By Giorgia Guglielmi A population of neurons in the brain stem, the stalk-like structure that connects the bulk of the brain to the spinal cord, acts as the master dial for the immune system.Credit: Voisin/Phanie/Science Photo Library Scientists have long known that the brain plays a part in the immune system — but how it does so has been a mystery. Now, scientists have identified cells in the brainstem that sense immune cues from the periphery of the body and act as master regulators of the body’s inflammatory response. The results, published on 1 May in Nature1, suggest that the brain maintains a delicate balance between the molecular signals that promote inflammation and those that dampen it — a finding that could lead to treatments for autoimmune diseases and other conditions caused by an excessive immune response. The discovery is akin to a black-swan event — unexpected but making perfect sense once revealed, says Ruslan Medzhitov, an immunologist at Yale University in New Haven, Connecticut. Scientists have known that the brainstem has many functions, such as controlling basic processes such as breathing. However, he adds, the study “shows that there is whole layer of biology that we haven’t even anticipated”. The brain is watching After sensing an intruder, the immune system unleashes a flood of immune cells and compounds that promote inflammation. This inflammatory response must be controlled with exquisite precision: if it’s too weak, the body is at greater risk of becoming infected; if it’s too strong, it can damage the body’s own tissues and organs. Previous work has shown that the vagus nerve, a large network of nerve fibres that links the body with the brain, influences immune responses. However, the specific brain neurons that are activated by immune stimuli remained elusive, says Hao Jin, a neuroimmunologist at the US National Institute of Allergy and Infectious Diseases in Bethesda, Maryland, who led the work. © 2024 Springer Nature Limited

Keyword: Neuroimmunology
Link ID: 29286 - Posted: 05.02.2024

By Dan Falk Daniel Dennett, who died in April at the age of 82, was a towering figure in the philosophy of mind. Known for his staunch physicalist stance, he argued that minds, like bodies, are the product of evolution. He believed that we are, in a sense, machines—but astoundingly complex ones, the result of millions of years of natural selection. Dennett wrote more than a dozen books, some of them aimed at a scholarly audience but many of them directed squarely at the inquisitive non-specialist—including bestsellers like Consciousness Explained, Breaking the Spell, and Darwin’s Dangerous Idea. Reading his works, one gets the impression of a mind jammed to the rafters with ideas. As Richard Dawkins put it in a blurb for Dennett’s last book, a memoir titled I’ve Been Thinking: “How unfair for one man to be blessed with such a torrent of stimulating thoughts.” Dennett spent decades puzzling over the existence of minds. How does non-thinking matter arrange itself into matter that can think, and even ponder its own existence? A long-time academic nemesis of Dennett’s, the philosopher David Chalmers, dubbed this the “Hard Problem” of consciousness. But Dennett felt this label needlessly turned a series of potentially-solvable problems into one giant unsolvable one: He was sure the so-called hard problem would evaporate once the various lesser (but still difficult) problems of understanding the brain’s mechanics were figured out. Because he viewed brains as miracle-free mechanisms, he saw no barrier to machine consciousness, at least in principle. Yet he had no fear of Terminator-style AI doomsday scenarios, either. (“The whole singularity stuff, that’s preposterous,” he once told an interviewer for The Guardian. “It distracts us from much more pressing problems.”) © 2024 NautilusNext Inc.,

Keyword: Consciousness; Attention
Link ID: 29285 - Posted: 05.02.2024

By J. David Creswell Let’s start thinking differently about exercise. Decades of exercise science research show that when people or animals are given a new exercise routine, they get healthier. But when thinking about the benefits of exercise, most people hold a strong body bias; they focus on how regular exercise builds more lean body mass, helps increase their strength and balance, or improves heart health. Exercise matters even more for our brains, it turns out, in ways that are often overlooked. Here’s how we know. Animal exercise studies typically run rats for weeks on running wheels. The animals gleefully run every night, sprinting several miles over the course of an evening. There are wonderful health benefits in these studies of voluntary running—improved muscle tone and cardiovascular health, and many brain benefits too. But in some studies, there’s an additional experimental condition where some rats exercise with one crucial difference: it’s no longer voluntary exercise. Instead of a freestanding running wheel, rats run on a mechanized wheel that spins, forcing the animals to cover the same distance as the voluntary runners. What happens? When the rats are forced to exercise on a daily basis for several weeks, their bodies become more physically fit, but their brains suffer. Animals regularly forced to exercise have the equivalent of an anxiety disorder, behaving on new tasks in highly anxious and avoidant ways. These animals are more anxious not only compared to the voluntary runners, but also to animals that are not given an opportunity to exercise at all. Yes, forced exercise might be worse than no exercise at all. This work suggests something important about the health benefits of exercise: it is not just about making our muscles work, but what exercise does to our brains. When exercise gives us a sense of control, mastery and joy, our brains become less anxious. If we take that away, by forcing exercise, we can shift it from helpful to harmful. © 2024 SCIENTIFIC AMERICAN,

