Most Recent Links
Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.
By Jessica Boddy Ever wonder what it looks like when brain cells chat up a storm? Researchers have found a way to watch the conversation in action without ever cracking open a skull. This glimpse into the brain’s communication system could open new doors to diagnosing and treating disorders from epilepsy to Alzheimer’s disease. Being able to see where—and how—living brain cells are working is “the holy grail in neuroscience,” says Howard Federoff, a neurologist at Georgetown University in Washington, D.C., who was not involved with the work. “This is a possible new tool that could bring us closer to that.” Neurons, which are only slightly longer than the width of a human hair, are laid out in the brain like a series of tangled highways. Signals must travel down these highways, but there’s a catch: The cells don’t actually touch. They’re separated by tiny gaps called synapses, where messages, with the assistance of electricity, jump from neuron to neuron to reach their destinations. The number of functional synapses that fire in one area—a measure known as synaptic density—tends to be a good way to figure out how healthy the brain is. Higher synaptic density means more signals are being sent successfully. If there are significant interruptions in large sections of the neuron highway, many signals may never reach their destinations, leading to disorders like Huntington disease. The only way to look at synaptic density in the brain, however, is to biopsy nonliving brain tissue. That means there’s no way for researchers to investigate how diseases like Alzheimer’s progress—something that could hold secrets to diagnosis and treatment. © 2016 American Association for the Advancement of Science
Keyword: Brain imaging
Link ID: 22472 - Posted: 07.23.2016
By ANNA WEXLER EARLIER this month, in the journal Annals of Neurology, four neuroscientists published an open letter to practitioners of do-it-yourself brain stimulation. These are people who stimulate their own brains with low levels of electricity, largely for purposes like improved memory or learning ability. The letter, which was signed by 39 other researchers, outlined what is known and unknown about the safety of such noninvasive brain stimulation, and asked users to give careful consideration to the risks. For the last three years, I have been studying D.I.Y. brain stimulators. Their conflict with neuroscientists offers a fascinating case study of what happens when experimental tools normally kept behind the closed doors of academia — in this case, transcranial direct current stimulation — are appropriated for use outside them. Neuroscientists began experimenting in earnest with transcranial direct current stimulation about 15 years ago. In such stimulation, electric current is administered at levels that are hundreds of times less than those used in electroconvulsive therapy. To date, more than 1,000 peer-reviewed studies of the technique have been published. Studies have suggested, among other things, that the stimulation may be beneficial for treating problems like depression and chronic pain as well as enhancing cognition and learning in healthy individuals. The device scientists use for stimulation is essentially a nine-volt battery attached to two wires that are connected to electrodes placed at various spots on the head. A crude version can be constructed with just a bit of electrical know-how. Consequently, as reports of the effects of the technique began to appear in scientific journals and in newspapers, people began to build their own devices at home. By late 2011 and early 2012, diagrams, schematics and videos began to appear online. © 2016 The New York Times Company
Link ID: 22471 - Posted: 07.23.2016
By Knvul Sheikh Although millions of women use hormone therapy, those who try it in hopes of maintaining sharp memory and preventing the fuzzy thinking sometimes associated with menopause may be disappointed. A new study indicates that taking estrogen does not significantly affect verbal memory and other mental skills. “There is no change in cognitive abilities associated with estrogen therapy for postmenopausal women, regardless of their age,” says Victor Henderson, a neurologist at Stanford University and the study’s lead author. Evidence of positive and negative effects of such hormone therapy has ping-ponged over the years, with some observational studies in postmenopausal women and research in animal models, suggesting it improves cognitive function and memory. But other previous research, including a long-term National Institutes of Health Women’s Health Initiative memory study published in 2004, has suggested that taking estrogen increases the risk of cognitive impairment and dementia in women over 65 years old. Henderson says one explanation for these contradictory findings may be that after menopause begins there is a “critical period” in which hormone therapy could still benefit relatively young women—if they start early enough. So in their study, which appears in the July 20 online Neurology, Henderson and his team recruited 567 healthy women, between ages 41 and 84, to examine how estrogen affected one group whose members were within six years of their last menstrual period and another whose members had started menopause at least 10 years earlier. © 2016 Scientific American
