Chapter 13. Memory, Learning, and Development

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By JAMIE EDGIN and FABIAN FERNANDEZ LAST week the biologist Richard Dawkins sparked controversy when, in response to a woman’s hypothetical question about whether to carry to term a child with Down syndrome, he wrote on Twitter: “Abort it and try again. It would be immoral to bring it into the world if you have the choice.” In further statements, Mr. Dawkins suggested that his view was rooted in the moral principle of reducing overall suffering whenever possible — in this case, that of individuals born with Down syndrome and their families. But Mr. Dawkins’s argument is flawed. Not because his moral reasoning is wrong, necessarily (that is a question for another day), but because his understanding of the facts is mistaken. Recent research indicates that individuals with Down syndrome can experience more happiness and potential for success than Mr. Dawkins seems to appreciate. There are, of course, many challenges facing families caring for children with Down syndrome, including a high likelihood that their children will face surgery in infancy and Alzheimer’s disease in adulthood. But at the same time, studies have suggested that families of these children show levels of well-being that are often greater than those of families with children with other developmental disabilities, and sometimes equivalent to those of families with nondisabled children. These effects are prevalent enough to have been coined the “Down syndrome advantage.” In 2010, researchers reported that parents of preschoolers with Down syndrome experienced lower levels of stress than parents of preschoolers with autism. In 2007, researchers found that the divorce rate in families with a child with Down syndrome was lower on average than that in families with a child with other congenital abnormalities and in those with a nondisabled child. © 2014 The New York Times Company

Keyword: Genes & Behavior; Aggression
Link ID: 20016 - Posted: 08.30.2014

Memory can be boosted by using a magnetic field to stimulate part of the brain, a study has shown. The effect lasts at least 24 hours after the stimulation is given, improving the ability of volunteers to remember words linked to photos of faces. Scientists believe the discovery could lead to new treatments for loss of memory function caused by ageing, strokes, head injuries and early Alzheimer's disease. Dr Joel Voss, from Northwestern University in Chicago, said: "We show for the first time that you can specifically change memory functions of the brain in adults without surgery or drugs, which have not proven effective. "This non-invasive stimulation improves the ability to learn new things. It has tremendous potential for treating memory disorders." The scientists focused on associative memory, the ability to learn and remember relationships between unrelated items. An example of associative memory would be linking someone to a particular restaurant where you both once dined. It involves a network of different brain regions working in concert with a key memory structure called the hippocampus, which has been compared to an "orchestra conductor" directing brain activity. Stimulating the hippocampus caused the "musicians" – the brain regions – to "play" more in time, thereby tightening up their performance. A total of 16 volunteers aged 21-40 took part in the study, agreeing to undergo 20 minutes of transcranial magnetic stimulation (TMS) every day for five days. © 2014 Guardian News and Media Limited

Keyword: Learning & Memory
Link ID: 20015 - Posted: 08.30.2014

by Michael Slezak It's odourless, colourless, tasteless and mostly non-reactive – but it may help you forget. Xenon gas has been shown to erase fearful memories in mice, raising the possibility that it could be used to treat post-traumatic stress disorder (PTSD) if the results are replicated in a human trial next year. The method exploits a neurological process known as "reconsolidation". When memories are recalled, they seem to get re-encoded, almost like a new memory. When this process is taking place, the memories become malleable and can be subtly altered. This new research suggests that at least in mice, the reconsolidation process might be partially blocked by xenon, essentially erasing fearful memories. Among other things, xenon is used as an anaesthetic. Frozen in fear Edward Meloni and his colleagues at Harvard Medical School in Boston trained mice to be afraid of a sound by placing them in a cage and giving them an electric shock after the sound was played. Thereafter, if the mice heard the noise, they would become frightened and freeze. Later, the team played the sound and then gave the mice either a low dose of xenon gas for an hour or just exposed them to normal air. Mice that were exposed to xenon froze for less time in response to the sound than the other mice. © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory
Link ID: 20014 - Posted: 08.30.2014

