Chapter 16. None

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By GRETCHEN REYNOLDS Mice do not, so far as we know, practice meditation. But in order to study how that activity affects human brains at the cellular level, researchers at the University of Oregon managed to put murine brains into a somewhat equivalent state. Their experiments, reported in March in the Proceedings of the National Academy of Sciences, suggest new ways of investigating how a person’s brain can constantly reshape itself. Past studies have suggested that people who meditate tend to have more white matter in and around the anterior cingulate cortex, a part of the brain involved in regulating emotions. Meditation also seems to intensify theta-wave activity, a type of rhythmic electrical pulsation often associated with a state of calm. Psychologists at Oregon speculated that the surge in theta waves stimulated the production of cells in the white matter. But they needed to develop an animal model of this activity; they obviously couldn’t examine the living brain tissue in meditating humans. So the psychologists asked colleagues in the university’s neuroscience department if they could increase theta-wave activity in mice, which were already being used to study brain states and neural plasticity, or the brain’s ability to rewire itself. Could the neuroscientists create a comparable effect in mice? Yes, it turned out, using a brain-research technique known as optogenetics, which uses light to turn on and off neurons, and mice that have been bred with specific genes responsive to light. The Oregon group, by pulsing the light at the same frequency found in human theta waves (eight hertz), were able to switch on the neurons in the anterior cingulate cortexes of the mice. They also exposed some mice to light at higher and lower frequencies and left others alone. Each treated mouse received 30 minutes of light therapy for 20 days, in an attempt to mimic the amount of meditation done in earlier human studies. Afterward, those mice exposed to the eight-hertz, thetalike light waves proved to be relatively calm in behavioral tests: they lingered in lighted portions of a special cage, while their twitchier counterparts ran for the shadows. © 2017 The New York Times Company

Keyword: Stress
Link ID: 23646 - Posted: 05.22.2017

By RONI CARYN RABIN Q. How can a blood test determine if I have prediabetes? How much weight do I need to lose to bring my numbers down? A. Doctors typically perform one of three blood tests to diagnose prediabetes, a condition marked by blood sugar (glucose) levels that are higher than normal but not high enough to qualify as diabetes. While prediabetes often leads to full-fledged Type 2 diabetes, many people can hold the condition in check if they lose a relatively small amount of weight and increase their physical activity, said Dr. Rhonda Bentley-Lewis, an assistant professor of medicine at Harvard Medical School. “I stress to my patients that we’re not talking about a huge amount of weight,” she said, “just 5 to 7 percent of one’s body weight” — or 10 to 14 pounds for someone who weighs 200 pounds. Two of the tests require fasting, which helps prevent results being distorted by a prior meal and provides “an even baseline,” Dr. Bentley-Lewis said. One, the fasting plasma glucose test, checks blood glucose levels after an 8 to 10 hour fast; results of 100 to 125 milligrams per deciliter indicate prediabetes. The other, the oral glucose tolerance test, is the most sensitive. It checks blood glucose levels after fasting and then two hours after you consume a sweetened drink; levels of 140 to 199 after the drink indicate prediabetes. A third test, the A1C test, may be the most convenient because it doesn’t require fasting. It measures your average blood glucose levels over the past two to three months; results of 5.7 percent to 6.4 percent, which indicate the percentage of red blood cells that have glucose attached to them, indicate prediabetes. Though doctors often repeat a test to confirm a diabetes diagnosis, they do not always do so for a prediabetes diagnosis, Dr. Bentley-Lewis said. Doctors can treat prediabetes with medication, but many patients prefer to try weight loss and exercise first, Dr. Bentley-Lewis said. Among thousands of people with prediabetes who participated in a national study called the Diabetes Prevention Program, 58 percent of those who adopted lifestyle changes, like losing a modest amount of weight, stepping up physical activity and reducing the amount of fat and calories in their diets, were able to prevent progression to full-blown diabetes. © 2017 The New York Times Company