By Emma Bryce In 1999, neuroscientist Gero Miesenböck dreamed of using light to expose the brain's inner workings. Two years later, he invented optogenetics, a technique that fulfils this goal: by genetically engineering cells to contain proteins that make them light-responsive, Miesenböck found he could shine light at the brain and trigger electrical activity in those cells. This technique gave scientists the tools to activate and control specific cell populations in the brain, for the first time. For example, Miesenböck, who directs the Centre for Neural Circuits and Behaviour at the University of Oxford, first used optogenetics to activate courtship responses in fruit flies, and even make headless flies take flight - groundbreaking experiments that allowed him to examine, in unprecedented detail, how neurons drive behaviour. Gero Miesenböck: There was almost a "eureka" moment. As is often the case, you tend to have your best ideas when you're not trying to have them: suddenly I had this idea - which I must have been incubating for a long time, because I was thinking about manipulating neurons in the brain genetically to emit light so I could visualise their activity. Suddenly I thought, "What if we just turn the thing upside down, and instead of reading activity, write activity using light and genetics?" That was the real breakthrough idea, and then of course came the big challenge of having to make it work. Brains are composed of many different kinds of nerve cells, and they are genetically distinct from one another. To deconstruct how the brain works we need to pinpoint the roles these individual classes of cells play in processing information. Optogenetics uses the genetic signatures that define individual cell types to address them selectively in the intact brain - that's the "genetics" component. The "opto" component is to use these genetic signatures to place light-sensitive molecules that are encoded in DNA within these cells.
Link ID: 22469 - Posted: 07.23.2016
By NATALIE ANGIER Their word is their bond, and they do what they say — even if the “word” on one side is a loud trill and grunt, and, on the other, the excited twitterings of a bird. Researchers have long known that among certain traditional cultures of Africa, people forage for wild honey with the help of honeyguides — woodpecker-like birds that show tribesmen where the best beehives are hidden, high up in trees. In return for revealing the location of natural honey pots, the birds are rewarded with the leftover beeswax, which they eagerly devour. Now scientists have determined that humans and their honeyguides communicate with each other through an extraordinary exchange of sounds and gestures, which are used only for honey hunting and serve to convey enthusiasm, trustworthiness and a commitment to the dangerous business of separating bees from their hives. The findings cast fresh light on one of only a few known examples of cooperation between humans and free-living wild animals, a partnership that may well predate the love affair between people and their domesticated dogs by hundreds of thousands of years. Claire N. Spottiswoode, a behavioral ecologist at Cambridge University, and her colleagues reported in the journal Science that honeyguides advertise their scout readiness to the Yao people of northern Mozambique by flying up close while emitting a loud chattering cry. For their part, the Yao seek to recruit and retain honeyguides with a distinctive vocalization, a firmly trilled “brrr” followed by a grunted “hmm.” In a series of careful experiments, the researchers then showed that honeyguides take the meaning of the familiar ahoy seriously. The birds were twice as likely to offer sustained help to Yao foragers who walked along while playing recordings of the proper brrr-hmm signal than they were to participants with recordings of normal Yao words or the sounds of other animals. © 2016 The New York Times Company
By Tanya Lewis Scientists have made significant progress toward understanding how individual memories are formed, but less is known about how multiple memories interact. Researchers from the Hospital for Sick Children in Toronto and colleagues studied how memories are encoded in the amygdalas of mice. Memories formed within six hours of each other activate the same population of neurons, whereas distinct sets of brain cells encode memories formed farther apart, in a process whereby neurons compete with their neighbors, according to the team’s study, published today (July 21) in Science. “Some memories naturally go together,” study coauthor Sheena Josselyn of the Hospital for Sick Children told The Scientist. For example, you may remember walking down the aisle at your wedding ceremony and, later, your friend having a bit too much to drink at the reception. “We’re wondering about how these memories become linked in your mind,” Josselyn said. When the brain forms a memory, a group of neurons called an “engram” stores that information. Neurons in the lateral amygdala—a brain region involved in memory of fearful events—are thought to compete with one another to form an engram. Cells that are more excitable or have higher expression of the transcription factor CREB—which is critical for the formation of long-term memories—at the time the memory is being formed will “win” this competition and become part of a memory. © 1986-2016 The Scientist
