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7 Things We Can Turn Off and On in the Brain

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iStock / Rebecca O'Connell

As much as we’d like to think we’re always in control of our own actions, a lot of human behavior, mood, and habit can be traced to involuntary reactions in the brain. As researchers learn more about what’s going on inside our heads, they’re finding the light switches that control some of our most basic functions—many of which can be turned off. 

1. Thirst

Researchers know the control center for thirst is somewhere in the hypothalamus, an almond-sized section of the human brain that regulates a number of our basic functions (hunger, sex drive, temperature). But recently, neuroscientists at Columbia University identified two specific populations of neurons in the hypothalamus of mice that control the impulse to hydrate, and they wanted to know what happens when they’re activated. By using a process called optogenetics, they manipulated these cells to make them sensitive to certain wavelengths of light. Then, fiber-optic cables were implanted in the brains of mice that when illuminated, turned the corresponding neurons on or off.

They found that one group of thirst neurons “evokes intense drinking behavior” when activated. How intense? Mice drank up to eight percent of their body weight in water when these neurons were switched on. That’s the equivalent of a human drinking a gallon and a half of water in 10 minutes.

The second group of neurons reduces the desire to drink, even when the animal is deprived of water. You can see video of some very thirsty mice from this study here.

2. Hunger

Using the same optogenetics technique, scientists at Johns Hopkins University have pinpointed the brain cells that control our impulse to eat. When these cells are activated in mice, the rodents are compelled to stuff themselves well beyond the point of being full. But when they’re shut down, the mice ignore food, even when they should be hungry. Researchers think this information could potentially help treat eating disorders in humans.

3. Consciousness

We consider consciousness and self-awareness to be defining characteristics of human life. So it may surprise you to know that such sacred traits can be turned off and on like a light switch in a lab setting. At George Washington University, Mohamad Koubeissi and his team accidentally flipped the switch while using electrodes to stimulate different parts of the brain in an epileptic woman.

When they stimulated a section called the claustrum, the patient lost consciousness, but she didn’t pass out. Instead she sat motionless with a blank stare and showed no response to cues around her. She snapped out of her trance when the stimulation stopped, and had no memory of the lapse. "Ultimately, if we know how consciousness is created and which parts of the brain are involved then we can understand who has it and who doesn't," says Christof Koch at the Allen Institute for Brain Science in Seattle. "Do robots have it? Do fetuses? Does a cat or dog or worm?” The caveat: because of her epilepsy, this woman had part of her hippocampus removed, so her brain is far from that of a “normal” person.

Other studies have shown the human brain may switch off self-awareness when we’re stressed, without any help from researchers. In 2006, neurobiologists from the Weizmann Institute of Science in Rehovot, Israel observed that when humans are forced to focus on a difficult task (particularly under a strict deadline), the area of our brains associated with introspection, the cortex, becomes quiet, and we go into a sort of robotic mode until the task is done. This ability could have evolved for purposes of self-defense. "If there is a sudden danger, such as the appearance of a snake, it is not helpful to stand around wondering how one feels about the situation," researcher Ilan Goldberg told New Scientist.

4. Pain

We can already ease pain with certain drugs, but many treatments come with side effects like dependency and tolerance. Saint Louis University researcher Daniela Salvemini and her team think they’ve found a way to treat chronic pain caused by nerve damage, including the physical agony caused by chemotherapy and bone cancer. By turning on the “A3 adenosine receptor” in the brain and spinal cord, Salvemini and her team were able to block pain caused by nerve damage in rodents, without any of the side effects associated with drug treatments.

5. Violence

What if we could reduce the human urge to fight? Dayu Lin from New York University zoomed in on the hypothalamus, the previously-mentioned hub of bodily functions, to look at the specific neurons that fire during acts of physical violence. By stimulating those neurons using optogenetics, Lin was able to turn male mice into vicious fighters that attacked anything in their vicinity—including inanimate objects, and both male and female mice. She could also calm them, quelling their violent urges by silencing these neurons. Could this strategy one day be used on people? "I think there's every reason to think that this would be true in humans," says Newton Canteras, a neuroscientist at the University of São Paulo in Brazil, and a co-author of this study.

