Chapter 16. None

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 81 - 100 of 2617

Results from a new study, funded in part by the National Center for Complementary and Integrative Health, demonstrate that mindfulness meditation works on a different pain pathway in the brain than opioid pain relievers. The researchers noted that because opioid and non-opioid mechanisms of pain relief interact synergistically, the results of this study suggest that combining mindfulness-based and pharmacologic/nonpharmacologic pain-relieving approaches that rely on opioid signaling may be particularly effective in treating pain. Previous research has shown that mindfulness meditation helps relieve pain, but researchers have been unclear about how the practice induces pain relief — specifically, if meditation is associated with the release of naturally occurring opiates. Researchers recorded pain reports in 78 healthy adults during meditation or a non-meditation control in response to painful heat stimuli and intravenous administration of the opioid antagonist naloxone (a drug that blocks the transmission of opioid activity) or placebo saline. Participants were randomized to one of four treatment groups: 1) meditation plus naloxone; 2) control plus naloxone; 3) meditation plus saline; or 4) control plus saline. People in the control groups were instructed to “close your eyes and relax until the end of the experiment.” The researchers found that participants who meditated during saline administration had significantly lower pain intensity and unpleasantness ratings compared to those who did not meditate while receiving saline. Importantly, data from the meditation plus naloxone group showed that naloxone did not block meditation’s pain-relieving effects. No significant differences in reductions of pain intensity or pain unpleasantness were seen between the meditation plus naloxone and the meditation plus saline groups. Participants who meditated during naloxone administration also had significantly greater reductions in pain intensity and unpleasantness than the control groups.

Keyword: Pain & Touch
Link ID: 22006 - Posted: 03.19.2016

Tracie McMillan When it comes to school breakfasts, two is better than none, says a new report released Thursday in the journal Pediatric Obesity. Researchers tracked nearly 600 middle-school students from fifth to seventh grade, looking to see if students ate no breakfast; ate breakfast at home or school; or ate both — and whether that affected obesity rates. The result: Weight gain among students who ate "double-breakfast" was no different than that seen among all other students. Meanwhile, the risk of obesity doubled among students who skipped breakfast or ate it inconsistently. "It seems it's a bigger problem to have kids skipping breakfast than to have these kids eating two breakfasts," says Marlene Schwartz of the Rudd Center for Food Policy and Obesity and one of the study's authors. "This study ... debunks an important misconception that school breakfast contributes to childhood obesity," says Duke Storen from Share Our Strength, a national group that runs anti-hunger and nutrition programs for children. While direct opposition to free school breakfast is unusual, says Storen, officials sometimes balk at implementing "alternative breakfast models" designed to encourage use of the program — such as offering breakfast in grab-and-go bags or in classrooms, rather than traditional sit-down meals in a cafeteria. That's a concern, say hunger advocates, because while eligibility rules for free and reduced-price breakfast are the same as for lunch, only about half as many children get subsidized breakfast as receive lunch, according to the Food Research and Action Center, an advocacy group. Indeed, the study was inspired in part by real-world concerns that school breakfast programs might promote obesity, says Schwartz. © 2016 npr

Keyword: Obesity
Link ID: 22005 - Posted: 03.19.2016

By C. CLAIBORNE RAY Current treatments for the so-called wet form of macular degeneration, involving injections inside the eye, are already “very effective” compared with laser treatments, which were used before intravitreal injections, said Dr. Ronald C. Gentile, the surgeon director at the New York Eye and Ear Infirmary of Mount Sinai. But several ways to improve their results are in the works, he said. The shots deliver drugs that fight a substance called vascular endothelial growth factor, and thus shrink the growth of what amounts to an abnormal blood vessel harming the retina. A major hurdle now involves the frequency and cost of the needed treatments. Once the drug is inside the eye, the effects wear off and a new injection is needed, Dr. Gentile said. The shots are also less effective in some patients. Even when they work well, some people need a shot as often as every four weeks, while some can wait two or three months. If both eyes are affected and the period of effectiveness is short, doctor visits can be very frequent, so drugs that last longer in the eyeball are being pursued. Researchers are working on slow-release medications as well as a delivery system that acts like a tiny pump in the eye, with a tank that can be refilled every six months. There is also a new drug target: a substance called platelet-derived growth factor that causes abnormal vessel growth as well. Combination drug treatments may be more effective against macular degeneration, Dr. Gentile said. The so-called dry form of macular degeneration, which often underlies the wet form, is harder to fight, he said, and although advances are being made, current antioxidant treatments with vitamins and minerals do not to improve vision; they just prevent it from worsening. © 2016 The New York Times Company