By PAM BELLUCK Memories and the feelings associated with them are not set in stone. You may have happy memories about your family’s annual ski vacation, but if you see a tragic accident on the slopes, those feelings may change. You might even be afraid to ski that mountain again. Now, using a technique in which light is used to switch neurons on and off, neuroscientists at the Massachusetts Institute of Technology appear to have unlocked some secrets about how the brain attaches emotions to memories and how those emotions can be adjusted. Their research, published Wednesday in the journal Nature, was conducted on mice, not humans, so the findings cannot immediately be translated to the treatment of patients. But experts said the experiments may eventually lead to more effective therapies for people with psychological problems such as depression, anxiety or post-traumatic stress disorder. “Imagine you can go in and find a particular traumatic memory and turn it off or change it somehow,” said David Moorman, an assistant professor of psychological and brain sciences at the University of Massachusetts Amherst, who was not involved in the research. “That’s still science fiction, but with this we’re getting a lot closer to it.” The M.I.T. scientists labeled neurons in the brains of mice with a light-sensitive protein and used pulses of light to switch the cells on and off, a technique called optogenetics. Then they identified patterns of neurons activated when mice created a negative memory or a positive one. A negative memory formed when mice received a mild electric shock to their feet; a positive one was formed when the mice, all male, were allowed to spend time with female mice. © 2014 The New York Times Company

Keyword: Learning & Memory; Aggression
Link ID: 20010 - Posted: 08.28.2014

by Penny Sarchet Memory is a fickle beast. A bad experience can turn a once-loved coffee shop or holiday destination into a place to be avoided. Now experiments in mice have shown how such associations can be reversed. When forming a memory of a place, the details of the location and the associated emotions are encoded in different regions of the brain. Memories of the place are formed in the hippocampus, whereas positive or negative associations are encoded in the amygdala. In experiments with mice in 2012, a group led by Susumo Tonegawa of the Massachusetts Institute of Technology managed to trigger the fear part of a memory associated with a location when the animals were in a different location. They used a technique known as optogenetics, which involves genetically engineering mice so that their brains produce a light-sensitive protein in response to a certain cue. In this case, the cue was the formation of the location memory. This meant the team could make the mouse recall the location just by flashing pulses of light down an optical fibre embedded in the skull. The mice were given electric shocks while their memories of the place were was being formed, so that the animals learned to associate that location with pain. Once trained, the mice were put in a new place and a pulse of light was flashed into their brains. This activated the neurons associated with the original location memory and the mice froze, terrified of a shock, demonstrating that the emotion associated with the original location could be induced by reactivating the memory of the place. © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory; Aggression
Link ID: 20009 - Posted: 08.28.2014

Learning is easier when it only requires nerve cells to rearrange existing patterns of activity than when the nerve cells have to generate new patterns, a study of monkeys has found. The scientists explored the brain’s capacity to learn through recordings of electrical activity of brain cell networks. The study was partly funded by the National Institutes of Health. “We looked into the brain and may have seen why it’s so hard to think outside the box,” said Aaron Batista, Ph.D., an assistant professor at the University of Pittsburgh and a senior author of the study published in Nature, with Byron Yu, Ph.D., assistant professor at Carnegie Mellon University, Pittsburgh. The human brain contains nearly 86 billion neurons, which communicate through intricate networks of connections. Understanding how they work together during learning can be challenging. Dr. Batista and his colleagues combined two innovative technologies, brain-computer interfaces and machine learning, to study patterns of activity among neurons in monkey brains as the animals learned to use their thoughts to move a computer cursor. “This is a fundamental advance in understanding the neurobiological patterns that underlie the learning process,” said Theresa Cruz, Ph.D., a program official at the National Center for Medical Rehabilitations Research at NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). “The findings may eventually lead to new treatments for stroke as well as other neurological disorders.”