Keyword: Learning & Memory
Link ID: 22467 - Posted: 07.23.2016
Carl Zimmer The brain looks like a featureless expanse of folds and bulges, but it’s actually carved up into invisible territories. Each is specialized: Some groups of neurons become active when we recognize faces, others when we read, others when we raise our hands. On Wednesday, in what many experts are calling a milestone in neuroscience, researchers published a spectacular new map of the brain, detailing nearly 100 previously unknown regions — an unprecedented glimpse into the machinery of the human mind. Scientists will rely on this guide as they attempt to understand virtually every aspect of the brain, from how it develops in children and ages over decades, to how it can be corrupted by diseases like Alzheimer’s and schizophrenia. “It’s a step towards understanding why we’re we,” said David Kleinfeld, a neuroscientist at the University of California, San Diego, who was not involved in the research. Scientists created the map with advanced scanners and computers running artificial intelligence programs that “learned” to identify the brain’s hidden regions from vast amounts of data collected from hundreds of test subjects, a far more sophisticated and broader effort than had been previously attempted. While an important advance, the new atlas is hardly the final word on the brain’s workings. It may take decades for scientists to figure out what each region is doing, and more will be discovered in coming decades. “This map you should think of as version 1.0,” said Matthew F. Glasser, a neuroscientist at Washington University School of Medicine and lead author of the new research. “There may be a version 2.0 as the data get better and more eyes look at the data. We hope the map can evolve as the science progresses.” © 2016 The New York Times Company
Keyword: Brain imaging
Link ID: 22466 - Posted: 07.21.2016
Ian Sample Science editor When the German neurologist Korbinian Brodmann first sliced and mapped the human brain more than a century ago he identified 50 distinct regions in the crinkly surface called the cerebral cortex that governs much of what makes us human. Now researchers have updated the 100-year-old map in a scientific tour de force which reveals that the human brain has at least 180 different regions that are important for language, perception, consciousness, thought, attention and sensation. The landmark achievement hands neuroscientists their most comprehensive map of the cortex so far, one that is expected to supersede Brodmann’s as the standard researchers use to talk about the various areas of the brain. Scientists at Washington University in St Louis created the map by combining highly-detailed MRI scans from 210 healthy young adults who had agreed to take part in the Human Connectome Project, a massive effort that aims to understand how neurons in the brain are connected. Most previous maps of the human brain have been created by looking at only one aspect of the tissues, such as how the cells look under a microscope, or how active areas become when a person performs a certain task. But maps made in different ways do not always look the same, which casts doubt on where one part of the brain stops and another starts. Writing in the journal Nature, Matthew Glasser and others describe how they combined scans of brain structure, function and connectivity to produce the new map, which confirmed the existence of 83 known brain regions and added 97 new ones. Some scans were taken while patients simply rested in the machine, while others were recorded as they performed maths tasks, listened to stories, or categorised objects, for example by stating whether an image was of a tool or an animal. © 2016 Guardian News and Media Limited
Keyword: Brain imaging
Link ID: 22465 - Posted: 07.21.2016
By Minaz Kerawala, For years, gamers, athletes and even regular people trying to improving their memory have resorted, with electrified enthusiasm, to "brain zapping" to gain an edge. The procedure, called transcranial direct current stimulation (tDCS), uses a battery and electrodes to deliver electrical pulses to the brain, usually through a cap or headset fitted close to the scalp. Proponents say these currents are beneficial for a range of neurological conditions like Alzheimer's and Parkinson's diseases, stroke and schizophrenia, but experts are warning that too little is known about the safety of tDCS. "You might end up with a placement of electrodes that doesn't do what you think it does and could potentially have long-lasting effects," said Matthew Krause, a neuroscientist at the Montreal Neurological Institute. All functions of the brain—thought, emotion and coordination—are carried out by neurons using pulses of electricity. "The objective of all neuroscience is to influence these electrical processes," Krause said. The brain's activity can be influenced by drugs that alter its electrochemistry or by external external electric fields. While mind-altering headsets may seem futuristic, tDCS is not a new procedure. Much of the pioneering work in the field was done in Montreal by Dr. Wilder Penfield in the 1920s and 30s. ©2016 CBC/Radio-Canada.