Keyword: ADHD
Link ID: 22004 - Posted: 03.19.2016

Nicola Davis Electrical brain stimulation could benefit stroke patients by boosting the effects of rehabilitation therapy, new research suggests. Writing in the journal Science Translational Medicine, the authors reveal that patients who were given electrical brain stimulation during a rehabilitation programme performed better on a range of tasks than those taking part in the rehabilitation programme. “It is an exciting message because there is so much frustration about people not reaching their true recovery potential,” said Professor Heidi Johansen-Berg, an author of the study from the University of Oxford, highlighting the fact that the cost of programmes and limited availability of therapists often restricts the amount of rehabilitation offered to patients. To probe the effects of brain stimulation, the researchers chose 24 patients who had experienced a stroke at least six months before, and who had difficulties with moving one hand. The participants were then split into two groups. The first group underwent nine consecutive days of rehabilitation training, with each session lasting an hour. For the first 20 minutes, the patients had two electrodes placed on their heads and a direct current applied, a process known as anodal transcranial direct current stimulation (tDCS). This is stimulation is thought to prime the brain for learning. © 2016 Guardian News and Media Limited

Keyword: Stroke
Link ID: 22000 - Posted: 03.17.2016

By KEN BELSON and ALAN SCHWARZ Perhaps no one will remember the setting, a hearing room for the House Energy and Commerce Committee, or the person who asked the question, a member of the House of Representatives from Illinois. But seven words spoken in the Rayburn House Office Building in Washington on Monday could profoundly affect the country’s most popular sport. After years of the N.F.L.‘s disputing evidence that connected football to chronic traumatic encephalopathy, the degenerative brain disease found in nearly 100 former players, a top official for the league for the first time acknowledged the link. To many, it was an echo of big tobacco’s confession in 1997 that smoking causes cancer and heart disease. Representative Jan Schakowsky, Democrat of Illinois, asked during a round-table discussion about concussions whether “there is a link between football and degenerative brain disorders like C.T.E.” Jeff Miller, the N.F.L.’s senior vice president for health and safety policy, said, “The answer to that is certainly, yes.” His response signaled a stunning about-face for the league, which has been accused by former players and independent experts of hiding the dangers of head injuries for decades. His reply came moments after a leading C.T.E. researcher — Dr. Ann McKee — had presented her findings, showing that dozens of former players who had died were afflicted with the disease. “The comments made by Jeff Miller yesterday accurately reflect the view of the N.F.L.,” Brian McCarthy, a league spokesman, said Tuesday, confirming that Mr. Miller had not misspoken. © 2016 The New York Times Company

Keyword: Brain Injury/Concussion
Link ID: 21997 - Posted: 03.16.2016

People who want to quit smoking are more likely to succeed if they go "cold turkey" by stopping abruptly, a study in Annals of Internal Medicine shows. Volunteers who used this approach were 25% more likely to remain abstinent half a year from the date that they give up than smokers who tried to gradually wean themselves off instead. The NHS says that picking a convenient date to quit is important. Make a promise, set a date and stick to it, it advises. And sticking to the "not a drag" rule can really help too. "Whenever you find yourself in difficulty say to yourself, 'I will not have even a single drag' and stick with this until the cravings pass," the service says. And it recommends seeing a GP to get professional support and advice to give up smoking. In the British Heart Foundation-funded study, nearly 700 UK volunteers were randomly assigned to one of two groups - a gradual quit group or an immediate quit group. All of the participants were also offered advice and support and access to nicotine patches and replacement therapy, like nicotine gum or mouth spray - services which are available for free on the NHS. After six months, 15.5% of the participants in the gradual-cessation group were abstinent compared with 22% in the abrupt-cessation group. Lead researcher Dr Nicola Lindson-Hawley, from Oxford University, said: "The difference in quit attempts seemed to arise because people struggled to cut down. It provided them with an extra thing to do, which may have put them off quitting altogether." Even though more people in the study said they preferred the idea of quitting gradually than abruptly, individuals were still more likely to stop for good in the abrupt group. © 2016 BBC.

