Chapter 13. Memory, Learning, and Development
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By DONALD G. McNEIL Jr. and CATHERINE SAINT LOUIS The Zika virus damages many fetuses carried by infected and symptomatic mothers, regardless of when in pregnancy the infection occurs, according to a small but frightening study released on Friday by Brazilian and American researchers. In a separate report published on Friday, other scientists suggested a mechanism for the damage, showing in laboratory experiments that the virus targets and destroys fetal cells that eventually form the brain’s cortex. The reports are far from conclusive, but the studies help shed light on a mysterious epidemic that has swept across more than two dozen countries in the Western Hemisphere, alarming citizens and unnerving public health officials. In the first study, published in The New England Journal of Medicine, researchers found that 29 percent of women who had ultrasound examinations after testing positive for infection with the Zika virus had fetuses that suffered “grave outcomes.” They included fetal death, tiny heads, shrunken placentas and nerve damage that suggested blindness. “This is going to have a chilling effect,” said Dr. Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases. “Now there’s almost no doubt that Zika is the cause.” The small size of the study, which looked at 88 women at one clinic in Rio de Janeiro, was a limitation, Dr. Fauci added. From such a small sample, it is impossible to be certain how often fetal damage may occur in a much larger population. © 2016 The New York Times Company
Keyword: Development of the Brain
Link ID: 21957 - Posted: 03.05.2016
Mo Costandi Most of us are well aware of the health risks associated with obesity. Being overweight or obese is associated with an increased risk of numerous other conditions, from high blood pressure, heart disease and stroke, to diabetes, gout and some forms of cancer. Self-control saps memory resources Read more Research published over the past few years shows that obesity also has neurological consequences – it is associated with altered function in, and shrinkage of, certain parts of the brain, particularly the frontal lobes, which are the seat of intelligence, and the hippocampus, which is critical for memory formation. A new study now shows that this in turn is associated with impaired memory function. Lucy Cheke of the University of Cambridge and her colleagues recruited 50 volunteers aged between 18 and 35, with Body Mass Indexes (BMIs) ranging from 18 (underweight) to 51 (extremely obese), and asked them to perform a computerised memory test called the “Treasure Hunt Task”. This involved moving food items around around complex scenes, such as a desert with palm trees, hiding them in various locations, and indicating afterwards where they had hidden them. The participants were then shown various locations from the computerised scenes, and some of the food items, and asked if they had hidden something in each of the locations, or where they had hidden each of the items. Finally, they were shown pairs of the food items they had seen, and asked to indicate which of each pair they had hidden first. © 2016 Guardian News and Media Limited
By Gretchen Reynolds Learning in midlife to juggle, swim, ride a bicycle or, in my case, snowboard could change and strengthen the brain in ways that practicing other familiar pursuits such as crossword puzzles or marathon training will not, according to an accumulating body of research about the unique impacts of motor learning on the brain. When most of us consider learning and intelligence, we think of activities such as adding numbers, remembering names, writing poetry, learning a new language. Such complex thinking generally is classified as “higher-order” cognition and results in activity within certain portions of the brain and promotes plasticity, or physical changes, in those areas. There is strong evidence that learning a second language as an adult, for instance, results in increased white matter in the parts of the brain known to be involved in language processing. Regular exercise likewise changes the brain, as I frequently have written, with studies in animals showing that running and other types of physical activities increase the number of new brain cells created in parts of the brain that are integral to memory and thinking. But the impacts of learning on one of the most primal portions of the brain have been surprisingly underappreciated, both scientifically and outside the lab. Most of us pay little attention to our motor cortex, which controls how well we can move. “We have a tendency to admire motor skills,” said Dr. John Krakauer, a professor of neurology and director of the Center for the Study of Motor Learning and Brain Repair at Johns Hopkins University in Baltimore. We like watching athletes in action, he said. But most of us make little effort to hone our motor skills in adulthood, and very few of us try to expand them by, for instance, learning a new sport. We could be short-changing our brains. © 2016 The New York Times Company
