By Lina Zeldovich, You can draw a straight line from the initial descriptions of many conditions—claustrophobia, for example, or vertigo—to their diagnostic criteria. Not so with autism. Its history has taken a less direct path with several detours, according to Jeffrey Baker, professor of pediatrics and history at Duke University in Durham, North Carolina. Autism was originally described as a form of childhood schizophrenia and the result of cold parenting, then as a set of related developmental disorders, and finally as a spectrum condition with wide-ranging degrees of impairment. Along with these shifting views, its diagnostic criteria have changed as well. Here is how the Diagnostic and Statistical Manual of Mental Disorders (DSM), the diagnostic manual used in the United States, has reflected our evolving understanding of autism. Why was autism initially considered a psychiatric condition? When Leo Kanner, an Austrian-American psychiatrist and physician, first described autism in 1943, he wrote about children with “extreme autistic aloneness,” “delayed echolalia” and an “anxiously obsessive desire for the maintenance of sameness.” He also noted that the children were often intelligent and some had extraordinary memory. As a result, Kanner viewed autism as a profound emotional disturbance that does not affect cognition. In keeping with his perspective, the second edition of the DSM, the DSM-II, published in 1952, defined autism as a psychiatric condition—a form of childhood schizophrenia marked by a detachment from reality. During the 1950s and 1960s, autism was thought to be rooted in cold and unemotional mothers, whom Bruno Bettelheim dubbed “refrigerator mothers.” © 2018 American Association for the Advancement of Science.

Keyword: Autism
Link ID: 24959 - Posted: 05.10.2018

Maria Temming An artificial intelligence that navigates its environment much like mammals do could help solve a mystery about our own internal GPS. Equipped with virtual versions of specialized brain nerve cells called grid cells, the AI could easily solve and plan new routes through virtual mazes. That performance, described online May 9 in Nature, suggests the grid cells in animal brains play a critical role in path planning. “This is a big step forward” in understanding our own navigational neural circuitry, says Ingmar Kanitscheider, a computational neuroscientist at the University of Texas at Austin not involved in the work. The discovery that rats track their location with the help of grid cells, which project an imaginary hexagonal lattice onto an animal’s surroundings, earned a Norwegian research team the 2014 Nobel Prize in physiology or medicine (SN Online: 10/6/14). Neuroscientists suspected these cells, which have also been found in humans, might help not only give mammals an internal coordinate system, but also plan direct paths between points (SN Online: 8/5/13). To test that idea, neuroscientist Caswell Barry at University College London, along with colleagues at Google DeepMind, created an AI that contained virtual nerve cells, or neurons, whose activity resembled that of real grid cells. The researchers trained this AI to navigate virtual mazes by giving the system reward signals when it reached its destination. |© Society for Science & the Public 2000 - 2018

Keyword: Learning & Memory; Robotics
Link ID: 24958 - Posted: 05.10.2018

Alison Abbott Scientists have used artificial intelligence (AI) to recreate the complex neural codes that the brain uses to navigate through space. The feat demonstrates how powerful AI algorithms can assist conventional neuroscience research to test theories about the brain’s workings — but the approach is not going to put neuroscientists out of work just yet, say the researchers. “It really was a very striking and remarkable convergence of form and function.” The computer program, details of which were published in Nature on 9 May1, was developed by neuroscientists at University College London (UCL) and AI researchers at the London-based Google company DeepMind. It used a technique called deep learning — a type of AI inspired by the structures in the brain — to train a computer-simulated rat to track its position in a virtual environment. The program surprised the scientists by spontaneously generating hexagonal-shaped patterns of activity akin to those generated by navigational cells in the mammalian brain called grid cells. Grid cells have been shown in experiments with real rats to be fundamental to how an animal tracks its own position in space. What’s more, the simulated rat was able to use the grid-cell-like coding to navigate a virtual maze so well that it even learnt to take shortcuts. © 2018 Macmillan Publishers Limited,

