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By Hannah Furfaro, RICAURTE, COLOMBIA—It's late afternoon in this tiny town tucked into the Colombian Andes, when Mercedes Triviño, 82, lights the wood stove to start to prepare dinner. Smoke fills the two-bedroom home she shares with six of her adult children. Francia, 38, one of the youngest, is the family's primary breadwinner. She brings home 28,000 Colombian pesos (roughly $10) a day harvesting papayas in the fields just outside town. "Really, what I earn is just enough for eating and nothing else," she says. Four of her siblings have fragile X syndrome, a genetic condition that causes intellectual disability, physical abnormalities, and often autism. Jair, 57, works alongside Francia when he can. Hector, 45, is also somewhat able to care for himself. Victor, 55, and Joanna, 35—who has both fragile X and Down syndrome—are less independent. As Mercedes serves coffee on this July afternoon, sweetening it with a hefty dose of sugar and offering her best cups to her guests, she talks about the condition that dominates the lives of her family and many others here. Her niece, Patricia, 48, who lives a few blocks away, cares for two adult sons and a nephew with fragile X. More distant kin in town, the Quinteros, also have grown children with the condition. Other neighbors are adults with fragile X who have no caretaker and look after one another. © 2018 American Association for the Advancement of Science

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25570 - Posted: 10.12.2018

Cassie Martin A new microscope is giving researchers an unprecedented view of how mammals are built, cell by cell. Light sheet microscopes use ultrathin laser beams to illuminate sections of a specimen while cameras record those lit-up sections. Previous iterations of the device have captured detailed portraits of living zebra fish and fruit fly embryos as they develop. Kate McDole, a developmental biologist at Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Va., and colleagues used a new-and-improved version to monitor the development of a larger, more complex organism: the mouse. Algorithms in the microscope tracked six-day-old mouse embryos in real time over roughly two days, keeping the device focused on the cell clusters as they grew. A suite of computer programs used the data — about a million images per embryo — to map the life history of each embryo’s every cell, the team reports October 11 in Cell. The result: dazzling views of mouse organs taking shape. As an embryo rapidly expands in size, the gut starts to form when part of the embryo collapses into a craterlike hole. And a structure that eventually forms the brain and spinal cord, called a neural tube, appears like a comet shooting across the night sky. Researchers also captured the first beats of heart cells. “These are processes no one has been able to watch before,” McDole says. Seeing the gut form in minutes was stunning. “We never expected it to be that fast or that dramatic. It’s not like you can Google these things.” |© Society for Science & the Public 2000 - 2018

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25568 - Posted: 10.12.2018

Laura Sanders Nearly two out of three U.S. kids spend more than two hours a day looking at screens, a new analysis of activity levels finds. And those children perform worse on memory, language and thinking tests than kids who spend less time in front of a device, the study of over 4,500 8- to 11-year-olds shows. The finding, published online September 26 in Lancet Child & Adolescent Health, bolsters concerns that heavy use of smartphones, tablets or televisions can hurt growing minds. But because the study captures a single snapshot in time, it’s still not known whether too much screen time can actually harm brain development, experts caution. Researchers used data gleaned from child and parent surveys on daily screen time, exercise and sleep, collected as part of a larger effort called the Adolescent Brain Cognitive Development Study. Cognitive abilities were also tested in that bigger study. As a benchmark for the new study, the researchers used expert guidelines set in 2016 that recommend no more than two hours of recreational screen time a day, an hour of exercise and between nine and 11 hours of nighttime sleep. Overall, the results are concerning, says study coauthor Jeremy Walsh, an exercise physiologist who at the time of the study was at the Children’s Hospital of Eastern Ontario Research Institute in Ottawa, Canada. Only 5 percent of the children met all three guidelines on screen time, exercise and sleep, the survey revealed. Twenty-nine percent of the children didn’t meet any of the guidelines, meaning that “they’re getting less than nine hours of sleep, they’re on their screens for longer than two hours and they’re not being physically active,” Walsh says. “This raises a flag.” |© Society for Science & the Public 2000 - 2018.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25497 - Posted: 09.27.2018