Keyword: Drug Abuse
Link ID: 21993 - Posted: 03.16.2016

By ERICA GOODE Their websites show peaceful scenes — young women relaxing by the ocean or caring for horses in emerald pastures — and boast of their chefs and other amenities. One center sends out invitations to a reception with cocktails and hors d’oeuvres. Another offers doctors and therapists all-expense-paid trips to visit and experience their offerings, including yoga classes. Several employ staff who call mental health professionals, saying they would love to have lunch. The marketing efforts by these for-profit residential care centers are aimed at patients with eating disorders and the clinicians who treat them. The programs have proliferated in recent years, with some companies expanding across the country. The rapid growth of the industry — there are more than 75 centers, compared with 22 a decade ago, according to one count — has been propelled by the Affordable Care Act and other changes in health insurance laws that have increased coverage for mental disorders, as well as by investments from private equity firms. The residential programs, their directors say, fill a dire need, serving patients from areas where no adequate treatment is available. “Only 15 to 30 percent of people have access to specialized care for eating disorders, which means there are a lot of people out there who have zippo,” said Doug Bunnell, the chief clinical officer for Monte Nido, a program that began in Malibu, Calif., and now operates centers in five states. But the advertising and the profusion of centers, which typically cost $1,000 a day but can run much higher, is raising concerns among some eating disorders experts, who worry that some programs may be taking advantage of vulnerable patients and their families. In the companies’ rush to expand, they argue, quality of treatment may be sacrificed for profit. And they question whether the spalike atmosphere of some programs is so comfortable that it fosters dependency. © 2016 The New York Times Company

Keyword: Anorexia & Bulimia
Link ID: 21990 - Posted: 03.15.2016

How did evolution produce a monstrous killer like T. rex? A fossil find in Central Asia is giving scientists a glimpse of the process. T. rex and other tyrannosaurs were huge, dominant predators, but they evolved from much smaller ancestors. The new discovery from Uzbekistan indicates that this supersizing happened quickly, and only after the appearance of some anatomical features that may have helped the monster tyrannosaurs hunt so effectively. The finding was reported Monday by Hans-Dieter Sues of the Smithsonian's National Museum of Natural History in Washington, Stephen Brusatte of the University of Edinburgh in Scotland, and others in a paper released by the Proceedings of the National Academy of Sciences. The discovery They report finding bones of a previously unknown member of the evolutionary branch that led to the huge tyrannosaurs. This earlier dinosaur lived about 90 million years ago, south of what is now the Aral Sea. It looked roughly like a T. rex, but was only about 10 to 12 feet long and weighed only about 600 pounds at most, Sues said. T. rex grew about four times as long and weighed more than 20 times as much. The discovery helps fill in a frustrating gap in the tyrannosaur fossil record. Before that gap, which began some 100 million years ago, the ancestral creatures were only about as big as a horse. Right after the gap, at about 80 million years ago, tyrannosaurs were multi-ton behemoths like T. rex. The new finding shows the forerunners were still relatively small even just 90 million years ago. So the size boom happened pretty quickly. Standard equipment ©2016 CBC/Radio-Canada.

