Chapter 13. Memory, Learning, and Development

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By GINA KOLATA Three diseases, leading killers of Americans, often involve long periods of decline before death. Two of them — heart disease and cancer — usually require expensive drugs, surgeries and hospitalizations. The third, dementia, has no effective treatments to slow its course. So when a group of researchers asked which of these diseases involved the greatest health care costs in the last five years of life, the answer they found might seem surprising. The most expensive, by far, was dementia. The study looked at patients on Medicare. The average total cost of care for a person with dementia over those five years was $287,038. For a patient who died of heart disease it was $175,136. For a cancer patient it was $173,383. Medicare paid almost the same amount for patients with each of those diseases — close to $100,000 — but dementia patients had many more expenses that were not covered. On average, the out-of-pocket cost for a patient with dementia was $61,522 — more than 80 percent higher than the cost for someone with heart disease or cancer. The reason is that dementia patients need caregivers to watch them, help with basic activities like eating, dressing and bathing, and provide constant supervision to make sure they do not wander off or harm themselves. None of those costs were covered by Medicare. For many families, the cost of caring for a dementia patient often “consumed almost their entire household wealth,” said Dr. Amy S. Kelley, a geriatrician at Icahn School of Medicine at Mt. Sinai in New York and the lead author of the paper published on Monday in the Annals of Internal Medicine. © 2015 The New York Times Company

Keyword: Alzheimers
Link ID: 21571 - Posted: 10.27.2015

By Dina Fine Maron Early-life exposure to anesthesia does not appear to lead to long-term cognitive problems, researchers announced today. New evidence from the first, randomized anesthesia trial in kids provides the strongest indication yet that exposing young children to anesthesia—at least for a brief time—will not saddle them with developmental deficits. The news comes just a couple of weeks after a medical advisory group reiterated its concerns about such exposures among children younger than four years. Previously, multiple animal and human studies have linked such exposure with cognitive impairment, but none of the information on humans came from a gold-standard, randomized study design that could help eliminate other reasons to explain such a connection. This is a “reassuring finding, but it is not the final answer,” says Dean Andropoulos, anesthesiologist in chief at Texas Children’s Hospital and an expert who was not involved in the work. The new study assesses only what happens to youngsters after a relatively brief bout with anesthetics, so it is possible that longer or repeated exposures to such chemicals may still cause neurodevelopmental issues. There may also be deficits in anesthesia-exposed children that are not measurable until later in life. The study followed more than 500 infants undergoing hernia repair across the U.S., Australia, the U.K., Canada, the Netherlands, New Zealand and Italy. The surgeries lasted an average of roughly an hour. About half of the children were randomly selected to be put under with general anesthesia, and the other half stayed awake during the surgery and received targeted anesthesic in a specific body region. The kids in the study were all younger than 60 weeks and were matched by where they had the surgery and whether they were born prematurely. © 2015 Scientific American

Keyword: Development of the Brain; Intelligence
Link ID: 21568 - Posted: 10.26.2015

Richard A. Friedman YOU can increase the size of your muscles by pumping iron and improve your stamina with aerobic training. Can you get smarter by exercising — or altering — your brain? Stories from Our Advertisers This is hardly an idle question considering that cognitive decline is a nearly universal feature of aging. Starting at age 55, our hippocampus, a brain region critical to memory, shrinks 1 to 2 percent every year, to say nothing of the fact that one in nine people age 65 and older has Alzheimer’s disease. The number afflicted is expected to grow rapidly as the baby boom generation ages. Given these grim statistics, it’s no wonder that Americans are a captive market for anything, from supposed smart drugs and supplements to brain training, that promises to boost normal mental functioning or to stem its all-too-common decline. The very notion of cognitive enhancement is seductive and plausible. After all, the brain is capable of change and learning at all ages. Our brain has remarkable neuroplasticity; that is, it can remodel and change itself in response to various experiences and injuries. So can it be trained to enhance its own cognitive prowess? The multibillion-dollar brain training industry certainly thinks so and claims that you can increase your memory, attention and reasoning just by playing various mental games. In other words, use your brain in the right way and you’ll get smarter. A few years back, a joint study by BBC and Cambridge University neuroscientists put brain training to the test. Their question was this: Do brain gymnastics actually make you smarter, or do they just make you better at doing a specific task? For example, playing the math puzzle KenKen will obviously make you better at KenKen. But does the effect transfer to another task you haven’t practiced, like a crossword puzzle? © 2015 The New York Times Company