By Sam Rose Imagine the following transformation. A pea-sized chunk of your skin breaks apart in a dish of salts and serums. The mixture is infected with viruses that make some cells smaller, more circular, and clump together. They’ve turned into stem cells. Then, a bath of other salts, serums, and factors coax them into becoming mature neurons. The neurons divide and organize themselves into three dimensional spheres. Inside the spheres, the neurons layer themselves like the neurons in your cerebral cortex. There’s not just one ball, but an army of tiny spheres. Each sphere contains thousands of neurons; each neuron with a copy of your DNA. The neurons communicate with each other with pulses of electricity. The spheres start to organize structures that look a lot like the different lobes and substructures of your brain. Some of the spheres may even form an optic cup, an early version of your retina. This may seem like a perverse form of human cloning carried out by a neuroscientist turned witch-doctor. But it’s real: an emerging laboratory model system that might one day help treat you or a loved one’s debilitating neurological disorder. They are called brain spheroids (or three-dimensional brain cultures or cerebral organoids) and are a relatively new creation. They were first described in a splashy study published in Nature in 2013 and are one of the most technically impressive forms of tissue culture. What brain spheroids are not, however, is as important as what they are. They’re not ‘mini-brains’. They’re not generating thoughts and emotions. Without any sensory input they lack grounding in the physical world. Brain spheroids are also very small. At 4 mm in diameter, they’re much smaller than a mouse’s brain. They’re this small because real developing brains need massive amounts of nutrients throughout the depth of their structure. Brain spheroids get their nutrients from a bath of serums. But without a network of blood vessels to deliver the serum to deeper parts of the spheroid, these parts starve. Attaching a functioning circulatory system to the spheroids isn’t feasible with current techniques, so making bigger, more developed spheroids seems unlikely at this point. © 2018 Scientific American

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25496 - Posted: 09.26.2018

Laura Sanders I’m relatively new to Oregon, but one of the ways I know I’m starting to settle in is my ability to recognize marijuana shops. Some are easy. But others, with names like The Agrestic and Mr. Nice Guy, are a little trickier to identify for someone who hasn’t spent much time in a state that has legalized marijuana. A growing number of states have legalized both medical and recreational marijuana. At the same time, women who are pregnant or breastfeeding are using the drug in increasing numbers. A 2017 JAMA study described both survey results and urine tests of nearly 280,000 pregnant women in Northern California, where medical marijuana was legalized in 1996. The study showed that in 2009, about 4 percent of the women tested used marijuana. In 2016, about 7 percent of women did. Those California numbers may be even higher now, since recreational marijuana became legal there this year. Some of those numbers may be due in part to women using marijuana to treat their morning sickness, a more recent study by some of the same researchers suggests. Their report, published August 20 in JAMA Internal Medicine, found that pregnant women with severe nausea and vomiting were 3.8 times more likely to use marijuana than pregnant women without morning sickness. So some pregnant women are definitely using the drug, and exposing their fetuses to it, too. Ingredients in marijuana are known to make their way to fetuses by crossing the placenta during pregnancy (and by entering breast milk after the baby is born). But what actually happens when those marijuana compounds arrive? © Society for Science and the Public

Related chapters from BN8e: Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology; Chapter 13: Memory, Learning, and Development
Link ID: 25439 - Posted: 09.12.2018

By Richard A. Friedman We hear a lot these days that modern digital technology is rewiring the brains of our teenagers, making them anxious, worried and unable to focus. Don’t panic; things are really not this dire. Despite news reports to the contrary, there is little evidence of an epidemic of anxiety disorders in teenagers. This is for the simple reason that the last comprehensive and representative survey of psychiatric disorders among American youth was conducted more than a decade ago, according to Kathleen Ries Merikangas, chief of the Genetic Epidemiology Research Branch at the National Institute of Mental Health. There are a few surveys reporting increased anxiety in adolescents, but these are based on self-reported measures — from kids or their parents — which tend to overestimate the rates of disorders because they detect mild symptoms, not clinically significant syndromes. So what’s behind the idea that teenagers are increasingly worried and nervous? One possibility is that these stories are the leading edge of a wave of anxiety disorders that has yet to be captured in epidemiological surveys. Or maybe anxiety rates have risen, but only in the select demographic groups — the privileged ones — that receive a lot of media attention. But it’s more likely that the epidemic is simply a myth. The more interesting question is why it has been so widely accepted as fact. One reason, I believe, is that parents have bought into the idea that digital technology — smartphones, video games and the like — are neurobiologically and psychologically toxic. If you believe this, it seems intuitive that the generations growing up with these ubiquitous technologies are destined to suffer from psychological problems. But this dubious notion comes from a handful of studies with serious limitations. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25429 - Posted: 09.10.2018