Keyword: Evolution
Link ID: 21989 - Posted: 03.15.2016

By Perri Klass, M.D. I got my good sleeper second. My oldest child, my first darling baby, did not reliably sleep through the night till he was well past 2. Since he is now an adult, I can skip right over all the questions of whether we could have trained him to self-soothe and stop calling for us in the night — we tried; we failed; we eventually gave up. The good sleeper was a good sleeper right from the beginning. She followed the timeline in the books, slept longer and longer between feedings, till she was reliably giving us a real night while she was still an infant and she never looked back. Had we matured as parents, become less anxious, more willing to let her learn how to soothe herself? Were our lives calmer? Well, no. In fact, kind of the opposite. We just got dealt two very different babies. I supervise pediatric residents as they learn to provide primary care, to offer guidance to parents as they struggle with all the complexities of baby and toddler sleep, eating, potty training, discipline and tantrums. All of the stuff that shapes your daily life with a small child, and I’m talking about an essentially healthy, normally developing small child. And the hardest thing to teach, especially to people who haven’t yet done any child-rearing, is how different those healthy, normal babies can be, right from the beginning. So we review our sensible pediatric rubrics that deal with these questions, from establishing good sleep patterns to setting limits to encouraging a healthy varied diet. But sometimes it seems that these rubrics work best with the children and families who need them least. Every child is a different assignment — and we can all pay lip service to that cheerfully enough. But the hard thing to believe is how different the assignments can be. Within the range of developmentally normal children, some parents have a much, much harder job than others: more drudge work, less gratification, more public shaming. It sometimes feels like the great undiscussed secret of pediatrics — and of parenting © 2016 The New York Times Company

Keyword: Development of the Brain
Link ID: 21988 - Posted: 03.15.2016

By Julia Shaw Our brains play tricks on us all the time, and these tricks can mislead us into believing we can accurately reconstruct our personal past. In reality, false memories are everywhere. False memories are recollections of things that you never actually experienced. These can be small memory errors, such as thinking you saw a yield sign when you actually saw a stop sign, or big errors like thinking you took a hot air balloon ride that never actually happened. If you want to know more about how we can come to misremember complex autobiographical events, here is a recipe and here is a video with footage from my own research. A few weeks ago I reached out to see what you actually wanted to know about this phenomenon on Reddit, and here are the answers to my six favorite questions. 1. Is there any way a person can check if their own memories are real or false? The way that I have interpreted the academic literature, once they take hold false memories are no different from true memories in the brain. This means that they have the same properties as any other memories, and are indistinguishable from memories of events that actually happened. The only way to check, is to find corroborating evidence for any particular memory that you are interested in “validating”. © 2016 Scientific American

Keyword: Learning & Memory
Link ID: 21985 - Posted: 03.15.2016

By HEATHER MURPHY Good morning. Or confusing morning, really. Come Daylight Saving Time each year, people often complain about how thrown off they feel by the shift of an hour. I thought they were just whiny. That is, until my dinosaur got jet lag and refused to glow. Since that’s not an everyday occurrence, let me explain the dinosaur first, and then I’ll get to how my dinosaur’s problems may be connected to your own struggles to function over the next few days. (Hint: It’s not only the loss of sleep that causes problems.) Created by a company called BioPop, my Dino Pet contains lots of itty bitty dinoflagellates. Dinoflagellates, if you are having trouble summoning a sixth-grade biology lesson, are usually ocean-dwelling, single-celled organisms also known as marine plankton. People typically encounter them when they clean the inside of their aquarium (this form is often referred “brown slime algae”) or if they happen to be kayaking through a bay filled with lots of bioluminescent ones. The ones that live in my plastic dinosaur (a Christmas gift) are the latter kind. Shake them just a bit and the transparent creatures become a glow-in-the-dark snow globe. Except that a week after I set my dinosaur up, it still refused to put on its shimmer show. I tried everything. I moved it from darker to lighter spots. I played it music and whispered encouraging words. But when I turned off the lights, my little dino remained depressingly dark. © 2016 The New York Times Company

Keyword: Biological Rhythms
Link ID: 21981 - Posted: 03.14.2016

Sara Reardon Elite ski jumpers rely on extreme balance and power to descend the steep slopes that allow them to reach up to 100 kilometres per hour. But the US Ski and Snowboard Association (USSA) is seeking to give its elite athletes an edge by training a different muscle: the mind. Working with Halo Neuroscience in San Francisco, California, the sports group is testing whether stimulating the brain with electricity can improve the performance of ski jumpers by making it easier for them to hone their skills. Other research suggests that targeted brain stimulation can reduce an athlete’s ability to perceive fatigue1. Such technologies could aid recovery from injury or let athletes try 'brain doping' to gain a competitive advantage. Yet many scientists question whether brain stimulation is as effective as its proponents claim, pointing out that studies have looked at only small groups of people. “They’re cool findings, but who knows what they mean,” says cognitive psychologist Jared Horvath at the University of Melbourne in Australia. The USSA is working with Halo to judge the efficacy of a device that delivers electricity to the motor cortex, an area of the brain that controls physical skills. The company claims that the stimulation helps the brain build new connections as it learns a skill. It tested its device in an unpublished study of seven elite Nordic ski jumpers, including Olympic athletes. © 2016 Nature Publishing Group,