Keyword: Learning & Memory; Intelligence
Link ID: 21567 - Posted: 10.26.2015

As we get older, most of us will experience some kind of brain degeneration. Typically, we lose the ability to make new neurons. Another problem is chronic, low-grade inflammation in the brain, which is implicated in many age-related brain disorders. To tackle both problems in one go, Ludwig Aigner at Paracelsus Medical University Salzburg in Austria and his colleagues targeted a set of receptors in the brain that, when activated, trigger inflammation. High numbers of these receptors are found in areas of the brain where neurons are born, suggesting they might also be involved in this process, too. A drug called montelukast (Singulair), regularly prescribed for asthma and allergic rhinitis, blocks these receptors, so Aigner and his colleagues tried it on young and old rats. The team used oral doses equivalent to those taken by people with asthma. The older animals were 20 months old – roughly equivalent to between 65 and 75 in human years. The younger rats were 4 months old – about 17 in human years. The animals were fed the drug daily for six weeks, while another set of young and old rats were left untreated. There were 20 young and 14 old rats in total. The rats took part in a range of learning and memory tests. One of these, for example, involved the rats being placed in a pool of water with a hidden escape platform. At the start of the study, untreated young rats learned to recognise landmarks and quickly find their way to the platform, while the untreated older animals struggled at the task. © Copyright Reed Business Information Ltd.

Keyword: Development of the Brain; Neurogenesis
Link ID: 21562 - Posted: 10.24.2015

Claire Cain Miller Boys are falling behind. They graduate from high school and attend college at lower rates than girls and are more likely to get in trouble, which can hurt them when they enter the job market. This gender gap exists across the United States, but it is far bigger for poor people and for black people. As society becomes more unequal, it seems, it hurts boys more. New research from social scientists offers one explanation: Boys are more sensitive than girls to disadvantage. Any disadvantage, like growing up in poverty, in a bad neighborhood or without a father, takes more of a toll on boys than on their sisters. That realization could be a starting point for educators, parents and policy makers who are trying to figure out how to help boys — particularly those from black, Latino and immigrant families. “It’s something about family disadvantage itself,” said David Figlio, a Northwestern University economist and co-author of a new paper, presented publicly for the first time on Thursday. “Black people in America are more disadvantaged than white people in America, and if we were to reduce the disadvantage, we may see a reduction in the relative gender gap as well.” Marianne Bertrand, an economist at University of Chicago who with Jessica Pan has studied the gender gap, also found that boys fare worse than girls in disadvantaged homes, and are more responsive than girls to parental time and resources. “Their findings were very consistent: Families that invest more in children are protective for boys,” she said. The reasons that boys react more negatively to disadvantage are varied and hard to pinpoint. Even in utero, boys are more sensitive to extreme stress than girls, and tend to have more unruly temperaments. Society discourages boys from showing vulnerability. Low-income families are often led by single mothers, which has been found to affect boys differently than girls. © 2015 The New York Times Company

Keyword: Development of the Brain; Sexual Behavior
Link ID: 21559 - Posted: 10.24.2015