Keyword: Learning & Memory; Aggression
Link ID: 20008 - Posted: 08.28.2014

|By Michael Leon I had been working quite happily on the basic biology of the brain when a good friend of mine called for advice about his daughter, who had just been diagnosed with autism. I could hear the anguish and fear in his voice when he asked me whether there was anything that could be done to make her better. I told him about the standard-care therapies, including Intensive Behavioral Intervention, Early Intensive Behavioral Intervention, Applied Behavior Analysis, and the Early Start Denver Model (ESDM). These therapies also are expensive, time-consuming and have variable outcomes, with the best outcomes seen for ESDM. There are, however, few ESDM therapists, and the cost of such intensive therapy can be quite high. Moreover, my friend’s daughter was already past the age of the oldest children in the study that demonstrated the efficacy of ESDM. My feeling was that there was a good chance that there was an effective therapy for her using a simple, inexpensive at-home approach involving daily exposure to a wide variety of sensory stimulation. This is a partial list of the disorders whose symptoms can be greatly reduced, or even completely reversed, with what is known as “environmental enrichment”: Autism Stroke Seizures Brain damage Neuronal death during aging ADHD Prenatal alcohol syndrome Lead exposure Multiple sclerosis Addiction Schizophrenia Memory loss Huntington’s disease Parkinson’s disease Alzheimer’s disease Down syndrome Depression But why haven’t you heard about this? The reason is that all of these disorders that have been successfully treated only in animal models of these neurological problems. However, the effects seen in lab animals can be dramatic. © 2014 Scientific American,

Keyword: Autism; Aggression
Link ID: 20003 - Posted: 08.27.2014

|By Roni Jacobson Children are notoriously unreliable witnesses. Conventional wisdom holds that they frequently “remember” things that never happened. Yet a large body of research indicates that adults actually generate more false memories than children. Now a new study finds that children are just as susceptible to false memories as adults, if not more so. Scientists may simply have been using the wrong test. Traditionally, researchers have explored false memories by presenting test subjects with a list of associated words (for instance, “weep,” “sorrow” and “wet”) thematically related to a word not on the list (in this case, “cry”) and then asking them what words they remember. Adults typically mention the missing related word more often than children do—possibly because their life experiences enable them to draw associations between concepts more readily, says Henry Otgaar, a forensic psychologist at Maastricht University in the Netherlands and co-author of the new paper, published in May in the Journal of Experimental Child Psychology. Instead of using word lists to investigate false memories, Otgaar and his colleagues showed participants pictures of scenes, including a classroom, a funeral and a beach. After a short break, they asked those participants whether they remembered seeing certain objects in each picture. Across three experiments, seven- and eight-year-old children consistently reported seeing more objects that were not in the pictures than adults did. © 2014 Scientific American

Keyword: Learning & Memory; Aggression
Link ID: 19999 - Posted: 08.27.2014

By Priyanka Pulla Humans are late bloomers when compared with other primates—they spend almost twice as long in childhood and adolescence as chimps, gibbons, or macaques do. But why? One widely accepted but hard-to-test theory is that children’s brains consume so much energy that they divert glucose from the rest of the body, slowing growth. Now, a clever study of glucose uptake and body growth in children confirms this “expensive tissue” hypothesis. Previous studies have shown that our brains guzzle between 44% and 87% of the total energy consumed by our resting bodies during infancy and childhood. Could that be why we take so long to grow up? One way to find out is with more precise studies of brain metabolism throughout childhood, but those studies don’t exist yet. However, a new study published online today in the Proceedings of the National Academy of Sciences (PNAS) spliced together three older data sets to provide a test of this hypothesis. First, the researchers used a 1987 study of PET scans of 36 people between infancy and 30 years of age to estimate age trends in glucose uptake by three major sections of the brain. Then, to calculate how uptake varied for the entire brain, they combined that data with the brain volumes and ages of 400 individuals between 4.5 years of age and adulthood, gathered from a National Institutes of Health study and others. Finally, to link age and brain glucose uptake to body size, they used an age series of brain and body weights of 1000 individuals from birth to adulthood, gathered in 1978. © 2014 American Association for the Advancement of Science.