Keyword: Stress; Depression
Link ID: 29284 - Posted: 05.02.2024

By Eileen Sullivan, Glenn Thrush and Zolan Kanno-Youngs The Justice Department said on Tuesday that it had recommended easing restrictions on marijuana in what could amount to a major change in federal policy. Even though the move, which kicks off a lengthy rule-making process, does not end the criminalization of the drug, it is a significant shift in how the government views the safety and use of marijuana for medical purposes. It also reflects the Biden administration’s effort to liberalize marijuana policy in a way that puts it more in line with the public as increasingly more Americans favor legalizing the drug. The decision comes at an opportune time for President Biden, who is trailing the presumptive Republican nominee, former President Donald J. Trump, as they approach the November election, according to a recent CNN poll. It could also lead to the softening of other laws and regulations that account for the use or possession of cannabis, including sentencing guidelines, banking and access to public housing. People familiar with the recommendation, speaking on the condition of anonymity, said Attorney General Merrick B. Garland planned to tell the White House Office of Management and Budget that the government should change the drug’s categorization. After the office assesses the recommendation, it will still face a long road before taking effect, including being subject to public comment. The Associated Press earlier reported the Justice Department decision. For more than half a century, marijuana has been considered a Schedule I drug, classified on the same level as highly addictive substances like heroin that the Drug Enforcement Administration describes as having no currently accepted medical use. Moving marijuana to Schedule III, as the Department of Health and Human Services recommended in August, would put it alongside less addictive substances like Tylenol with codeine, ketamine and testosterone, meaning that it would be subject to fewer restrictions on production and research, and that eventually it could be prescribed by a doctor. © 2024 The New York Times Company

Keyword: Drug Abuse
Link ID: 29283 - Posted: 05.02.2024

By Sabrina Malhi The phrase “anger kills” might have a more literal meaning: New research suggests a possible reason frequent anger has been linked to an increased risk of cardiovascular disease. The study, published Wednesday in the Journal of the American Heart Association, emphasizes the potential health risks associated with intense anger and illuminates the influence of negative emotions on our overall well-being. Funded by the National Institutes of Health, the study involved 280 healthy adults who were randomly assigned to a different eight-minute task, each designed to elicit feelings of anger, anxiety, sadness or neutrality. Before and after these emotional tasks, researchers assessed the participants’ endothelial health. Endothelial cells, which line the insides of blood vessels, are essential for maintaining vessel integrity and are vital for proper circulation and cardiovascular health. The findings revealed that anger had a significant negative impact on endothelial function, limiting the blood vessels’ ability to dilate. The response was not as pronounced with anxiety or sadness. According to Daichi Shimbo, a cardiologist and professor of medicine at Columbia University Irving Medical Center and the lead study author, this research marks a step toward understanding how different negative emotions particularly affect physical health. “It's fascinating that anxiety and sadness did not have the same effect as anger, suggesting that the ways in which negative emotions contribute to heart disease differ,” Shimbo said.

Keyword: Emotions; Stress
Link ID: 29282 - Posted: 05.02.2024

In 2023, students protested against a new policy in Texas, where parents would be notified if their child asks to be identified as transgender.Credit: Brett Coomer/Houston Chronicle/Getty This week, Nature is launching a collection of opinion articles on sex and gender in research. Further articles will be published in the coming months. The series will highlight the necessity and challenges of studying a topic that is both hugely under-researched and, increasingly, the focus of arguments worldwide — many of which are neither healthy nor constructive. Some scientists have been warned off studying sex differences by colleagues. Others, who are already working on sex or gender-related topics, are hesitant to publish their views. Such a climate of fear and reticence serves no one. To find a way forward we need more knowledge, not less. Nearly 20 researchers from diverse fields, including neuroscience, psychology, immunology and cancer, have contributed to the series, which provides a snapshot of where scholars studying sex and gender are aligned — and where they are not. In time, we hope this collection will help to shape research, and provide a reference point for moderating often-intemperate debates. In practice, people use sex and gender to mean different things. But researchers studying animals typically use sex to refer to male and female individuals, as defined by various anatomical and other biological features. In studies involving humans, participants are generally asked to identify their own sex and/or gender category. Here, gender usually encompasses social and environmental factors, including gender roles, expectations and identity. © 2024 Springer Nature Limited

