Chapter 16. None

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Laurel Hamers People hooked on cocaine are more likely to stick to other habits, too. They’re also less sensitive to negative feedback that tends to push nonaddicts away from harmful habitual behaviors, new research published in the June 17 Science suggests. The findings might help explain why cocaine addicts will do nearly anything to keep using the drug, despite awareness of its negative consequences. Instead, treatments that encourage new, healthier habits in place of drug use might click better. Similar results have been demonstrated with mice and rats, but the effect hadn’t been well-established in humans. There’s no pharmacological treatment approved by the U.S. Food and Drug Administration that targets cocaine addiction as there is for opioid addiction. So the best treatment currently focuses on changing patients’ behavior — and it’s not easy. “It’s such a devastating situation for families,” says Karen Ersche, a psychologist at the University of Cambridge who led the study. Drug users “know they’ll lose their job. They’ll tell you they want to change, but still they carry on using the drug. It seems incomprehensible.” Habits can be helpful because they free up brainpower for other things. A new driver has to think through every push of the pedal and flick of the turn signal, while an experienced one can perform these actions almost effortlessly, allowing them to also carry on a conversation. But people can also snap out of that automation when necessary, slamming on the brakes when a deer darts across the road. It’s harder for someone addicted to cocaine to get off autopilot. © Society for Science & the Public 2000 - 2016.

Keyword: Drug Abuse
Link ID: 22340 - Posted: 06.20.2016

By Jane E. Brody Smokers who think they are escaping the lung-damaging effects of inhaled tobacco smoke may have to think again, according to the findings of two major new studies, one of which the author originally titled “Myth of the Healthy Smoker.” Chronic obstructive pulmonary disease, or C.O.P.D., may be among the best known dangers of smoking, and current and former smokers can be checked for that with a test called spirometry that measures how much air they can inhale and how much and how quickly they can exhale. Unfortunately, this simple test is often skipped during routine medical checkups of people with a history of smoking. But more important, even when spirometry is done, the new studies prove that the test often fails to detect serious lung abnormalities that cause chronic cough and sputum production and compromise a person’s breathing, energy level, risk of serious infections and quality of life. “Current or former smokers without airflow obstruction may assume that they are disease-free,” but that’s not necessarily the case, one of the research teams pointed out. These researchers projected that there are 35 million current or former smokers older than 55 in the United States with unrecognized smoking-caused lung disease or impairments. Many, if not most, of these people could get worse with time, even if they have quit smoking. They are also unlikely to be referred for pulmonary rehabilitation, a treatment that can head off encroaching disability. Perhaps most important, those currently smoking may be inclined to think they’ve dodged the bullet and so can continue to smoke with impunity. Doctors, who are often reluctant to urge patients with symptoms to quit smoking, may be even less likely to recommend smoking cessation to those with normal spirometry results. Referring to C.O.P.D., one of the researchers, Dr. Elizabeth A. Regan, said, “Smoking is really taking a terrible toll on our society.” Dr. Regan, a clinical researcher at National Jewish Health in Denver, is the lead author of one of the new studies, published last year in JAMA Internal Medicine. “We live happily in the world thinking that only a small percentage of people who smoke get this devastating disease,” she said. “However, the lungs of millions of people in the United States are negatively impacted by smoking, and our methods for identifying their lung disease are relatively insensitive.” © 2016 The New York Times Company

Keyword: Drug Abuse
Link ID: 22339 - Posted: 06.20.2016

Gary Stix Unlike biochemistry and psychology, brain science did not exist as a separate academic field until the middle of the 20th century. In recent decades, neuroscience has emerged as a star among the biological disciplines. In 2014 a workshop organized by the National Academy of Medicine met to ponder the question of whether all bodes well for the scientists-to-be who are now getting their PhDs and laboring away at postdoctoral fellowships. Will the field be able to absorb this wealth of new talent—and is it preparing students with the quantitative skills needed to understand the workings of an organ with some 86 billion neurons and hundreds of trillions of connections among all of those cells? Steven Hyman of the Broad Institute of Harvard and MIT, who helped with the planning of the workshop and was recently president of the Society for Neuroscience (SfN), welcomed the flood of doctoral students choosing neuroscience, but warned: “Insofar as talented young people are discouraged from academic careers by funding levels so low that they produce debilitating levels of competition or simply foreclose opportunities, the U.S. and the world are losing an incredibly precious resource.” I got in touch with one member of the National Academy of Medicine panel, Huda Akil of the University of Michigan Medical School, the lead author on a paper in Neuron that summarized the workshop’s findings. Akil, also a former SfN president, is a noted researcher in the neurobiology of emotions. © 2016 Scientific American,

