Chapter 7. Life-Span Development of the Brain and Behavior

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By Elizabeth Anne Brown Forget the soul — it turns out the eyes may be the best window to the brain. Changes to the retina may foreshadow Alzheimer’s and Parkinson’s diseases, and researchers say a picture of your eye could assess your future risk of neurodegenerative disease. Pinched off from the brain during embryonic development, the retina contains layers of neurons that seem to experience neurodegenerative disease along with their cousins inside the skull. The key difference is that these retinal neurons, right against the jellylike vitreous of the eyeball, live and die where scientists can see them. Early detection “is sort of the holy grail,” said Ron Petersen, director of Mayo Clinic’s Alzheimer’s Disease Research Center and the Mayo Clinic Study of Aging. By the time a patient complains of memory problems or tremors, the machinery of neurodegenerative disease has been at work probably for years or decades. Experts liken it to a cancer that only manifests symptoms at Stage 3 or 4. When patients begin to feel neurodegenerative disease’s impact on their daily life, it’s almost too late for treatment. Catching the warning signs of neurodegenerative disease earlier could give patients more time to plan for the future — whether that’s making caregiving arrangements, spending more time with family or writing the Great American novel. In the longer term, researchers hope the ability to notice brain changes before symptoms begin could eventually lead to early treatments more successful at slowing or stopping the progress of Parkinson’s and Alzheimer’s, since no such treatment is currently available. The hope is that “the sooner we intervene, the better we will be” at preventing cognitive impairment, Petersen said © 1996-2021 The Washington Post

Keyword: Alzheimers; Parkinsons
Link ID: 27713 - Posted: 02.28.2021

by Charles Q. Choi Blood levels of proteins associated with the autism-linked gene PTEN could influence the course of the condition, according to a new study. Tests measuring these molecules could also help clinicians diagnose autism and other neurological conditions, and chart their trajectories, the researchers say. “We might be able to make useful clinical predictions about outcomes that can help to tailor interventions earlier and to help patients and families plan for what is needed,” says lead investigator Thomas Frazier, professor of psychology at John Carroll University in University Heights, Ohio. The PTEN gene encodes a protein that suppresses tumors and also influences the connections between neurons. Mutations in PTEN are linked not only to benign tumors and several types of cancer, but also to autism and macrocephaly, or an unusually large head. Much remains unknown, however, about why PTEN mutations can affect people with and without autism differently. For example, PTEN mutations are often associated with impaired mental function in autistic people but not as often in non-autistic people, whose traits can vary widely. In the new study, Frazier and his colleagues examined how the mutations affect blood levels of not just PTEN protein, but also the proteins it interacts with. Molecular links: The team assessed the blood levels of various proteins — as well as intelligence quotient (IQ) and other factors related to mental function — in 25 autistic and 16 non-autistic participants with PTEN mutations and macrocephaly, all about 9 years old on average. The researchers also examined 20 participants, about 14 years old on average, with autism, macrocephaly and no PTEN mutations. © 2021 Simons Foundation

Keyword: Autism; Genes & Behavior
Link ID: 27711 - Posted: 02.28.2021

By Kelly Servick Put human stem cells in a lab dish with the right nutrients, and they’ll do their best to form a little brain. They’ll fail, but you’ll get an organoid: a semiorganized clump of cells. Organoids have become a powerful tool for studying brain development and disease, but researchers assumed these microscopic blobs only mirror a brain’s prenatal development—its earliest and simplest stages. A study today reveals that with enough time, organoid cells can take on some of the genetic signatures that brain cells display after birth, potentially expanding the range of disorders and developmental stages they can recreate. “Things that, before I saw this paper, I would have said you can’t do with organoids … actually, maybe you can,” says Madeline Lancaster, a developmental geneticist at the Medical Research Council’s Laboratory of Molecular Biology. For example, Lancaster wasn’t optimistic about using organoids to study schizophrenia, which is suspected to emerge in the brain after birth, once neural communication becomes more complex. But she now wonders whether cells from a person with this disorder—once “reprogrammed” to a primitive, stem cell state and coaxed to mature within a brain organoid—could reveal important cellular differences underlying the condition. Stanford University neurobiologist Sergiu Pașca has been making brain organoids for about 10 years, and his team has learned that some of these tissue blobs can thrive in a dish for years. In the new study, they teamed up with neurogeneticist Daniel Geschwind and colleagues at the University of California, Los Angeles (UCLA), to analyze how the blobs changed over their life spans. © 2021 American Association for the Advancement of Science.