Keyword: Learning & Memory; Robotics
Link ID: 24957 - Posted: 05.10.2018

by Karin Brulliard For several years, an animal rights organization has sought to convince New York courts that chimpanzees kept by private owners are “legal persons” with a right to be free. For several years, the courts have rejected that argument. New York’s highest court did the same on Tuesday, denying an appeal of a lower court’s refusal to grant writs of habeas corpus to two caged chimps named Tommy and Kiko. But in a striking concurring opinion that was cheered by the chimps’ advocates, one judge wrote that the legal question at the heart of the case — whether all animals are mere property or things — is far from settled. “Does an intelligent nonhuman animal who thinks and plans and appreciates life as human beings do have the right to the protection of the law against arbitrary cruelties and enforced detentions visited on him or her?” wrote Eugene Fahey, one of five Court of Appeals judges who ruled on the matter. “This is not merely a definitional question, but a deep dilemma of ethics and policy that demands our attention.” The 5-to-0 vote upheld a June decision by a lower appeals court that, like courts before it, ruled that chimpanzees could not be legal persons because they cannot take on legal duties. The Nonhuman Rights Project, which has asked courts to move Tommy and Kiko to a sanctuary, says the interpretation is flawed. The group’s director, Steven M. Wise, has noted in interviews that both infants or comatose people possess rights despite an inability to assume legal duties and that primate experts say chimps have rights and responsibilities within peer groups and in settings with humans. © 1996-2018 The Washington Post

Keyword: Animal Rights
Link ID: 24956 - Posted: 05.10.2018

By Nicholas Bakalar Some earlier observational studies have suggested that children who are exclusively breast-fed have higher I.Q.s through adolescence, and even higher incomes at age 30. But a randomized trial, a more rigorous type of study that better controls for socioeconomic and family variables, found that breast-feeding in infancy had no discernible effect on cognitive function by the time children reached age 16. Researchers studied 13,557 children in Belarus, assigning them as newborns either to a program that promoted exclusive and prolonged breast-feeding or to usual care. Mothers and children were followed with six pediatrician visits during the first year of life to assess breast-feeding habits. The study is in PLOS Medicine. At age 16, the children took tests measuring verbal and nonverbal memory, word recognition, executive function, visual-spatial orientation, information processing speed and fine motor skills. There was no difference in scores between the two groups, except that breast-feeders had slightly higher scores in verbal function. “If you want to breast-feed in hope of increasing cognitive functioning scores, you may find some benefits in the early years,” said the lead author, Seungmi Yang, an assistant professor of epidemiology at McGill University in Montreal. “But the effect is going to be reduced substantially at adolescence. Other factors, such as birth order and parental education, are more influential.” © 2018 The New York Times Company

Keyword: Development of the Brain; Intelligence
Link ID: 24955 - Posted: 05.10.2018

By Vanessa Zainzinger Two years ago, when the U.S. Congress approved a major rewrite of the nation’s chemical safety law, lawmakers ordered federal regulators to take steps to reduce the number of animals that companies use to test compounds for safety. But a recent analysis by two animal welfare groups found that the number of animal tests requested or required by the Environmental Protection Agency (EPA) jumped dramatically last year, from just a few dozen tests involving fewer than 7000 animals in 2016, to more than 300 tests involving some 75,000 rats, rabbits, and other vertebrates. The cause of the increase isn’t clear. But the new law imposes stricter requirements on a broader array of chemicals than its predecessor, including both new products and ones already on the market, and experts say EPA staff may be trying to comply by gathering more test data from companies. Both industry and animal welfare groups are alarmed by the trend, and are asking agency officials to clarify why they are requesting the tests—and how they plan to reduce the number in the future. In a 27 March letter to EPA officials, the two Washington, D.C.–based groups that produced the analysis—People for the Ethical Treatment of Animals (PETA) and the Physicians Committee for Responsible Medicine (PCRM)—wrote that the “appalling” number of animals being used in tests “indicates EPA is failing to balance” its responsibility to evaluate chemicals’ risks against its obligation to pursue alternatives to animal testing. © 2018 American Association for the Advancement of Science.

