Chapter 7. Life-Span Development of the Brain and Behavior
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Virginia Hughes Trauma is insidious. It not only increases a person’s risk for psychiatric disorders, but can also spill over into the next generation. People who were traumatized during the Khmer Rouge genocide in Cambodia tended to have children with depression and anxiety, for example, and children of Australian veterans of the Vietnam War have higher rates of suicide than the general population. Trauma’s impact comes partly from social factors, such as its influence on how parents interact with their children. But stress also leaves ‘epigenetic marks’ — chemical changes that affect how DNA is expressed without altering its sequence. A study published this week in Nature Neuroscience finds that stress in early life alters the production of small RNAs, called microRNAs, in the sperm of mice (K. Gapp et al. Nature Neurosci. http://dx.doi.org/10.1038/nn.3695; 2014). The mice show depressive behaviours that persist in their progeny, which also show glitches in metabolism. The study is notable for showing that sperm responds to the environment, says Stephen Krawetz, a geneticist at Wayne State University School of Medicine in Detroit, Michigan, who studies microRNAs in human sperm. (He was not involved in the latest study.) “Dad is having a much larger role in the whole process, rather than just delivering his genome and being done with it,” he says. He adds that this is one of a growing number of studies to show that subtle changes in sperm microRNAs “set the stage for a huge plethora of other effects”. In the new study, Isabelle Mansuy, a neuroscientist at the University of Zurich, Switzerland, and her colleagues periodically separated mother mice from their young pups and exposed the mothers to stressful situations — either by placing them in cold water or physically restraining them. These separations occurred every day but at erratic times, so that the mothers could not comfort their pups (termed the F1 generation) with extra cuddling before separation. © 2014 Nature Publishing Group,
By Emily Chung, CBC News If you're in your late 20s or older, you're not as sharp as you used to be, suggests a study of gamers playing the popular video game Starcraft 2. The study analyzed the way 3,305 people, aged 16 to 44, played the game against a single random opponent of similar skill, in order to measure the gamers' cognitive motor performance. Cognitive motor performance is how quickly your brain reacts to things happening around you, allowing you to act during tasks such as driving. The analysis revealed exactly when advancing age starts to take its toll on brain performance – at the tender age of 24 years. The results were published late last week in the journal PLOS ONE. Joe Thompson, lead author of the study, said he was surprised by how early the decline started and how big the age effect was, even among those in their 30s. "If you're 39, competing against a 24-year-old and you're both in the otherwise same level of skill," Thompson said, "the effect of age is expected to offset a great deal of your learning." Starcraft 2 is a popular strategy game, similar in concept to Risk, where players compete to build armies and conquer a science fictional world. Unlike Risk, however, players don't take turns. "Starcraft is like high-speed chess," said Thompson, a PhD student who plays the game himself. "You simply can make as many moves as you want, as fast as you can go." Players can't see the whole "world" at once, as they mine resources needed to build up their armies, as they attack their opponents, and as they defend against opponents' attacks, they need to quickly move their screen around from one part of the world to another. © CBC 2014
by Simon Makin Could drama workshops help children with autism-spectrum disorders? Results from a pilot study called Imagining Autism suggests this might be the case. The research involved 22 children aged between 7 and 12 and consisted of one 45-minute session every week for 10 weeks. During this time, groups of four children entered an enclosed themed environment, such as a forest or outer space. These environments were designed to engage all senses simultaneously, using lights, sounds, puppetry and interactive digital elements. Trained performers used improvisation techniques to encourage the children to engage creatively with the environment and each other, both physically and verbally. The hope was that the sessions would help develop the children's communication, social interaction, and imagination skills – the "triad of impairments" seen in autism. Children were assessed before the intervention, and again between two and six weeks after the sessions ended. As well as looking at whether behaviours used to diagnose autism changed after the drama sessions, the researchers also assessed emotion recognition, imitation, IQ and theory of mind – the ability to infer what others are thinking and feeling. Subjective ratings were also gathered from parents and teachers and follow-up assessments were conducted up to a year later. At the early assessments, all children showed some improvement. The most significant change was in the number of facial expressions recognised, a key communication skill. Nine children improved on this. Six children improved on their level of social interaction. The majority of these changes were also seen at the follow-up assessments. © Copyright Reed Business Information Ltd.