Keyword: Movement Disorders
Link ID: 21979 - Posted: 03.12.2016

By Dominic Howell BBC News Gum disease has been linked to a greater rate of cognitive decline in people with Alzheimer's disease, early stage research has suggested. The small study, published in PLOS ONE, looked at 59 people who were all deemed to have mild to moderate dementia. It is thought the body's response to gum inflammation may be hastening the brain's decline. The Alzheimer's Society said if the link was proven to be true, then good oral health may help slow dementia. The body's response to inflammatory conditions was cited as a possible reason for the quicker decline. Inflammation causes immune cells to swell and has long been associated with Alzheimer's. Researchers believe their findings add weight to evidence that inflammation in the brain is what drives the disease. 'Six-fold increase' The study, jointly led by the University of Southampton and King's College London, cognitively assessed the participants, and took blood samples to measure inflammatory markers in their blood. Their oral health was also assessed by a dental hygienist who was unaware of the cognitive outcomes. Of the sample group, 22 were found to have considerable gum disease while for the remaining 37 patients the disease was much less apparent. The average age of the group with gum disease was 75, and in the other group it was 79. A majority of participants - 52 - were followed up at six months, and all assessments were repeated. The presence of gum disease - or periodontitis as it is known - was associated with a six-fold increase in the rate of cognitive decline, the study suggested. © 2016 BBC

Keyword: Alzheimers
Link ID: 21976 - Posted: 03.12.2016

Carl Zimmer Scientists recently turned Harvard’s Skeletal Biology Laboratory into a pop-up restaurant. It would have fared very badly on Yelp. Katherine D. Zink, then a graduate student, acted as chef and waitress. First, she attached electrodes to the jaws of diners to record the activity in the muscles they use to chew food. Then she brought out the victuals. Some volunteers received a three-course vegetarian meal of carrots, yams or beets. In one course, the vegetables were cooked; in the second, they were raw and sliced; in the last course, Dr. Zink simply served raw chunks of plant matter. Other patrons got three courses of meat (goat, in this case). Dr. Zink grilled the meat in the first course, but offered it raw and sliced in the second. In the third course, her volunteers received an uncooked lump of goat flesh. In some of the trials, the volunteers chewed the food until it was ready to swallow and then spat it out. Dr. Zink painstakingly picked apart those food bits and measured their size. Every week, we'll bring you stories that capture the wonders of the human body, nature and the cosmos. “If that was all my dissertation was, I would have quit graduate school,” Dr. Zink said. “It was as lovely as it sounds.” Dr. Zink persevered, however, because she was exploring a profound question about our origins: How did our ancestors evolve from small-brained, big-jawed apes into large-brained, small-jawed humans? Scientists studying the fossil record have long puzzled over this transition, which happened around two million years ago. Before then, early human relatives — known as hominins — were typically about the size of chimpanzees, with massive teeth and a brain only a third the size of humans’ current brains. © 2016 The New York Times Company

Keyword: Evolution; Obesity
Link ID: 21975 - Posted: 03.10.2016

By Jerome Siegel To say whether an animal sleeps requires that we define sleep. A generally accepted definition is that sleep is a state of greatly reduced responsiveness and movement that is homeostatically regulated, meaning that when it is prevented for a period of time, the lost time is made up—an effect known as sleep rebound. Unfortunately, the application of this definition is sometimes difficult. Can an animal sleep while it is moving and responsive? How unresponsive does an animal have to be? How much of the lost sleep has to be made up for it to be considered homeostatically regulated? Is the brain activity that characterizes sleep in humans necessary and sufficient to define sleep in other animals? Apart from mammals, birds are the only other animals known to engage in both slow-wave and rapid eye movement (REM) sleep. Slow-wave sleep, also called non-REM sleep, is characterized by slow, high-amplitude waves of electrical activity in the cortex and by slow, regular respiration and heart rate. During REM sleep, animals exhibit a waking-like pattern of cortical activity, as well as physiological changes including jerky eye twitches and increased variability of heart rate and respiration. (See “The A, B, Zzzzs.”) But many more animals, including some insects and fish, engage in behaviors that might be called sleep, such as resting with slow but regular respiration and heart rates and a desensitization to environmental stimuli. In addition to diversity in the neural and physiological correlates of sleep, species vary tremendously in the intensity, frequency, and duration of sleep. Some animals tend to nap intermittently throughout the day, while others, including humans, tend to consolidate their sleep into a single, long slumber. The big brown bat is the current sleep champion, registering 20 hours per day; giraffes and elephants doze less than four hours daily. © 1986-2016 The Scientist