Keyword: Obesity
Link ID: 23634 - Posted: 05.19.2017

By GRETCHEN REYNOLDS When young athletes sustain concussions, they are typically told to rest until all symptoms disappear. That means no physical activity, reading, screen time, or friends, and little light exposure, for multiple days and, in severe cases, weeks. Restricting all forms of activity after a concussion is known as “cocooning.” But now new guidelines, written by an international panel of concussion experts and published this month in the British Journal of Sports Medicine, question that practice. Instead of cocooning, the new guidelines suggest that most young athletes should be encouraged to start being physically active with a day or two after the injury. “The brain benefits from movement and exercise, including after a concussion,” says Dr. John Leddy, a professor of orthopedics at the Jacobs School of Medicine and Biomedical Sciences at the University at Buffalo, and one of the co-authors of the new guidelines. There has long been controversy, of course, about the best ways to identify and treat sports-related concussions. Twenty years ago, athletes who banged their heads during play were allowed to remain in the practice or game, even if they stumbled, seemed disoriented, or were “seeing stars.” Little was known then about any possible immediate or long-term consequences from head trauma during sports or about the best responses on the sidelines and afterward. Since then, mounting evidence has indicated that sports-related concussions are not benign and require appropriate treatment. The question has been what these appropriate treatments should be. In the early 2000s, dozens of the world’s premier experts on sports-related concussions started meeting to review studies about concussions, with plans to issue a consensus set of guidelines on how best to identify and deal with the condition. © 2017 The New York Times Company

Keyword: Brain Injury/Concussion
Link ID: 23633 - Posted: 05.18.2017

Lesley McClurg When her youngest daughter, Naomi, was in middle school, Ellen watched the teen disappear behind a screen. Her once bubbly daughter went from hanging out with a few close friends after school to isolating herself in her room for hours at a time. (NPR has agreed to use only the pair's middle names, to protect the teen's medical privacy.) "She started just lying there, not moving and just being on the phone," says Ellen. "I was at a loss about what to do." Ellen didn't realize it then, but her daughter was sinking into a pattern of behavior that some psychiatrists recognize from their patients who abuse drugs or alcohol. It's a problem, they say, that's akin to an eating disorder or gambling disorder – some consider it a kind of internet addiction. Estimates of how many people are affected vary widely, researchers say, and the problem isn't restricted to kids and teens, though some – especially those who have depression or anxiety disorder — may be particularly vulnerable. Naomi had always been kind of a nerd — a straight-A student who also sang in a competitive choir. But she desperately wanted to be popular, and the cool kids talked a lot about their latest YouTube favorites. "I started trying to watch as many videos as I could so, like, I knew as much as they did," says Naomi. "The second I got out of school, I was checking my phone." That's not unusual behavior for many teens and adults these days. © 2017 npr

Keyword: Drug Abuse
Link ID: 23631 - Posted: 05.18.2017

Katherine Isbister The fidget spinner craze has been sweeping elementary and middle schools. As of May 17 every one of the top 10 best-selling toys on Amazon was a form of the hand-held toy people can spin and do tricks with. Kids and parents are even making them for themselves using 3D printers and other more homespun crafting techniques. But some teachers are banning them from classrooms. And experts challenge the idea that spinners are good for conditions like ADHD and anxiety. Meanwhile, the Kickstarter online fundraising campaign for the Fidget Cube – another popular fidget toy in 2017 – raised an astounding US$6.4 million, and can be seen on the desks of hipsters and techies across the globe. My research group has taken a deep look at how people use fidget items over the last several years. What we found tells us that these items are not a fad that will soon disappear. Despite sometimes being an annoying distraction for others, fidget items can have some practical uses for adults; our inquiry into their usefulness for children is underway. Fidgeting didn’t start with the spinner craze. If you’ve ever clicked a ballpoint pen again and again, you’ve used a fidget item. As part of our work, we’ve asked people what items they like to fidget with and how and when they use them. (We’re compiling their answers online and welcome additional contributions.) © 2010–2017, The Conversation US, Inc.