Keyword: Miscellaneous
Link ID: 22338 - Posted: 06.20.2016

By Nancy Szokan Let’s begin by defining something psychologists call “ego depletion.” This is the idea that all of us have only a certain amount of self-control, and if we use up too much in one part of our lives, we will have less to use in others. An early example came from a 1998 study in which participants were tempted with a chocolate treat before being given a difficult puzzle: Those who resisted the temptation seemed to have used up some of their willpower, because they gave up on the puzzle faster than the treat eaters. There have been many subsequent studies about ego depletion, including its apparent effects on physical performance: In 2012, athletes who were given a difficult mental task before a physical challenge exhibited less determination to do well on the sports test than those who hadn’t done the puzzle. But recently a replication study (in which researchers repeat a published experiment to see if they come up with the same results) tested more than 2,000 participants at 24 labs and found the ego depletion effect to be very small or nonexistent. I Which, as Lea Winerman reports, has led such psychologists as Michael Inzlicht of the University of Toronto to a crisis of confidence. Maybe, he thinks, ego depletion and the other social psychological effects he has made a career of studying are “proven” by unreliable research. “I used to think there were errors, but that the errors were minor and it was fine,” Winerman quotes Inzlicht as saying in the June issue of Monitor on Psychology, a publication of the American Psychological Association. “But as I started surveying the field, I started thinking we’ve been making some major mistakes.”

Keyword: Attention
Link ID: 22337 - Posted: 06.20.2016

Lisa Fine Jess Thom says the word "biscuit" about 16,000 times every day. Her brother-in-law counted once. That's just one of the tics that Thom, a London-based performance artist, has to manage as part of her life with Tourette's syndrome, a neurological disorder characterized by involuntary vocal or motor tics. Specialists say the condition affects as many as 300,000 children in the United States, though many are undiagnosed. Thom has had tics since childhood, but she wasn't diagnosed until her 20s. "What disables me ... is other people's misunderstanding," she says. "What's exciting is that it's something we all have power to change." The condition is far more common than many people realize, and many misperceptions about it still exist, says Kevin McNaught, executive vice president of the advocacy group Tourette Association of America. "It's not a rare disorder," McNaught says, citing an estimated 1 in 100 school-age children with the condition, including many who aren't diagnosed until adulthood, if at all. Michael Chichioco, a California high school senior who has Tourette's syndrome, says he used to be bullied at school, with kids trying to trigger him to have outbursts. His tics come out more prominently when he is nervous or excited. © 2016 npr

Keyword: Tourettes
Link ID: 22335 - Posted: 06.18.2016

By Karen Weintraub Many people think they can teach themselves to need less sleep, but they’re wrong, said Dr. Sigrid Veasey, a professor at the Center for Sleep and Circadian Neurobiology at the University of Pennsylvania’s Perelman School of Medicine. We might feel that we’re getting by fine on less sleep, but we’re deluding ourselves, Dr. Veasey said, largely because lack of sleep skews our self-awareness. “The more you deprive yourself of sleep over long periods of time, the less accurate you are of judging your own sleep perception,” she said. Multiple studies have shown that people don’t functionally adapt to less sleep than their bodies need. There is a range of normal sleep times, with most healthy adults naturally needing seven to nine hours of sleep per night, according to the National Sleep Foundation. Those over 65 need about seven to eight hours, on average, while teenagers need eight to 10 hours, and school-age children nine to 11 hours. People’s performance continues to be poor while they are sleep deprived, Dr. Veasey said. Extended vacations are the best times to assess how much sleep you truly need. Once you catch up on lost sleep and are not sleep deprived, the amount you end up sleeping is a good measure how much you need every night. You can ask yourself the questions, “Do you feel that your brain is much sharper, your temper is better, you’re paying attention more effectively? If those answers are yes, than definitely get the sleep,” said Dr. Veasey, who realized -- to her chagrin -- that she needs nine hours of sleep a night to function effectively. Health issues like pain, sleep apnea or autoimmune disease can increase people's need for sleep, said Andrea Meredith, a neuroscientist at the University of Maryland School of Medicine. © 2016 The New York Times Company