Link ID: 19494 - Posted: 04.16.2014
Scientists haven’t pinpointed a definitive cause for Alzheimer’s disease—a fatal brain disorder that robs people of their memory and cognitive abilities. But now researchers have uncovered an intriguing clue about why more women than men develop the condition. A particular gene variant, found in a quarter of the population and long known to raise people’s risk for the disease, seems less menacing in men, new research shows. The findings could have implications for potential gender-specific treatments, some Alzheimer’s investigators suggest. Though a small percentage of Alzheimer’s cases arise from genetic mutations that cause obvious disease before the age of 65, the vast majority of people who develop the condition do so later in life from undefined triggers, some thought to be genetic. In 1993, scientists found that people who inherit a gene variant called apolipoprotein E4 (APOE4) are more prone to the common form of Alzheimer’s that strikes in late life. There’s also a “risk-neutral” variant (APOE3) and a much rarer version of the gene (APOE2) that decreases a person’s risk for Alzheimer’s. Shortly thereafter, other research groups replicated the finding and some data hinted that APOE4 raises Alzheimer’s risk more in women than in men. Indeed, when scientists combed through a massive data set containing 5930 Alzheimer’s patients and 8607 dementia-free elderly from 40 independent studies, they reported in 1997 that females with the APOE4 variant were four times more likely to have Alzheimer’s compared with people with the more common, neutral form of the gene. However, in men, APOE4 seemed virtually harmless. “It was a pretty big effect,” says Michael Greicius, a neurologist at Stanford University Medical Center in California, of the analysis. Yet the findings didn’t create much of a stir at the time. © 2014 American Association for the Advancement of Science
Simon Baron-Cohen, professor of developmental psychopathology at the University of Cambridge and director of the Autism Research Center, replies: Your mother is correct that the scientific evidence points to the brain of people with autism and Asperger's syndrome as being different but not necessarily “disordered.” Studies have shown that the brain in autism develops differently, in terms of both structure and function, compared with more typical patterns of development, and that certain parts of the brain are larger or smaller in people who have autism compared with those who have a more typical brain. One structural difference resides in the brain's corpus callosum, which connects the right and left hemispheres. Most studies show that the corpus callosum is smaller in certain sections in people with autism, which can limit connectivity among brain regions and help explain why people with autism have difficulty integrating complex ideas. An example of a functional difference is in the activity of the ventromedial prefrontal cortex, which is typically active in tasks involving theory of mind—the ability to imagine other people's thoughts and feelings—but is underactive when people with autism perform such tasks. The brain of those with autism also shows advantages. When some people with this condition are asked to complete detail-oriented tasks, such as finding a target shape in a design, they are quicker and more accurate. Additionally, those with autism generally exhibit less activity in the posterior parietal cortex, involved in visual and spatial perception, which suggests that their brain is performing the task more efficiently. © 2014 Scientific American
By CATHERINE SAINT LOUIS Doctors are prescribing opioid painkillers to pregnant women in astonishing numbers, new research shows, despite the fact that risks to the developing fetus are largely unknown. Of 1.1 million pregnant women enrolled in Medicaid nationally, nearly 23 percent filled an opioid prescription in 2007, up from 18.5 percent in 2000, according to a study published last week in Obstetrics and Gynecology, the largest to date of opioid prescriptions among pregnant women. Medicaid covers the medical expenses for 45 percent of births in the United States. The lead author, Rishi J. Desai, a research fellow at Brigham and Women’s Hospital, said he had expected to “see some increase in trend, but not this magnitude.” “One in five women using opioids during pregnancy is definitely surprising,” he said. In February, a study of 500,000 privately insured women found that 14 percent were dispensed opioid painkillers at least once during pregnancy. From 2005 to 2011, the percentage of pregnant women prescribed opioids decreased slightly, but the figure exceeded 12 percent in any given year, according to Dr. Brian T. Bateman, an anesthesiologist at Massachusetts General Hospital, and his colleagues. Their research was published in Anesthesiology. Dr. Joshua A. Copel, a professor of obstetrics, gynecology and reproductive sciences at Yale School of Medicine in New Haven, Conn., said he was taken aback by the findings, which come even as conscientious mothers-to-be increasingly view pregnancy as a time to skip caffeine, sushi and even cold cuts. “To hear that there’s such a high use of narcotics in pregnancy when I see so many women who worry about a cup of coffee seems incongruous,” he said. In both studies, the opioids most prescribed during pregnancy were codeine and hydrocodone. Oxycodone was among the top four. Women usually took the drugs for a week or less; however, just over 2 percent of women in both studies took them for longer periods. © 2014 The New York Times Company
