Chapter 16. None
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Founded by two men in Akron, Ohio, in 1935, Alcoholics Anonymous has since spread around the world as a leading community-based method of overcoming alcohol dependence and abuse. Many people swear by the 12-step method, which has become the basis of programs to treat the abuse of drugs, gambling, eating disorders and other compulsive behaviors. But not everyone's a fan. In a recent critique of AA, author Gabrielle Glaser writes in the April issue of The Atlantic that, "Nowhere in the field of medicine is treatment less grounded in modern science." Glaser, whose 2013 book, Her Best-Kept Secret, explores what she calls "the epidemic of female drinking" in the U.S., says recent research on the brain suggests that the abstinence advocated by AA isn't the only solution — or even the best for many people. Cognitive therapy combined with the medication naltrexone, Glaser says, can help ease cravings and has been shown in some studies to help some problem drinkers learn to drink moderately without quitting. Glaser's magazine story has drawn fire from defenders of AA, including Huffington Post writer Tommy Rosen, who calls himself "a person in long-term recovery (23 years) who overcame severe drug addiction and alcoholism in great part due to the 12 Steps." Glaser's article, Rosen writes, is "painfully one-sided." Therapist and psychology reporter Robi Ludwig told Glaser and the host of MSNBC's program All in With Chris Hayes last week that she thinks it's "very dangerous to put out the idea that AA doesn't work. Does it work for everybody? No. There's not going to be one form of treatment that works for everybody." © 2015 NPR
Keyword: Drug Abuse
Link ID: 20729 - Posted: 03.28.2015
Patrick Fuller is a neuroscientist at Harvard Medical School's esteemed Division of Sleep Medicine. What have you found in your research on the "neurocircuit basis" that supports sleep? In specific reference to our recent work on the brainstem slow-wave-sleep promoter "center," we showed that this region of the brain is first connected (synaptically) to an important wake-promoting region of the brainstem that in turn is connected with important wake-promoting circuitry of the forebrain, which itself connects to the cerebral cortex. Essentially, we provided a circuit "wiring diagram" by which activation of brainstem sleep-promoting neurons might produce "whole brain" sleep. The reason I emphasize the word "neurocircuit" in our work is because I believe that in order to understand how the brain accomplishes virtually anything, one must first understand the functional cellular and synaptic "scaffolding" from which brain phenomena emerge. Tell me about how circadian regulation affects our sleep and wakeful consciousness. So it all starts (and ends!) with a little biological clock in our brain. The so-called "master" circadian clock is actually a collection of neurons located in a small region of the hypothalamus, itself a very small structure. (In humans, the hypothalamus is about the size of an almond.) This clock is remarkable for many reasons, perhaps most notably that no other region of the brain can assume its function if/when it is damaged. The clock's fundamental role is to keep us "synchronized" with the Earth's light-dark cycle as well as keep our body's internal rhythms synchronized with one another. And we now know that proper external and internal synchronization is fundamental to our physical and mental well-being. ©2015 TheHuffingtonPost.com, Inc.