Link ID: 22464 - Posted: 07.21.2016
You drift off to dreamland just fine but then something, a noise, a partner's tossing and turning, jars you awake. Now your mind races with an ever expanding to-do list of worries that you can't shut off. When the alarm buzzes, you start the day feeling grouchy and slightly dazed. Nearly six in 10 Canadians say they wake up feeling tired. About 40 per cent of Canadians will exhaust themselves with a sleep disorder at some point in their lifetime, studies suggest. It's common for people to wake up in the middle of the night. What's important is not to let it snowball, sleep specialists say. Our sleep cycles include brief periods of wakefulness but deep sleep makes us forget about these awakenings. "It's normal to have one or two a night," said Dr. Brian Murray, a sleep neurologist at Sunnybrook Health Sciences Centre and a professor at the University of Toronto. "It's when it's multiple that I worry." Sleep experts say if someone wakes up multiple times a night, it's a red flag. Chronic sleep problems are linked to heart disease, high blood pressure and some cancers. It can also affect hormone levels, which increases the risk of obesity and Type 2 diabetes, sleep specialists say. Julie Snyder of Toronto said she has stretches of days or weeks when she'll consistently wake up at 1:15 a.m., and again at 4 a.m. The broken sleep leaves her feeling short on patience. ©2016 CBC/Radio-Canada.
Link ID: 22463 - Posted: 07.21.2016
By David Levine Almost seven percent of U.S. adults—about 15.7 million people—are diagnosed with major depression disorder, according to the National Institute of Mental Health (NIMH). The Centers for Disease Control and Prevention report that depression causes 200 million lost workdays each year at a cost to employers of between $17 billion and $44 billion. The statistics for anxiety disorders are not great either. The most common mental illnesses in the U.S., they affect 40 million adults age 18 and older, costing the economy more than $42 billion a year. In my twenties, I developed panic disorder. I failed to get better on most medications and therapy. As I reported in an article earlier this year, it took me years to find a medication that worked. Because it took me so long to be diagnosed and treated properly, I have always been interested in alternative treatments for depression and anxiety. Two years ago I attended two sessions at the World Science Festival on the use of electrical therapy to treat depression and anxiety. The first event was Spark of Genius? Awakening a Better Brain, a panel discussion moderated by ABC News Chief Health & Medical Editor Richard Besser. The panel discussed what is known about treating the brain and the ethical and legal complications of brain enhancement. (You can watch it online at the World Science Festival website.) The second panel, "Electric Medicine and the Brain" was moderated by John Rennie, former editor in chief of Scientific American His panel focused on the use of "electroceuticals," a term coined by researchers at GlaxoSmithKline to refer to all implantable devices being used to treat mental illnesses and being explored in the treatment of metabolic, cardiovascular and inflammatory disorders. © 2016 Scientific American
Link ID: 22462 - Posted: 07.20.2016
Davide Castelvecchi People can detect flashes of light as feeble as a single photon, an experiment has demonstrated — a finding that seems to conclude a 70-year quest to test the limits of human vision. The study, published in Nature Communications on 19 July1, “finally answers a long-standing question about whether humans can see single photons — they can!” says Paul Kwiat, a quantum optics researcher at the University of Illinois at Urbana–Champaign. The techniques used in the study also open up ways of testing how quantum properties — such as the ability of photons to be in two places at the same time — affect biology, he adds. “The most amazing thing is that it’s not like seeing light. It’s almost a feeling, at the threshold of imagination,” says Alipasha Vaziri, a physicist at the Rockefeller University in New York