By Carl Zimmer In a study carried out over the summer, a group of volunteers drank a white, peppermint-ish concoction laced with billions of bacteria. The microbes had been engineered to break down a naturally occurring toxin in the blood. The vast majority of us can do this without any help. But for those who cannot, these microbes may someday become a living medicine. The trial marks an important milestone in a promising scientific field known as synthetic biology. Two decades ago, researchers started to tinker with living things the way engineers tinker with electronics. They took advantage of the fact that genes typically don’t work in isolation. Instead, many genes work together, activating and deactivating one another. Synthetic biologists manipulated these communications, creating cells that respond to new signals or respond in new ways. Until now, the biggest impact has been industrial. Companies are using engineered bacteria as miniature factories, assembling complex molecules like antibiotics or compounds used to make clothing. In recent years, though, a number of research teams have turned their attention inward. They want to use synthetic biology to fashion microbes that enter our bodies and treat us from the inside. The bacterial concoction that volunteers drank this summer — tested by the company Synlogic — may become the first synthetic biology-based medical treatment to gain approval by the Food and Drug Administration. The bacteria are designed to treat a rare inherited disease called phenylketonuria, or PKU. People with the condition must avoid dietary protein in foods such as meat and cheese, because their bodies cannot break down a byproduct, an amino acid called phenylalanine. As phenylalanine builds up in the blood, it can damage neurons in the brain, leading to delayed development, intellectual disability and psychiatric disorders. The traditional treatment for PKU is a strict low-protein diet, accompanied by shakes loaded with nutritional supplements. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25419 - Posted: 09.05.2018

By Jane E. Brody The day my identical twin boys were delivered by an emergency cesarean, I noticed a behavioral difference. Twin A, who had been pushed against an unyielding pelvis for several hours, spent most of his first day alert and looking around, while Twin B, who had been spared this pre-birth stress, slept calmly like a typical newborn. My husband and I did our best to treat them equally, but Twin A was more of a challenge to hold — we called him “our lobster baby” — while Twin B was easily cuddled. As the boys developed, we saw other differences. Twin B rehearsed all the ambulatory milestones — crawling, walking, cycling, skating, etc. — while his twin watched, then copied the skill when it was mastered. Although they shared all their genes and grew up with the same adoring parents, clearly there were differences in these boys that had been influenced by other factors in their environment, both prenatal and postnatal. The relative importance of nature and nurture to how a child develops has been debated by philosophers and psychologists for centuries, and has had strong — and sometimes misguided — influences on public policy. The well-intentioned Head Start program, for example, was designed to give children from deprived environments an academic leg up. But it might have been more effective to teach their caregivers parenting and nurturing skills, as well as how to enrich the children’s environment and resist bad influences. Children learn from what they see around them, and if what they mainly experience is violence, abuse, truancy and no expectations for success, their chances for a wholesome future are compromised from the start. As my son Erik Engquist, a fellow journalist who was Twin A, put it: “Genes define your potential, but your environment largely determines how you turn out. The few who escape negative influences are outliers.” © 2018 The New York Times Company

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 13: Memory, Learning, and Development
Link ID: 25359 - Posted: 08.21.2018

By Kerri Smith, Cole Skinner was hanging from a wall above an abandoned quarry when he heard a car pull up. He and his friends bolted, racing along a narrow path on the quarry’s edge and hopping over a barbed-wire fence to exit the grounds. The chase is part of the fun for Skinner and his friend Alex McCallum-Toppin, both 15 and pupils at a school in Faringdon, UK. The two say that they seek out places such as construction sites and disused buildings—not to get into trouble, but to explore. There are also bragging rights to be earned. “It’s just something you can say: ‘Yeah, I’ve been in an abandoned quarry’,” says McCallum-Toppin. “You can talk about it with your friends.” Science has often looked at risk-taking among adolescents as a monolithic problem for parents and the public to manage or endure. When Eva Telzer, a neuroscientist at the University of North Carolina in Chapel Hill, asks family, friends, undergraduates or researchers in related fields about their perception of teenagers, “there’s almost never anything positive,” she says. “It’s a pervasive stereotype.” But how Alex and Cole dabble with risk—considering its social value alongside other pros and cons—is in keeping with a more complex picture emerging from neuroscience. Adolescent behaviour goes beyond impetuous rebellion or uncontrollable hormones, says Adriana Galván, a neuroscientist at the University of California, Los Angeles. “How we define risk-taking is going through a shift.” © 2018 Scientific American