By Jonathan Webb Science reporter, BBC News Three British researchers have won a prize worth one million euros, awarded each year for an "outstanding contribution to European neuroscience". Tim Bliss, Graham Collingridge and Richard Morris revealed how strengthened connections between brain cells can store our memories. Our present understanding of memory is built on their work, which unpicked the mechanisms and molecules involved. This is the first time the Brain Prize has been won by an entirely UK team. It is awarded by a Danish charitable foundation and the 2016 winners were announced in London on Tuesday. Speaking to journalists at a media conference, Prof Morris explained it was the "chemistry of memory" that he and his colleagues had managed to illuminate. Fire together, wire together "Before this team got going, we had some idea about particular areas of the brain that might be involved in memory… but what we didn't have was any real understanding of how it worked," explained the professor, who works at the University of Edinburgh. The "team" of three winners never worked together in the same laboratory, but they have collaborated over the years. "Memories change the brain - the brain is plastic," said Prof Bliss, who worked for many years at the National Institute of Medical Research in London and is now affiliated with the Francis Crick Institute. Those changes occur at the junctions between nerve cells - synapses - and were described in a pioneering study by Bliss and a Norwegian colleague, Terje Lømo, in the 1970s. © 2016 BBC.
Keyword: Learning & Memory
Link ID: 21947 - Posted: 03.03.2016
Ewan Birney The Daily Mail recently ran an article about how alcohol abuse could harm future generations, via the (exciting-sounding) mechanism of trans-generational epigenetics. This is an emotive topic, combining a commonplace habit (drinking beer and wine) with a scary outcome (harming your children, grandchildren and future generations) and adding a twist of science for gravitas. It’s not surprising that this research has been handed a megaphone by the mainstream press – but does the science stack up? To start with, the research was carried out in rats, as multi-generational experiments on humans are both grossly unethical and logistically extremely hard. This crucial bit of information is missing from both the Daily Mail headline and the paper’s title. Secondly, the big effects of alcohol consumption were mainly seen on the rats’ children and grandchildren – the effects on their great grandchildren were smaller. That is really important, because if there’s no effect on great grandchildren, it’s probably not due to epigenetics. Drinking large amounts of alcohol (for a rat) whilst pregnant would be expected to have an effect on the children and even the grandchildren. This is because the eggs of female mammals are made early on in foetal development, whilst a daughter is developing in the womb. So if that cell (the egg) also gives rise to a daughter, she will have directly experienced exposures that occurred during her maternal grandmother’s pregnancy. © 2016 Guardian News and Media Limited or its affiliated companies.
By James Gallagher Health editor, BBC News website People who are obese have a worse memory than their thinner friends, a small study shows. Tests on 50 people showed being overweight was linked to worse "episodic memory" or the ability to remember past experiences. The study in the Quarterly Journal of Experimental Psychology argues that a less vivid memory of recent meals may lead to overeating. However, other aspects of memory - such as general knowledge - were unaffected. Tests on rats have previously shown that with burgeoning waistlines come poorer performances in memory tests, but the evidence in humans has been mixed. The latest experiments looked at episodic memory - the video tape in your mind - that remembers the smell of a cup of coffee or the feel of holding someone's hand. Fifty people with a Body Mass Index (BMI) ranging from 18 (healthy) to 51 (very obese) took part in a memory test - a bit like doing a treasure hunt on your own. They had to "hide" objects at different times and on different scenes displayed on a computer screen. They were later asked to recall what they had hidden, when and where. The results showed obese people's scores were 15% lower than thinner people. Dr Lucy Cheke, from the University of Cambridge, told the BBC News website: "The suggestion we're making is that a higher BMI is having some reduction on the vividness of memory, but they're not drawing blanks and having amnesia. "But if they have a less strong memory of a recent meal, with a less strong impact in the mind, then they may have less ability to regulate how much they eat later on." Hunger hormones play a huge role in how much we eat, but it is already recognised that our minds have a key role too. © 2016 BBC
Keyword: Learning & Memory
Link ID: 21933 - Posted: 02.27.2016
The dodo is an extinct flightless bird whose name has become synonymous with stupidity. But it turns out that the dodo was no bird brain, but instead a reasonably brainy bird. Scientists said on Wednesday they figured out the dodo's brain size and structure based on an analysis of a well-preserved skull from a museum collection. They determined its brain was not unusually small but rather completely in proportion to its body size. They also found the dodo may have had a better sense of smell than most birds, with an enlarged olfactory region of the brain. This trait, unusual for birds, probably let it sniff out ripe fruit to eat. The research suggests the dodo, rather than being stupid, boasted at least the same intelligence as its fellow members of the pigeon and dove family. Mauritius Dodo bird A skeleton of a Mauritius Dodo bird stands at an exhibition in the Mauritius Institute Museum in Port Louis in this Dec. 27, 2005 file photo. (Reuters) "If we take brain size — or rather, volume, as we measured here — as a proxy for intelligence, then the dodo was as smart as a common pigeon," paleontologist Eugenia Gold of Stony Brook University in New York state said. "Common pigeons are actually smarter than they get credit for, as they were trained as message carriers during the world wars." ©2016 CBC/Radio-Canada.