Keyword: Development of the Brain; Aggression
Link ID: 19998 - Posted: 08.26.2014

By DAVID LEVINE MONTREAL — When twins have similar personalities, is it mainly because they share so much genetic material or because their physical resemblance makes other people treat them alike? Most researchers believe the former, but the proposition has been hard to prove. So Nancy L. Segal, a psychologist who directs the Twin Studies Center at California State University, Fullerton, decided to test it — and enlisted an unlikely ally. He is François Brunelle, a photographer in Montreal who takes pictures of pairs of people who look alike but are not twins. Dr. Segal was sent to Mr. Brunelle’s website by a graduate student who knew of her research with twins. When she saw the photographs, she realized that the unrelated look-alikes would be ideal study subjects: She could compare their similarities and differences to those of actual twins. “I reasoned that if personality resides in the face,” she said, “then unrelated look-alikes should be as similar in behavior as identical twins reared apart. Alternatively, if personality traits are influenced by genetic factors, then unrelated look-alikes should show negligible personality similarity.” For 14 years, Mr. Brunelle, 64, has been working on a project he calls “I’m Not a Look-Alike!”: more than 200 black-and-white portraits of pairs who do, in fact, look startlingly alike. “I originally named the project ‘Look-Alikes,’ but I felt it was boring and some of the subjects did not feel they looked alike,” he said. “The new name gives ownership to the people I photographed and allows viewers of my website to decide for themselves if the people look alike or not.” Most come to him through social media links to his website. “It has taken on a life of its own,” he said. “I have heard from people in China — and even a man who has an uncle in Uzbekistan who is a dead ringer for former President George W. Bush.” © 2014 The New York Times Company

Keyword: Genes & Behavior
Link ID: 19997 - Posted: 08.26.2014

|By Mark Fischetti Parents, students and teachers often argue, with little evidence, about whether U.S. high schools begin too early in the morning. In the past three years, however, scientific studies have piled up, and they all lead to the same conclusion: a later start time improves learning. And the later the start, the better. Biological research shows that circadian rhythms shift during the teen years, pushing boys and girls to stay up later at night and sleep later into the morning. The phase shift, driven by a change in melatonin in the brain, begins around age 13, gets stronger by ages 15 and 16, and peaks at ages 17, 18 or 19. Does that affect learning? It does, according to Kyla Wahlstrom, director of the Center for Applied Research and Educational Improvement at the University of Minnesota. She published a large study in February that tracked more than 9,000 students in eight public high schools in Minnesota, Colorado and Wyoming. After one semester, when school began at 8:35 a.m. or later, grades earned in math, English, science and social studies typically rose a quarter step—for example, up halfway from B to B+. Two journal articles that Wahlstrom has reviewed but have not yet been published reach similar conclusions. So did a controlled experiment completed by the U.S. Air Force Academy, which required different sets of cadets to begin at different times during their freshman year. A 2012 study of North Carolina school districts that varied school times because of transportation problems showed that later start times correlated with higher scores in math and reading. Still other studies indicate that delaying start times raises attendance, lowers depression rates and reduces car crashes among teens, all because they are getting more of the extra sleep they need. © 2014 Scientific American

Keyword: Biological Rhythms; Aggression
Link ID: 19989 - Posted: 08.25.2014

By PAM BELLUCK As a baby’s brain develops, there is an explosion of synapses, the connections that allow neurons to send and receive signals. But during childhood and adolescence, the brain needs to start pruning those synapses, limiting their number so different brain areas can develop specific functions and are not overloaded with stimuli. Now a new study suggests that in children with autism, something in the process goes awry, leaving an oversupply of synapses in at least some parts of the brain. The finding provides clues to how autism develops from childhood on, and may help explain some symptoms like oversensitivity to noise or social experiences, as well as why many people with autism also have epileptic seizures. It could also help scientists in the search for treatments, if they can develop safe therapies to fix the system the brain uses to clear extra synapses. The study, published Thursday in the journal Neuron, involved tissue from the brains of children and adolescents who had died from ages 2 to 20. About half had autism; the others did not. The researchers, from Columbia University Medical Center, looked closely at an area of the brain’s temporal lobe involved in social behavior and communication. Analyzing tissue from 20 of the brains, they counted spines — the tiny neuron protrusions that receive signals via synapses — and found more spines in children with autism. The scientists found that at younger ages, the number of spines did not differ tremendously between the two groups of children, but adolescents with autism had significantly more than those without autism. Typical 19-year-olds had 41 percent fewer synapses than toddlers, but those in their late teenage years with autism had only 16 percent fewer than young children with autism. © 2014 The New York Times Company