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 25350 - Posted: 08.18.2018

Decca Aitkenhead Annual media coverage of August’s exam results has traditionally conformed to an unwritten rule that all photos must show euphoric teenagers celebrating multiple A*s. This year, the images may tell a different story. Radical reforms to GCSEs are widely predicted to produce disappointment, and many teenagers are bracing themselves for the worst. Parents may be unsympathetic, however, if their 15- or 16-year-old spent the exam year ignoring all their wise advice to revise, and instead lay in bed until lunchtime and partied all night with friends. Even if the exam results turn out to be good, many will wonder why their teenager took so many risks with their future. Sarah-Jayne Blakemore looks barely older than a teenager herself. The award-winning professor of cognitive neuroscience at University College London is, in fact, 44 and has made the study of the adolescent brain her life’s work. She has been critical of the very existence of GCSEs, arguing that they impose “enormous stress” on teenagers at a time when their brains are going through huge change. “Until about 15 or 20 years ago,” she says, “we just didn’t know that the brain develops at all within the teenage years.” Until then, it was assumed that teenage behaviour was almost entirely down to hormonal changes in puberty, but brain scans and psychological experiments have now found that adolescence is a critical period of neurological change, much of which is responsible for the unique characteristics of adolescent behaviour. Far from being a defective or inferior version of an adult brain, the adolescent mind is both unique and – to Blakemore – beautiful. “Teenagers,” she says tenderly, “are brilliant.” © 2018 Guardian News and Media Limited

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25348 - Posted: 08.18.2018

by Lindsey Bever It was a solution no parent wants to hear: To get rid of a brain tumor and stop their young son's seizures, surgeons would need to cut out one-sixth of his brain. But for Tanner Collins, it was the best option. A slow-growing tumor was causing sometimes-daily seizures, and medications commonly used to treat them did not seem to be working, his father said. But removing a portion of his brain was no doubt risky. That region — the right occipital and posterior temporal lobes — is important for facial recognition, and, without it, Tanner's parents wondered if he would recognize them. Tanner, who was 6 at the time, underwent surgery at the University of Pittsburgh Medical Center's Children's Hospital. Although his brain has had to work to adapt since then, he's had no major problems. Other than some visual impairment, Tanner, now 12, said he's “perfectly fine.” “As far as I’m concerned, I’m a perfectly normal 12-year-old boy,” Tanner said. Tanner's case was published Tuesday in the scientific journal Cell Reports, explaining how the 12-year-old's brain learned to adapt after a part largely responsible for visual processing was taken out. Marlene Behrmann, a cognitive neuroscientist and lead author of the paper, said Tanner was one of the first pediatric patients studied over the past several years in her laboratory at Carnegie Mellon University to determine the extent to which a child's brain can reorganize itself after certain sections are surgically removed. In Tanner's case, she said, surgeons took out his right occipital and posterior temporal lobes, which made up about one-third of the right hemisphere of his brain. © 1996-2018 The Washington Post

Related chapters from BN8e: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 13: Memory, Learning, and Development
Link ID: 25287 - Posted: 08.03.2018