Elizabeth Blair The muppet Julia has not yet made her TV debut, but the wide-eyed little girl with a big smile is the star of her own "digital storybook" called "We're Amazing, 1,2,3." For over a year now, Sesame Street has been working with organizations such as Autism Speaks and Autism Self Advocacy to help reduce the stigma associated with autism spectrum disorder. As part of the campaign "See Amazing in All Children," the adorable muppet Abby Cadabby explains in one YouTube video, "Lots of kids have autism and that just means their brains work a little differently." Julia is not the first fictional media character with autism. But Michael Robb, Director of Research for Common Sense Media, an organization that rates and reviews media aimed at children, says Sesame Street's move is "pretty groundbreaking." "It can be difficult to start a conversation about children with disabilities. It's even harder when that difference isn't visible," he says. After looking through "We're Amazing, 1,2,3," Robb says the story could help children be more understanding of how Julia is different. "It's very real in terms of talking in simple language. It spells out these things in concrete ways that kids can understand. It shows ways she's just like other kids. It shows how making simple accommodations can help Julia." According to Dr. Jeanette Betancourt, Senior Vice President of U.S. Social Impact at Sesame Workshop, says Sesame Street producers are waiting to hear back from the autism community before introducing Julia to the show on TV. © 2015 npr

Keyword: Autism
Link ID: 21557 - Posted: 10.24.2015

Alzheimer's disease can be detected decades before onset, using a virtual reality test, a study suggests. People aged 18 to 30 were asked to navigate through a virtual maze to test the function of certain brain cells. Those with a high genetic risk of Alzheimer's could be identified by their performance, according to German neuroscientists. The findings could help future research, diagnosis and treatment, they report in the journal Science. The scientists, led by Lukas Kunz of the German Centre for Neurodegenerative Diseases in Bonn, say the high risk group navigated the maze differently and had reduced functioning of a type of brain cell involved in spatial navigation. The findings could give an insight into why people with dementia can find navigating the world around them challenging, they say. "Our results could provide a new basic framework for preclinical research on Alzheimer's disease and may provide a neurocognitive explanation of spatial disorientation in Alzheimer's disease," they report in Science. Although genes play a role in dementia, their effects are complex with many unknowns. Dr Laura Phipps of Alzheimer's Research, said the latest study focused on healthy younger people at higher genetic risk of Alzheimer's, suggesting they may already show alterations in spatial navigation several decades before the disease could start. © 2015 BBC.

Keyword: Alzheimers
Link ID: 21555 - Posted: 10.23.2015

By Tara Parker-Pope Children who regularly use antibiotics gain weight faster than those who have never taken the drugs, according to new research that suggests childhood antibiotics may have a lasting effect on body weight well into adulthood. The study, published in the International Journal of Obesity, examined the electronic medical records of 163,820 children ages 3 to 18, counting antibiotic prescriptions, body weight and height. The records, which covered pediatric exams from 2001 through 2012, showed that one in five — over 30,000 children — had been prescribed antibiotics seven or more times. By the time those children reached age 15, they weighed, on average, about 3 pounds more than children who had received no antibiotics. While earlier studies have suggested a link between antibiotics and childhood weight gain, they typically have relied on a mother’s memories of her child’s antibiotic use. The new research is significant because it’s based on documented use of antibiotics in a child’s medical record. “Not only did antibiotics contribute to weight gain at all ages, but the contribution of antibiotics to weight gain gets stronger as you get older,” said Dr. Brian S. Schwartz, the first author and a professor in the department of environmental health sciences at the Johns Hopkins Bloomberg School of Public Health. Scientists have known for years that antibiotic use promotes weight gain in livestock, which is why large food producers include low doses of antibiotics in the diets of their animals. © 2015 The New York Times Company