Keyword: Autism; Aggression
Link ID: 19988 - Posted: 08.22.2014

|By Jason G. Goldman When you do not know the answer to a question, say, a crossword puzzle hint, you realize your shortcomings and devise a strategy for finding the missing information. The ability to identify the state of your knowledge—thinking about thinking—is known as metacognition. It is hard to tell whether other animals are also capable of metacognition because we cannot ask them; studies of primates and birds have not yet been able to rule out simpler explanations for this complex process. Scientists know, however, that some animals, such as western scrub jays, can plan for the future. Western scrub jays, corvids native to western North America, are a favorite of cognitive scientists because they are not “stuck in time”—that is, they are able to remember past events and are known to cache their food in anticipation of hunger, according to psychologist Arii Watanabe of the University of Cambridge. But the question remained: Are they aware that they are planning? Watanabe devised a way to test them. He let five birds watch two researchers hide food, in this case a wax worm. The first researcher could hide the food in any of four cups lined up in front of him. The second had three covered cups, so he could place the food only in the open one. The trick was that the researchers hid their food at the same time, forcing the birds to choose which one to watch. If the jays were capable of metacognition, Watanabe surmised, the birds should realize that they could easily find the second researcher's food. The wax worm had to be in the singular open cup. They should instead prefer keeping their eyes on the setup with four open cups because witnessing where that food went would prove more useful in the future. And that is exactly what happened: the jays spent more time watching the first researcher. The results appeared in the July issue of the journal © 2014 Scientific American,

Keyword: Learning & Memory; Aggression
Link ID: 19985 - Posted: 08.22.2014

by Sarah Zielinski PRINCETON, N.J. — Learning can be a quick shortcut for figuring out how to do something on your own. The ability to learn from watching another individual — called social learning — is something that hasn’t been documented in many species outside of primates and birds. But now a lizard can be added to the list of critters that can learn from one another. Young eastern water skinks were able to learn by watching older lizards, Martin Whiting of Macquarie University in Sydney reported August 10 at the Animal Behavior Society meeting at Princeton University. The eastern water skink, which reaches a length of about 30 centimeters, can be found near streams and waterways in eastern Australia. The lizards live up to eight years, and while they don’t live in groups, they often see each other in the wild. That could provide an opportunity for learning from each other. Whiting and his colleagues worked with 18 mature (older than 5 years) and 18 young (1.5 to 2 years) male skinks in the lab. The lizards were placed in bins with a barrier in the middle that was either opaque or transparent. In the first of two experiments, the skinks were given a yellow-lidded container with a mealworm inside. They had to learn to open the lid to get the food. In that task, skinks that could see a demonstrator through a transparent barrier were no better at opening the lid than those who had to figure it out on their own. After watching a demonstrator lizard (top row), the skink in the other half of the tub was supposed to have learned that a mealworm was beneath the blue lid. The skink in the middle arena, however, failed the task when he opened the white lid first.D.W.A. Noble et al/Biology Letters 2014 © Society for Science & the Public 2000 - 2013.