Link ID: 20728 - Posted: 03.28.2015
By Nicholas Bakalar Air pollution — even for just one day — significantly increases the risk of stroke, a large review of studies has found. Researchers pooled data from 103 studies involving 6.2 million stroke hospitalizations and deaths in 28 countries. The analysis, published online in BMJ, found that all types of pollution except ozone were associated with increased risk for stroke, and the higher the level of pollution, the more strokes there were. Daily increases in pollution from nitrogen dioxide, sulfur dioxide, carbon monoxide and particulate matter were associated with corresponding increases in strokes and hospital admissions. The strongest associations were apparent on the day of exposure, but increases in particulate matter had longer-lasting effects. The exact reason for the effect is unclear, but studies have shown that air pollution can constrict blood vessels, increase blood pressure and increase the risk for blood clots. Other research has tied air pollution to a higher risk of heart attacks, stroke and other ills. The lead author, Dr. Anoop Shah, a lecturer in cardiology at the University of Edinburgh, said that there was little an individual can do when air pollution spikes. “If you’re elderly, or have co-morbid conditions, you should stay inside,” he said. But policies leading to cleaner air would have the greatest impact, he said. “It’s a question of getting cities and countries to change.” © 2015 The New York Times Company
Jon Hamilton A biotech company and two scientists hope to change that. On Wednesday, Avalanche Biotechnologies in Menlo Park and the University of Washington in Seattle announced a licensing agreement to develop the first treatment for colorblindness. The deal brings together a gene therapy technique developed by Avalanche with the expertise of vision researchers at the University of Washington. "Our goal is to be treating colorblindness in clinical trials in patients in the next one to two years," says Thomas Chalberg, the founder and CEO of Avalanche. Dalton the squirrel monkey during the color vision test. i Dalton the squirrel monkey during the color vision test. Courtesy of Neitz Laboratory The agreement has its roots in a scientific breakthrough that occurred six years ago. That's when two vision researchers at the University of Washington used gene therapy to cure a common form of colorblindness in squirrel monkeys. "This opened the possibility of ultimately getting this to cure colorblindness in humans," says Jay Neitz, who runs the Color Vision Lab at UW along with his wife, Maureen Neitz. The couple knew that transferring their success from monkey to man would be a challenge. But they were determined, says Maureen Neitz. "We've spent our entire careers writing NIH grants where we say our goal is to improve human health." © 2015 NPR
Link ID: 20725 - Posted: 03.26.2015
By BONNIE ROCHMAN Reasons Why I Shouldn’t Have to Go Tonight: If I wanted to talk about it, I would. / It’s my body. / It’s a waste of time. / It’s a waste of money. / I know what I need to know. / It sounds pretty stupid to me. PLEASE DON’T MAKE ME GO. I DON’T WANT TO GO. The plea came from Leah Likin, a fifth grader. It was addressed to her mother, who had registered both of them for a two-part course on puberty called “For Girls Only.” The missive, which included additional objections, failed: Mother took daughter anyway. But Leah had plenty of company, peers who shared her resistance, their arms crossed, their eyes downcast. Last year, the course, which is split into sessions for preteen boys and girls and held mostly in and around Seattle, and also in the Bay Area, pulled in 14,000 attendees. They heard about it from their pediatricians, or through word of mouth. The creator of the course, Julie Metzger, has been trying for nearly three decades to turn what’s so often at best a blush-inducing experience — the “facts of life” talk — into a candid dialogue between parents and children. In the mid-1980s, she was a graduate student at the University of Washington School of Nursing when she reviewed survey data on how women had learned about menarche, or the onset of menstruation, for her master’s thesis. Most reported getting information from gym class or their mothers. “You can picture those conversations lasting from 10 seconds to 10 hours,” Metzger says. “And I thought, Wouldn’t it be interesting if you actually had a class where you sit with your parents and hear these things from someone? What if that class were fun and funny and interactive?” Metzger, who is 56 and vigorous, with flushed cheeks and blue eyes, says she has always been comfortable talking about sexuality; her father was a urologist, her mother a nurse. “Hand me a microphone,” she says. “I get so into this topic that I can make myself cry in front of the class, and it’s real.” © 2015 The New York Times Company
Keyword: Sexual Behavior
Link ID: 20722 - Posted: 03.26.2015