Keyword: Sleep
Link ID: 22333 - Posted: 06.18.2016

Alva Noë Sometimes the mind wanders. Thoughts pop into consciousness. Ideas or images are present when just a moment before they were not. Scientists recently have been turning their attention to making sense of this. One natural picture of the phenomenon goes something like this. Typically, our thoughts and feelings are shaped by what we are doing, by what there is around us. The world captures our attention and compels our minds this way or that. What explains the fact that you think of a red car when there is a red car in front of you is, well, the red car. And similarly, it is that loud noise that causes you to orient yourself to the commotion that is producing it. In such cases, we might say, the mind is coupled to the world around it and the world, in a way, plays us the way a person might play a piano. But sometimes, even without going to sleep, we turn away from the world. We turn inward. We are contemplative or detached. We decouple ourselves from the environment and we are set free, as it were, to let our minds play themselves. This natural picture has gained some support from the discovery of the so-called Default Mode Network. The DMN is a network of neural systems whose activation seems to be suppressed by active engagement with the world around us; DMN, in contrast, is activated (or rather, it tends to return to baseline levels of activity) precisely when we detach ourselves from what's going on around us. The DMN is the brain running in neutral. One of the leading hypotheses to explain mind-wandering and the emergence of spontaneous thoughts is that this is the result of the operation of the brain's Default Mode Network. (See this for a review of this literature.) © 2016 npr

Keyword: Attention
Link ID: 22331 - Posted: 06.18.2016

Laura Sanders If you want to lock new information into your brain, try working up a sweat four hours after first encountering it. This precisely timed trick, described June 16 in Current Biology, comes courtesy of 72 people who learned the location of 90 objects on a computer screen. Some of these people then watched relaxing nature videos, while others worked up a sweat on stationary bikes, alternating between hard and easy pedaling for 35 minutes. This workout came either soon after the cram session or four hours later. Compared with both the couch potatoes and the immediate exercisers, the people who worked out four hours after their learning session better remembered the objects’ locations two days later. The delayed exercisers also had more consistent activity in the brain’s hippocampus, an area important for memory, when they remembered correctly. That consistency indicates that the memories were stronger, Eelco van Dongen of the Donders Institute in the Netherlands and colleagues propose. The researchers don’t yet know how exercise works its memory magic, but they have a guess. Molecules sparked by aerobic exercise, including the neural messenger dopamine and the protein BDNF, may help solidify memories by reorganizing brain cell connections. Citations E. van Dongen et al. Physical exercise performed four hours after learning improves memory retention and increases hippocampal pattern similarity during retrieval. Current Biology. Published online June 16, 2016. doi: 10.1016/j.cub.2016.04.071. © Society for Science & the Public 2000 - 2016

Keyword: Learning & Memory
Link ID: 22330 - Posted: 06.18.2016

By Clare Wilson Pass the sick bag. A device that allows people to empty a portion of their stomach contents into a toilet after a meal has just got the go-ahead from the US Food and Drug Administration. The device is approved for use by people who are severely obese, defined as having a body mass index of over 35 kg/m2. The stomach-churning device, which is already available in some European countries, involves a tube being placed into the stomach in a short surgical procedure. The end of the tube contains a valve that lies flush against the skin. Normally it is kept closed, but after meals, the person can connect the valve to another tube to drain about a third of their partially digested food into the toilet. It cannot remove more food than this, because the end of the internal tube is positioned higher than most of the stomach’s contents. Manufacturer Aspire Bariatrics, based in Pennsylvania, says users need to chew their food well and eat more slowly to stop the 6 millimetre tube from getting blocked, and that this in itself helps reduce overeating. “You get some solid chunks,” says Kathy Crothall, head of Aspire Bariatrics. “If a patient doesn’t chew their food very carefully they won’t get anything out of this device.” The device, called AspireAssist, has a safety feature within the valve that means it can only be used three times a day for up to six weeks. After this time it stops working and part of the device must be replaced. © Copyright Reed Business Information Ltd.