Keyword: Development of the Brain
Link ID: 27705 - Posted: 02.23.2021

By Cathleen O’Grady As Samuel West combed through a paper that found a link between watching cartoon violence and aggression in children, he noticed something odd about the study participants. There were more than 3000—an unusually large number—and they were all 10 years old. “It was just too perfect,” says West, a Ph.D. student in social psychology at Virginia Commonwealth University. Yet West added the 2019 study, published in Aggressive Behavior and led by psychologist Qian Zhang of Southwest University of Chongqing, to his meta-analysis after a reviewer asked him to cast a wider net. West didn’t feel his vague misgivings could justify excluding it from the study pool. But after Aggressive Behavior published West’s meta-analysis last year, he was startled to find that the journal was investigating Zhang’s paper while his own was under review. It is just one of many papers of Zhang’s that have recently been called into question, casting a shadow on research into the controversial question of whether violent entertainment fosters violent behavior. Zhang denies any wrongdoing, but two papers have been retracted. Others live on in journals and meta-analyses—a “major problem” for a field with conflicting results and entrenched camps, says Amy Orben, a cognitive scientist at the University of Cambridge who studies media and behavior. And not just for the ivory tower, she says: The research shapes media warning labels and decisions by parents and health professionals. © 2021 American Association for the Advancement of Science.

Keyword: Aggression; Development of the Brain
Link ID: 27695 - Posted: 02.17.2021

In a study led by National Institutes of Health researchers, scientists found that five genes may play a critical role in determining whether a person will suffer from Lewy body dementia, a devastating disorder that riddles the brain with clumps of abnormal protein deposits called Lewy bodies. Lewy bodies are also a hallmark of Parkinson’s disease. The results, published in Nature Genetics, not only supported the disease’s ties to Parkinson’s disease but also suggested that people who have Lewy body dementia may share similar genetic profiles to those who have Alzheimer’s disease. “Lewy body dementia is a devastating brain disorder for which we have no effective treatments. Patients often appear to suffer the worst of both Alzheimer’s and Parkinson’s diseases. Our results support the idea that this may be because Lewy body dementia is caused by a spectrum of problems that can be seen in both disorders,” said Sonja Scholz, M.D., Ph.D., investigator at the NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and the senior author of the study. “We hope that these results will act as a blueprint for understanding the disease and developing new treatments.” The study was led by Dr. Scholz’s team and researchers in the lab of Bryan J. Traynor, M.D., Ph.D., senior investigator at the NIH’s National Institute on Aging (NIA). Lewy body dementia usually affects people over 65 years old. Early signs of the disease include hallucinations, mood swings, and problems with thinking, movements, and sleep. Patients who initially have cognitive and behavioral problems are usually diagnosed as having dementia with Lewy bodies, but are sometimes mistakenly diagnosed with Alzheimer’s disease. Alternatively, many patients, that are initially diagnosed with Parkinson’s disease, may eventually have difficulties with thinking and mood caused by Lewy body dementia. In both cases, as the disease worsens, patients become severely disabled and may die within eight years of diagnosis.

Keyword: Alzheimers; Parkinsons
Link ID: 27694 - Posted: 02.17.2021

By Sabrina Imbler Over the course of her 32 years, Cheyenne the red-bellied lemur has had many soul mates. Her first was a mate in the traditional sense, a male red-bellied lemur who lived monogamously with Cheyenne for many years at the Duke Lemur Center in Durham, N.C. When he died, the elderly Cheyenne moved on to Geb, a geriatric crowned lemur; his young mate, Aria, had recently left him for a an even younger lemur. Cheyenne and Geb shared several years of peaceful, platonic companionship until Geb died in 2018 at the venerable age of 26. Cheyenne now lives with Chloris, a 32-year-old ring-tailed lemur who has full cataracts in one eye and arthritis in her tail. The two spend their days as many couples do, elderly or not: sleeping, hanging out, grooming each other and cuddling. “Right now Chloris and Cheyenne are snuggled up like a yin-yang symbol,” Britt Keith, the head lemur keeper, said on a call from the D wing of the center, which houses many of the center’s geriatric lemurs. The goal of Cheyenne and Chloris’s pairing is not for them to breed; the lemurs are both post-reproductive females. Rather, it is companionship, the comfort of having someone to spend your twilight days with and a soft body to snuggle up to at night — and, in Cheyenne and Chloris’s case, also during the day. “They sleep a lot,” Ms. Keith said. In the wild, lemurs generally do not want for company. Red-bellied lemurs form extremely tight, long-term bonds with their mates, and pairs rarely stray more than than three dozen feet apart, according to Stacey Tecot, a lemur primatologist at the University of Arizona. Crowned lemurs like Geb and ring-tailed lemurs like Chloris are not monogamous but have rich social lives, said Nicholas Grebe, a postdoctoral researcher who studies lemur behavior at Duke University and who knows Cheyenne and Chloris. © 2021 The New York Times Company