by Giuseppe Gangarossa When we think about sex hormones, notably estrogens and androgens, we usually associate them with sex, gender and body development. Like all hormones, they are chemical messengers, substances produced in one part of the body that go on to tell other parts what to do. However, we often have the tendency to forget the enormous impact that these steroid hormones have on brain functions. From animal studies, it has become clear that during early development, exposure of the brain to testosterone and estradiol, hormones present in both males and females, leads to irreversible changes in the nervous system (McCarthy et al., 2012). A growing and very appealing body of science suggests that sex hormones play a neuromodulatory role in cognitive brain function (Janowsky, 2006). Moreover, testosterone dysfunctions (hypogonadism, chemical castration, etc.) have shown to be associated with memory defects. However, in spite of these advances, it still remains an enigma how sex hormones affect the brain. In an interesting paper published in PLOS ONE, Picot and colleagues tried to fill in one piece of the puzzle. They investigated the neurobiological effects of cerebral androgen receptor (AR) ablation on hippocampal plasticity and cognitive performance in male rodents (Picot et al., 2016). Although several reports have already highlighted a link between sex hormones and cognitive function (Galea et al., 2008; Janowsky, 2006), much more needs to be done to fully elucidate the “non-sexual” functions of androgens.
By Meeri Kim Teenagers tend to have a bad reputation in our society, and perhaps rightly so. When compared to children or adults, adolescents are more likely to engage in binge drinking, drug use, unprotected sex, criminal activity, and reckless driving. Risk-taking is like second nature to youth of a certain age, leading health experts to cite preventable and self-inflicted causes as the biggest threats to adolescent well-being in industrialized societies. But before going off on a tirade about groups of reckless young hooligans, consider that a recent study may have revealed a silver lining to all that misbehavior. While adolescents will take more risks in the presence of their peers than when alone, it turns out that peers can also encourage them to learn faster and engage in more exploratory acts. A group of 101 late adolescent males were randomly assigned to play the Iowa Gambling Task, a psychological game used to assess decision making, either alone or observed by their peers. The task involves four decks of cards: two are “lucky” decks that will generate long-term gain if the player continues to draw from them, while the other two are “unlucky” decks that have the opposite effect. The player chooses to play or pass cards drawn from one of these decks, eventually catching on to which of the decks are lucky or unlucky — and subsequently only playing from the lucky ones.