Ashley Yeager Neuroscientist Gavin Clowry didn’t intend to grow a miniature human brain in a rat pup. But a few months ago, that’s essentially what happened. “We were astonished when we saw it,” recalls the faculty member at Newcastle University in the UK. Clowry and his colleagues had derived human neural stem cells from induced pluripotent stem cells, diffused them into a 3-D gel, and transplanted the gel into the young rats’ brains to test the cells’ ability to survive. A month later, much to the team’s surprise, the human cells had formed columns of tightly packed progenitor cells surrounded by immature neurons. “They looked like organoids,” says Clowry, who published the results in May. Organoids are tiny collections of tissue made from cells that self-organize into 3-D structures that mimic the anatomy of fully formed organs. Clowry attributes the unexpected development of the human brain organoids to the complex environment of the rat’s brain, where diverse cell types interact to keep neurons operating. That’s not to say cerebral organoids can’t also be grown in a dish. Scientists published the first description of lab-grown, human brain organoids in 2013. But even cultured mini-brains appear to benefit from an in vivo environment. Clowry’s study appeared in the literature just three weeks after a paper from Fred “Rusty” Gage and his colleagues at the Salk Institute for Biological Studies in La Jolla, California, described how they had transplanted lab-grown human brain organoids into the brains of mice and watched as the animals’ native blood vessels and immune cells infiltrated the organoids. Gage’s team also noted that the cells in the implanted organoids were sending and receiving signals to and from the mice’s native nerve cells. As Clowry and his colleagues would later observe in rat brains, the organoids were being integrated into the animals’ brains. © 1986 - 2018 The Scientist

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25284 - Posted: 08.02.2018

by Bethany Brookshire An astonishing number of things that scientists know about brains and behavior are based on small groups of highly educated, mostly white people between the ages of 18 and 21. In other words, those conclusions are based on college students. College students make a convenient study population when you’re a researcher at a university. It makes for a biased sample, but one that’s still useful for some types of studies. It would be easy to think that for studies of, say, how the typical brain develops, a brain is just a brain, no matter who’s skull its resting in. A biased sample shouldn’t really matter, right? Wrong. Studies heavy in rich, well-educated brains may provide a picture of brain development that’s inaccurate for the American population at large, a recent study found. The results provide a strong argument for scientists to pay more attention to who, exactly, they’re studying in their brain imaging experiments. It’s “a solid piece of evidence showing that those of us in neuroimaging need to do a better job thinking about our sample, where it’s coming from and who we can generalize our findings to,” says Christopher Monk, who studies psychology and neuroscience at the University of Michigan in Ann Arbor. The new study is an example of what happens when epidemiology experiments — studies of patterns in health and disease — crash into studies of brain imaging. “In epidemiology we think about sample composition a lot,” notes Kaja LeWinn, an epidemiologist at the University of California in San Francisco. Who is in the study, where they live and what they do is crucial to finding out how disease patterns spread and what contributes to good health. But in conversations with her colleagues in psychiatry about brain imaging, LeWinn realized they weren’t thinking very much about whose brains they were looking at. Particularly when studying healthy populations, she says, there was an idea that “a brain is a brain is a brain.” |© Society for Science & the Public 2000 - 2018

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25197 - Posted: 07.12.2018

Laura Sanders I’m making my way through my third round of breastfeeding a newborn and taking stock of how things are going. Some aspects are definitely easier: My milk came in really quickly (a perk of being a repeat lactator), the fancy breastfeeding baby holds are no longer mysterious to me and I already own all of the weird pillows I need to prop up my tiny baby. But one thing isn’t easier this time around: the bone-crushing, mind-numbing exhaustion. Just like my other two, this sweet baby seems to eat all the time. All day. All night. Sometimes multiple times an hour, especially in the witching hours of the evening. This frequency got me curious about the biology of newborns’ stomachs. Just how small are they? Are they so microscopic that one can hold only enough sustenance to keep my newborn satisfied for a thousandth of a second? Birth educators and medical professionals often use a marble to illustrate the size of a newborn’s stomach, a tiny orb that holds about 5 to 7 milliliters of liquid. But that small estimate has come into question. A 2008 review published in the Journal of Human Lactation points out that there aren’t many solid studies on the size of the infant stomach, and some of the ones that do exist come to different conclusions. Another review of existing studies concluded that the average newborn stomach is slightly smaller than a Ping-Pong ball and can hold about 20 milliliters, or about two-thirds of an ounce. © Society for Science and the Public

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 8: Hormones and Sex
Link ID: 25189 - Posted: 07.10.2018