Keyword: Animal Rights
Link ID: 24954 - Posted: 05.09.2018

by Lindsey Bever For years, Kendra Jackson battled an incessantly runny nose — sniffling and sneezing, blowing and losing sleep each night. Jackson said she initially thought she was getting a cold, then, as her symptoms persisted, doctors suggested it was likely seasonal allergies, putting her among the more than 50 million Americans who struggle with them each year. But the symptoms never cleared up, and, as the years went by, Jackson started to worry that it might be something worse. She told ABC affiliate KETV this week her nose ran “like a waterfall, continuously, and then it would run to the back of my throat.” “Everywhere I went,” she added, “I always had a box of Puffs, always stuffed in my pocket.” She had frequent headaches. And she could rarely sleep. Doctors at Nebraska Medicine in Omaha recently diagnosed Jackson with a cerebrospinal fluid (CSF) leak, a condition in which the watery liquid surrounding the brain spills out through a hole or tear in the skull and then drains into the ears or the nose, according to Johns Hopkins Medicine. The doctors told Jackson that she was losing an estimated half-pint of the fluid per day through her nose, according to KETV. © 1996-2018 The Washington Post

Keyword: Pain & Touch; Brain Injury/Concussion
Link ID: 24953 - Posted: 05.09.2018

By Lloyd I. Sederer Psychoactive drugs chemically alter the brain and change the way we feel, think, perceive and understand our world. They are ubiquitous: alcohol, cannabis, opioids, tobacco, stimulants, sedatives and hallucinogens, to name a few. Some occur naturally—nature’s contribution to our bodies and psyches—and some are synthesized in labs to impact the same brain receptors as do those found in forests, deserts and open fields. We are in a psychoactive drug epidemic in our country, most notably the opioids, because of their tragic death toll. We need solutions to the epidemic to save lives, families and communities—and government treasuries. But if we focus only on the drug itself, whatever it may be, we will miss what really matters when it comes to how human beings respond to psychoactive agents. Here are nine things that matter when it comes to drugs: 1. Age. It’s one thing to start drinking or smoking dope when you are 21. It is very different when at 12 or 13 or 15, even 18. That’s because the human brain is still under construction until well into the 20s, later for males than females. It takes almost three decades for the brain to fully lay down the fatty substance, myelin, that surrounds the nerve connections and permits reflection and controls impulsive action, for the cortex to stand a chance against the drive centers deeper in the brain. Repetitive or high doses of psychoactive drugs like cannabis, alcohol and hallucinogens interfere with the normal development of the brain. Not a good thing, and cause for controls on the access youth can have to substances. © 2018 Scientific American

Keyword: Drug Abuse
Link ID: 24952 - Posted: 05.09.2018

By Gretchen Reynolds Exercise changes the brains and sperm of male animals in ways that later affect the brains and thinking skills of their offspring, according to a fascinating new study involving mice. The findings indicate that some of the brain benefits of physical activity may be passed along to children, even if a father does not begin to exercise until adulthood. We already have plenty of scientific evidence showing that exercise is good for our brains, whether we are mice or people. Among other effects, physical activity can strengthen the connections between neurons in the hippocampus, a crucial part of the brain involved in memory and learning. Stronger neuronal connections there generally mean sharper thinking. Studies also indicate that exercise, like other aspects of lifestyle, can alter how genes work — whether and when they get turned on or off, for instance — and those changes can get passed on to children. This process is known as epigenetics. But it had not been clear whether structural changes in the brain caused by exercise might also have epigenetic effects that would result in meaningful changes in the brains of the next generation. In other words, would exercise by a parent help to produce smarter babies? And, in particular, would this process occur in males, who contribute sperm but not a womb and its multitude of hormones, cells and tissues to their children? To find out, researchers at the German Center for Neurodegenerative Diseases in Göttingen, Germany, and other institutions gathered a large group of genetically identical male mice. Because the animals were genetically the same at the start, any differences in their bodies and behavior that cropped up later should be a result of lifestyle. © 2018 The New York Times Company