Keyword: Emotions; Pain & Touch
Link ID: 27692 - Posted: 02.15.2021

By Leslie Nemo Ironically, this tangle of brain cells is helping scientists tease apart a larger problem: how to help people with Alzheimer’s disease. Matheus Victor, a researcher at the Massachusetts Institute of Technology, photographed these neurons after coaxing them to life in a petri dish in the hope that the rudimentary brain tissue will reveal why a new therapy might alleviate Alzheimer’s symptoms. In humans and mice, a healthy memory is associated with a high level of synced neurons that turn on and off simultaneously. Those with neurological conditions such as Alzheimer’s and Parkinson’s disease often have fewer brain cells blinking unanimously. A couple of years ago Victor’s lab leader Li-Huei Tsai and her team at M.I.T. found that when they surrounded mice genetically predisposed to Alzheimer’s with sound pulses beating 40 times a second, the rodents performed better on memory-related tasks. The animals also lost some amyloid plaques, protein deposits in the brain that are characteristic of the disease. The researchers had previously performed a similar study with light flickering at the same rate, and the mice were found to experience additional improvements when the sound and light pulses were combined. Astoundingly, the mouse neurons synced up to the 40-beats-per-second rhythm of the audio pulses, though the mechanism behind this result and the reason the shift improves symptoms remain a mystery. To help solve it, the researchers want to watch how brain tissue responds to the stimulants at the cellular level. The goal is to one day understand how this exposure treatment might work for people, so the team is growing human brain cells in the lab and engineering them to respond to sound and light without eyes and ears. “We are trying to mimic the sensory stimulation in mice but missing a lot of the hardware that makes it possible. So this is a bit of a hack,” Victor says. © 2021 Scientific American

Keyword: Alzheimers; Brain imaging
Link ID: 27690 - Posted: 02.15.2021

Ariana Remmel Researchers have created tiny, brain-like ‘organoids’ that contain a gene variant harboured by two extinct human relatives, Neanderthals and Denisovans. The tissues, made by engineering human stem cells, are far from being true representations of these species’ brains — but they show distinct differences from human organoids, including size, shape and texture. The findings, published1 in Science on 11 February, could help scientists to understand the genetic pathways that allowed human brains to evolve. Can lab-grown brains become conscious? “It’s an extraordinary paper with some extraordinary claims,” says Gray Camp, a developmental biologist at the University of Basel in Switzerland, whose lab last year reported2 growing brain organoids that contained a gene common to Neanderthals and humans. The latest work takes the research further by looking at gene variants that humans lost in evolution. But Camp remains sceptical about the implications of the results, and says the work opens more questions that will require investigation. Humans are more closely related to Neanderthals and Denisovans than to any living primate, and some 40% of the Neanderthal genome can still be found spread throughout living humans. But researchers have limited means to study these ancient species’ brains — soft tissue is not well preserved, and most studies rely on inspecting the size and shape of fossilized skulls. Knowing how the species’ genes differ from humans’ is important because it helps researchers to understand what makes humans unique — especially in our brains. © 2021 Springer Nature Limited

Keyword: Development of the Brain; Evolution
Link ID: 27687 - Posted: 02.13.2021

By Jamie Talan When Fred “Rusty” Gage began his career in neuroscience more than four decades ago, the general thinking was that adult human brain cells just don’t reproduce and that their numbers are fixed. You lose them, they are gone forever. But Gage’s studies on adult human brain cells in the 1990s surprised everyone, including himself, when he and his colleagues found that exercise — such as running — and enriched, complex and variable environments can give rise to new populations of cells that serve the brain well. He has been a serious runner most of his life, so this was good news on every level. Now 70 and president of the Salk Institute for Biological Sciences in the La Jolla neighborhood in San Diego, Gage is still trying to figure out how adults can continue to make new brain cells and keep their brains healthier and resistant to disease. As head of the institute, he also supports his colleagues’ broader work in novel approaches to treating cancer, how the properties in the food we eat shape our brains, the effect of isolation on brain functioning, and plant biology and climate change. The Washington Post spoke with Gage on a video conference call recently to talk about growing up overseas, including in Frankfurt, Germany, and Rome; honing his interests in various labs; and giving mice a running wheel in their cages that sparked a key finding in understanding neuron growth in the brain © 1996-2021 The Washington Post