Jon Hamilton Doctors are much more likely to level with patients who have cancer than patients who have Alzheimer's, according to a report released this week by the Alzheimer's Association. The report found that just 45 percent of Medicare patients who'd been diagnosed with Alzheimer's said they were informed of the diagnosis by their doctor. By contrast, more than 90 percent of Medicare patients with cancer said they were told by their doctor. "What we found is really shocking," says Beth Kallmyer, vice president of constituent services for the Alzheimer's Association. "This is reminiscent of what happened in the 1960s and 1970s with cancer," she says. "But that's changed now, and it really needs to change for Alzheimer's as well." For years, the association's help line has been receiving complaints from family members who say that doctors are reluctant to reveal an Alzheimer's diagnosis, Kallmyer says. So the association decided to investigate by studying medical records and survey results from Medicare recipients. To make sure that Alzheimer's patients hadn't simply forgotten what a doctor said, the group also looked at Medicare survey responses from family members and other caregivers. The result wasn't much better: Just 53 percent said a doctor told them of the patient's diagnosis. © 2015 NPR
Link ID: 20721 - Posted: 03.25.2015
By Rachel Feltman I'm not usually one for heartstring-tugging ads, but this collaboration between Valspar Paint and EnChroma, a company that makes color-boosting sunglasses for the color-blind, is pretty cool. And the coolest thing about the glasses in the above video is that they weren't designed to help the color-blind at all. Smithsonian Magazine reports that EnChroma Labs founder Don McPherson (a materials scientist) had originally engineered the glasses with surgeons in mind. The lenses contained rare earth iron and absorbed a ton of light to protect surgeons performing laser eye surgery. The boosted absorption also made colors pop more vibrantly, allowing them to more easily distinguish among different tissues during surgery. But the stellar eye protection and vibrant colors meant that many surgeons wanted to wear them outside the operating room. McPherson himself started using them as regular sunglasses. And when a color-blind friend tried them on, he was amazed: He could distinguish orange traffic cones from the grass and pavement around them. He was perceiving color in a way he never had before. Now EnChroma sells the glasses (which have been specifically tailored for color blindness since the accidental discovery) for a few hundred bucks a pop. McPherson explains that all people have three photopigments in the eye, also known as cones, which are sensitive to blue, green and red. Blue operates fairly independently, while the red and green cones, in most humans, overlap, affecting the perception of certain colors. For example, if 10 photons landed on the red cone and 100 landed on the green cone, the object viewed would appear more green. Whereas if an equal number of photons landed on the red and green cones, the color perceived would be yellow.
Link ID: 20720 - Posted: 03.25.2015
Alice Park We start to talk before we can read, so hearing words, and getting familiar with their sounds, is obviously a critical part of learning a language. But in order to read, and especially in order to read quickly, our brains have to “see” words as well. At least that’s what Maximilian Riesenhuber, a neuroscientist at Georgetown University Medical Center, and his colleagues found in an intriguing brain-mapping study published in the Journal of Neuroscience. The scientists recruited a small group of college students to learn a set of 150 nonsense words, and they imaged their brains before and after the training. Before they learned the words, their brains registered them as a jumble of symbols. But after they were trained to give them a meaning, the words looked more like familiar words they used every day, like car, cat or apple. The difference in way the brain treated the words involved “seeing” them rather than sounding them out. The closest analogy would be for adults learning a foreign language based on a completely different alphabet system. Students would have to first learn the new alphabet, assigning sounds to each symbol, and in order to read, they would have to sound out each letter to put words together. In a person’s native language, such reading occurs in an entirely different way.
Link ID: 20719 - Posted: 03.25.2015
By Harriet Brown If you’re one of the 45 million Americans who plan to go on a diet this year, I’ve got one word of advice for you: Don’t. You’ll likely lose weight in the short term, but your chance of keeping if off for five years or more is about the same as your chance of surviving metastatic lung cancer: 5 percent. And when you do gain back the weight, everyone will blame you. Including you. This isn’t breaking news; doctors know the holy trinity of obesity treatments—diet, exercise, and medication—don’t work. They know yo-yo dieting is linked to heart disease, insulin resistance, higher blood pressure, inflammation, and, ironically, long-term weight gain. Still, they push the same ineffective treatments, insisting they’ll make you not just thinner but healthier. In reality, 97 percent of dieters regain everything they lost and then some within three years. Obesity research fails to reflect this truth because it rarely follows people for more than 18 months. This makes most weight-loss studies disingenuous at best and downright deceptive at worst. One of the principles driving the $61 billion weight-loss industries is the notion that fat is inherently unhealthy and that it’s better, health-wise, to be thin, no matter what you have to do to get there. But a growing body of research is beginning to question this paradigm. Does obesity cause ill health, result from it, both, or neither? Does weight loss lead to a longer, healthier life for most people? Studies from the Centers for Disease Control and Prevention repeatedly find the lowest mortality rates among people whose body mass index puts them in the “overweight” and “mildly obese” categories.