Keyword: Epigenetics; Learning & Memory
Link ID: 24951 - Posted: 05.09.2018

By Roni Dengler Just looking at a picture of a skinny model on the cover of Glamour or Elle makes many women feel bad about their own weight. Now, science is backing them up. The largest study of its kind finds images of thinner women make even healthy weight women less satisfied with their own bodies—but looking at heavier women makes them feel better. Researchers showed nearly 200 18- to 25-year-old female study participants with a “healthy” body mass index score between 19 and 25 images of normal-, underweight-, or overweight-looking women of the same age and ethnicity. All the images were originally of healthy weight women, but researchers altered some of the pictures to make the models appear larger or smaller by increasing or decreasing the width of the images by 150 pixels. Women who viewed images of the resulting healthy and “overweight” models reported feeling more satisfied with their own body size than women who viewed images of “underweight” models did. After looking at pictures of “underweight” models, women’s satisfaction with their own bodies hardly changed, whereas after seeing healthy weight models, women reported feeling nearly 9% more satisfied with their own body size, for example. Plus, women who viewed images of normal and overweight models perceived their own bodies as smaller, including women who came into the study already feeling highly dissatisfied with their bodies—similar to how eating disorder patients feel. Participants rated whether they thought they were too thin or too fat on a 0-to-10 scale when looking at themselves in a mirror. How they scored themselves dropped by almost 6% after looking at pictures of healthy and overweight models, researchers report today in Royal Society Open Science. In addition, these women felt better about themselves after seeing images of overweight women. And those differences in body satisfaction stuck around for 24 hours. © 2018 American Association for the Advancement of Science.

Keyword: Anorexia & Bulimia
Link ID: 24950 - Posted: 05.09.2018

By John Horgan Which is more fundamental, mind or matter? You would think, in our ultra-materialistic era, that debate would be settled. But a surprising number of philosophers and scientists still resist the idea that mind is a mere afterthought of matter. One is Bernardo Kastrup, a computer engineer and author of several books, including Why Materialism Is Baloney. In “Should Quantum Anomalies Make Us Rethink Reality?”, recently posted by Scientific American, Kastrup contends that quantum mechanics—as well as cognitive science, which suggests that minds construct rather than passively mirroring reality--undermines the assumption that the physical world exists independently of our observations. He calls for a new paradigm that makes mind “the essence—cognitively but also physically—of what we perceive when we look at the world around ourselves.” On Twitter, physicist Sean Carroll slammed Kastrup’s “bad article on quantum mechanics,” and science journalist Michael Moyer called it “voodoo.” That’s a bit harsh. Kastrup’s interpretation of quantum mechanics reminds me of that of the great physicist John Wheeler. Decades ago, Wheeler pointed out deep resonances between quantum mechanics and information theory. An electron behaves like a particle or a wave depending on how we interrogate it. Information theory, similarly, posits that all messages can be reduced to “binary units,” or bits, which are answers to yes or no questions. © 2018 Scientific American

Keyword: Consciousness
Link ID: 24949 - Posted: 05.07.2018

By Aaron E. Carroll The benefits and harms of medical marijuana can be debated, but more states are legalizing pot, even for recreational use. A new evaluation of marijuana’s risks is overdue. Last year, the National Academies of Sciences, Medicine and Engineering released a comprehensive report on cannabis use. At almost 400 pages long, it reviewed both potential benefits and harms. Let’s focus on the harms. The greatest concern with tobacco smoking is cancer, so it’s reasonable to start there with pot smoking. A 2005 systematic review in the International Journal of Cancer pooled the results of six case-control studies. No association was found between smoking marijuana and lung cancer. Another 2015 systematic review pooled nine case-control studies and could find no link to head and neck cancers. Another meta-analysis of three case-control studies of testicular cancer found a statistically significant link between heavier pot smoking and one type of testicular cancer. But this evidence was judged to be “limited” because of limitations in the research (all of which was from the 1990s). There’s no evidence, or not enough to say, of a link between pot use and esophageal cancer, prostate cancer, cervical cancer, non-Hodgkin’s lymphoma, penile cancer or bladder cancer. There’s also no evidence, or not enough to say, that pot has any effect on sperm or eggs that could increase the risk of cancer in any children of pot smokers. (Using marijuana while pregnant does pose other risks, as discussed below.) Heart disease Another major risk with cigarettes, heart disease, isn’t clearly seen with pot smoking. Only two studies quantified the risk between marijuana use and heart attacks. One found no relationship at all, and the other found that pot smoking may be a trigger for a heart attack in the hour after smoking. But this finding was based on nine patients, and may not be generalizable. © 2018 The New York Times Company