Keyword: Learning & Memory; Aggression
Link ID: 19984 - Posted: 08.22.2014

By TARA PARKER-POPE When the antidrug educator Tim Ryan talks to students, he often asks them what they know about marijuana. “It’s a plant,” is a common response. But more recently, the answer has changed. Now they reply, “It’s legal in Colorado.” These are confusing times for middle and high school students, who for most of their young lives have been lectured about the perils of substance abuse, particularly marijuana. Now it seems that the adults in their lives have done an about-face. Recreational marijuana is legal in Colorado and in Washington, and many other states have approved it for medical use. Lawmakers, the news media and even parents are debating the merits of full-scale legalization. “They are growing up in a generation where marijuana used to be bad, and maybe now it’s not bad,” said Mr. Ryan, a senior prevention specialist with FCD Educational Services, an antidrug group that works with students in the classroom. “Their parents are telling them not to do it, but they may be supporting legalization of it at the same time.” Antidrug advocates say efforts to legalize marijuana have created new challenges as they work to educate teenagers and their parents about the unique risks that alcohol, marijuana and other drugs pose to the developing teenage brain. These educators say their goal is not to vilify marijuana or take a stand on legalization; instead, they say their role is to convince young people and their parents that the use of drugs is not just a moral or legal issue, but a significant health issue. “The health risks are real,” said Steve Pasierb, the chief executive of the Partnership for Drug-Free Kids. “Every passing year, science unearths more health risks about why any form of substance use is unhealthy for young people.” © 2014 The New York Times Company

Keyword: Drug Abuse; Aggression
Link ID: 19976 - Posted: 08.19.2014

Claudia M. Gold When I hear debate over the association between SSRI’s (selective serotonin re-uptake inhibitors, a class of antidepressant medication) and suicidal behavior in children and adolescents, I am immediately brought back to a night in the early 2000's. As the covering pediatrician I was called to the emergency room to see a young man, a patient of a pediatrician in a neighboring town, who had attempted suicide by taking a nearly lethal overdose. That night, as I watched over him in the intensive care unit, I learned that he was a high achieving student and athlete who, struggling under the pressures of the college application process, had been prescribed an SSRI by his pediatrician. His parents described a transformation in his personality over the months preceding the suicide attempt that was so dramatic that I ordered a CT scan to see if he had a brain tumor. It was normal. When, in the coming years the data emerged about increasing suicidal behavior following use of SSRI's, I recognized in retrospect that his change in behavior was a result of the medication. But at the time I knew nothing of these serious side effects. At that time, coinciding with pharmaceutical industry's aggressive marketing campaign directed at the public as well as a professional audience, these drugs were becoming increasingly popular with pediatricians. As the possible serious side effects of these medications came increasingly in to awareness, the FDA issued the controversial "black box warning" that the drugs carried an increased risk of suicidal behavior. Following the black box warning, pediatricians, myself included, became reluctant to prescribe these medications. We did not have the time or experience to provide the recommended increased monitoring and close follow-up.

Keyword: Depression; Aggression
Link ID: 19975 - Posted: 08.19.2014

by Clare Wilson Figuring out how the brain works is enough to make your head spin. But now we seem to have a handle on how it gets its folded shape. The surface layer of the brain, or cortex, is also referred to as our grey matter. Mammals with larger brains have a more folded cortex, and the human brain is the most wrinkled of all, cramming as much grey matter into our skulls as possible. L. Mahadevan at Harvard University and his colleagues physically modelled how the brain develops in the embryo, using a layer of gel to stand in for the grey matter. This gel adhered to the top of a solid hemisphere of gel representing the white matter beneath. In the embryo, grey matter grows as neurons are created or others migrate to the cortex from the brain's centre. By adding a solvent to make the grey matter gel expand, the team mimicked how the cortex might grow in the developing brain. They didn't model what effect, if any, the skull would have had. Hills and valleys The team varied factors such as the stiffness of the gels and the depth of the upper layer to find a combination that led to similarly shaped wrinkles as those of the human brain, with smooth "hills" and sharply cusped "valleys". There are several theories about how the brain's folds form. These include the possibility that more neurons migrate to the hills, making them rise above the valleys, or that the valleys are pulled down by the axons – fibres that connect neurons to each other – linking highly interconnected parts of the brain together. © Copyright Reed Business Information Ltd.