Keyword: Obesity; Development of the Brain
Link ID: 21544 - Posted: 10.22.2015

Keikantse Matlhagela Susumu Tonegawa unlocked the genetic secrets behind antibodies' diverse structures, which earned him the Nobel Prize in Physiology or Medicine in 1987. Having since moved fields, he tells Keikantse Matlhagela about his latest work on the neuroscience of happy and sad memories. You started as a chemist, then you moved into molecular biology and now you are a neuroscientist. Why change fields? Strangely, the only people to ask me about this are journalists — my students never ask. I see myself as a scientist who is interested in what's going on inside of us. It doesn't matter whether it is chemistry or immunology or neuroscience, I just do research on what I find interesting. The switch from chemistry to immunology did not seem like a big shift when I was young, but immunology to neuroscience was. After about 15 years spent researching immunology I wanted to explore an area of science where there are still big, unresolved questions. The brain is probably the most mysterious subject there is. Do you keep up to date with the field in which you won your Nobel prize? I am sorry to say that I haven't been paying a lot of attention to immunology in recent years because I am preoccupied with my work on memory. I have friends, of course, from that time — very close friends. But my friends are not young. Even though they are experts, they are also retired. We tend not to talk about immunology a whole lot. © 2015 Macmillan Publishers Limited

Keyword: Learning & Memory
Link ID: 21542 - Posted: 10.22.2015

By Emily Underwood CHICAGO—In 1898, Italian biologist Camillo Golgi found something odd as he examined slices of brain tissue under his microscope. Weblike lattices, now known as "perineuronal nets," surrounded many neurons, but he could not discern their purpose. Many dismissed the nets as an artifact of Golgi's staining technique; for the next century, they remained largely obscure. Today, here at the annual meeting of the Society for Neuroscience, researchers offered tantalizing new evidence that holes in these nets could be where long-term memories are stored. Scientists now know that perineuronal nets (PNNS) are scaffolds of linked proteins and sugars that resemble cartilage, says neuroscientist Sakina Palida, a graduate student in Roger Tsien's lab at the University of California,San Diego, and co-investigator on the study. Although it's still unclear precisely what the nets do, a growing body of research suggests that PNNs may control the formation and function of synapses, the microscopic junctions between neurons that allow cells to communicate, and that may play a role in learning and memory, Palida says. One of the most pressing questions in neuroscience is how memories—particularly long-term ones—are stored in the brain, given that most of the proteins inside neurons are constantly being replaced, refreshing themselves anywhere from every few days to every few hours. To last a lifetime, Palida says, some scientists believe that memories must somehow be encoded in a persistent, stable molecular structure. Inspired in part by evidence that destroying the nets in some brain regions can reverse deeply ingrained behaviors, Palida’s adviser Tsien, a Nobel-prize-winning chemist, recently began to explore whether PNNs could be that structure. Adding to the evidence were a number of recent studies linking abnormal PNNs to brain disorders including schizophrenia and Costello syndrome, a form of intellectual disability. © 2015 American Association for the Advancement of Science.

Keyword: Learning & Memory; Brain imaging
Link ID: 21540 - Posted: 10.21.2015

Jon Hamilton Babies born prematurely are much more likely than other children to develop autism, ADHD and emotional disorders. Now researchers think they may have an idea about how that could happen. There's evidence that preemies are born with weak connections in some critical brain networks, including those involved in focus, social interactions, and emotional processing, researchers reported at the Society for Neuroscience meeting in Chicago. A study comparing MRI scans of the brains of 58 full-term babies with those of 76 babies born at least 10 weeks early found that "preterm infants indeed have abnormal structural brain connections," says Cynthia Rogers, an assistant professor of psychiatry at Washington University School of Medicine in St. Louis. "We were really interested that the tracts that we know connect areas that are involved in attention and emotional networks were heavily affected," Rogers says. That would make it harder for these brain areas to work together to focus on a goal or read social cues or regulate emotions, she says. The team used two different types of MRI to study the nerve fibers that carry signals from one part of the brain to another and measure how well different areas of the brain are communicating. Full-term infants were scanned shortly after they were born, while premature infants were scanned near their expected due date. The researchers are continuing to monitor the brains of the children in their study to see which ones actually develop disorders. © 2015 NPR

Keyword: Development of the Brain; Brain imaging
Link ID: 21539 - Posted: 10.21.2015