City, who led the work and tried out the experience himself. Experiments on cells from frogs have shown that sensitive light-detecting cells in vertebrate eyes, called rod cells, do fire in response to single photons2. But, in part because the retina processes its information to reduce ‘noise’ from false alarms, researchers hadn’t been able to confirm whether the firing of one rod cell would trigger a signal that would be transmitted all the way to the brain. Nor was it clear whether people would be able to consciously sense such a signal if it did reach the brain. Experiments to test the limits of human vision have also had to wait for the arrival of quantum-optics technologies that can reliably produce one photon of light at a time. © 2016 Macmillan Publishers Limited
Link ID: 22461 - Posted: 07.20.2016
Ian Sample Science editor They were once considered merely lazy and adorable. But new research into the antics of the slow loris has revealed a wilder side to the docile creatures. Given the chance the innocent-eyed beasts will neck the most alcoholic drinks they can lay their paws on. The ability of the slow loris to seek out the most potent brew in reach was discovered by researchers in the US who wanted to know whether the animals favoured highly-fermented nectar over the less alcoholic forms secreted by plants in their natural habitats. As sugary nectar ferments in the wild, its calorie content rises, making it a potentially more valuable source of energy. In a series of tests with Dharma, an adult female slow loris, biologists at Dartmouth College in New Hampshire found that when presented with a choice of sugary solutions laced with different amounts of alcohol, the loris speedily settled on the most intoxicating. But while the animal was quickly drawn to the nectar substitutes, which contained between 1% and 4% alcohol, the slow loris displayed what the researchers describe as “a relative aversion to tap water”, which was used as a control. Dharma was not alone in her taste for drink. The scientists ran the same series of experiments with two nocturnal aye aye lemurs, a male called Merlin and a female called Morticia. Once again, the primates homed in on the most alcoholic of sugary solutions the researchers knocked up to mimic fermented nectar. © 2016 Guardian News and Media Limited
Research supported by the National Institutes of Health has identified brain patterns in humans that appear to underlie “resilient coping,” the healthy emotional and behavioral responses to stress that help some people handle stressful situations better than others. People encounter stressful situations and stimuli everywhere, every day, and studies have shown that long-term stress can contribute to a broad array of health problems. However, some people cope with stress better than others, and scientists have long wondered why. The new study, by a team of researchers at Yale University, New Haven, Connecticut, is now online in the Proceedings of the National Academy of Sciences. “This important finding points to specific brain adaptations that predict resilient responses to stress,” said George F. Koob, Ph.D., director of the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of NIH and a supporter of the study. “The findings also indicate that we might be able to predict maladaptive stress responses that contribute to excessive drinking, anger, and other unhealthy reactions to stress.” In a study of human volunteers, scientists led by Rajita Sinha, Ph.D., and Dongju Seo, Ph.D., used a brain scanning technique called functional magnetic resonance imaging (fMRI) to measure localized changes in brain activation during stress. Study participants were given fMRI scans while exposed to highly threatening, violent and stressful images followed by neutral, non-stressful images for six minutes each. While conducting the scans, researchers also measured non-brain indicators of stress among study participants, such as heart rate, and levels of cortisol, a stress hormone, in blood. The brain scans revealed a sequence of three distinct patterns of response to stress, compared to non-stress exposure.