Keyword: Sleep; Evolution
Link ID: 21974 - Posted: 03.10.2016

Monya Baker A surgical technique to treat cataracts in children spurs stem cells to generate a new, clear lens. Discs made of multiple types of eye tissue have been grown from human stem cells — and that tissue has been used to restore sight in rabbits. The work, reported today in Nature1, suggests that induced pluripotent stem (iPS) cells — stem cells generated from adult cells — could one day be harnessed to provide replacement corneal or lens tissue for human eyes. The discs also could be used to study how eye tissue and congenital eye diseases develop. “The potential of this technique is mind-boggling,” says Mark Daniell, head of corneal research at the Centre for Eye Research Australia in Melbourne, who was not involved in the research. “It’s almost like an eye in a dish.” A second, unrelated paper in Nature2 describes a surgical procedure that activates the body’s own stem cells to regenerate a clear, functioning lens in the eyes of babies born with cataracts. The two studies are “amazing, almost like science fiction”, Daniell says. In the first study, a team led by Kohji Nishida, an ophthalmologist at Osaka University Graduate School of Medicine in Japan, cultivated human iPS cells to produce discs that contained several types of eye tissue. © 2016 Nature Publishing Group

Keyword: Vision
Link ID: 21971 - Posted: 03.10.2016

By Anahad O'Connor Mark Mattson, a neuroscientist at the National Institute on Aging in Maryland, has not had breakfast in 35 years. Most days he practices a form of fasting — skipping lunch, taking a midafternoon run, and then eating all of his daily calories (about 2,000) in a six-hour window starting in the afternoon. “Once you get used to it, it’s not a big deal,” said Dr. Mattson, chief of the institute’s laboratory of neurosciences. “I’m not hungry at all in the morning, and this is other people’s experience as well. It’s just a matter of getting adapted to it.” In a culture in which it’s customary to eat three large meals a day while snacking from morning to midnight, the idea of regularly skipping meals may sound extreme. But in recent years intermittent fasting has been gaining popular attention and scientific endorsement. It has been promoted in best-selling books and endorsed by celebrities like the actors Hugh Jackman and Benedict Cumberbatch. The late-night talk show host Jimmy Kimmel claims that for the past two years he has followed an intermittent fasting program known as the 5:2 diet, which entails normal eating for five days and fasting for two — a practice Mr. Kimmel credits for his significant weight loss. Fasting to improve health dates back thousands of years, with Hippocrates and Plato among its earliest proponents. Dr. Mattson argues that humans are well suited for it: For much of human history, sporadic access to food was likely the norm, especially for hunter-gatherers. As a result, we’ve evolved with livers and muscles that store quickly accessible carbohydrates in the form of glycogen, and our fat tissue holds long-lasting energy reserves that can sustain the body for weeks when food is not available. “From an evolutionary perspective, it’s pretty clear that our ancestors did not eat three meals a day plus snacks,” Dr. Mattson said. © 2016 The New York Times Company