Keyword: ADHD; Attention
Link ID: 23630 - Posted: 05.18.2017

Sarah Boseley in Porto A balloon that can be swallowed and then filled with water while in the stomach can help obese people to lose large amounts of weight without invasive surgery, a new study has shown. Bariatric surgery to reduce the size of the stomach is highly effective, but anaesthesia for somebody who is very overweight can be risky. Those who want to undergo the surgery must also undergo a long period of preparation to ready them physically and psychologically. It is expensive, and there is a long waiting list in the UK, even though NHS guidance recommends it be considered. The balloon is swallowed like a pill, but with a long thin tube attached. Ultrasound is used to determine when the balloon is in place in the stomach, and it is then filled with water through the tube. The tube then detaches and is pulled back up the throat and out. Unlike gastric surgery, the balloon is a temporary measure. After 16 weeks, it bursts in the stomach, the water is released and the balloon itself is excreted. A small study presented at the European Congress on Obesity in Porto, Portugal, showed that the 38 patients enrolled in the trial had lost a mean 15.2kg (33.5 lbs) by the end of the 16 weeks, which amounted to about a third (mean 31%) of their excess weight.

Keyword: Obesity
Link ID: 23629 - Posted: 05.18.2017

Tina Hesman Saey Face-to-face, a human and a chimpanzee are easy to tell apart. The two species share a common primate ancestor, but over millions of years, their characteristics have morphed into easily distinguishable features. Chimps developed prominent brow ridges, flat noses, low-crowned heads and protruding muzzles. Human noses jut from relatively flat faces under high-domed crowns. Those facial features diverged with the help of genetic parasites, mobile bits of genetic material that insert themselves into their hosts’ DNA. These parasites go by many names, including “jumping genes,” “transposable elements” and “transposons.” Some are relics of former viruses assimilated into a host’s genome, or genetic instruction book. Others are self-perpetuating pieces of genetic material whose origins are shrouded in the mists of time. “Transposable elements have been with us since the beginning of evolution. Bacteria have transposable elements,” says evolutionary biologist Josefa González. She doesn’t think of transposons as foreign DNA. They are parts of our genomes — like genes. “You cannot understand the genome without understanding what transposable elements are doing,” says González, of the Institute of Evolutionary Biology in Barcelona. She studies how jumping genes have influenced fruit fly evolution. Genomes of most organisms are littered with the carcasses of transposons, says Cédric Feschotte, an evolutionary geneticist at the University of Utah in Salt Lake City. Fossils of the DNA parasites build up like the remains of ancient algae that formed the white cliffs of Dover. One strain of maize, the organism in which Nobel laureate Barbara McClintock first discovered transposable elements in the 1940s, is nearly 85 percent transposable elements (SN: 12/19/09, p. 9). Corn is an extreme example, but humans have plenty, too: Transposable elements make up nearly half of the human genome. |© Society for Science & the Public 2000 - 2017

Keyword: Development of the Brain; Genes & Behavior
Link ID: 23627 - Posted: 05.17.2017

By Roman Liepelt and Jack Brooks An amputee struggles to use his new prosthetic limb. A patient with a frontal-lobe brain lesion insists that her left hand has a mind of its own. The alleged criminal claims in court that he did not fire the gun, even though several eyewitnesses watched him do it. Each of these individuals is grappling with two elements of the mind-body connection: ownership, or an ability to separate ourselves from the physical and social environments, and agency, a conviction that we have control over our limbs. We are quick to investigate a sticker placed on our forehead when looking in a mirror, recognizing the foreign object as abnormal. The human brain typically handles these phenomena by comparing neural signals encoding the intended action with those signals carrying sensory feedback. When we are born, we make erratic reaching and kicking movements to map our body and to calibrate our sensorimotor system. During infancy, these movements solidify our self-awareness, and around the time we first walk, we are quick to investigate a sticker placed on our forehead when looking in a mirror, recognizing the foreign object as abnormal. By the age of four, our brains are proficient at distinguishing self and other. In the amputee, the brain lesion patient, and the defendant on trial, the sense of self is disrupted due to discordance between sensory feedback from the limb and the brain’s expectations of how a movement should feel. © 1986-2017 The Scientist