Interestingly, Lin and her team found violence-inducing neurons overlap and compete with neurons associated with sex. In fact, the act of sex temporarily suppresses the violent urges in mice.

6. Bad habits

Can’t stop biting your nails? Plagued by an urge to crack your knuckles? Neuroscientists have found the brain cells responsible for habit formation, at least in rats. By turning these neurons on or off, they are able to eliminate or encourage the formation of new habits. To test this, they gave lab rats a new habit. With a little help from a tasty reward, scientists trained the rodents to navigate a maze until it became so habitual that they’d do it even after the reward was replaced by punishment. But when the neurons were inhibited in the lab, the habit disappeared.

Right now, this kind of procedure would be too invasive to try on humans, says Professor Ann Graybiel, a member of the McGovern Institute for Brain Research at MIT. But it does pave the way for similar, more advanced treatments in the future.

7. Parkinson’s, depression—and maybe Alzheimer’s

Using electrodes embedded in the brain, a neurosurgeon from the University of Toronto named Andres Lozano is harnessing electricity to treat some of humanity’s most vexing ailments. For example, Lozano knows which neurons in the brain are misfiring to cause the severe shaking associated with Parkinson’s disease. In his TED Talk, he explains, “we use electricity to dictate how they fire, and we try to block their misbehavior using electricity. So in this case, we are suppressing the activity of abnormal neurons.” As a result of this suppression, tremors can be dramatically reduced.

Lozano has done similar work with areas in the brain that cause severe depression and is “seeing very striking results in these patients,” he says. Can this approach work for memory? In 2014, he launched a clinical trial to treat 50 people with mild Alzheimer’s with electrical stimulation “to get these areas of the brain that were not using glucose to use glucose once again.” We’ll know in April if the treatment worked.

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Here's What You Need to Know Before Getting Inked or Pierced, According to Doctors
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Getting inked or pierced is a rite of passage for many teens and young adults. But before getting that belly ring or butterfly on your back, experts want you to be aware of the risks, which are reviewed in a new clinical report from the American Academy of Pediatrics (AAP). According to NPR, it's the first set of recommendations the professional association has ever released on the practices.

Forthcoming in the October 2017 issue of Pediatrics and available online, the report provides a general assessment of the types and methods used to perform body modifications, along with potential health and social consequences. Here are a few main takeaways:

—It's unclear how often tattoos cause health complications, but they're generally believed to be rare, with the greatest risk being infection. One recent study found that nanoparticles in ink can travel to and linger in lymph nodes for an extended period. That said, you should check with your doctor to make sure all of your immunizations are up to date before getting either a tattoo or piercing, and that you're not taking any immunity-compromising medicines.

—Before shelling out your hard-earned cash on a tattoo, make sure it's something you'll likely still appreciate in five to 10 years, as it costs anywhere from $49 to $300 per square inch to remove a tattoo with lasers. (This might provide all the more incentive to opt for a small design instead of a full sleeve.)

—About half of people 18 to 29 years of age have some kind of piercing or tattoo, according to Dr. Cora Breuner, who is chair of the AAP committee on adolescence. Many individuals don't regret getting one, with some reporting that tattoos make them feel sexier. But while millennials appear to be cool with metal and ink, hiring managers might not be too pleased: In a 2014 survey of 2700 people, 76 percent said they thought a tattoo or piercing had hindered their chances of getting hired, and nearly 40 percent thought tattooed employees reflected poorly on their employers.

—Not all tattoo parlors are created equal, as each state has different regulations. Keep a close eye on whether your artist uses fresh disposable gloves, fresh needles, and unused ink poured into a new container. This helps prevent infection.