By LISA SANDERS, M.D. The middle-aged couple knocked at the door of the townhouse. When no one answered, the woman took her key and let them in. She called her daughter’s name as she hurried through the rooms. They had been trying to reach their 27-year-old daughter by phone all day, and she hadn’t answered. They found her upstairs, lying in bed and mumbling incoherently. The mother rushed over, but her daughter showed no signs of recognition. She and her husband quickly carried her to the car. Four months before, the mother told the emergency-room doctor at SSM Health St. Mary’s Hospital in St. Louis, her daughter had a procedure called gastric-sleeve surgery to help her lose weight. She came home after just a couple of days and felt great. She looked bright and eager. Once she started to eat, though, nausea and vomiting set in. After almost every meal, she would throw up. It’s an unusual but well-known complication of this kind of surgery. The cause is not clearly understood, but the phenomenon is sometimes linked to reflux. The surgeon tried different medications to stop the nausea and vomiting and to reduce the acid in her stomach, but they didn’t help. She had the surgery in order to lose weight, but now she was losing weight too quickly. After a month of vomiting, her doctors thought maybe she had developed gallstones — a common problem after rapid weight loss. But even after her gallbladder was removed, the young woman continued to vomit after eating. © 2015 The New York Times Company

Keyword: Learning & Memory; Obesity
Link ID: 21534 - Posted: 10.21.2015

Susan Gaidos CHICAGO — Eating a high-fat diet as a youngster can affect learning and memory during adulthood, studies have shown. But new findings suggest such diets may not have long-lasting effects. Rats fed a high-fat diet for nearly a year recovered their ability to navigate their surroundings. University of Texas at Dallas neuroscientist Erica Underwood tested spatial memory for rats fed a high-fat diet for either 12 weeks or 52 weeks, immediately after weaning. After rats placed in a chamber-filled box containing Lego-like toys became familiar with the box, the researchers moved the toys to new chambers. Later, when placed in the box, rats who ate high-fat foods for 12 weeks appeared confused and had difficulty finding the toys. But rats that ate high-fat foods for nearly a year performed as well as those fed a normal diet. Underwood repeated the experiment, posing additional spatial memory tests to new groups of rats. The findings were the same: Over the long-term, rats on high-fat diets recovered their ability to learn and remember. Studies of brain cells revealed that rats on the long-term high-fat diet showed reduced excitability in nerve cells from the hippocampus, the same detrimental effects seen in rats on the short-term high-fat diet. “The physiology that should create a dumber animal is there, but not the behavior,” said Lucien Thompson of UT Dallas, who oversaw the study. Underwood and Thompson speculate that some other part of the brain may be compensating for this reduction in neural response. © Society for Science & the Public 2000 - 2015.

Keyword: Obesity; Learning & Memory
Link ID: 21533 - Posted: 10.21.2015

By Brook Borel and Spectrum In a lab in Sacramento, California, a wall of plastic boxes lined with corncob bedding holds around 800 mice. Even in this clean and bright room, the smell of so many mice concentrated in one place is overpowering — pungent, and familiar to anyone who has spent time with a pet hamster or gerbil. Most of the boxes hold four adult mice, which flit about, noses twitching as they stare out at the humans staring in. But in one of the boxes, a sleek white mouse is tucked in a corner suckling her litter of half a dozen or so squirmy, dark-furred pups. In most research labs, the fate of these pups would be determined by their sex. The males would spend their lives as test subjects. The females would either be kept for breeding or simply euthanized because they’re not ideal for experiments: They’re supposedly more difficult to work with and generate less consistent data than males do, and it costs too much to maintain both males and females, which must be housed separately. Or so the rationale has gone. But these little female pups are different. The lab where they live is run by Jill Silverman and Mu Yang, researchers at the University of California, Davis (UC Davis) MIND Institute. The two scientists study the behavior of about 15 autism mouse models, and they have always included both males and females in their work. When the pups get older, they will learn to paddle through water mazes or bury black marbles in their bedding, giving researchers insight into how their memory and behavior compare with that of typical mice. Finding the best animal behavioral models of autism is essential because behavior is at the heart of the disorder. In people, autism is diagnosed based on behavioral criteria: abnormal social interactions, difficulties with communication and repetitive actions. © 2015 Scientific American