Keyword: Obesity
Link ID: 21969 - Posted: 03.09.2016

By Virginia Morell Butterflies may not have a human’s sharp vision, but their eyes beat us in other ways. Their visual fields are larger, they’re better at perceiving fast-moving objects, and they can distinguish ultraviolet and polarized light. Now, it turns out that one species of swallowtail butterfly from Australasia, the common bluebottle (Graphium sarpedon, pictured), known for its conspicuous blue-green markings, is even better equipped for such visual tasks. Each of their eyes, scientists report in Frontiers in Ecology and Evolution, contains at least 15 different types of photoreceptors, the light-detecting cells required for color vision. These are comparable to the rods and cones found in our eyes. To understand how the spectrally complex retinas of butterflies evolved, the researchers used physiological, anatomical, and molecular experiments to examine the eyes of 200 male bluebottles collected in Japan. (Only males were used because the scientists failed to catch a sufficient number of females.) They found that different colors stimulate each class of receptor. For instance, UV light stimulates one, while slightly different blue lights set off three others; and green lights trigger four more. Most insect species have only three classes of photoreceptors. Even humans have only three cones, yet we still see millions of colors. Butterflies need only four receptor classes for color vision, including spectra in the UV region. So why did this species evolve 11 more? The scientists suspect that some of the receptors must be tuned to perceive specific things of great ecological importance to these iridescent butterflies—such as sex. For instance, with eyes alert to the slightest variation in the blue-green spectrum, male bluebottles can spot and chase their rivals, even when they’re flying against a blue sky. © 2016 American Association for the Advancement of Science

Keyword: Vision
Link ID: 21968 - Posted: 03.09.2016

By GINA KOLATA Marty and Matt Reiswig, two brothers in Denver, knew that Alzheimer’s disease ran in their family, but neither of them understood why. Then a cousin, Gary Reiswig, whom they barely knew, wrote a book about their family, “The Thousand Mile Stare.” When the brothers read it, they realized what they were facing. In the extended Reiswig family, Alzheimer’s disease is not just a random occurrence. It results from a mutated gene that is passed down from parent to child. If you inherit the mutated gene, Alzheimer’s will emerge at around age 50 — with absolute certainty. Your child has a 50-50 chance of suffering the same fate. The revelation came as a shock. And so did the next one: The brothers learned that there is a blood test that can reveal whether one carries the mutated gene. They could decide to know if they had it. Or not. It’s a dilemma more people are facing as scientists discover more genetic mutations linked to diseases. Often the newly discovered gene increases risk, but does not guarantee it. Sometimes knowing can be useful: If you have a gene mutation that makes colon cancer much more likely , for example, then frequent colonoscopies may help doctors stave off trouble. But then there are genes that make a dreaded disease a certainty: There is no way to prevent it, and no way to treat it. Marty Reiswig, 37, saw his father, now in the final stages of Alzheimer’s, slowly lose his ability to think, to remember, to care for himself, or even to recognize his wife and sons. Mr. Reiswig knows that if he has the gene, he has perhaps a bit more than a decade before the first symptoms appear. If he has it, his two young children may have it, too. He wavers about getting tested. © 2016 The New York Times Company

Keyword: Alzheimers; Genes & Behavior
Link ID: 21967 - Posted: 03.08.2016

Our eyes constantly send bits of information about the world around us to our brains where the information is assembled into objects we recognize. Along the way, a series of neurons in the eye uses electrical and chemical signals to relay the information. In a study of mice, National Institutes of Health scientists showed how one type of neuron may do this to distinguish moving objects. The study suggests that the NMDA receptor, a protein normally associated with learning and memory, may help neurons in the eye and the brain relay that information. “The eye is a window onto the outside world and the inner workings of the brain,” said Jeffrey S. Diamond, Ph.D., senior scientist at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS), and the senior author of the study published in Neuron. “Our results show how neurons in the eye and the brain may use NMDA receptors to help them detect motion in a complex visual world.” Vision begins when light enters the eye and hits the retina, which lines the back of the eyeball. Neurons in the retina convert light into nerve signals which are then sent to the brain. Using retinas isolated from mice, Dr. Alon Poleg-Polsky, Ph.D. a postdoctoral fellow in Dr. Diamond’s lab, studied neurons called directionally selective retinal ganglion cells (DSGCs), which are known to fire and send signals to the brain in response to objects moving in specific directions across the eye. Electrical recordings showed that some of these cells fired when a bar of light passed across the retina from left to right, whereas others responded to light crossing in the opposite direction. Previous studies suggested these unique responses are controlled by incoming signals sent from neighboring cells at chemical communication points called synapses. In this study, Dr. Poleg-Polsky discovered that the activity of NMDA receptors at one set of synapses may regulate whether DSGCs sent direction-sensitive information to the brain.

Keyword: Vision
Link ID: 21966 - Posted: 03.08.2016