Keyword: Pain & Touch
Link ID: 23625 - Posted: 05.17.2017

Shelly Fan The first time I heard that shooting electrical currents across your brain can boost learning, I thought it was a joke. But evidence is mounting. According to a handful of studies, transcranial direct current stimulation (tDCS), the poster child of brain stimulation, is a bona fide cognitive booster: By directly tinkering with the brain’s electrical field, some research has found that tDCS enhances creativity, bolsters spatial and math learning and even language aquisition – sometimes weeks after the initial zap. For those eager to give their own brains a boost, this is good news. Various communities have sprung up to share tips and tricks on how to test the technique on themselves, often using self-rigged stimulators powered by 9-volt batteries. Scientists and brain enthusiasts aren’t the only people interested. The military has also been eager to support projects involving brain stimulation with the hope that the technology could one day be used to help soldiers suffering from combat-induced memory loss. But here’s the catch: The end results are inconsistent at best. While some people swear by the positive effects anecdotally, others report nothing but a nasty scalp burn from the electrodes. In a meta-analysis covering over 20 studies, a team from Australia found no significant effects of tDCS on memory. Similar disparities pop up for other brain stimulation techniques. It’s not that brain stimulation isn’t doing anything – it just doesn’t seem to be doing something consistently across a diverse population. So what gives? © 2010–2017, The Conversation US, Inc.

Keyword: Learning & Memory
Link ID: 23624 - Posted: 05.17.2017

Sarah Boseley People who are obese run an increased risk of heart failure and stroke even if they appear healthy, without the obvious warning signs such as high blood pressure or diabetes, according to a major new study. The findings, presented at the European Congress on Obesity in Porto, Portugal, may be the final death knell for the claim that it is possible to be obese but still metabolically healthy – or “fat but fit” – say scientists. Several studies in the past have suggested that the idea of “metabolically healthy” obese individuals is an illusion, but they have been smaller than this one. The new study, from the University of Birmingham, involved 3.5 million people, approximately 61,000 of whom developed coronary heart disease. Is it possible to be healthy and obese? The issue has been controversial. Obesity is usually measured by body mass index (BMI) – a ratio of weight against height. It is generally agreed to be imperfect because athletes and very fit people with dense muscle can have the same BMI as somebody who is obese. The scientists examined electronic health records from 1995 to 2015 in the Health Improvement Network – a large UK general practice database. They found records for 3.5 million people who were free of coronary heart disease at the starting point of the study and divided them into groups according to their BMI and whether they had diabetes, high blood pressure [hypertension], and abnormal blood fats [hyperlipidemia], which are all classed as metabolic abnormalities. Anyone who had none of those was classed as “metabolically healthy obese”.

Keyword: Obesity
Link ID: 23623 - Posted: 05.17.2017

By TAMAR LEWIN Nearly 40 years after the world was jolted by the birth of the first test-tube baby, a new revolution in reproductive technology is on the horizon — and it promises to be far more controversial than in vitro fertilization ever was. Within a decade or two, researchers say, scientists will likely be able to create a baby from human skin cells that have been coaxed to grow into eggs and sperm and used to create embryos to implant in a womb. The process, in vitro gametogenesis, or I.V.G., so far has been used only in mice. But stem cell biologists say it is only a matter of time before it could be used in human reproduction — opening up mind-boggling possibilities. With I.V.G., two men could have a baby that was biologically related to both of them, by using skin cells from one to make an egg that would be fertilized by sperm from the other. Women with fertility problems could have eggs made from their skin cells, rather than go through the lengthy and expensive process of stimulating their ovaries to retrieve their eggs. “It gives me an unsettled feeling because we don’t know what this could lead to,” said Paul Knoepfler, a stem cell researcher at the University of California, Davis. “You can imagine one man providing both the eggs and the sperm, almost like cloning himself. You can imagine that eggs becoming so easily available would lead to designer babies.” © 2017 The New York Times Company

Keyword: Stem Cells; Development of the Brain
Link ID: 23622 - Posted: 05.17.2017

By Sandrine Ceurstemont Hear them roar. Lionfish have been recorded making sounds for the first time. Decoding these sounds could give us an insight into secret lives of this voracious invasive species – and help us keep tabs on its spread. Many fish produce sounds to communicate with each other as low-pitched noises travel far underwater. “It’s a dominant mode of communication,” says Alex Bogdanoff at North Carolina State University. Bogdanoff and his team decided to investigate the lionfish’s ability to produce sound after hearing reports from several divers that they make noises. This invasive species has been spreading through the Caribbean and east coast of the US. They often devour several organisms at a time, which is drastically reducing some native fish populations and altering ecosystems. The team recorded the underwater soundscape in an outdoor tank for five days, at first with a single lionfish and then with a group of five individuals. Occasionally, they stirred up the water with a net to see whether stress caused the fish to make different sounds. The team found that the fish often produced a rhythmic sound similar to a heartbeat and to calls made by other fish. But they also produced another noise made up of a much quicker series of beats (listen to the audio file, below). “It sounds like the rapid beating of a drum,” says Bogdanoff. Lionfish seemed to alter their calls when they were agitated, producing quicker and louder pulses. In follow-up experiments, the team found that they made sounds throughout the day, but were more vocal in the morning and evening. Sounds are likely to vary between individuals as well. Bogdanoff and his team are now working on identifying these differences. They already have evidence that body size affects the noises that lionfish make. Males and females are likely to make different calls, so that they can find one another and reproduce. © Copyright New Scientist Ltd.