Laura Sanders In a multivirus competition, a newcomer came out on top for its ability to transport genetic cargo to a mouse’s brain cells. The engineered virus AAV-PHP.B was best at delivering a gene that instructed Purkinje cells, the dots in the micrograph above, to take on a whitish glow. Unaffected surrounding cells in the mouse cerebellum look blue. Cargo carried by viruses like AAV-PHP.B could one day replace faulty genes in the brains of people. AAV-PHP.B beat out other viruses including a similar one called AAV9, which is already used to get genes into the brains of mice. Genes delivered by AAV-PHP.B also showed up in the spinal cord, retina and elsewhere in the body, Benjamin Deverman of Caltech and colleagues report in the February Nature Biotechnology. Similar competitions could uncover viruses with the ability to deliver genes to specific types of cells, the researchers write. Selective viruses that can also get into the brain would enable deeper studies of the brain and might improve gene therapy techniques in people. © Society for Science & the Public 2000 - 2016
By DONALD G. McNEIL Jr. A baby with a shrunken, misshapen head is surely a heartbreaking sight. But reproductive health experts are warning that microcephaly may be only the most obvious consequence of the spread of the Zika virus. Even infants who appear normal at birth may be at higher risk for mental illnesses later in life if their mothers were infected during pregnancy, many researchers fear. The Zika virus, they say, closely resembles some infectious agents that have been linked to the development of autism, bipolar disorder and schizophrenia. Schizophrenia and other debilitating mental illnesses have no single cause, experts emphasized in interviews. The conditions are thought to arise from a combination of factors, including genetic predisposition and traumas later in life, such as sexual or physical abuse, abandonment or heavy drug use. But illnesses in utero, including viral infections, are thought to be a trigger. “The consequences of this go way beyond microcephaly,” said Dr. W. Ian Lipkin, who directs The Center for Infection and Immunity at Columbia University. Here is a look at the most prominent rumors and theories about Zika virus, along with responses from scientists. Among children in Latin America and the Caribbean, “I wouldn’t be surprised if we saw a big upswing in A.D.H.D., autism, epilepsy and schizophrenia,” he added. “We’re looking at a large group of individuals who may not be able to function in the world.” © 2016 The New York Times Company
By Nicholas Bakalar The popular heartburn drugs known as proton pump inhibitors have been linked to a range of ills: bone fractures, kidney problems, infections and more. Now a large new study has found that they are associated with an increased risk for dementia as well. Proton pump inhibitors, or P.P.I.s, are widely available both by prescription and over the counter under various brand names, including Prevacid, Prilosec and Nexium. German researchers, using a database of drug prescriptions, studied P.P.I. use in 73,679 men and women older than 75 who were free of dementia at the start of the study. Over an average follow-up period of more than five years, about 29,000 developed Alzheimer’s disease or other dementias. The study is in JAMA Neurology. After controlling for age, sex, depression, diabetes, stroke, heart disease and the use of other medicines, they found that regular use of P.P.I.s increased the risk for dementia in men by 52 percent and in women by 42 percent, compared with nonusers. “Our study does not prove that P.P.I.s cause dementia,” said the senior author, Britta Haenisch of the German Center for Neurodegenerative Diseases. “It can only provide a statistical association. This is just a small part of the puzzle. “Clinicians, pharmacists and patients have to weigh the benefits against the potential side effects,” she continued, “and future studies will help to better inform these decisions.” © 2016 The New York Times Company
Link ID: 21910 - Posted: 02.19.2016
By Gretchen Reynolds Some forms of exercise may be much more effective than others at bulking up the brain, according to a remarkable new study in rats. For the first time, scientists compared head-to-head the neurological impacts of different types of exercise: running, weight training and high-intensity interval training. The surprising results suggest that going hard may not be the best option for long-term brain health. As I have often written, exercise changes the structure and function of the brain. Studies in animals and people have shown that physical activity generally increases brain volume and can reduce the number and size of age-related holes in the brain’s white and gray matter. Exercise also, and perhaps most resonantly, augments adult neurogenesis, which is the creation of new brain cells in an already mature brain. In studies with animals, exercise, in the form of running wheels or treadmills, has been found to double or even triple the number of new neurons that appear afterward in the animals’ hippocampus, a key area of the brain for learning and memory, compared to the brains of animals that remain sedentary. Scientists believe that exercise has similar impacts on the human hippocampus. These past studies of exercise and neurogenesis understandably have focused on distance running. Lab rodents know how to run. But whether other forms of exercise likewise prompt increases in neurogenesis has been unknown and is an issue of increasing interest, given the growing popularity of workouts such as weight training and high-intensity intervals. So for the new study, which was published this month in the Journal of Physiology, researchers at the University of Jyvaskyla in Finland and other institutions gathered a large group of adult male rats. The researchers injected the rats with a substance that marks new brain cells and then set groups of them to an array of different workouts, with one group remaining sedentary to serve as controls. © 2016 The New York Times Company