|By Simon Makin Scientists have observed that reading ability scales with socioeconomic status. Yet music might help close the gap, according to Nina Kraus and her colleagues at Northwestern University. Kraus's team tested the auditory abilities of teenagers aged 14 or 15, grouped by socioeconomic status (as indexed by their mother's level of education, a commonly used surrogate measure). The researchers recorded the kids' brain waves with EEG as they listened to a repeated syllable against soft background sound and when they heard nothing. They found that children of mothers with a lower education had noisier, weaker and more variable neural activity in response to sound and greater activity in the absence of sound. The children also scored lower on tests of reading and working memory. Kraus thinks music training is worth investigating as a possible intervention for such auditory deficits. The brains of trained musicians differ from nonmusicians, and they also enjoy a range of auditory advantages, including better speech perception in noise, according to research from Kraus's laboratory. The researchers admit that this finding could be the result of preexisting differences that predispose some people to choose music as a career or hobby, but they point out that some experimental studies show that musical training, whether via one-on-one lessons or in group sessions, enhances people's response to speech. Most recently Kraus's group has shown that these effects may last. Kraus surveyed 44 adults aged 55 to 76 and found that four or more years of musical training in childhood was linked to faster neural responses to speech, even for the older adults who had not picked up an instrument for more than 40 years. © 2014 Scientific American
By Dominic Basulto The latest numbers from the Center for Disease Control showing a steep rise in the number of children with autism are so off the charts that it’s hard not to come to one of two conclusions: There’s something wrong in the way that we measure the data or there’s something extraordinary going on. 1 in 68 American children now has autism, up from 1 in 88 children just two years ago, an increase of 30 percent. A decade ago, one in 166 children were diagnosed as having autism. In 1975, it was 1 in 5000. Plot this as a graph using CDC data and you get a hockey stick curve showing exponential growth in autism over just the past decade. If you accept the first conclusion – that we’re simply not measuring autism correctly – there’s actually a fair amount of evidence to suggest that as much as 53 percent of the variation in data can be explained away by factors such as better diagnosis, better detection and better awareness. And it’s true that the very definition of “autism” continues to change to include a much wider description of symptoms along a spectrum, so it’s only natural to expect an increase in the number of cases if we’re making it easier to define people as having autism. There’s even a growing consensus in the scientific community that the current numbers are “no cause for alarm” and may actually underestimate the incidence of autism in the population, due to problems in collecting information in more rural areas and among some demographic groups. That still leaves approximately 50 percent of the rise in autism cases to explain through science. It won’t be easy. There may be as many as 60 different disorders that are associated with autism, and a multitude of factors at work, with most of them thought to be linked to changes in our environment or genetic factors resulting from increasing parental age. As a result, even the Chief Science Officer at Autism Speaks concedes that what causes autism remains a mystery. © 1996-2014 The Washington Post
Link ID: 19474 - Posted: 04.12.2014