Link ID: 20718 - Posted: 03.25.2015
By Kate Baggaley Mutations on a gene necessary for keeping cells clean can cause Lou Gehrig’s disease, scientists report online March 24 in Nature Neuroscience. The gene is one of many that have been connected to the condition. In amyotrophic lateral sclerosis, also known as Lou Gehrig’s disease, nerve cells that control voluntary movement die, leading to paralysis. Scientists have previously identified mutations in 29 genes that are linked with ALS, but these genes account for less than one-third of all cases. To track down more genes, a team of European researchers looked at the protein-coding DNA of 252 ALS patients with a family history of the disease, as well as of 827 healthy people. The team discovered eight mutations on a gene called TBK1 that were associated with ALS. TBK1 normally codes for a protein that controls inflammation and cleans out damaged proteins from cells. “We do not know which of these two principle functions of TBK1 is the more relevant one” to ALS, says coauthor Jochen Weishaupt, a neurologist at Ulm University in Germany. In cells with one of the eight TBK1 mutations, the protein either is missing or lacks components that it needs to interact with other proteins, the researchers found. TBK1 mutations may explain 2 percent of ALS cases that run in families, which make up about 10 percent of all incidences of the disease, Weishaupt says. © Society for Science & the Public 2000 - 2015
By NICHOLAS BAKALAR Concussions are not as common in Major League Baseball as they are in professional football, but they happen often enough, with players getting hit by pitches, running into walls or catching a knee in the head sliding into a base. Catchers are particularly at risk — a foul tip off the mask will snap the neck back and give the brain a solid rattle. Collisions at the plate take a toll, too. Now, a study published in the American Journal of Sports Medicine suggests that position players in the majors who sustain concussions do not hit as effectively in their first weeks back after their injury. Under Major League Baseball rules, players can return after a concussion if they pass the concussion protocol — a series of interviews and tests of physical and mental functioning. But the new study found that even after passing the tests and having no apparent symptoms, hitters showed an initial decline when they returned to action. The study identified 66 position players who had concussions between 2007 and 2013, including some who never went on the disabled list. The study then compared their performance in the weeks before and after the injury. The gap was noticeable. In the two weeks before their injuries, the players hit .249 with a .315 on base percentage and a .393 slugging average. For the two weeks after the injury, their line was .227/.287/.347. Baseball instituted a seven-day disabled list in 2011, specifically to let players recover from concussions while allowing the team to maintain a full roster. But there is no set time that a player must stay out after a concussion. If he passes the protocol, he is cleared to play. © 2015 The New York Times Company
Keyword: Brain Injury/Concussion
Link ID: 20715 - Posted: 03.24.2015
By Brian Handwerk In the U.S., legal hurdles have long hampered research into marijuana. But as more states approve medical and even recreational marijuana, scientific inquiries have spiked, especially studies aimed at finding out what exactly is in today's weed—and what it does to our bodies. In Colorado, which made marijuana legal in November 2012, the latest results show that the pot lining store shelves is much more potent than the weed of 30 years ago. But the boost in power comes at a cost—modern marijuana mostly lacks the components touted as beneficial by medical marijuana advocates, and it is often contaminated with fungi, pesticides and heavy metals. “There's a stereotype, a hippy kind of mentality, that leads people to assume that growers are using natural cultivation methods and growing organically," says Andy LaFrate, founder of Charas Scientific, one of eight Colorado labs certified to test cannabis. "That's not necessarily the case at all." LaFrate presented his results this week at a meeting of the American Chemical Society (ACS) in Denver. LaFrate says he's been surprised at just how strong most of today's marijuana has become. His group has tested more than 600 strains of marijuana from dozens of producers. Potency tests, the only ones Colorado currently requires, looked at tetrahydrocannabinol (THC), the psychoactive compound that produces the plant's famous high. They found that modern weed contains THC levels of 18 to 30 percent—double to triple the levels that were common in buds from the 1980s. That's because growers have cross-bred plants over the years to create more powerful strains, which today tout colorful names like Bruce Banner, Skunkberry and Blue Cookies.