Keyword: Obesity
Link ID: 22327 - Posted: 06.16.2016

Susan Milius The Nyctibatrachus humayuni frogs live only in India’s Western Ghats, a region of still-unexplored biodiversity. Video now shows that the mating male of the species positions himself loosely on a female’s back, with his hands on the ground or leaves. From this position, called a dorsal straddle, the male then releases sperm directly onto the female’s back. Then, in an unusual move, he retreats before she lays the eggs. Sperm trickling down the female’s back and legs fertilize the eggs, an international research team reports June 14 in PeerJ. It’s the first time biologists have documented this loose straddling position. More typically, male frogs, which don’t deliver sperm into a female reproductive tract, hold tight and contact freshly deposited eggs to fertilize them. Bombay night frogs do on occasion crawl over their eggs, but researchers found the eggs are already fertilized. Biologists studying the challenges of external fertilization have previously cataloged six basic forms of male frog mating grasp, or amplexus. Four take some kind of back-hug approach or a head straddle. Other species position themselves rump-to-rump or, in what’s called glued amplexus, with the male dangling from a behemoth female. Position is hardly the only unexpected feature of courting Bombay night frogs. Females give courtship croaks, one of only a few dozen female-vocal species among the 6,500-plus known kinds of frogs. © Society for Science & the Public 2000 - 2016

Keyword: Sexual Behavior
Link ID: 22326 - Posted: 06.16.2016

By Gretchen Reynolds Physical activity is good for our brains. A wealth of science supports that idea. But precisely how exercise alters and improves the brain remains somewhat mysterious. A new study with mice fills in one piece of that puzzle. It shows that, in rodents at least, strenuous exercise seems to beneficially change how certain genes work inside the brain. Though the study was in mice, and not people, there are encouraging hints that similar things may be going on inside our own skulls. For years, scientists have known that the brains of animals and people who regularly exercise are different than the brains of those who are sedentary. Experiments in animals show that, for instance, exercise induces the creation of many new cells in the hippocampus, which is a part of the brain essential for memory and learning, and also improves the survival of those fragile, newborn neurons. Researchers believe that exercise performs these feats at least in part by goosing the body’s production of a substance called brain-derived neurotropic factor, or B.D.N.F., which is a protein that scientists sometimes refer to as “Miracle-Gro” for the brain. B.D.N.F. helps neurons to grow and remain vigorous and also strengthens the synapses that connect neurons, allowing the brain to function better. Low levels of B.D.N.F. have been associated with cognitive decline in both people and animals. Exercise increases levels of B.D.N.F. in brain tissue. But scientists have not understood just what it is about exercise that prompts the brain to start pumping out additional B.D.N.F. So for the new study, which was published this month in the journal eLIFE, researchers with New York University’s Langone Medical Center and other institutions decided to microscopically examine and reverse engineer the steps that lead to a surge in B.D.N.F. after exercise. They began by gathering healthy mice. Half of the animals were put into cages that contained running wheels. The others were housed without wheels. For a month, all of the animals were allowed to get on with their lives. Those living with wheels ran often, generally covering several miles a day, since mice like to run. The others remained sedentary. © 2016 The New York Times Company

Keyword: Development of the Brain; Trophic Factors
Link ID: 22325 - Posted: 06.15.2016