By Maia Szalavitz When a family member, spouse or other loved one develops an opioid addiction — whether to pain relievers like Vicodin or to heroin — few people know what to do. Faced with someone who appears to be driving heedlessly into the abyss, families often fight, freeze or flee, unable to figure out how to help. Families are sometimes overwhelmed with conflicting advice about what should come next. Much of the advice given by treatment groups and programs ignores what the data says in a similar way that anti-vaccination or climate skeptic websites ignore science. The addictions field is neither adequately regulated nor effectively overseen. There are no federal standards for counseling practices or rehab programs. In many states, becoming an addiction counselor doesn’t require a high school degree or any standardized training. “There’s nothing professional about it, and it’s not evidence-based,” said Dr. Mark Willenbring, the former director of treatment research at the National Institute on Alcohol Abuse and Alcoholism, who now runs a clinic that treats addictions. Consequently, families are often given guidance that bears no resemblance to what the research evidence shows — and patients are commonly subjected to treatment that is known to do harm. People who are treated as experts firmly proclaim that they know what they are doing, but often turn out to base their care entirely on their own personal and clinical experience, not data. “Celebrity Rehab with Dr. Drew,” which many people see as an example of the best care available, for instance, used an approach that is not known to be effective for opioid addiction. More than 13 percent of its participants died after treatment,1 mainly of overdoses that could potentially have been prevented with evidence-based care. Unethical practices such as taking kickbacks for patient referrals are also rampant.
Rachel Ehrenberg The brain doesn’t really go out like a light when anesthesia kicks in. Nor does neural activity gradually dim, a new study in monkeys reveals. Rather, intermittent flickers of brain activity appear as the effects of an anesthetic take hold. Some synchronized networks of brain activity fall out of step as the monkeys gradually drift from wakefulness, the study showed. But those networks resynchronized when deep unconsciousness set in, researchers reported in the July 20 Journal of Neuroscience. That the two networks behave so differently during the drifting-off stage is surprising, says study coauthor Yumiko Ishizawa of Harvard Medical School and Massachusetts General Hospital. It isn’t clear what exactly is going on, she says, except that the anesthetic’s effects are a lot more complex than previously thought. Most studies examining the how anesthesia works useelectroencephalograms, or EEGs, which record brain activity using electrodes on the scalp. The new study offers unprecedented surveillance by eavesdropping via electrodes implanted inside macaque monkeys’ brains. This new view provides clues to how the brain loses and gains consciousness. “It’s a very detailed description of something we know very little about,” says cognitive neuroscientist Tristan Bekinschtein of the University of Cambridge, who was not involved with the work. Although the study is elegant, it isn’t clear what to make of the findings, he says. “These are early days.” |© Society for Science & the Public 2000 - 2016.
Link ID: 22457 - Posted: 07.20.2016
By TRIP GABRIEL DO you remember June 27, 2015? If you knew you had been on a sailboat, and that the weather was miserable, and that afterward you had a beer with the other sailors, would you expect to recall — even one year later — at least a few details? I was on that boat, on a blustery Saturday on Long Island Sound. But every detail is missing from my memory, as if snipped out by an overzealous movie editor. The earliest moment I recall from the day is lying in an industrial tube with a kind of upturned colander over my face, fighting waves of claustrophobia. My mind was densely fogged, but I understood that I was in an M.R.I. machine. Someone was scanning my brain. Other hazy scenes followed: being wheeled into a hospital room. My wife, Alice, hovering in the background. A wall clock that read minutes to midnight, an astonishing piece of information. What had happened to the day? Late that night, alone in the room, I noticed two yellow Post-its on the bedside table in Alice’s writing: “You have a condition called transient global amnesia. It will last Hours not DAYS. You’re going to be fine. Your CT scan was clear. You sailed today and drove yourself home,” the note read in part. I had never heard of transient global amnesia, a rare condition in which you are suddenly unable to recall recent events. Its causes are unknown. Unlike other triggers of memory loss, like a stroke or epileptic seizures, the condition is considered harmless, and an episode does not last long. “We don’t understand why it happens,” a neurologist would later tell me. “There are a million theories.” © 2016 The New York Times Company
Keyword: Learning & Memory
Link ID: 22456 - Posted: 07.19.2016
By Alice Klein Blame grandpa. A study in mice shows that the grandsons of obese males are more susceptible to the detrimental health effects of junk food, even if their fathers are lean and healthy. The finding adds to evidence that new traits can be passed down the family line without being permanently recorded in a family’s genes – a phenomenon called transgenerational epigenetics. Last year, a study found that the DNA in the sperm of obese men is modified in thousands of places, and that these sperm also contain short pieces of RNA. These are epigenetic modifications – they don’t affect the precise code of genes, but instead may affect how active particular genes are. Now Catherine Suter at Victor Chang Cardiac Research Institute in Sydney and her team have investigated the longer-term effects of paternal obesity. To do this, they mated obese male mice with lean female mice. They found that, compared with the offspring of lean males, both the sons and grandsons of the obese males were more likely to show the early signs of fatty liver disease and diabetes when given a junk food diet. The same effect wasn’t seen in daughters or granddaughters. Even when the sons of the obese males were fed a healthy diet and kept at a normal weight, their sons still had a greater tendency to develop obesity-related conditions when exposed to a junk diet. © Copyright Reed Business Information Ltd.