Keyword: Drug Abuse
Link ID: 20712 - Posted: 03.24.2015
By Siri Carpenter “I don’t look like I have a disability, do I?” Jonas Moore asks me. I shake my head. No, I say — he does not. Bundled up in a puffy green coat, Moore, 35 and sandy-haired, doesn’t stand out in the crowd seeking refuge from the winter cold in a drafty Starbucks. His handshake is firm and his blue eyes meet mine as we talk. He comes across as intelligent and thoughtful, if perhaps a bit reserved. His disability — a form of autism — is invisible. That’s part of the problem, Moore says. Like most people with an autism spectrum disorder, he finds relationships challenging. In the past, he has been quick to anger and has had what he calls meltdowns. Those who don’t know he has autism can easily misinterpret his actions. “People think that when I do misbehave I’m somehow intentionally trying to be a jerk,” Moore says. “That’s just not the case.” His difficulty managing emotions has gotten him into some trouble, and he has had a hard time holding onto jobs — an outcome he might have avoided, he says, if his co-workers and bosses had better understood his intentions. Over time, things have gotten better. Moore has held the same job for five years, vacuuming commercial buildings on a night cleaning crew. He attributes his success to getting the right amount of medication and therapy, to time’s maturing him and to the fact that he works mostly alone. Moore is fortunate. His parents help support him financially. He has access to good mental health care where he lives in Wisconsin. And he has found a job that suits him. Many adults with autism are not so lucky.
Link ID: 20711 - Posted: 03.24.2015
|By Susana Martinez-Conde and Stephen L. Macknik All visual art is illusory in that it involves a departure from reality, a filtering through the mind of the artist. This subjectivity applies not only to abstract works but also to representational art, in which the artist translates his or her perception into a physical object capable of inducing a similar perception in the viewer. Painters render the three-dimensional world on a flat surface. These representations are enough to suspend our visual system's disbelief and trigger barrages of neuronal firing that become visions of bathers, bridges and water lilies. It is never about reality but about how the artist sees and wants to portray it. This artistic vision is a mishmash of expectations, memories, assumptions, imagination and intent. It is also, in a sense, a reflection of neural shortcuts and basic visual processes. The picture becomes even more complicated when painters suffer from pathologies of the eyes or brain that force them to see their surroundings in ways that diverge from standard experience. The artwork produced by such artists allows us to participate in their perception—and misperception—of the world. For example, failing vision can translate into an eerie loss of precision and detail in paintings. The pictures of American artist Georgia O'Keeffe became flatter and less intricate as she developed bilateral age-related macular degeneration, a retinal disease that affects central, high-resolution vision. The later works of American painter Mary Cassatt similarly show an uncharacteristic absence of delicacy in faces as she developed cataracts. French impressionist Claude Monet also had cataracts, which rendered his paintings imprecise and muted in color. After he underwent successful cataract surgery, his paintings regained definition and vibrancy. As the examples in this column attest, the effects of vision or brain diseases can sometimes be traced in great works of art. © 2015 Scientific American
Link ID: 20710 - Posted: 03.24.2015
By ANDREW POLLACK An experimental drug for Alzheimer’s disease sharply slowed the decline in mental function in a small clinical trial, researchers reported Friday, reviving hopes for an approach to therapy that until now has experienced repeated failures. The drug, being developed by Biogen Idec, could achieve sales of billions of dollars a year if the results from the small trial are replicated in larger trials that Biogen said it hoped to begin this year. Experts say that there are no really good drugs now to treat Alzheimer’s. Biogen’s stock has risen about 50 percent since early December, when the company first announced that the drug had slowed cognitive decline in the trial, without saying by how much. Analysts and investors had been eagerly awaiting the detailed results, some of them flying to France to hear Biogen researchers present them at a neurology meeting on Friday. The drug, called aducanumab, met and in some cases greatly exceeded Wall