Keyword: Neurogenesis
Link ID: 27683 - Posted: 02.13.2021

By Gina Kolata Is it possible to predict who will develop Alzheimer’s disease simply by looking at writing patterns years before there are symptoms? According to a new study by IBM researchers, the answer is yes. And, they and others say that Alzheimer’s is just the beginning. People with a wide variety of neurological illnesses have distinctive language patterns that, investigators suspect, may serve as early warning signs of their diseases. For the Alzheimer’s study, the researchers looked at a group of 80 men and women in their 80s — half had Alzheimer’s and the others did not. But, seven and a half years earlier, all had been cognitively normal. The men and women were participants in the Framingham Heart Study, a long-running federal research effort that requires regular physical and cognitive tests. As part of it, they took a writing test before any of them had developed Alzheimer’s that asks subjects to describe a drawing of a boy standing on an unsteady stool and reaching for a cookie jar on a high shelf while a woman, her back to him, is oblivious to an overflowing sink. The researchers examined the subjects’ word usage with an artificial intelligence program that looked for subtle differences in language. It identified one group of subjects who were more repetitive in their word usage at that earlier time when all of them were cognitively normal. These subjects also made errors, such as spelling words wrongly or inappropriately capitalizing them, and they used telegraphic language, meaning language that has a simple grammatical structure and is missing subjects and words like “the,” “is” and “are.” The members of that group turned out to be the people who developed Alzheimer’s disease. The A.I. program predicted, with 75 percent accuracy, who would get Alzheimer’s disease, according to results published recently in The Lancet journal EClinicalMedicine. © 2021 The New York Times Company

Keyword: Alzheimers; Language
Link ID: 27677 - Posted: 02.03.2021

by Laura Dattaro Genetic variants that contribute to autism may also be involved in attention deficit hyperactivity disorder (ADHD) and Tourette syndrome, according to a new study. In 2019, researchers from the Psychiatric Genomics Consortium linked variants associated with autism to seven neuropsychiatric conditions, including anorexia, bipolar disorder and schizophrenia. Despite the genetic overlap, though, some of those conditions, such as anorexia and Tourette syndrome, don’t tend to co-occur. The new work homes in on Tourette syndrome — a motor and tic condition — and three diagnoses that often present with it: More than half of people with Tourette also have obsessive-compulsive disorder (OCD) or ADHD, and up to 20 percent have autism. Because all four conditions can involve impulsive and compulsive behaviors, some scientists have proposed that they exist along a spectrum, with ADHD on one end, OCD on the other, and autism and Tourette in the middle. The goal of looking at all the conditions on this spectrum together is to elucidate the genetics underlying their traits, says lead investigator Peristera Paschou, associate professor of biological sciences at Purdue University in West Lafayette, Indiana. “There is a lot of value in zooming out and trying to think across what would be strict diagnostic categories,” Paschou says. Gene associations: The researchers analyzed data from previous studies that involved a total of 93,294 people with at least one of the four conditions, along with 51,311 controls. They looked at common variants — single-letter changes to DNA that appear in more than 1 percent of the population — shared by any two of the four conditions. © 2021 Simons Foundation