By NATALIE ANGIER At birth, the least weasel is as small and light as a paper clip, and the tiny ribs that press visibly against its silvery pink skin give it a segmented look, like that of an insect. A newborn kit is exceptionally underdeveloped, with sealed eyes and ears that won’t open for five or six weeks, an age when puppies and kittens are ready to be weaned. A mother weasel, it seems, has no choice but to deliver her young half-baked. As a member of the mustelid clan — a noble but often misunderstood family of carnivorous mammals that includes ferrets, badgers, minks and wolverines — she holds to a slender, elongated body plan, the better to pursue prey through tight spaces that most carnivores can’t penetrate. Bulging baby bumps would jeopardize that sylphish hunting physique. The solution? Give birth to the equivalent of fetuses and then finish gestating them externally on mother’s milk. “If you want access to small environments, you can’t have a big belly,” said William J. Zielinski, a mustelid researcher with the United States Forest Service in Arcata, Calif. “You don’t see fat weasels.” For Dr. Zielinski and other mustelid-minded scientists, weasels exemplify evolutionary genius and compromise in equal measure, the piecing together of exaggerated and often contradictory traits to yield a lineage of fierce, fleet, quick-witted carnivores that can compete for food against larger celebrity predators like the big cats, wolves and bears. Researchers admit that wild mustelids can be maddening to study. Most species are secretive loners, shrug off standard radio collars with ease, and run close to the ground “like small bolts of brown lightning,” as one team noted. Now you see them, no, you didn’t. Nevertheless, through a mix of dogged field and laboratory studies, scientists have lately made progress in delineating the weasel playbook, and it’s a page turner, or a page burner. © 2016 The New York Times Company

Keyword: Evolution
Link ID: 22321 - Posted: 06.14.2016

By Julia Shaw Can you trust your memory? Picture this. You are in a room full of strangers and you are going around introducing yourself. You say your name to about a dozen people, and they say their names to you. How many of these names are you going to remember? More importantly, how many of these names are you going to misremember? Perhaps you call a person you just met John instead of Jack. This kind of thing happens all the time. Now magnify the situation. You are talking to a close friend, and you disclose something important to them, perhaps even something traumatic. You might, for example, say you witnessed the Paris attacks in 2015. But, how can you know for sure that your memory is accurate? Like most people, you probably feel that misremembering someone’s name is totally different from misremembering an important and emotional life event. That you could never forget #JeSuisParis, and will always have stable and reliable memories of such atrocities. I’m sure that is what those who witnessed 9/11, the 7/7 bombings in London or the assassination of JFK also thought. However, when experimenters conduct research on the accuracy of these so-called “flashbulb memories,” they find that many people make grave errors in their recollections of important historical and personal events. And these errors are more than just omissions. © 2016 Scientific American

Keyword: Learning & Memory
Link ID: 22320 - Posted: 06.14.2016

[Agata Blaszczak-Boxe, Contributing Writer] People who use marijuana for many years respond differently to natural rewards than people who don't use the drug, according to a new study. Researchers found that people who had used marijuana for 12 years, on average, showed greater activity in the brain's reward system when they looked at pictures of objects used for smoking marijuana than when they looked at pictures of a natural reward — their favorite fruits. "This study shows that marijuana disrupts the natural reward circuitry of the brain, making marijuana highly salient to those who use it heavily," study author Dr. Francesca Filbey, an associate professor of behavioral and brain science at the University of Texas at Dallas, said in a statement. "In essence, these brain alterations could be a marker of transition from recreational marijuana use to problematic use." [11 Odd Facts About Marijuana] In the study, researchers looked at 59 marijuana users who had used marijuana daily for the past 60 days, and had used the drug on at least 5,000 occasions during their lives. The researchers wanted to see whether the brains of these long-term marijuana users would respond differently to picures of objects related to marijuana use than they did to natural rewards, such as their favorite fruits, compared with people who did not use marijuana.