Street expectations in terms of how much the highest dose slowed cognitive decline. However, there was a high incidence of a particular side effect that might make it difficult to use the highest dose. Still, the net impression was positive. “Out-of-the-ballpark efficacy, acceptable safety,” Ravi Mehrotra, an analyst at Credit Suisse, wrote on Friday. Shares of Biogen rose $42.33, or 10 percent, to $475.98. Alzheimer’s specialists were impressed, but they cautioned that it was difficult to read much from a small early-stage, or Phase 1, trial that was designed to look at safety, not the effect on cognition. Also, other Alzheimer’s drugs that had looked promising in early studies ended up not working in larger trials. “It’s certainly encouraging,” said Dr. Samuel Gandy, director of the Center for Cognitive Health at Mount Sinai Hospital in New York, who was not involved in the study. He said the effect of the highest dose was “pretty impressive.” © 2015 The New York Times Company
Link ID: 20709 - Posted: 03.21.2015
by Emiko Jozuka Touch, says David J. Linden, is something we take for granted. "It's very hard to imagine it gone," he tells WIRED.co.uk. "You can imagine what it's like to be blind or deaf, or have no sense of smell, but there's no way to turn off touch". Touch might not be an obvious starting point for Linden, who is a professor of neuroscience at the John Hopkins University, studying learning and memory. But according to the professor, "the story of the neuroscience underlying touch has yet to be told". Pointing to the advances made in touch research over the last 20 years, Linden tells us that his own interest in the topic was sparked over lunch by colleagues working in the School of Medicine. Making the complex links between the brain and our sense of touch accessible to a wider audience is no easy feat. Yet in his recent book entitled, Touch: The Science of Hand, Heart, and Mind, Linden offers anecdotal and factual ways in to exploring different aspects of touch, whether that be in the form of pain, itches, hot and cold sensations or caresses. "We think of touch as being a one sense modality, but it's many different sensors in the skin acting in parallel," says Linden. He explains how the information in the form of, for example, an itch, pain or caress relays to the brain, dividing them into either discriminative or emotional forms of touch. The discriminative touch allows a person to understand where the body is being touched, or to understand if an object is textured, smooth or 3D. While emotional touch is what makes pain feel emotionally negative, or an orgasm feel positive, says Linden.
Keyword: Pain & Touch
Link ID: 20708 - Posted: 03.21.2015
By Martin Enserink The Human Brain Project (HBP) has listened to the critics, the reviewers, and the mediators. At a meeting in Paris, the board of directors of the €1 billion project yesterday approved a series of recommendations for reform, proposed by a mediation committee, which will change both HBP’s governance and its research program. Critics of the troubled project welcome the move. “We are absolutely delighted that the board has adopted these recommendations,” says computational neuroscientist Peter Dayan of University College London, one of the hundreds of researchers who signed an open letter last year calling for a major reorganization of HBP. Dayan was a member of the mediation committee charged with finding a way out of the crisis after the publication of the letter. That panel’s report—a summary of which was released on 10 March—roundly acknowledges that the critics were right. The committee “largely supports and emphasizes the critique voiced by parts of the scientific community regarding objectives, scientific approach, governance and management practices,” the report says. The mediation committee said that HBP, now administered by the Swiss Federal Institute of Technology in Lausanne (EPFL), should be run by a new, international entity. “In a first concrete step towards implementing that vision, the board [of directors] has created a governance working group composed of former or current heads of international scientific organisations,” an HBP press release issued today said. (They include CERN, the European Space Agency, and the European Molecular Biology Laboratory.) © 2015 American Association for the Advancement of Science
Keyword: Brain imaging
Link ID: 20704 - Posted: 03.21.2015