Keyword: Autism; Tourettes
Link ID: 27676 - Posted: 02.03.2021

by Peter Hess Mice missing a copy of the autism-linked gene MAGEL2 have trouble discerning between a familiar mouse and an unfamiliar one, but treating them with the social hormone vasopressin reverses this deficit, according to a new study. Mutations in or deletions of MAGEL2 are linked to autism and several related conditions, including Prader-Willi syndrome, which is characterized by intellectual disability, poor muscle tone, difficulty feeding and problems with social interactions. The new findings suggest that these social issues in people stem from impairments in vasopressin’s function in a brain region called the lateral septum, which relays signals between the hippocampus and the ventral tegmental area. They also hint that vasopressin treatment could remedy those issues, says Elizabeth Hammock, assistant professor of psychology and neuroscience at Florida State University in Tallahassee, who was not involved with the study. A 2020 study showed that low levels of vasopressin in cerebrospinal fluid can flag many infants who are later diagnosed with autism. But clinical trials have shown that either providing vasopressin or blocking its effects can improve social communication in autistic children. Because of these seemingly contradictory results, “a better understanding of how alterations in the vasopressinergic system leads to social deficits and how vasopressin administration could resolve some of these problems was needed,” says co-lead researcher Freddy Jeanneteau, professor of neuroscience at Montpellier University in Montpellier, France. © 2021 Simons Foundation

Keyword: Autism; Hormones & Behavior
Link ID: 27665 - Posted: 01.27.2021

By Clay Risen In 1978, James R. Flynn, a political philosopher at the University of Otago, in New Zealand, was writing a book about what constituted a “humane” society. He considered “inhumane” societies as well — dictatorships, apartheid states — and, in his reading, came across the work of Arthur R. Jensen, a psychologist at the University of California, Berkeley. Dr. Jensen was best known for an article he published in 1969 claiming that the differences between Black and white Americans on I.Q. tests resulted from genetic differences between the races — and that programs that tried to improve Black educational outcomes, like Head Start, were bound to fail. Dr. Flynn, a committed leftist who had once been a civil rights organizer in Kentucky, felt instinctively that Dr. Jensen was wrong, and he set out to prove it. In 1980 he published a thorough, devastating critique of Dr. Jensen’s work — showing, for example, that many groups of whites scored as low on I.Q. tests as Black Americans. But he didn’t stop there. Like most researchers in his field, Dr. Jensen had assumed that intelligence was constant across generations, pointing to the relative stability of I.Q. tests over time as evidence. But Dr. Flynn noticed something that no one else had: Those tests were recalibrated every decade or so. When he looked at the raw, uncalibrated data over nearly 100 years, he found that I.Q. scores had gone up, dramatically. “If you scored people 100 years ago against our norms, they would score a 70,” or borderline mentally disabled, he said later. “If you scored us against their norms, we would score 130” — borderline gifted. Just as groundbreaking was his explanation for why. The rise was too fast to be genetic, nor could it be that our recent ancestors were less intelligent than we are. Rather, he argued, the last century has seen a revolution in abstract thinking, what he called “scientific spectacles,” brought on by the demands of a technologically robust industrial society. This new order, he maintained, required greater educational attainment and an ability to think in terms of symbols, analogies and complex logic — exactly what many I.Q. tests measure. © 2021 The New York Times Company

Keyword: Learning & Memory; Development of the Brain
Link ID: 27664 - Posted: 01.27.2021

by Angie Voyles Askham Mutations that affect a histone called H3.3 can lead to a neurodegenerative condition marked by developmental delay and congenital anomalies, according to a new study. Histones act as spools for DNA, making it possible to pack the strands of genetic material tightly within the nucleus. They also serve as gatekeepers for protein production, physically blocking proteins from interacting with genes, or allowing them access to turn genes on and off. Autism has been tied to mutations in proteins that modify histones and disrupt this gatekeeping process. The new work is among the first to link atypical neurodevelopment and degeneration to mutations that affect a histone itself. It focuses on 46 people with a mutation in either of two genes that code for H3.3. All have a diagnosis of developmental delay. Many also have other medical conditions, such as seizures, heart defects and atypical development of the head and face. “We see this [result] as a Rosetta Stone,” says lead researcher Elizabeth Bhoj, assistant professor of pediatrics and human genetics at the University of Pennsylvania. In addition to providing information about this particular cohort, the findings could help explain the role that histones play in neurodevelopmental conditions in general, she says. Earlier studies have associated H3.3 with cancer, but none of the participants in the new study have tumors. About 21 percent, however, show signs of neurodegeneration, and 26 percent have shrinkage in the cerebral cortex, the brain’s outer layer, suggesting the condition may be progressive. “It’s an impressive collection of novel mutations that seem to be converging on a set of clinical features,” says James Noonan, associate professor of genetics and neuroscience at Yale School of Medicine, who was not involved in the study. © 2021 Simons Foundation