Jyoti Madhusoodanan Growing up in a stressful social environment leaves lasting marks on young chromosomes, a study of African American boys has revealed. Telomeres, repetitive DNA sequences that protect the ends of chromosomes from fraying over time, are shorter in children from poor and unstable homes than in children from more nurturing families. When researchers examined the DNA of 40 boys from major US cities at age 9, they found that the telomeres of children from harsh home environments were 19% shorter than those of children from advantaged backgrounds. The length of telomeres is often considered to be a biomarker of chronic stress. The study, published today in the Proceedings of the National Academy of Sciences1, brings researchers closer to understanding how social conditions in childhood can influence long-term health, says Elissa Epel, a health psychologist at the University of California, San Francisco, who was not involved in the research. Participants’ DNA samples and socio-economic data were collected as part of the Fragile Families and Child Wellbeing Study, an effort funded by the US National Institutes of Health to track nearly 5,000 children, the majority of whom were born to unmarried parents in large US cities in 1998–2000. Children's environments were rated on the basis of their mother's level of education; the ratio of a family’s income to needs; harsh parenting; and whether family structure was stable, says lead author Daniel Notterman, a molecular biologist at Pennsylvania State University in Hershey. © 2014 Nature Publishing Group
By BENEDICT CAREY Therapists who specialize in autism often use a child’s own interests, toys or obsessions as a way to connect, and sometimes to reward effort and progress on social skills. The more eye contact a child makes, for example, the more play time he or she gets with those precious maps or stuffed animals. But now a group of scientists and the author of a new book are suggesting that those favorite activities could be harnessed in a deeper, more organic way. If a child is fascinated with animated characters like Thomas the Tank Engine, why not use those characters to prompt and reinforce social development? Millions of parents do this routinely, if not systematically, flopping down on the floor with a socially distant child to playact the characters themselves. “We individualize therapy to each child already, so if the child has an affinity for certain animated characters, it’s absolutely worth studying a therapy that incorporates those characters meaningfully,” said Kevin Pelphrey, director of the child neuroscience laboratory at Yale. He and several other researchers, including John D. E. Gabrieli of M.I.T., Simon Baron-Cohen of the University of Cambridge and Pamela Ventola of Yale, are proposing a study to test the approach. The idea came from Ron Suskind, a former Wall Street Journal reporter whose new book “Life, Animated” describes his family’s experience reaching their autistic son, Owen, through his fascination with Disney movies like “The Little Mermaid” and “Beauty and the Beast.” It was Mr. Suskind’s story that first referred to ‘“affinity therapy.” He approached the researchers to put together a clinical trial based on the idea that some children can develop social and emotional instincts through the characters they love. Experts familiar with his story say the theory behind the therapy is plausible, given what’s known from years of studying the effects of other approaches. © 2014 The New York Times Company
Link ID: 19459 - Posted: 04.08.2014
By KENNETH CHANG This occasional column explores topics covered in Science Times 25 years ago to see what has changed — and what has not. The claim about babies was startling: A test administered to infants as young as 6 months could predict their score on an intelligence test years later, when they started school. “Why not test infants and find out which of them could take more in terms of stimulation?” Joseph F. Fagan III, the psychologist at Case Western Reserve University in Cleveland who developed the test, was quoted as saying in an article by Gina Kolata on April 4, 1989. “It’s not going to hurt anybody, that’s for sure.” In the test, the infant looks at a series of photographs — first a pair of identical faces, then the same face paired with one the baby hasn’t seen. The researchers measure how long the baby looks at the new face. “On the surface, it tests novelty preference,” said Douglas K. Detterman, a colleague of Dr. Fagan’s at Case Western. For reasons not quite understood, babies of below-average intelligence do not exhibit the same attraction to novelty. Dr. Fagan suggested that the test could be used to identify children with above-average intelligence in poorer families so they could be exposed to enrichment programs more readily available to wealthier families. But his primary motivation, said Cynthia R. Holland, his wife and longtime collaborator, was to look for babies at the other end of the intelligence curve, those who would fall behind as they grew up. “His hope was always was to identify early on, in the first year of life, kids who were at risk, cognitively, so we could focus our resources on them and help them out,” said Dr. Holland, a professor of psychology at Cuyahoga Community College. 25 YEARS LATER For the most part, the validity of the Fagan test holds up. Indeed, Dr. Fagan (who died last August) and Dr. Holland revisited infants they had tested in the 1980s, and found that the Fagan scores were predictive of the I.Q. and academic achievement two decades later when these babies turned 21. © 2014 The New York Times Company