Sukanya Charuchandra At times a predominant layer of the developing brain, the subplate disappears in the adult human brain—or so researchers believed. In findings published in Cell Stem Cell on June 21, scientists propose that neurons from the human subplate, which underlies the tissue that will become the cortex, relocate into the cortex. The researchers found high levels of a protein, known to help cells migrate into the cortex, in stem cell–derived subplate neurons. These relocated subplate cells may be associated with neurological diseases. “A lot of the genes associated with autism are first expressed in the subplate,” M. Zeeshan Ozair, a coauthor on the paper, says in a statement. “And if subplate neurons don’t die but instead become part of the cortex, they will carry those mutations with them.” M.Z. Ozair et al., “hPSC modeling reveals that fate selection of cortical deep projection neurons occurs in the subplate,” Cell Stem Cell, doi:10.1016/j.stem.2018.05.024, 2018. © 1986 - 2018 The Scientist Magazine

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25146 - Posted: 06.27.2018

Jennifer Ouellette Gerardo Ortiz remembers well the time in 2010 when he first heard his Indiana University colleague John Beggs talk about the hotly debated “critical brain” hypothesis, an attempt at a grand unified theory of how the brain works. Ortiz was intrigued by the notion that the brain might stay balanced at the “critical point” between two phases, like the freezing point where water turns into ice. A condensed matter physicist, Ortiz had studied critical phenomena in many different systems. He also had a brother with schizophrenia and a colleague who suffered from epilepsy, which gave him a personal interest in how the brain works, or doesn’t. Ortiz promptly identified one of the knottier problems with the hypothesis: It’s very difficult to maintain a perfect tipping point in a messy biological system like the brain. The puzzle compelled him to join forces with Beggs to investigate further. Ortiz’s criticism has beleaguered the theory ever since the late Danish physicist Per Bak proposed it in 1992. Bak suggested that the brain exhibits “self-organized criticality,” tuning to its critical point automatically. Its exquisitely ordered complexity and thinking ability arise spontaneously, he contended, from the disordered electrical activity of neurons. Bak’s canonical example of a self-organized critical system is a simple sandpile. If you drop individual grains of sand on top of a sandpile one by one, each grain has a chance of causing an avalanche. Bak and colleagues showed that those avalanches will follow a “power law,” with smaller avalanches occurring proportionally more frequently than larger ones. So if there are 100 small avalanches in which 10 grains slide down the side of the sandpile during a given period, there will be 10 larger avalanches involving 100 grains in the same period, and just one large avalanche involving 1,000 grains. When a huge avalanche collapses the whole pile, the base widens, and the sand begins to pile up again until it returns to its critical point, where, again, avalanches of any size may occur. The sandpile is incredibly complex, with millions or billions of tiny elements, yet it maintains an overall stability. All Rights Reserved © 2018

Related chapters from BN8e: Chapter 6: Evolution of the Brain and Behavior; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25137 - Posted: 06.25.2018

Veronique Greenwood The question most of genetics tries to answer is how genes connect to the traits we see. One person has red hair, another blonde hair; one dies at age 30 of Huntington’s disease, another lives to celebrate a 102nd birthday. Knowing what in the vast expanse of the genetic code is behind traits can fuel better treatments and information about future risks and illuminate how biology and evolution work. For some traits, the connection to certain genes is clear: Mutations of a single gene are behind sickle cell anemia, for instance, and mutations in another are behind cystic fibrosis. But unfortunately for those who like things simple, these conditions are the exceptions. The roots of many traits, from how tall you are to your susceptibility to schizophrenia, are far more tangled. In fact, they may be so complex that almost the entire genome may be involved in some way, an idea formalized in a theory put forward last year. Starting about 15 years ago, geneticists began to collect DNA from thousands of people who shared traits, to look for clues to each trait’s cause in commonalities between their genomes, a kind of analysis called a genome-wide association study (GWAS). What they found, first, was that you need an enormous number of people to get statistically significant results — one recent GWAS seeking correlations between genetics and insomnia, for instance, included more than a million people. Second, in study after study, even the most significant genetic connections turned out to have surprisingly small effects. The conclusion, sometimes called the polygenic hypothesis, was that multiple loci, or positions in the genome, were likely to be involved in every trait, with each contributing just a small part. (A single large gene can contain several loci, each representing a distinct part of the DNA where mutations make a detectable difference.) All Rights Reserved © 2018