Link ID: 21902 - Posted: 02.17.2016
Meghan Rosen The people of Flint, Mich., are drinking bottled water now, if they can get it. Volunteers deliver it door-to-door and to local fire stations. The goal is to keep the city’s residents from ingesting so much lead. Success – or lack thereof – could have consequences not just now, but for generations to come. Late last year, scientists raised alarms over a link between the city’s lead-tainted water and the growing number of children with high lead levels in their blood. It’s a serious problem. Lead is toxic to the brain, something scientists have long known. “Lead is probably the most well-known neurotoxin to man,” says Mona Hanna-Attisha, the pediatrician who first connected lead in Flint’s water to lead exposure in kids. And as scientists are beginning to find out, the damage that lead inflicts on children may be long-lasting. In addition to harming kids during youth, lead could contribute to disorders that develop later in life, such as Alzheimer’s disease or schizophrenia. Lead’s reach could extend even further, too — beyond those who drank the contaminated water to their children and grandchildren. Flint’s kids “will have to be followed throughout their whole life, and maybe into the next generation or two,” says Douglas Ruden, a neural toxicologist at Wayne State University in Detroit. A few months of drinking clean water will help bring the kids’ lead levels back down, he says. “But the damage is done.” And it’s permanent. In the United States, lead is everywhere. Decades of burning leaded gasoline spewed lead into the air, and the element settled in the upper layer of soil, clinging to particles of dirt. © Society for Science & the Public 2000 - 2016.
By BENEDICT CAREY Over the past few decades, cognitive scientists have found that small alterations in how people study can accelerate and deepen learning, improving retention and comprehension in a range of subjects, including math, science and foreign languages. The findings come almost entirely from controlled laboratory experiments of individual students, but they are reliable enough that software developers, government-backed researchers and various other innovators are racing to bring them to classrooms, boardrooms, academies — every real-world constituency, it seems, except one that could benefit most: people with learning disabilities. Now, two new studies explore the effectiveness of one common cognitive science technique — the so-called testing effect — for people with attention-deficit problems, one of the most commonly diagnosed learning disabilities. The results were mixed. They hint at the promise of outfoxing learning deficits with cognitive science, experts said, but they also point to the difficulties involved. The learning techniques developed by cognitive psychologists seem, in some respects, an easy fit for people with attention deficits: breaking up study time into chunks, mixing related material in a session, varying study environments. Each can produce improvements in retention or comprehension, and taken together capture the more scattered spirit of those with attention deficit hyperactivity disorder, especially children. The testing effect has proved especially reliable for other students, and it is a natural first choice to measure the potential application to A.D.H.D. The principle is straightforward: Once a student is familiar with a topic, testing himself on it deepens the recall of the material more efficiently than restudying. © 2016 The New York Times Company
By SINDYA N. BHANOO The human brain is attracted to things that were once pleasing even if they no longer are, researchers report. Study participants were asked to find red and green objects on a computer screen filled with different colored objects. They received small rewards for finding the objects: $1.50 for the red ones and 25 cents for the green ones. The next day, while brain scans were conducted, participants were asked to find certain shapes on the screen. There was no reward, and color was irrelevant. Still, when a red object appeared, participants focused on it, and scans showed dopamine was released in their brains. “They are not getting a reward for that, yet part of the brain is saying, ‘Oh, there’s a reward — pay attention to it,’” said Susan M. Courtney, a cognitive neuroscientist at Johns Hopkins University and a co-author of the study in Current Biology. The findings may help researchers develop pharmaceutical treatments for problems like food or drug addiction. © 2016 The New York Times Company
By Lindsey Tanner CHICAGO — Two blood-building drugs injected soon after birth may give premature babies a lasting long-term edge, boosting brain development and IQ by age 4, a first-of-its-kind study found. The study was small but the implications are big if larger, longer studies prove the drugs help level the playing field for these at-risk newborns, the researchers and other experts say. Preemies who received the medicines scored much better by age 4 on measures of intelligence, language and memory than those who did not. The medicine-receiving group’s scores on an important behavior measure were just as high as a control group of 4-year-olds born on time at a normal weight. The results are “super exciting,” said Robin Ohls, the lead author and a pediatrics professor at the University of New Mexico. She said it is the first evidence of long-term benefits of the drugs when compared with no blood-boosting treatment. Although the treated babies didn’t do as well as the normal-weight group on most measures, their scores were impressive and suggest greater brain development than the other preemies, Ohls said. They scored about 12 points higher on average on IQ tests than the untreated infants but about 10 points lower than the normal-weight group. On tests measuring memory and impulsive behavior, the treated babies fared as well as those born at normal weight.