Keyword: ADHD
Link ID: 23620 - Posted: 05.17.2017

By ROXANNE KHAMSI What lengths will a dog go to for a bite of sausage? Last November, scientists at the University of Cambridge in Britain persuaded several dozen pet owners to bring their Labrador retrievers to its veterinary school for a true test of will. Inside a mostly empty white room, a research associate let each dog sniff a hot dog before demonstratively placing it inside a small plastic hamster cage on the floor and sealing it shut with black duct tape. Some of the Labs showed only passing interest in the trapped sausage and spent more time exploring the rest of the room. But others stayed laser-focused on the treat. One in particular, a black Labrador named Ash, went into a tizzy, banging the cage around and not giving up until he pried the tape loose with his teeth and ate the hot dog. As it turns out, Ash has more than just determination and a precise tooth grip. He also has a gene mutation linked to obesity. Ash is not overweight, perhaps because his owner keeps him on a rigid diet. But Eleanor Raffan, the researcher who designed the study, suspects his underlying gene mutation and his food-induced frenzy in the experiment are linked. She hasn’t yet analyzed all the data from this latest study, but it has become a mission of hers to understand what makes some canines so voracious. Raffan’s curiosity about this traces back 15 years, to when she became a veterinary surgeon and saw firsthand that certain breeds are more likely than others to put on extra weight. Shortly afterward, when scientists published the first complete dog genome, Raffan decided she wanted to search for DNA mutations that might contribute to heaviness. She got a doctorate in genetics and in 2013 began the GOdogs Project — short for the genetics of obesity in dogs — at Cambridge. She notes that because of the way people have bred dogs, there’s a small gene pool within each breed, making the animals simpler to study: “The way the jiggery-pokery of genetics works means that it’s remarkably easy to get to map the sites where disease-​causing genes are in dogs,” Raffan says. © 2017 The New York Times Company

Keyword: Obesity; Genes & Behavior
Link ID: 23619 - Posted: 05.16.2017

A healthy teenager in the US state of South Carolina died from drinking several highly-caffeinated drinks too quickly, a coroner has ruled. Davis Allen Cripe collapsed at a high school in April after drinking a McDonalds latte, a large Mountain Dew soft drink and an energy drink in just under two hours, Gary Watts said. The 16-year-old died from a "caffeine-induced cardiac event causing a probable arrhythmia". He had no pre-existing heart condition. The teenager weighed 90kg (200 lbs) but would not have been considered morbidly obese, Mr Watts said. "This is not a caffeine overdose," Mr Watts told Reuters news agency. "We're not saying that it was the total amount of caffeine in the system, it was just the way that it was ingested over that short period of time, and the chugging of the energy drink at the end was what the issue was with the cardiac arrhythmia." Caffeine would probably not have been seen as a factor in the teenager's death if witnesses had not been able to tell officials what he had been drinking before his death, the Richland County coroner said. The main witness could not say which brand of energy drink Davis drank but said it was from a container the size of a large soft drink. "We're not trying to speak out totally against caffeine," Mr Watts said. "We believe people need to pay attention to their caffeine intake and how they do it, just as they do with alcohol or cigarettes." The American Academy of Paediatrics (AAP) has warned against children and teenagers consuming energy drinks, saying their ingredients have not been tested on children and "no-one can ensure they are safe". It says they have side-effects including irregular heartbeats and blood pressure changes. © 2017 BBC.