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 25134 - Posted: 06.25.2018

Richard Harris One of the enduring mysteries of biology is why so much of the DNA in our chromosomes appears to be simply junk. In fact, about half of the human genome consists of repetitive bits of DNA that cut and paste themselves randomly into our chromosomes, with no obvious purpose. A study published Thursday finds that some of these snippets may actually play a vital role in the development of embryos. The noted biologist Barbara McClintock, who died in 1992, discovered these odd bits of DNA decades ago in corn, and dubbed them "jumping genes." (She won a Nobel prize for that finding in 1983.) McClintock's discovery stimulated generations of scientists to seek to understand this bizarre phenomenon. Some biologists have considered these weird bits of DNA parasites, since they essentially hop around our chromosomes and infect them, sometimes disrupting genes and leaving illness in their wake. But Miguel Ramalho-Santos, a biologist at the University of California, San Francisco, doesn't like that narrative. "It seemed like a waste of this real estate in our genome — and in our cells — to have these elements and not have them there for any particular purpose," Ramalho-Santos says. "So we just asked a very simple question: Could they be doing something that's actually beneficial?" He and his colleagues focused on a jumping gene called LINE-1; all told, copies of it make up a whopping 20 percent of our entire DNA. Ramalho-Santos' lab studies embryos, so the team wondered whether LINE-1 played any role in prompting a single fertilized egg to develop into an embryo. © 2018 npr

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25130 - Posted: 06.23.2018

By Jon Cohen Until now, researchers wanting to understand the Neanderthal brain and how it differed from our own had to study a void. The best insights into the neurology of our mysterious, extinct relatives came from analyzing the shape and volume of the spaces inside their fossilized skulls. But a recent marriage of three hot fields—ancient DNA, the genome editor CRISPR, and "organoids" built from stem cells—offers a provocative, if very preliminary, new option. At least two research teams are engineering stem cells to include Neanderthal genes and growing them into "minibrains" that reflect the influence of that ancient DNA. None of this work has been published, but Alysson Muotri, a geneticist at the University of California, San Diego (UCSD) School of Medicine, described his group's Neanderthal organoids for the first time this month at a UCSD conference called Imagination and Human Evolution. His team has coaxed stem cells endowed with Neanderthal DNA into pea-size masses that mimic the cortex, the outer layer of real brains. Compared with cortical minibrains made with typical human cells, the Neanderthal organoids have a different shape and differences in their neuronal networks, including some that may have influenced the species's ability to socialize. "We're trying to recreate Neanderthal minds," Muotri says. Muotri focused on one of approximately 200 protein-coding genes that differ between Neanderthals and modern humans. Known as NOVA1, it plays a role in early brain development in modern humans and also is linked to autism and schizophrenia. Because it controls splicing of RNA from other genes, it likely helped produce more than 100 novel brain proteins in Neanderthals. Conveniently, just one DNA base pair differs between the Neanderthal gene and the modern human one. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25116 - Posted: 06.21.2018

By Sara Goudarzi The presidents of the National Academies of Sciences, Engineering, and Medicine issued a statement Wednesday advocating for the U.S. Department of Homeland Security to stop separating migrant families. The statement cites research that indicates endangerment of those involved. Last week the American Psychological Association released a letter opposing the Trump administration’s policy of taking immigrant children from their parents at the border. Under the zero-tolerance immigration policy, since May more than 2,300 immigrant children—some of them babies—have been forcibly separated from their parents attempting to enter the U.S. from Mexico. Also Wednesday, as the backlash and public outcry continue to grow, Pres. Donald Trump said he would sign an executive order to stop separating families at the order. It was unclear when children already separated might be reunited with their families. But even if reunited soon, medical experts say the effects of separation can potentially last a lifetime. Scientific American spoke with Alan Shapiro, assistant clinical professor in pediatrics at Albert Einstein College of Medicine, about the effects of separation trauma and other health and mental consequences of breaking up families. Shapiro is also senior medical director for Community Pediatric Programs (CPP), a collaboration between the Children’s Hospital at Montefiore in New York City and the Children’s Health Fund, and medical director and co-founder of Terra Firma, a partnership that provides medical and legal services to immigrant children. © 2018 Scientific American

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory, Learning, and Development
Link ID: 25115 - Posted: 06.21.2018