Keyword: Autism; Epigenetics
Link ID: 27660 - Posted: 01.23.2021

By Gina Kolata In a small clinical trial, an experimental Alzheimer’s drug slowed the rate at which patients lost the ability to think and care for themselves, the drug maker Eli Lilly announced on Monday. The findings have not been published in any form, and not been widely reviewed by other researchers. If accurate, it is the first time a positive result has been found in a so-called Phase 2 study, said Dr. Lon S. Schneider, professor of psychiatry, neurology and gerontology at the University of Southern California. Other experimental drugs against Alzheimer’s were never tested in Phase 2 trials, moving straight to larger Phase 3 trials, or failed to produce positive results. The Phase 3 studies themselves have repeatedly had disappointing results. The two-year study involved 272 patients with brain scans indicative of Alzheimer’s disease. Their symptoms ranged from mild to moderate. The drug, donanemab, a monoclonal antibody, binds to a small part of the hard plaques in the brain made of a protein, amyloid, that are hallmarks of Alzheimer’s disease. Patients received the drug by infusion every four weeks. Participants who received the drug had a 32 percent deceleration in the rate of decline, compared with those who got a placebo. In six to 12 months, plaques were gone and stayed gone, said Dr. Daniel Skovronsky, the company’s chief scientific officer. At that point, patients stopped getting the drug — they got a placebo instead — for the duration of the study. The small study needs to be replicated, noted Dr. Michael Weiner, a leading Alzheimer’s researcher at the University of California, San Francisco. Still, “this is big news,” he said. “This holds out hope for patients and their families.” Eli Lilly did not release the sort of pertinent data needed for a thorough analysis, Dr. Schneider said. For example, the company provided only percentages describing declines in function among the participants, not the actual numbers. © 2021 The New York Times Company

Keyword: Alzheimers
Link ID: 27648 - Posted: 01.15.2021

by Sarah DeWeerdt Children with autism may have a subtly different set of bacteria in their gut than their non-autistic siblings, according to unpublished data presented virtually on Tuesday at the 2021 Society for Neuroscience Global Connectome. The prospect that manipulating the microbiome could ease gastrointestinal problems and other autism traits has tantalized many families of autistic children. But studies of the gut microbiome in people with autism are scarce and have shown conflicting results, and mouse studies can be difficult to interpret. For the new work, researchers recruited 111 families that each have two children — one with autism and one without — born within two years of each other and aged 2 to 7 years old. “We tried to be as careful as possible by using a control cohort that were siblings,” says study leader Maude David, assistant professor of microbiology at Oregon State University in Corvallis. This study design helped control for variables such as household environment, pets and other factors that can shape the microbiome, she says. The researchers collected stool samples from the children at three time points, two weeks apart. The repeated sampling reduced the likelihood that short-term shifts in the children’s gut microbiome — due to transient environmental influences, such as day-to-day dietary changes — would skew the results. © 2021 Simons Foundation

Keyword: Autism
Link ID: 27644 - Posted: 01.15.2021

Our staff took a look back at the papers we wrote about in 2020 that most shaped our understanding of autism and how to diagnose or treat it. Despite the chaos of this year, there were many to consider. But we reviewed them all, asked some researchers for input and winnowed the list down to 10. Some of our selections highlight new insights into factors that influence autism traits, including fever, mitochondria and exons — the protein-coding parts of genes. Others expand our understanding of the genes and genetic regions linked to autism, as well as their roles in related conditions. Two new gene therapies for autism-related syndromes also caught our eye. And we single out a study of the sperm from men who have children on the spectrum, and a look at what happens to the toddlers who screen positive for autism. Here are our picks for the past year’s most notable papers, in reverse chronological order. DNA helix1. Mutations in the same exon linked to similar autism traits People with autism who carry DNA variants in the same exon, or protein-coding region of a gene, have more similar cognitive abilities and behaviors than those who carry mutations in different regions of the same gene, this study found. A separate study detailed how one particular exon contributes to social behavior and cognitive abilities in mice; a third paper described a new tool that helps researchers determine how mutations in an exon affect the number of protein isoforms a gene can express. © 2021 Simons Foundation