Keyword: Development of the Brain
Link ID: 19974 - Posted: 08.19.2014

Sara Reardon The National Science Foundation (NSF)’s role in the Brain Research through Advancing Innovative Neurotechnologies (BRAIN) Initiative is starting to take shape. On 18 August, the NSF awarded 36 small grants totalling US$10.8 million to projects studying everything from electrodes that measure chemical and electronic signals to artificial intelligence programs to identify brain structures. The three agencies participating in the BRAIN Initiative have taken markedly different approaches. The Defense Advanced Research Projects Agency, which received $50 million this year for the neuroscience programme, is concentrating on prosthetics and treatments for brain disorders that affect veterans, such as post-traumatic stress disorder. It has already awarded multi-million dollar grants to several teams. The National Institutes of Health, which received $40 million this year, has put together a 146-page plan to map and observe the brain over the next decade, and will announce its first round of grant recipients next month. The NSF, by contrast, has cast a wider net. The agency sent an request in March for informal, two-page project ideas. The only criterion was that the projects somehow address the properties of neural circuits. The response was overwhelming, says James Deshler, deputy director of the NSF’s Division of Biological Infrastructure. The agency had expected to fund about 12 grants, but decided to triple that number after receiving nearly 600 applications. “People started finding money in different pockets,” Deshler says. The wide-ranging list of winning projects includes mathematical models that help computers recognize different parts and patterns in the brain, physical tools such as new types of electrodes, and other tools that integrate and link neural activity to behaviour. © 2014 Nature Publishing Group

Keyword: Development of the Brain; Aggression
Link ID: 19973 - Posted: 08.19.2014

Helen Shen For most adults, adding small numbers requires little effort, but for some children, it can take all ten fingers and a lot of time. Research published online on 17 August in Nature Neuroscience1 suggests that changes in the hippocampus — a brain area associated with memory formation — could help to explain how children eventually pick up efficient strategies for mathematics, and why some children learn more quickly than others. Vinod Menon, a developmental cognitive neuroscientist at Stanford University in California, and his colleagues presented single-digit addition problems to 28 children aged 7–9, as well as to 20 adolescents aged 14–17 and 20 young adults. Consistent with previous psychology studies2, the children relied heavily on counting out the sums, whereas adolescents and adults tended to draw on memorized information to calculate the answers. The researchers saw this developmental change begin to unfold when they tested the same children at two time points, about one year apart. As the children aged, they began to move away from counting on fingers towards memory-based strategies, as measured by their own accounts and by decreased lip and finger movements during the task. Using functional magnetic resonance imaging (fMRI) to scan the children's brains, the team observed increased activation of the hippocampus between the first and second time point. Neural activation decreased in parts of the prefrontal and parietal cortices known to be involved in counting, suggesting that the same calculations had begun to engage different neural circuits. © 2014 Nature Publishing Group

Keyword: Development of the Brain; Aggression
Link ID: 19971 - Posted: 08.18.2014

by Andy Coghlan Pioneering studies of post-mortem brain tissues have yielded the first evidence of a potential association between Alzheimer's disease and the epigenetic alteration of gene function. The researchers stress, however, that more research is needed to find out if the changes play a causal role in the disease or occur as a result of it. We already have some evidence that the risk of developing Alzheimer's might be elevated by poor diet, lack of exercise, and inflammatory conditions such as diabetes, obesity and clogging of blood vessels with fatty deposits. The new research hints that the lifestyle changes that raise Alzheimer's risk may be taking effect through epigenetic changes. The idea is strengthened by the fact that the brain tissue samples studied in the new work came from hundreds of people, many of whom had Alzheimer's when they died, and that a number of genes identified were found by two teams working independently, one in the UK and one in the US. "The results are compelling and consistent across four cohorts of patients taken across the two studies," says Jonathan Mill at the University of Exeter, who led the UK-based team. "It's illuminated new genetic pathways affecting the disease and, given the lack of success tackling Alzheimer's so far, new leads are going to be vital." "We can now focus our efforts on understanding how these genes are associated with the disease," says Philip De Jager of the Brigham and Women's Hospital in Boston, who headed the US team. © Copyright Reed Business Information Ltd.

Keyword: Alzheimers; Aggression
Link ID: 19969 - Posted: 08.18.2014