Keyword: Drug Abuse; Pain & Touch
Link ID: 24948 - Posted: 05.07.2018

Anna Gorman When 47-year-old Edward Vega arrived in jail, he couldn't quiet the voices in his head. He felt paranoid, as though he was losing control. "I knew if I didn't get my medication, I was going to hurt someone," says Vega. He was right. A week after being arrested for alleged drug possession, Vega says, he assaulted a fellow inmate and ended up in isolation, which only made him feel worse. Finally, a doctor prescribed drugs that Vega says helped. He had been taking them on the outside but ran out just before he was arrested. "The medication hasn't totally taken away the voices, but I am able to differentiate reality from fiction," says Vega, who was released three months ago. The number of inmates in California who've been prescribed psychiatric drugs has jumped about 25 percent in five years, according to a recent analysis of state data. These inmates now account for about a fifth of the county jail population across the state. The increase might be a reflection of the growing number of inmates with mental illness, though it also might stem from improved identification of people in need of treatment, say researchers from California Health Policy Strategies, a Sacramento-based consulting firm. Amid a severe shortage of psychiatric beds and community-based treatment throughout the state and nation, jails have become repositories for people in the throes of acute mental health crises. © 2018 npr

Keyword: Schizophrenia
Link ID: 24947 - Posted: 05.07.2018

By LISA SANDERS, M.D. The young woman rubbed her eyes. The numbers and letters on her computer screen jumped erratically. So did the world around her. This had happened before, but late at night when she was tired, never in the middle of the day. The light from the screen suddenly seemed too bright. And her headache, the one that was always present these days, tightened from a dull ache to a squeezing pressure on the back of her head and neck. Nearly in tears from pain and frustration, the 19-year-old called her mother. She couldn’t see; she couldn’t drive. Could her mother pick her up from work? The problems with her eyes began in grade school. Two years earlier, she nearly went blind. All she could see on the left was a rim of light. Everything else was blocked by a big black spot. And then a black dot appeared in her right eye as well. Her parents took her to see many eye doctors, only to be told that there was nothing wrong. One doctor told them that she had “emotional blindness.” The young woman’s vision somehow got a lot better on its own, and though the black dot still obstructed some of her vision, for the last eight months she’d been able to drive — so important in this small mountain town an hour north of San Diego. Now she couldn’t see for what seemed like a different reason. The young woman’s mother arranged for her to go to San Diego to see a neuro-ophthalmologist — a doctor who specializes in vision problems that originate in the brain. When they got to the office, though, the young woman’s vision and headache had returned to their imperfect but baseline state. She told the doctor that her symptoms were least intrusive in the morning; standing and walking seemed to make everything worse. Come back later, the doctor instructed. Mother and daughter walked around and shopped. When a couple of hours later the daughter’s eyes started jumping and her headache worsened, they hurried back to the office. © 2018 The New York Times Company