Keyword: Autism; Sexual Behavior
Link ID: 21531 - Posted: 10.20.2015

Mr Tickle can’t bamboozle a baby. Unlike grown-ups, young infants don’t let the positioning of their bodies confuse their sense of touch. If adults who can see are touched on each hand in quick succession while their hands are crossed, they can find it hard to name which hand was touched first. Adults who have been blind from birth don’t have this difficulty, but people who become blind later in life have the same trouble as those who can still see. “That suggests that early on in life, something to do with visual experience is crucial in setting up a typical way of perceiving touch,” says Andrew Bremner at Goldsmiths, University of London. To investigate how this develops in infancy, Bremner and his colleagues compared how babies reacted to having one foot tickled. With their legs crossed over, babies aged 6 months moved the foot being tickled half of the time. But 4-month-olds did better, moving the tickled foot 70 per cent of the time – as often as they did with their legs uncrossed. The team concludes that at 4 months, babies haven’t yet learned to relate what they touch to the physical space that their body occupies. For many adults, the concept might be difficult to envision. “It’s like imagining that you feel a touch on your body, but not really knowing how that’s related to what you’re looking at,” says Bremner. “It’s almost like you have multiple sensory worlds: a visual world, an auditory world and a tactile world, which are separate and not combined in space.” © Copyright Reed Business Information Ltd.

Keyword: Pain & Touch; Development of the Brain
Link ID: 21530 - Posted: 10.20.2015

Peter Andrey Smith Nearly a year has passed since Rebecca Knickmeyer first met the participants in her latest study on brain development. Knickmeyer, a neuroscientist at the University of North Carolina School of Medicine in Chapel Hill, expects to see how 30 newborns have grown into crawling, inquisitive one-year-olds, using a battery of behavioural and temperament tests. In one test, a child's mother might disappear from the testing suite and then reappear with a stranger. Another ratchets up the weirdness with some Halloween masks. Then, if all goes well, the kids should nap peacefully as a noisy magnetic resonance imaging machine scans their brains. “We try to be prepared for everything,” Knickmeyer says. “We know exactly what to do if kids make a break for the door.” Knickmeyer is excited to see something else from the children — their faecal microbiota, the array of bacteria, viruses and other microbes that inhabit their guts. Her project (affectionately known as 'the poop study') is part of a small but growing effort by neuroscientists to see whether the microbes that colonize the gut in infancy can alter brain development. The project comes at a crucial juncture. A growing body of data, mostly from animals raised in sterile, germ-free conditions, shows that microbes in the gut influence behaviour and can alter brain physiology and neurochemistry. © 2015 Nature Publishing Group

Keyword: Obesity; Development of the Brain
Link ID: 21521 - Posted: 10.16.2015

By Christopher Intagliata "Babies come prepared to learn any of the world's languages." Alison Bruderer, a cognitive scientist at the University of British Columbia. "Which means no matter where they're growing up in the world, their brains are prepared to pick up the language they're listening to around them." And listen they do. But another key factor to discerning a language’s particular sounds may be for babies to move their tongues as they listen. Bruderer and her colleagues tested that notion by sitting 24 sixth-month-olds in front of a video screen and displaying a checkerboard pattern, while they played one of two tracks: a single, repeated "D" sound in Hindi, <> or two slightly different, alternating "D" sounds. <> The idea here is that babies have a short attention span, so novel things hold their gaze. And indeed, the babies did stare at the screen longer while the alternating "D"s played than for the single “D”—indicating they could detect the novelty. Until, that is, the researchers blocked the babies' tongue movements by having them suck on a teething device. Then the effect disappeared, with the babies unable to differentiate [single D sound] from [alternating D sounds]. And when the babies used a different teether that did not block tongue movement, they once again appeared to comprehend the difference between the Ds. The study is in the Proceedings of the National Academy of Sciences. © 2015 Scientific American