—The advice is similar for getting pierced: Make sure the piercer puts on new, disposable gloves and uses new equipment from a sterile container. Tongue piercings can cause tooth chippings, so be careful of that—and remove any piercings before you play contacts sports.

The full report is available online.

[h/t NPR]

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The Body
7 Essential Facts About the Pelvis
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The human body is an amazing thing. For each one of us, it’s the most intimate object we know. And yet most of us don’t know enough about it: its features, functions, quirks, and mysteries. Our series The Body explores human anatomy, part by part. Think of it as a mini digital encyclopedia with a dose of wow.

The pelvis, which crooner Elvis was famous for thrusting around in ways that raised eyebrows, is not actually a single body part but a term that refers to a collection of bones, muscles and organs below the waist. We spoke to Katherine Gillogley, department chair of obstetrics and gynecology with Mercy Medical Group in Sacramento, California, for these seven facts about the pelvis.

1. SO WHAT IS THE PELVIS, EXACTLY?

"The pelvis refers to the lower abdominal area in both men and women," Gillogley says. "An important function of the pelvis region is to protect organs used for digestion and reproduction, though all its functions are crucial," she says. It protects the bladder, both large and small intestines, and male and female reproductive organs. Another key role is to support the hip joints.

2. THE PELVIC BONES FORM A BASIN.

Four bones come together to form a bowl-like shape, or basin: the two hip bones, the sacrum (the triangle-shaped bone at the low back) and the coccyx (also known as the tailbone).

3. YOUR PELVIC FLOOR IS LIKE A TRAMPOLINE.

At the bottom of the pelvis lies your pelvic floor. You don't have to worry about sweeping it, but you might want to do Kegel exercises to keep it strong. The pelvic floor is like a "mini-trampoline made of firm muscle," according the Continence Foundation of Australia. Just like a trampoline, the pelvic floor is flexible and can move up and down. It also creates a surface (floor) for the pelvic organs to lie upon: the bladder, uterus, and bowels. It has holes, too, for vagina, urethra, and anus to pass through.

4. IT PLAYS A KEY PART IN WALKING.

Anyone who has ever broken a pelvic bone or pulled a pelvic muscle will know just how key a role the pelvis plays in such functions as walking and standing. "The pelvis also acts as a solid foundation for the attachment of the spinal column and legs," says Gillogley.

5. THE FEMALE PELVIS STARTS OUT LARGER, BUT NARROWS OVER TIME.

Gillogley says that the female pelvis "tends to be larger and wider" than the male, most likely to accommodate a baby during pregnancy and to make childbirth possible. However, women's pelvises narrow as they age, suggesting that they start out wider to accommodate childbearing and then shift when that is no longer necessary. A shifting pelvis shape is thought to be a key part of our evolutionary history, as it changed as when we began walking upright.    

6. PREGNANCY CHANGES THE PELVIS FOREVER.

During pregnancy the body secretes a hormone known as relaxin to help the body accommodate the growing baby and soften the cervix. However, what happens is, "the joints between the pelvic bones actually loosen and slightly separate during pregnancy and childbirth," Gillogley says. Sometimes, however, relaxin can make the joints too loose, causing a painful syndrome known as symphysis pubis dysfunction (SPD), causing the pelvic joint to become unstable, causing pain and weakness in the pelvis, perineum and even upper thighs during walking and other activities. Many women with the condition have to wear a pelvic belt. It usually resolves after pregnancy is over, though physical therapy may be necessary.

7. IT'S ACCIDENT PRONE.

According to the American Association for the Surgery of Trauma, about 8 to 9 percent of blunt trauma includes pelvic injury, Gillogley says. "These accidents include falls, motor vehicle crashes, bicycle accidents, and pedestrians being struck by moving vehicles. With these serious injuries, pelvic bones can fracture or dislocate and sometimes bladder injury even occurs." So take care with your pelvis—in worse-case scenarios, breaks of the pelvic bones can require pins, rods, and surgery to fix.

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