Keyword: Autism; Genes & Behavior
Link ID: 27641 - Posted: 01.09.2021

by Sarah DeWeerdt A drug that has been tested in clinical trials as a treatment for depression restores social memory in a mouse model of 22q11.2 deletion syndrome, according to a new study. The findings hint that the drug might also be useful to treat social cognitive difficulties in people with conditions such as autism, experts say. People who are missing one copy of a chromosomal region known as 22q11.2 have heart abnormalities, distinctive facial features and an increased risk of schizophrenia and other psychiatric conditions. About 16 percent have autism. People with the syndrome also have a smaller-than-average hippocampus, a structure that functions as the brain’s memory hub. The findings extend what researchers know about the role of the hippocampus in social behavior by suggesting that a small region of the hippocampus known as CA2 springs to life when an animal encounters an individual it hasn’t met before. A strength of the study is that it describes the basic biology of a brain circuit, shows how that circuit is disrupted in a mouse model and identifies a therapeutic target to reverse those disruptions, says Anthony LaMantia, professor of developmental disorders and genetics at Virginia Polytechnic Institute and State University in Blacksburg, who was not involved in the work. “This is one of the best papers sort of going from soup to nuts that has come out.” Previous studies showed that CA2 is crucial for social memory, the ability to recognize and remember others. “But we really didn’t have a good handle on what type of information CA2 was providing to the rest of the brain,” says study leader Steven Siegelbaum, professor of neuroscience and pharmacology at Columbia University. © 2020 Simons Foundation

Keyword: Autism; Genes & Behavior
Link ID: 27635 - Posted: 12.22.2020

by Peter Hess Two types of neurons process social information, a new mouse study suggests, but only one is disrupted in mice missing the autism-linked gene FMR1. The neurons reside in a brain region called the hypothalamus, and both send signals via the hormone oxytocin. The deletion of FMR1, however, affects these cells differently: The loss of FMR1 in the smaller, ‘parvocellular’ neurons diminishes the mice’s interest in social interactions — but only those involving peers, the new work shows. The gene’s loss from the larger, ‘magnocellular’ neurons, by contrast, does not disrupt the animals’ interactions with either peers or parents. “There are a lot of different types of social behaviors, and not all of them are impaired in autism,” says lead investigator Gül Dölen, assistant professor of neuroscience at Johns Hopkins University in Baltimore, Maryland. Whereas peer-to-peer social interactions are troublesome for many autistic people, other social interactions — such as parental connections — are on par with those seen in non-autistic people, she says. This new understanding of the different neurons’ functions could help explain why clinical trials of oxytocin for treating autism traits have shown mixed results. It could also help scientists develop more effective treatments, experts say. “There are these two different kinds of neurons that we’ve known about for a really long time, and each of their contributions to social behavior has never really been dissected out,” says Larry Young, chief of behavioral neuroscience and psychiatric disorders at Emory University in Atlanta, Georgia, who was not involved with the study. “It’s really important for the future of drug development.” © 2020 Simons Foundation

Keyword: Autism; Hormones & Behavior
Link ID: 27632 - Posted: 12.19.2020

By Cara Giaimo The rooms that make up the Bloomington Drosophila Stock Center at Indiana University are lined wall to wall with identical shelves. Each shelf is filled with uniform racks, and each rack with indistinguishable glass vials. The tens of thousands of fruit fly types within the vials, though, are each magnificently different. Some have eyes that fluoresce pink. Some jump when you shine a red light on them. Some have short bodies and iridescent curly wings, and look “like little ballerinas,” said Carol Sylvester, who helps care for them. Each variety doubles as a unique research tool, and it has taken decades to introduce the traits that make them useful. If left unattended, the flies would die in a matter of weeks, marooning entire scientific disciplines. Throughout the Covid-19 pandemic, workers across industries have held the world together, taking on great personal risk to care for sick patients, maintain supply chains and keep people fed. But other essential jobs are less well-known. At the Stock Center dozens of employees have come to work each day, through a lockdown and afterward, to minister to the flies that underpin scientific research. Tiny Bug, Huge Impact To most casual observers, fruit flies are little dots with wings that hang out near old bananas. But over the course of the last century, researchers have turned the insect — known to science as Drosophila melanogaster — into a sort of genetic switchboard. Biologists regularly develop new “strains” of flies, in which particular genes are turned on or off. Studying these slight mutants can reveal how those genes function — including in humans, because we share over half of our genes with Drosophila. For instance, researchers discovered what is now called the hippo gene — which helps regulate organ size in both fruit flies and vertebrates — after flies with a defect in it grew up to be unusually large and wrinkly. Further work with the gene has indicated that such defects may contribute to the unchecked cell growth that leads to cancer in people. © 2020 The New York Times Company

Keyword: Genes & Behavior; Development of the Brain
Link ID: 27624 - Posted: 12.15.2020