Keyword: Development of the Brain
Link ID: 21896 - Posted: 02.15.2016
Laura Sanders WASHINGTON — Tiny orbs of brain cells swirling in lab dishes may offer scientists a better way to study the complexities of the human brain. Toxicologist Thomas Hartung described these minibrains, grown from stem cells derived from people’s skin cells, at the annual meeting of the American Association for the Advancement of Science. Insights from experiments on animals are often difficult to apply to humans, Hartung, of Johns Hopkins University, said in a news briefing February 12. “We need something else,” he said. “We are not 150-pound rats.” These minibrains aren’t flashy. Other minibrain systems created by scientists in the past have complex neural structures and elaborate development (SN: 9/21/13, p. 5), representing the Ferraris and Maseratis of minibrains, Hartung said. In contrast, he said, his minibrains are Mini Coopers. But these bare-bones models, made of busy nerve cells and support cells in a sphere about the size of a fly eye, offer a standardized system that can reliably test the effects of a wide range of drugs. Hartung and colleagues are developing a company to make minibrains quickly available to researchers who could use them to study such disorders as autism, depression and Alzheimer’s disease, he said. The minibrains would cost about as much as a lab rat. © Society for Science & the Public 2000 - 2016
Keyword: Development of the Brain
Link ID: 21895 - Posted: 02.15.2016
Mo Costandi Tell me where dwell the thoughts, forgotten till thou call them forth? Tell me where dwell the joys of old, and where the ancient loves, And when will they renew again, and the night of oblivion past, That I might traverse times and spaces far remote, and bring Comforts into a present sorrow and a night of pain? Where goest thou, O thought? To what remote land is thy flight? If thou returnest to the present moment of affliction, Wilt thou bring comforts on thy wings, and dews and honey and balm, Or poison from the desert wilds, from the eyes of the envier? In his epic poem, Visions of the Daughters of Albion, William Blake wonders about the nature of memory, its ability to mentally transport us to distant times and places, and the powerful emotions, both positive and negative, that our recollections can evoke. The poem contains questions that remain highly pertinent today, such as what happens to our long-lost memories, and how do we retrieve them? More than two centuries later, the mechanisms of memory storage and retrieval are the most intensively studied phenomena in the brain sciences. It’s widely believed that memory formation involves the strengthening of connections between sparsely distributed networks of neurons in a brain structure called the hippocampus, and that subsequent retrieval involves reactivation of the same neuronal ensembles. And yet, neuroscientists still struggle to answer Blake’s questions definitely. Now, a team of researchers at the University of Geneva have made another important advance in our understanding of the neural mechanisms underlying memory formation. Using a state-of-the-art method called optogenetics, they show how the neuronal ensembles that encode memories emerge, revealing that ensembles containing too many neurons – or too few – impair memory retrieval. © 2016 Guardian News and Media Limited
Keyword: Learning & Memory
Link ID: 21893 - Posted: 02.13.2016