By NICHOLAS BAKALAR A new study adds to the evidence that the use of antidepressants during pregnancy is associated with a higher risk of premature birth, though many factors most likely play a role and the relationship is complex. Researchers reviewed data from 41 studies, some of which controlled for factors like smoking, alcohol or coffee drinking, weight gain during pregnancy, and other behavioral and health issues. They found no increase in the risk of early birth with the use of antidepressants during the first trimester, a 53 percent higher risk over all and a 96 percent higher risk with antidepressant use late in pregnancy. Depression itself is a risk factor for premature births, and a few studies tried to account for this by using, as a control, a group of women with a diagnosis of depression who did not take antidepressants during their pregnancy. Generally, researchers still found a higher, though diminished, risk from taking antidepressants. The review was published in March in PLOS One. Does this mean that all pregnant women should avoid these drugs? No, said the senior author, Dr. Adam C. Urato, an assistant professor of maternal-fetal medicine at Tufts University. Risks and benefits have to be balanced, he said. “It’s very complex, and depends on the severity of the disease,” Dr. Urato added. “The point is that we have to get the right information out so that we can let pregnant women make an informed decision.” © 2014 The New York Times Company
A high-resolution map of the human brain in utero is providing hints about the origins of brain disorders including schizophrenia and autism. The map shows where genes are turned on and off throughout the entire brain at about the midpoint of pregnancy, a time when critical structures are taking shape, researchers Wednesday in the journal Nature. "It's a pretty big leap," says , an investigator at the in Seattle who played a central role in creating the map. "Basically, there was no information of this sort prior to this project." Having a map like this is important because many psychiatric and behavioral problems appear to begin before birth, "even though they may not manifest until teenage years or even the early 20s," says , director of the . The human brain is often called the most complex object in the universe. Yet its basic architecture is created in just nine months, when it grows from a single cell to more than 80 billion cells organized in a way that will eventually let us think and feel and remember. "We're talking about a remarkable process," a process controlled by our genes, Lein says. So he and a large team of researchers decided to use genetic techniques to create a map that would help reveal this process. Funding came from the 2009 federal stimulus package. The massive effort required tens of thousands of brain tissue samples so small that they had to be cut out with a laser. Researchers used brain tissue from aborted fetuses, which the Obama administration has authorized over the objections of abortion opponents. ©2014 NPR
by Bob Holmes People instinctively organise a new language according to a logical hierarchy, not simply by learning which words go together, as computer translation programs do. The finding may add further support to the notion that humans possess a "universal grammar", or innate capacity for language. The existence of a universal grammar has been in hot dispute among linguists ever since Noam Chomsky first proposed the idea half a century ago. If the theory is correct, this innate structure should leave some trace in the way people learn languages. To test the idea, Jennifer Culbertson, a linguist at George Mason University in Fairfax, Virginia, and her colleague David Adger of Queen Mary University of London, constructed an artificial "nanolanguage". They presented English-speaking volunteers with two-word phrases, such as "shoes blue" and "shoes two", which were supposed to belong to a new language somewhat like English. They then asked the volunteers to choose whether "shoes two blue" or "shoes blue two" would be the correct three-word phrase. In making this choice, the volunteers – who hadn't been exposed to any three-word phrases – would reveal their innate bias in language-learning. Would they rely on familiarity ("two" usually precedes "blue" in English), or would they follow a semantic hierarchy and put "blue" next to "shoe" (because it modifies the noun more tightly than "two", which merely counts how many)? © Copyright Reed Business Information Ltd.
