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iStock / Rebecca O'Connell
iStock / Rebecca O'Connell

7 Things We Can Turn Off and On in the Brain

iStock / Rebecca O'Connell
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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Animals
Where Do Birds Get Their Songs?
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iStock

Birds display some of the most impressive vocal abilities in the animal kingdom. They can be heard across great distances, mimic human speech, and even sing using distinct dialects and syntax. The most complex songs take some practice to learn, but as TED-Ed explains, the urge to sing is woven into songbirds' DNA.

Like humans, baby birds learn to communicate from their parents. Adult zebra finches will even speak in the equivalent of "baby talk" when teaching chicks their songs. After hearing the same expressions repeated so many times and trying them out firsthand, the offspring are able to use the same songs as adults.

But nurture isn't the only factor driving this behavior. Even when they grow up without any parents teaching them how to vocalize, birds will start singing on their own. These innate songs are less refined than the ones that are taught, but when they're passed down through multiple generations and shaped over time, they start to sound similar to the learned songs sung by other members of their species.

This suggests that the drive to sing as well as the specific structures of the songs themselves have been ingrained in the animals' genetic code by evolution. You can watch the full story from TED-Ed below, then head over here for a sample of the diverse songs produced by birds.

[h/t TED-Ed]

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Animals
Watch the First-Ever Footage of a Baby Dumbo Octopus
NOAA, Wikimedia Commons // Public Domain
NOAA, Wikimedia Commons // Public Domain

Dumbo octopuses are named for the elephant-ear-like fins they use to navigate the deep sea, but until recently, when and how they developed those floppy appendages were a mystery. Now, for the first time, researchers have caught a newborn Dumbo octopus on tape. As reported in the journal Current Biology, they discovered that the creatures are equipped with the fins from the moment they hatch.

Study co-author Tim Shank, a researcher at the Woods Hole Oceanographic Institution in Massachusetts, spotted the octopus in 2005. During a research expedition in the North Atlantic, one of the remotely operated vehicles he was working with collected several coral branches with something strange attached to them. It looked like a bunch of sandy-colored golf balls at first, but then he realized it was an egg sac.

He and his fellow researchers eventually classified the hatchling that emerged as a member of the genus Grimpoteuthis. In other words, it was a Dumbo octopus, though they couldn't determine the exact species. But you wouldn't need a biology degree to spot its resemblance to Disney's famous elephant, as you can see in the video below.

The octopus hatched with a set of functional fins that allowed it to swim around and hunt right away, and an MRI scan revealed fully-developed internal organs and a complex nervous system. As the researchers wrote in their study, Dumbo octopuses enter the world as "competent juveniles" ready to jump straight into adult life.

Grimpoteuthis spends its life in the deep ocean, which makes it difficult to study. Scientists hope the newly-reported findings will make it easier to identify Grimpoteuthis eggs and hatchlings for future research.

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