Keyword: Drug Abuse
Link ID: 23618 - Posted: 05.16.2017

Aimee Cunningham For black adults, moving out of a racially segregated neighborhood is linked to a drop in blood pressure, according to a new study. The finding adds to growing evidence of an association between a lack of resources in many predominately black neighborhoods and adverse health conditions among their residents, such as diabetes and obesity. Systolic blood pressure — the pressure in blood vessels when the heart beats — of black adults who left their highly segregated communities decreased just over 1 millimeter of mercury on average, researchers report online May 15 in JAMA Internal Medicine. This decline, though small, could reduce the overall incidence of heart failure and coronary heart disease. “It’s the social conditions, not the segregation itself, that’s driving the relationship between segregation and blood pressure,” says Thomas LaVeist, a medical sociologist at George Washington University in Washington, D.C., who was not involved with the study. “Maybe hypertension is not so much a matter of being genetically predisposed.” That’s important, LaVeist adds, because it means that racial health disparity “can be fixed. It’s not necessarily contained in our DNA; it’s contained in the social DNA.” Racial segregation can impact a neighborhood’s school quality, employment opportunities or even whether there is a full-service grocery store nearby. Social policies that improve residents’ access to education, employment and fresh foods can “have spillover effects in health,” says Kiarri Kershaw, an epidemiologist at Northwestern University Feinberg School of Medicine in Chicago. © Society for Science & the Public 2000 - 2017.

Keyword: Stress
Link ID: 23617 - Posted: 05.16.2017

By BENEDICT CAREY MONTREAL — The driving instructor wiped his brow with a handkerchief, and not just because of the heat. His student — a grown woman, squinting over the dashboard — was ramming the curb in an effort to parallel park. “We reached an agreement, right then and there: He let me pass the test, and I promised never to drive,” Brenda Milner said, smiling to herself at the decades-old memory. “You see, my spatial skills aren’t so good. That’s primarily a right-brain function.” Dr. Milner, a professor of psychology in the department of neurology and neurosurgery at McGill University in Montreal, is best known for discovering the seat of memory in the brain, the foundational finding of cognitive neuroscience. But she also has a knack for picking up on subtle quirks of human behavior and linking them to brain function — in the same way she had her own, during the driving test. At 98, Dr. Milner is not letting up in a nearly 70-year career to clarify the function of many brain regions — frontal lobes, and temporal; vision centers and tactile; the left hemisphere and the right — usually by painstakingly testing people with brain lesions, often from surgery. Her prominence long ago transcended gender, and she is impatient with those who expect her to be a social activist. It’s science first with Dr. Milner, say close colleagues, in her lab and her life. Perched recently on a chair in her small office, resplendent in a black satin dress and gold floral pin and banked by moldering towers of old files, she volleyed questions rather than answering them. “People think because I’m 98 years old I must be emerita,” she said. “Well, not at all. I’m still nosy, you know, curious.” Dr. Milner continues working, because she sees no reason not to. Neither McGill nor the affiliated Montreal Neurological Institute and Hospital has asked her to step aside. She has funding: In 2014 she won three prominent achievement awards, which came with money for research. She has a project: a continuing study to investigate how the healthy brain’s intellectual left hemisphere coordinates with its more aesthetic right one in thinking and memory. © 2017 The New York Times Company

Keyword: Learning & Memory
Link ID: 23615 - Posted: 05.16.2017

Michelle Trudeau Bears do it; bats do it. So do guinea pigs, dogs and humans. They all yawn. It's a common animal behavior, but one that is something of a mystery. There's still no consensus on the purpose of a yawn, says Robert Provine, professor of psychology and neuroscience at the University of Maryland, Baltimore County. Provine has studied what he calls "yawn science" since the early 1980s, and he's published dozens of research articles on it. He says the simple yawn is not so simple. "Yawning may have the dubious distinction of being the least understood common human behavior," Provine says. There are many causes for yawning. Boredom, sleepiness, hunger, anxiety and stress — all cause changes in brain chemistry, which can trigger a spontaneous yawn. But it's not clear what the yawn accomplishes. One possibility is the yawn perks you up by increasing heart rate, blood pressure and respiratory function. "[Yawning] stirs up our physiology and it plays an important role in shifting from one state to another," Provine says. When violinists get ready to go on stage to play a concerto, they often yawn, says Provine. So do Olympians right before a competition, or paratroopers getting ready to do their first jump. One study found that yawning has a similar impact on the brain as a dose of caffeine. But not all yawn researchers agree with this theory. © 2017 npr