Keyword: Drug Abuse
Link ID: 22317 - Posted: 06.14.2016

By C. CLAIBORNE RAY Insects have an odor-sensing system that is roughly analogous to that of vertebrates, according to “The Neurobiology of Olfaction,” a survey published in 2010. Different species have varying numbers of odor receptors, special molecules that are attuned to specific odor molecules. Genes govern the production of each kind of receptor; the more genes, the more kinds of receptor. A big difference with insects is that their olfactory receptors are basically external, often within hairlike groups of cells, called sensilla, on the antennas, not inside a collection organ like a nose. Sign Up for the Science Times Newsletter Every week, we'll bring you stories that capture the wonders of the human body, nature and the cosmos. The odorant molecules encounter odorant-binding proteins, assumed to guide them to the long receptor nerve cells, called axons. Electrical signals are sent along the axons. The axons are usually connected to specific processing centers in the brain called glomeruli, held in a region called the antennal lobe. There the signals are analyzed. Depending on the nature, quantity and timing of the odor signals received, still other cells appear to excite or inhibit reactions. Exactly how the reaction system works is not yet fully understood. The Florida carpenter ant and the Indian jumping ant both have wide-ranging abilities to sense odors, with more than 400 genes to make different odor receptors, a 2012 study found. The fruit fly has only 61. The research also found marked differences in the smelling ability of the sexes, with the female ants well ahead. © 2016 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 22316 - Posted: 06.14.2016

By Devi Shastri Calling someone a “bird brain” might not be the zinger of an insult you thought it was: A new study shows that—by the total number of forebrain neurons—some birds are much brainier than we thought. The study, published online today in the Proceedings of the National Academy of Sciences, found that 28 bird species have more neurons in their pallial telencephalons, the brain region responsible for higher level learning, than mammals with similar-sized brains. Parrots and songbirds in particular packed in the neurons, with parrots (like the gray parrot, above) ranging from 227 million to 3.14 billion, and songbirds—including the notoriously intelligent crow—from 136 million to 2.17 billion. That’s about twice as many neurons as primates with brains of the same mass and four times as many as rodent brains of the same mass. To come up with their count, the researchers dissected the bird brains and then dissolved them in a detergent solution, ensuring that the cells were suspended in what neuroscientist Suzana Herculano-Houzel of Vanderbilt University in Nashville calls “brain soup.” This allowed them to label, count, and estimate how many neurons were in a particular brain region. The region that they focused on allows some birds to hone skills like tool use, planning for the future, learning birdsong, and mimicking human speech. One surprising finding was that the neurons were much smaller than expected, with shorter and more compact connections between cells. The team’s next step is to examine whether these neurons started out small or instead shrank in order to keep the birds light enough for flights. One thing, at least, is clear: It’s time to find a new insult for your less brainy friends. © 2016 American Association for the Advancement of Science

Keyword: Evolution; Animal Communication
Link ID: 22315 - Posted: 06.14.2016

Angus Chen Rachel Star Withers runs a YouTube channel where she performs goofy stunts on camera and talks about her schizophrenia. Since 2008, when the then 22-year-old revealed her diagnosis online, tens of thousands of people have seen her videos. Some of them have a psychotic disorder or mood disorders themselves, or know people who do. They say her explanation about what a symptom like hallucinations feels like can be really helpful. So can Rachel's advice on ways to cope with them, like getting a dog or a cat. If the animal doesn't react to the hallucination, then it's probably not real, she says. We talked with people about how Withers' videos have helped them understand these diseases. What follows is a Q&A with two of these people. The interviews have been edited for length and clarity. Julia Billingsley is 22 years old and from Peoria, Ill. She learned she has schizophrenia last year, but she says her earliest encounter with the disease was back when she was very young. Her mother has schizophrenia, too, Billingsley says, and often had a delusion that their home was bugged. Julia, you started developing symptoms last year. Do you remember the first thing that happened to you? I'd just started dating my current boyfriend. And I'd be over at his house and I'd go to the bathroom. And this thought, this intrusive thought that wasn't my own at all would pop into my head like with force. And it would be like, hey. This room is bugged. And I was like, what? It made me stop. I stopped what I was doing and I didn't understand why my brain was thinking that. © 2016 npr

