a force that works kind of like a magnet. When you jump in the air, you come back down because gravity is pulling you towards the center of the Earth. Gravity does a lot more than just keep your feet on the ground. The strong pull of planets has created whole solar systems and galaxies. The Earth's gravity pulls in the Moon, which orbits (or circles) around it. Objects that orbit planets are called satellites (SAT-uh-lights). Some other planets have one or more moons of their own. The largest planet in our solar system, Jupiter, has 63 known moons! The Sun also has a gravitational (grav-uh-TAY-shun-ull) pull. It pulls all the planets in our solar system around it. Just like the Moon circles the Earth, the Earth circles the Sun.   

This force is something that all objects have—even you! The reason you don’t have tiny objects stuck to you is because you’re not big enough to have a strong enough pull. Even really big things like whales aren’t large enough to have a gravitational pull. Only really, really big things like stars, planets, and moons have it. 

The Moon is big enough to have its own pull. Its gravity tugs on the Earth's oceans. That's why we have ocean tides. But the Moon's gravity isn't as strong as the Earth’s. That’s why the astronauts who visited the Moon were able to jump really high. If those same astronauts went to a bigger planet, like Jupiter, the gravity would be a lot stronger. There, they would feel much heavier, and they wouldn't be able to jump much at all. People in spaceships are not near anything with a big gravitational force, so they can float in the air inside the spaceship. 

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