Keyword: Vision; Movement Disorders
Link ID: 24946 - Posted: 05.07.2018

by Erin Blakemore Want to cure Alzheimer’s? Get in line. Researchers have long been puzzled by the disease and vexed by how long it’s taking to unravel its mysteries. One group of scientists is helping speed up that process with assistance from the public. “Stall Catchers,” a game created by Cornell University’s Human Computation Institute, turns the hunt for a cure from frustrating to fun. In the game, players watch short movies — made using a multiphoton microscope — that show blood flowing through the brains of living mice. Players work on a data set of thousands of images to point out “stalls” — areas of reduced blood flow caused by white blood cells accumulating on the sides of the vessels. The films might seem far removed from the experience typical of people with Alzheimer’s disease: difficulty concentrating, jumbled speech and confusion. But they may be closely linked: It’s thought that reduced blood flow in the brain is at least partially responsible for Alzheimer’s symptoms. When a blood vessel in the brain gets stalled, blood doesn’t flow as it should. A single stalled capillary might seem like no big deal, but in mice with Alzheimer’s disease, up to 2 percent of brain capillaries can be stalled. Because vessels in the brain are so interconnected, that can restrict overall brain blood flow by up to 30 percent. Reduced blood flow has been found in the brains of humans with Alzheimer’s disease, too. © 1996-2018 The Washington Post

Keyword: Alzheimers
Link ID: 24945 - Posted: 05.07.2018

Susan Milius Pick an animal. Choose wisely because in this fantasy you’ll transform into the creature and duel against one of your own. If you care about survival, go for the muscular, multispiked stag roaring at a rival. Never, ever pick the wingless male fig wasp. Way too dangerous. This advice sounds exactly wrong. But that’s because many stereotypes of animal conflict get the real biology backward. All-out fighting to the death is the rule only for certain specialized creatures. Whether a species is bigger than a breadbox has little to do with lethal ferocity. Many creatures that routinely kill their own kind would be terrifying, if they were larger than a jelly bean. Certain male fig wasps unable to leave the fruit they hatch in have become textbook examples, says Mark Briffa, who studies animal combat. Stranded for life in one fig, these males grow “big mouthparts like a pair of scissors,” he says, and “decapitate as many other males as they possibly can.” The last he-wasp crawling has no competition to mate with all the females in his own private fruit palace. In contrast, big mammals that inspire sports-team mascots mostly use antlers, horns and other outsize male weaponry for posing, feinting and strength testing. Duels to the death are rare. |© Society for Science & the Public 2000 - 2018.

Keyword: Aggression
Link ID: 24944 - Posted: 05.05.2018

By Simon Baron-Cohen Five years ago, the American Psychiatric Association (APA) established autism spectrum disorder (ASD) as an umbrella term when it published the fifth edition of the Diagnostic and Statistical Manual (DSM-5), the primary guide to taxonomy in psychiatry. In creating this single diagnostic category, the APA also removed the subgroup called Asperger syndrome that had been in place since 1994. At the 2018 annual meeting of the International Society for Autism Research (INSAR), there will be plenty of discussion about diagnostic terminology: Despite the many advantages of a single diagnostic category, scientists will be discussing whether, to achieve greater scientific or clinical progress, we need subtypes. The APA created a single diagnostic label of ASD to recognize the important concept of the spectrum, since the way autism is manifested is highly variable. All autistic individuals share core features, including social and communication difficulties, unusually narrow interests, a strong need for repetition and, often, sensory issues. Yet these core features vary enormously in how they are manifested, and in how disabling they are. This variability provides one meaning of the term spectrum, and the single diagnostic label ASD makes space for this considerable variability. The term spectrum also refers to the heterogeneity in autism. There are huge disparities in many areas, such as language development or IQ, and in the presence or absence of co-occurring medical conditions and disabilities. This heterogeneity is also part of what is meant by a spectrum. And some autistic people also have very evident talents. This is another sense of the term spectrum, and the single diagnostic label makes room for this source of diversity, too. © 2018 Scientific America