Michaeleen Doucleff Malaria is one of the oldest scourges of mankind. Yet it's been a mystery how the deadliest form of the disease kills children. One doctor in Michigan has dedicated her life to figuring that out. Now she and her team report their findings in this week's issue of the New England Journal of Medicine. The key to solving the mystery was looking inside the brain. Most of the time malaria causes a bad fever and body aches. But in rare cases — often in children — the parasite gets stuck in the capillaries of the brain. The child has a seizure, goes into a coma and can die. This all happens in only two or three days, says Dr. Terrie Taylor of Michigan State University. "These are bright, happy children who are suddenly felled by a disease that quickly renders them unconscious. And quickly kills them. It's a catastrophe." The sudden death of a child devastates not just the family but the whole community, Taylor says: "Imagine the ripple effects on their friends and their siblings. Suddenly their friends are gone. Just gone." Since 1986, Taylor has been treating children with severe malaria at Queen Elizabeth Central Hospital in Blantyre, Malawi. Seeing so many families deal with these huge losses, year after year, made Taylor focus her career on one goal: Figuring out why some children die from cerebral malaria but others soon recover. © 2015 NPR
Keyword: Development of the Brain
Link ID: 20702 - Posted: 03.19.2015
|By Erez Ribak and The Conversation UK The human eye is optimised to have good colour vision at day and high sensitivity at night. But until recently it seemed as if the cells in the retina were wired the wrong way round, with light travelling through a mass of neurons before it reaches the light-detecting rod and cone cells. New research presented at a meeting of the American Physical Society has uncovered a remarkable vision-enhancing function for this puzzling structure. About a century ago, the fine structure of the retina was discovered. The retina is the light-sensitive part of the eye, lining the inside of the eyeball. The back of the retina contains cones to sense the colours red, green and blue. Spread among the cones are rods, which are much more light-sensitive than cones, but which are colour-blind. Before arriving at the cones and rods, light must traverse the full thickness of the retina, with its layers of neurons and cell nuclei. These neurons process the image information and transmit it to the brain, but until recently it has not been clear why these cells lie in front of the cones and rods, not behind them. This is a long-standing puzzle, even more so since the same structure, of neurons before light detectors, exists in all vertebrates, showing evolutionary stability. Researchers in Leipzig found that glial cells, which also span the retinal depth and connect to the cones, have an interesting attribute. These cells are essential for metabolism, but they are also denser than other cells in the retina. In the transparent retina, this higher density (and corresponding refractive index) means that glial cells can guide light, just like fibre-optic cables. © 2015 Scientific American
By PAM BELLUCK What happens to forgotten memories — old computer passwords, friends’ previous phone numbers? Scientists have long held two different theories. One is that memories do not diminish but simply get overshadowed by new memories. The other is that older memories become weaker, that pulling to mind new passwords or phone numbers degrades old recollections so they do not interfere. The difference could be significant. If old memories stay strong and are merely papered over by new ones, they may be easier to recover. That could be positive for someone trying to remember an acquaintance’s name, but difficult for someone trying to lessen memories of abuse. It could suggest different strategies for easing traumatic memories, evaluating witness testimony about crimes, or helping students study for tests. Now, a study claims to provide evidence of memory’s weakening by showing that people’s ability to remember something and the pattern of brain activity that thing generates both appear to diminish when a competing memory gets stronger. Demonstrating sophisticated use of brain scans in memory research, authors of the study, published Monday in the journal Nature Neuroscience, appear to have identified neural fingerprints of specific memories, distinguishing brain activity patterns produced when viewing a picture of a necklace, say, from a picture of binoculars or other objects. The experiment, conducted by scientists in Birmingham and Cambridge, England, involved several stages with 24 participants first trained to associate words to two unrelated black and white pictures from lists of famous people, ordinary objects or scenes. © 2015 The New York Times Company
Keyword: Learning & Memory
Link ID: 20695 - Posted: 03.17.2015