Keyword: Language; Development of the Brain
Link ID: 21517 - Posted: 10.16.2015

Kerri Smith Scientists have discovered two extra neurons in a worm species that — they thought — already had its entire nervous system mapped. “It is a bit of a shock,” says Richard Poole, a developmental biologist at University College London (UCL), and one of the team that found the neurons by accident. The researchers call them mystery cells of the male, or MCMs, because they are found only in male nematode worms. The neurons help the worms learn when to prioritize mating over eating, revealing how a seemingly simple brain can be capable of a complex learned behaviour — and one that differs between the sexes. Caenorhabditis elegans worms are the model animal of choice for many neuroscientists, because their neural circuits are so simple that they can be mapped in full. They have two sexes: hermaphrodite and male. Hermaphrodites, the best studied, have just 302 neurons, but males have more — the MCMs raise their total to 385 neurons1. The two ‘mystery’ cells were discovered when Poole’s colleague at UCL, Arantza Barrios, was looking at the distribution of a peptide often found in neurons, called pdf-1. She saw cells light up where she thought they should not — near the worm’s nose. The neurons develop when male worms reach maturity, the researchers worked out. Their report is published in Nature1. Sex or food? © 2015 Nature Publishing Group,

Keyword: Sexual Behavior; Development of the Brain
Link ID: 21514 - Posted: 10.15.2015

By Martin Enserink Researchers who conduct animal studies often don't use simple safeguards against biases that have become standard in human clinical trials—or at least they don't report doing so in their scientific papers, making it impossible for readers to ascertain the quality of the work, an analysis of more than 2500 journal articles shows. Such biases, conscious or unconscious, can make candidate medical treatments look better than they actually are, the authors of the analysis warn, and lead to eye-catching results that can't be replicated in larger or more rigorous animal studies—or in human trials. Neurologist Malcolm MacLeod of the Centre for Clinical Brain Sciences at the University of Edinburgh and his colleagues combed through papers reporting the efficacy of drugs in eight animal disease models and checked whether the authors reported four measures that are widely acknowledged to reduce the risk of bias. First, if there was an experimental group and a control group, were animals randomly assigned to either one? (This makes it impossible for scientists to, say, assign the healthiest mice or rats to a treatment group, which could make a drug look better than it is.) Second, were the researchers who assessed the outcomes of a trial—for instance, the effect of a treatment on an animal's health—blinded to which animal underwent what procedure? Third, did the researchers calculate in advance the sample size needed to show that they didn't just accumulate data until they found something significant? And finally, did they make a statement about their conflicts of interest? © 2015 American Association for the Advancement of Science

Keyword: Animal Rights; Attention
Link ID: 21507 - Posted: 10.14.2015

By SINDYA N. BHANOO Tiny nematode worms called Caenorhabditis elegans have a peculiar reproductive story: Most females are hermaphrodites that make sperm, self-fertilize and produce more hermaphrodites. Males are few, and are known to mate with each other. Now, a new study reports that a variation in a single gene results in male worms with excretory pores that attract the sexual attentions of other males. “Other males copulate with this excretory pore, located on the neck,” said Matthew Rockman, a biologist at New York University. He and his colleagues reported their findings in the journal Current Biology. Although male worms are rare in the wild, they are easily bred in the laboratory. Researchers report that the gene variant, known as plep-1, may somehow be altering the chemical profile of the excretions in a way that makes them more attractive to other males. Copulation often does not work out well for the male that is approached, Dr. Rockman said. Males that mate with the excretory pore of another male usually leave behind a plug that weakens the worm and reduces life expectancy. Hermaphrodites with the variation of the same gene also have a lower life expectancy and do not reproduce as well. Next, the researchers want to learn what it is about a mutation in the plep-1 gene that makes males attractive to other males. © 2015 The New York Times Company

Keyword: Sexual Behavior; Genes & Behavior
Link ID: 21503 - Posted: 10.13.2015