Keyword: Autism
Link ID: 24943 - Posted: 05.05.2018

By Andrew Joseph, Researchers have been left empty-handed so far in their quest to uncover some measurable biological signal that could be used to diagnose autism spectrum disorder, leaving clinicians to identify the condition just based on a child’s behavior. But on Wednesday, scientists reported in the journal Science Translational Medicine that a hormone that regulates blood pressure could be one of those signposts. They found that low concentrations of the molecule—called arginine vasopressin, or AVP—in the cerebrospinal fluid corresponded to autism-like social behavior in male monkeys, while a high AVP concentration signaled the most social animals. And they discovered similar results when looking at AVP concentrations in the cerebrospinal fluid, or CSF, of a small group of boys. “It’s really exciting work,” said Dr. Mollie Meffert, a molecular neuroscientist at Johns Hopkins, who was not involved in the study. “One of the most interesting things is the finding that the vasopressin in the CSF correlates with sociality in the macaques and in autism with children.” Meffert said if vasopressin concentrations are confirmed to correspond to autism, they could perhaps be used to diagnose the condition and as a gauge to measure the effect of treatment candidates. And Karen Parker, the lead author of the study and associate professor of psychiatry and behavioral sciences at Stanford, said that the hormone could become a drug target if future studies show boosting its levels can assuage the social impairments of autism spectrum disorder. © 2018 Scientific American

Keyword: Autism; Hormones & Behavior
Link ID: 24942 - Posted: 05.05.2018

By Emily Underwood Getting old can be a real itch. In addition to having memory and muscle loss, many elderly people develop supersensitive skin that gets itchy at the lightest touch. Scientists don’t know what causes this miserable condition, called alloknesis, or how to treat it. Now, however, a study in mice has revealed a counterintuitive mechanism for the disorder: a loss of pressure-sensing cells in the skin. Although the findings have yet to be replicated in humans, the study raises the possibility that boosting the function of these cells could treat chronic itch in people, both young and old. Chronic itch is different from chemical itch, which occurs when the immune system reacts to a foreign substance, such as oil from a poison oak leaf or saliva in a mosquito bite. Instead, chronic—or mechanical—itch is usually triggered by light pressure, such as the brush of fibers from a sweater. The condition is maddening, and when people repeatedly scratch their fragile, dry skin, it can lead to major health problems, including infections, says study author Hongzhen Hu, an anesthesiology researcher at the Washington University School of Medicine in St. Louis, Missouri. Like people, mice visibly itch more with age. To find out why, Hu and colleagues used a hair-thin nylon filament to apply a precise amount of pressure to a patch of shaved skin on young and old rodents’ necks. Young mice didn’t respond much to the gentle touch, but the older mice scratched furiously at the spot. Analyzing skin samples from mice of both ages, the team found that older mice had far fewer pressure-sensing Merkel cells than young mice did. The fewer Merkel cells a mouse had, the more their touch-related itch problems increased in response to the filament, the researchers report today in Science. © 2018 American Association for the Advancement of Science.

Keyword: Pain & Touch; Development of the Brain
Link ID: 24941 - Posted: 05.05.2018

By Viviane Callier A human genetic variant in a gene involved in sensing cold temperatures became more common when early humans migrated out of Africa into colder climates between 20,000 and 30,000 years ago, a study published today (May 3) in PLOS Genetics shows. The advantage conferred by this variant isn’t definitively known, but the researchers suspect that it influences the gene’s expression levels, which in turn affect the degree of cold sensation. The observed pattern of positive selection strongly indicates that the allele was beneficial, but that benefit had a tradeoff—bringing with it a higher risk of getting migraines. “This paper is the latest in a series of papers showing that humans really have adapted to different environments after some of our ancestors migrated out of Africa,” explains evolutionary geneticist Rasmus Nieslen of the University of California, Berkeley, who was not involved in the study. “There are a number of adaptations associated with moving into an artic climate, but none with as clear a connection to cold as this one,” he adds. Although studies have demonstrated some striking examples of recent human adaptation, for instance, warding off infectious diseases such as malaria or having the ability to digest milk, relatively little was known about the evolutionary responses to fundamental features of the environment, namely, temperature and climate. “Obviously, humans lived in Africa for a long time, and one of the main environmental factors that changed as humans migrated north was temperature,” explains population geneticist Aida Andres. So she and Felix Key the Max Planck Institute in Leipzig homed in on a gene, TRPM8, that encodes a cation channel in the neurons that innervate the skin. It is activated by cold temperatures and necessary for sensing cold and for thermoregulation. If there was a place to look for human adaptation, this gene looked like a good candidate. © 1986-2018 The Scientist

Keyword: Pain & Touch; Evolution
Link ID: 24940 - Posted: 05.05.2018