Tina Hesman Saey ORLANDO, Fla. — Weight gain may depend on how an individual’s genes react to certain diets, a new study in mice suggests. Four strains of mice fared differently on four different diets, William Barrington of North Carolina State University in Raleigh reported July 15 at the Allied Genetics Conference. One strain, the A/J mouse, was nearly impervious to dietary changes. Those mice didn’t gain much weight or have changes in insulin or cholesterol no matter what they ate: a fat-and-carbohydrate-laden Western diet, traditional Mediterranean or Japanese diet (usually considered healthy) or very low-carbohydrate, fat-rich fare known as the ketogenic diet. In contrast, NOD/ShiLtJ mice gained weight on all but the Japanese diet. Those mice’s blood sugar shot up — a hallmark of diabetes — on a Mediterranean diet, but decreased on the Japanese diet. FVB/NJ mice didn’t get fat on the Western diet, but became obese and developed high cholesterol and other health problems on the ketogenic diet. The opposite was true for C57BL/6J mice. They became obese and developed cholesterol and other problems linked to heart disease and diabetes in people on the Western diet, but not on the ketogenic diet. They also fattened up on the Mediterranean diet. © Society for Science & the Public 2000 - 2016.
Link ID: 22454 - Posted: 07.19.2016
By Maggie Koerth-Baker Q: I want to hear what the loudest thing in the world is! — Kara Jo, age 5 No. No, you really don’t. See, there’s this thing about sound that even we grown-ups tend to forget — it’s not some glitter rainbow floating around with no connection to the physical world. Sound is mechanical. A sound is a shove — just a little one, a tap on the tightly stretched membrane of your ear drum. The louder the sound, the heavier the knock. If a sound is loud enough, it can rip a hole in your ear drum. If a sound is loud enough, it can plow into you like a linebacker and knock you flat on your butt. When the shock wave from a bomb levels a house, that’s sound tearing apart bricks and splintering glass. Sound can kill you. Consider this piece of history: On the morning of Aug. 27, 1883, ranchers on a sheep camp outside Alice Springs, Australia, heard a sound like two shots from a rifle. At that very moment, the Indonesian volcanic island of Krakatoa was blowing itself to bits 2,233 miles away. Scientists think this is probably the loudest sound humans have ever accurately measured. Not only are there records of people hearing the sound of Krakatoa thousands of miles away, there is also physical evidence that the sound of the volcano’s explosion traveled all the way around the globe multiple times. Now, nobody heard Krakatoa in England or Toronto. There wasn’t a “boom” audible in St. Petersburg. Instead, what those places recorded were spikes in atmospheric pressure — the very air tensing up and then releasing with a sigh, as the waves of sound from Krakatoa passed through. There are two important lessons about sound in there: One, you don’t have to be able to see the loudest thing in the world in order to hear it. Second, just because you can’t hear a sound doesn’t mean it isn’t there. Sound is powerful and pervasive and it surrounds us all the time, whether we’re aware of it or not.
Link ID: 22453 - Posted: 07.19.2016