by Aviva Rutkin Don't blame baby for trying to eat that Lego piece. Humans may have a brain circuit dedicated to grabbing stuff and putting it in our mouths, and it probably develops in the womb. Researchers and parents alike have long known that babies stick all manner of things in their mouths from very early on. Some fetuses even suck their thumbs. As putting something in the mouth seems advanced compared to the other, limited actions of newborns, Angela Sirigu of the Institute of Cognitive Sciences in Bron, France, and colleagues wondered whether the behaviour is encoded in the brain from birth. To investigate, they studied 26 people of different ages while they were undergoing brain surgery. The researchers found that they were able to make nine of the unconscious patients bring their hands up and open their mouths, just by stimulating a part of the brain we know is linked to those actions in non-human primates. Brain pudding Because this behaviour is encoded in the same region as in other primates, it may be there from birth or earlier, the researchers say. If it was learned, you would expect it to involve multiple brain areas, and those could vary between individuals. Newborn kangaroos are able to climb into their mother's pouch and baby wildebeests can run away from lions, but our babies appear helpless and have to learn most complex actions. The new work suggests that the way our brain develops is more like what happens in other animals than previously thought. © Copyright Reed Business Information Ltd.
Keyword: Development of the Brain
Link ID: 19431 - Posted: 04.01.2014
By SAM WANG A STUDY published last week found that the brains of autistic children show abnormalities that are likely to have arisen before birth, which is consistent with a large body of previous evidence. Yet most media coverage focuses on vaccines, which do not cause autism and are given after birth. How can we help people separate real risks from false rumors? Over the last few years, we’ve seen an explosion of studies linking autism to a wide variety of genetic and environmental factors. Putting these studies in perspective is an enormous challenge. In a database search of more than 34,000 scientific publications mentioning autism since its first description in 1943, over half have come since 2008. As a statistically minded neuroscientist, I suggest a different approach that relies on a concept we are familiar with: relative odds. As a single common measuring stick to compare odds, I have chosen the “risk ratio,” a measure that allows the bigger picture to come into focus. For a variety of studies I asked the same question: How large is the increased risk for autism? My standard for comparison was the likelihood in the general population of autism spectrum disorder. Here’s an example. Start from the fact that the recorded rate of autism is now 1 in 68, according to a report released last week by the Centers for Disease Control and Prevention. If babies born in purple farmhouses have a rate of autism of 2 in 68, this doubling means that the purple farmhouse carries a risk ratio of 2. However, correlation is not causation, and there is no need to repaint that farmhouse just yet. © 2014 The New York Times Company
Link ID: 19429 - Posted: 03.31.2014
By SABRINA TAVERNISE In 1972, researchers in North Carolina started following two groups of babies from poor families. In the first group, the children were given full-time day care up to age 5 that included most of their daily meals, talking, games and other stimulating activities. The other group, aside from baby formula, got nothing. The scientists were testing whether the special treatment would lead to better cognitive abilities in the long run. Forty-two years later, the researchers found something that they had not expected to see: The group that got care was far healthier, with sharply lower rates of high blood pressure and obesity, and higher levels of so-called good cholesterol. The study, which was published in the journal Science on Thursday, is part of a growing body of scientific evidence that hardship in early childhood has lifelong health implications. But it goes further than outlining the problem, offering evidence that a particular policy might prevent it. “This tells us that adversity matters and it does affect adult health,” said James Heckman, a professor of economics at the University of Chicago who led the data analysis. “But it also shows us that we can do something about it, that poverty is not just a hopeless condition.” The findings come amid a political push by the Obama administration for government-funded preschool for 4-year-olds. But a growing number of experts, Professor Heckman among them, say they believe that more effective public programs would start far earlier — in infancy, for example, because that is when many of the skills needed to take control of one’s life and become a successful adult are acquired. © 2014 The New York Times Company
by Laura Sanders Ever-increasing numbers of autism diagnoses have parents worried about a skyrocketing epidemic, and this week’s news may only drive alarm higher. Perhaps it shouldn’t. In 2010, 1 in 68 (or 14.7 per 1,000) 8-year-olds had an autism spectrum disorder, the Centers for Disease Control and Prevention now estimates. That number is a substantial increase from 2008, which had an estimate of 1 in 88 (or 11.3 per 1,000). But the numbers might not reflect a spike in actual cases. Instead, the rise might be driven, at least in part, by an increase in diagnoses. The estimates are drawn from a collection of organizations that provide services to children with autism, including doctors, schools and social service agencies. As awareness builds and more people look for signs of autism, these numbers will keep going up. Regional spottiness suggests that better autism detection is feeding the increase. The autism rate in Alabama is just one in 175, while the rate in New Jersey is one in 45, the CDC reports. It would be surprising, and scientifically really important, if children in Alabama were truly much more protected from the disorder. Instead, differences in diagnosis rates are probably at play. If these alarmingly high numbers are driven by professionals and parents better spotting autism, that’s nothing to be alarmed at. On the contrary: This is good news. The earlier therapies begin, the better kids with autism do. That’s the idea behind CDC’s “Learn the Signs: Act Early” program to educate people about signs that something might be amiss with a child. So our best move is to find the kids who need help, and find them when they’re young. Most kids, including the ones in the new CDC survey, aren’t diagnosed with autism until about age 4 1/2. But whatever goes wrong happens long before then. © Society for Science & the Public 2000 - 2013.