Keyword: Schizophrenia
Link ID: 22312 - Posted: 06.13.2016

By ALAN COWELL LONDON — When Muhammad Ali died last week, the memories spooled back inevitably to the glory days of the man who called himself the Greatest, a champion whose life intertwined with America’s traumas of race, faith and war. It was a chronicle of valor asserted in the most public of arenas scrutinized by an audience that spanned the globe. But there was another narrative, just as striking to some admirers, of a private courage beyond his klieg-lit renown. For the minority afflicted by Parkinson’s disease, Ali’s 30-year struggle with the same illness magnified the broader status he built from his boxing prowess as a black man who embraced radical Islam, refused to fight in Vietnam, earned the opprobrium of the establishment and yet emerged as an icon. “It was his longest bout, and one that ultimately he could not win,” the reporter Patrick Sawer wrote in The Telegraph, referring to Ali’s illness. Yet the affliction “only served to increase the worldwide admiration he had gained before the disease robbed him of his powers.” As a global superstar, Ali touched many lands, and Britain felt a particular bond. Boxing fans recalled his far-flung bouts — the “Rumble in the Jungle” against George Foreman in Zaire, as the Democratic Republic of Congo was then called, in 1974; “The Thrilla in Manila” in the Philippines against Joe Frazier a year later. But in Britain, his two defeats in the 1960s of Henry Cooper, a much-loved British heavyweight who died in 2011, and his feisty appearances in prime-time television interviews left an indelible mark. © 2016 The New York Times Company

Keyword: Parkinsons
Link ID: 22308 - Posted: 06.11.2016

Michael Graziano Ever since Charles Darwin published On the Origin of Species in 1859, evolution has been the grand unifying theory of biology. Yet one of our most important biological traits, consciousness, is rarely studied in the context of evolution. Theories of consciousness come from religion, from philosophy, from cognitive science, but not so much from evolutionary biology. Maybe that’s why so few theories have been able to tackle basic questions such as: What is the adaptive value of consciousness? When did it evolve and what animals have it? The Attention Schema Theory (AST), developed over the past five years, may be able to answer those questions. The theory suggests that consciousness arises as a solution to one of the most fundamental problems facing any nervous system: Too much information constantly flows in to be fully processed. The brain evolved increasingly sophisticated mechanisms for deeply processing a few select signals at the expense of others, and in the AST, consciousness is the ultimate result of that evolutionary sequence. If the theory is right—and that has yet to be determined—then consciousness evolved gradually over the past half billion years and is present in a range of vertebrate species. Even before the evolution of a central brain, nervous systems took advantage of a simple computing trick: competition. Neurons act like candidates in an election, each one shouting and trying to suppress its fellows. At any moment only a few neurons win that intense competition, their signals rising up above the noise and impacting the animal’s behavior. This process is called selective signal enhancement, and without it, a nervous system can do almost nothing. © 2016 by The Atlantic Monthly Group

Keyword: Consciousness; Evolution
Link ID: 22306 - Posted: 06.09.2016

Tina Hesman Saey Gut microbes cause obesity by sending messages via the vagus nerve to pack on pounds, new research in rodents suggests. Bacteria in the intestines produce a molecule called acetate, which works through the brain and nervous system to make rats and mice fat, researchers report in the June 9 Nature. If the results hold up in humans, scientists would understand one mechanism by which gut microbes induce obesity: First, the microbes convert fats in food to a short-chain fatty acid called acetate. Acetate in the blood somehow makes its way to the brain. The brain sends a signal through the vagus nerve to the pancreas to increase insulin production. Insulin tells fat cells to store more energy. Fat builds up, leading to obesity. Acetate also increases levels of a hunger hormone called ghrelin, which could lead animals and people to eat even more, says Yale University endocrinologist Gerald Shulman, who led the study. “This is a tour-de-force paper,” says biochemist Jonathan Schertzer of McMaster University in Hamilton, Canada. Most studies that examine the health effects of intestinal microbes just list which bacteria, viruses, fungi and other microorganisms make up the gut microbiome, Schertzer says. But a catalog of differences between lean and obese individuals doesn’t address what those microbes do, he says. “What’s in name?” he asks. “When you find a factor that actually influences metabolism, that’s important.” © Society for Science & the Public 2000 - 2016.

Keyword: Obesity
Link ID: 22305 - Posted: 06.09.2016