Keyword: Emotions
Link ID: 23613 - Posted: 05.15.2017

By Susana Martinez-Conde There is something deeply disconcerting about mirrors. The myriad reflecting surfaces that surround us in our everyday lives help us conduct many necessary tasks, such as applying makeup, shaving, or driving a car. But despite our constant use of mirrors, our nervous systems remain surprisingly ill-equipped to grasp the mechanics of refraction and reflection. Some magic tricks take advantage of such perceptual limitations, and are the origin of phrases such as “it’s all smoke and mirrors,” or “it’s all done with mirrors.” Kokichi Sugihara, a mathematical engineer at Meiji University in Japan, has exploited our poor understanding of mirrors to create new and spectacular varieties of perceptual magic. Our May/June Illusions column features mirror-based illusions by Sugihara and others. How can you use a mirror to vanish half an object? To make your own half-disappearing hexagon, follow the diagram above (you can print it from this template). Part A is the upper half of the object, which you will need to fold along the two edges, forming 120-degree angles. Part B, or the lower half of the object, is a flat structure and should not be folded. Glue both parts together matching the “a” and “b” letters. For the strongest effect, tilt the mirror slightly downward. © 2017 Scientific American

Keyword: Vision
Link ID: 23612 - Posted: 05.15.2017

By STEPH YIN In most mammals, us included, biological sex is determined by a lottery between two letters: X and Y, the sex chromosomes. Inherit one X each from mom and dad, and develop ovaries, a womb and a vagina. Inherit an X from mom and a Y from dad, and develop testes and a penis. But there are rare, mysterious exceptions. A small number of rodents have no Y chromosomes, yet are born as either females or males, not hermaphrodites. Now, scientists may be one step closer to figuring out how sex determination works in one of these rodents. In a study published in Science Advances on Friday, Japanese scientists suggested that cells of the endangered Amami spiny rat, from Japan, are sexually flexible and capable of adapting to either ovaries or testes. When the researchers injected stem cells derived from a female rat into male embryos of laboratory mice, the cells developed into and survived as sperm precursors in adult males. The result was surprising since scientists have never been able to generate mature sperm from female stem cells, largely because sperm production normally requires the Y chromosome. Found only in the subtropical forests of an island in Japan called Amami Oshima, Amami spiny rats are threatened by habitat destruction, competition with black rats not native to the island and predation by mongooses and feral cats and dogs. Their range has been reduced to less than 300 square miles, an area smaller than New York City. Both female and male Amami spiny rats have only one X chromosome, an arrangement only known to occur in a handful of rodents among mammals. Arata Honda, associate professor at the University of Miyazaki and the lead author of the paper, said in an email that he was partly motivated to study Amami spiny rats in the hope that learning about them might reduce their risk of extinction. © 2017 The New York Times Company

Keyword: Sexual Behavior
Link ID: 23611 - Posted: 05.13.2017

By Helen Thomson People in a minimally conscious state have been “woken” for a whole week after a brief period of brain stimulation. The breakthrough suggests we may be on the verge of creating a device that can be used at home to help people with disorders of consciousness communicate with friends and family. People with severe brain trauma can fall into a coma. If they begin to show signs of arousal but not awareness, they are said to be in a vegetative state. If they then show fluctuating signs of awareness but cannot communicate, they are described as being minimally consciousness. In 2014, Steven Laureys at the University of Liège in Belgium and his colleagues discovered that 13 people with minimal consciousness and two people in a vegetative state could temporarily show new signs of awareness when given mild electrical stimulation. The people in the trial received transcranial direct current stimulation (tDCS), which uses low-level electrical stimulation to make neurons more or less likely to fire. This was applied once over an area of the brain called the prefrontal cortex, which is involved in “higher” cognitive functions such as consciousness. Soon after, they showed signs of consciousness, including moving their hands or following instructions using their eyes. Two people were even able to answer questions for 2 hours by moving their body, before drifting back into their previous state. © Copyright New Scientist Ltd.

Keyword: Consciousness
Link ID: 23610 - Posted: 05.13.2017