Link ID: 19424 - Posted: 03.29.2014
Ewen Callaway An equine oddity with the head of a zebra and the rump of a donkey, the last quagga (Equus quagga quagga) died in 1883. A century later, researchers published1 around 200 nucleotides sequenced from a 140-year-old piece of quagga muscle. Those scraps of DNA — the first genetic secrets pulled from a long-dead organism — revealed that the quagga was distinct from the mountain zebra (Equus zebra). More significantly, the research showed that from then on, examining fossils would no longer be the only way to probe extinct life. “If the long-term survival of DNA proves to be a general phenomenon,” geneticists Russell Higuchi and Allan Wilson of the University of California, Berkeley, and their colleagues noted in their quagga paper1, “several fields including palaeontology, evolutionary biology, archaeology and forensic science may benefit.” At first, progress was fitful. Concerns over the authenticity of ancient-DNA research fuelled schisms in the field and deep scepticism outside it. But this has faded, thanks to laboratory rigour that borders on paranoia and sequencing techniques that help researchers to identify and exclude contaminating modern DNA. These advances have fostered an ancient-genomics boom. In the past year, researchers have unveiled the two oldest genomes on record: those of a horse that had been buried in Canadian permafrost for around 700,000 years2, and of a roughly 400,000-year-old human relative from a Spanish cavern3. A Neanderthal sequence every bit as complete and accurate as a contemporary human genome has been released4, as has the genome of a Siberian child connecting Native Americans to Europeans5. © 2014 Nature Publishing Group
By Greg Miller Nobody knows what causes autism, a condition that varies so widely in severity that some people on the spectrum achieve enviable fame and success while others require lifelong assistance due to severe problems with communication, cognition, and behavior. Scientists have found countless clues, but so far they don’t quite add up. The genetics is complicated. The neuroscience is conflicted. Now, a new study adds an intriguing, unexpected, and sure-to-be controversial finding to the mix: It suggests the brains of children with autism contain small patches where the normally ordered arrangement of neurons in the cerebral cortex is disrupted. “We’ve found locations where there appears to be a failure of normal development,” said Eric Courchesne, a neuroscientist at the University of California, San Diego and an author of the study, which appears today in the New England Journal of Medicine. “It’s been really difficult to identify a lesion or anything in the brain that’s specific and diagnostic of autism,” said Thomas Insel, director of the National Institute of Mental Health, one of several agencies that funded the project. The new study is notable because it applies sophisticated molecular labeling methods to postmortem tissue from people with autism who died as children, which is incredibly hard to come by, Insel says. “If it’s real, if it’s replicated and it’s a consistent finding, it’s more evidence that autism starts prenatally and only manifests itself when kids start to have trouble with language or social behavior around age two or three,” Insel said. “These kinds of changes in cellular architecture would happen during brain development, probably around the first part of the second trimester.” © 2014 Condé Nast