Keyword: Sexual Behavior
Link ID: 29281 - Posted: 05.02.2024

By Dana G. Smith When it comes to aging, we tend to assume that cognition gets worse as we get older. Our thoughts may slow down or become confused, or we may start to forget things, like the name of our high school English teacher or what we meant to buy at the grocery store. But that’s not the case for everyone. For a little over a decade, scientists have been studying a subset of people they call “super-agers.” These individuals are age 80 and up, but they have the memory ability of a person 20 to 30 years younger. Most research on aging and memory focuses on the other side of the equation — people who develop dementia in their later years. But, “if we’re constantly talking about what’s going wrong in aging, it’s not capturing the full spectrum of what’s happening in the older adult population,” said Emily Rogalski, a professor of neurology at the University of Chicago, who published one of the first studies on super-agers in 2012. A paper published Monday in the Journal of Neuroscience helps shed light on what’s so special about the brains of super-agers. The biggest takeaway, in combination with a companion study that came out last year on the same group of individuals, is that their brains have less atrophy than their peers’ do. The research was conducted on 119 octogenarians from Spain: 64 super-agers and 55 older adults with normal memory abilities for their age. The participants completed multiple tests assessing their memory, motor and verbal skills; underwent brain scans and blood draws; and answered questions about their lifestyle and behaviors. The scientists found that the super-agers had more volume in areas of the brain important for memory, most notably the hippocampus and entorhinal cortex. They also had better preserved connectivity between regions in the front of the brain that are involved in cognition. Both the super-agers and the control group showed minimal signs of Alzheimer’s disease in their brains. © 2024 The New York Times Company

Keyword: Learning & Memory; Development of the Brain
Link ID: 29280 - Posted: 04.30.2024

By Tim Vernimmen Most amphibians aren’t exactly doting parents — they just find a partner and release as many eggs or sperm as possible, in hopes that viable larvae will hatch from at least some fertilized eggs, and at least some of those larvae will survive to adulthood. Yet in as many as one in five amphibian species, one or both parents stick around to care for their offspring, using a staggering variety of strategies. The most well-known amphibian parents are the brightly colored poison frogs, a group of around 200 species that will repeatedly be leaping into view in this article. Yet their parenting skills may not be as exceptional as once thought, says biologist Jennifer Stynoski of the University of Costa Rica, who decided to study this group when she spotted them on a field trip as a student years ago. “I think they’ve just received a lot of attention because they’re so beautiful. They’re very cute to study.” So — what makes an exemplary amphibian parent? Much remains to be discovered, but some common principles have emerged. Stay away from the water Unlike reptiles and the birds that evolved from them, the ancestors of today’s amphibians never developed eggs with tough, watertight shells. This means their eggs need water to survive, as do the gilled larvae that usually come wriggling out. Yet the ponds in which many amphibians deposit their eggs are full of other animals, many eager to supplement their diet by slurping up a mouthful of eggs. “This must be one reason why so many species have evolved ways to lay their eggs away from the water,” says behavioral ecologist Eva Ringler of the University of Bern in Switzerland. © 2024 Annual Reviews

Keyword: Sexual Behavior; Evolution
Link ID: 29279 - Posted: 04.30.2024

By Kristen French Combat in nature is often a matter of tooth and claw, fang and talon. But some creatures have devised devious and dramatic ways to weaponize their bodily fluids, expelling them in powerful streams for the purposes of attack or self-defense. Researcher Elio Challita became fascinated by fluid ejections in nature when he began studying an insect called the sharpshooter, which pees one droplet at a time using a method called superpropulsion. These insects consume 300 times their own body weight per day in xylem sap, a watery solution of minerals and other nutrients found in the roots, stems, and leaves of plants. To efficiently expel the resulting waste, they use a kind of internal catapult that helps overcome the surface tension in the droplets. Challita and a team of researchers from the Bhamla Lab at Georgia Tech decided to survey the biomechanics and fluid dynamics that govern fluid ejections across the animal kingdom to see what commonalities they could find. Among others, they identified a number of creatures that use bodily fluids as powerful weapons in the fight for survival. These fluid ejections defy gravity and rebel against traditional notions of predator-prey tactics. The team’s review, “Fluid Ejections in Nature,” is forthcoming in the Annual Review of Chemical and Biological Engineering. 1. Ringnecked Spitting Cobra Cobras of the Naja genus defend against threats by spitting venom with extreme precision toward the eyes of an enemy, up to 6.5 feet away. These snakes release the venom through hollow microscopic fangs and can adjust the distribution of their spit with rapid movements. Spitting cobras have a venom discharge orifice that is more circular in shape than non-spitting species, which gives the venom more forward force. Contraction in the venom gland also helps. A 90-degree bend near the lip of the orifice gives the snake more precise control over venom flow. Naja pallida cobras can spit venom at average speeds of 1.27 milliliters per second. © 2024 NautilusNext Inc.,

Keyword: Neurotoxins; Evolution
Link ID: 29278 - Posted: 04.30.2024

Jon Hamilton Scientists have found a way to restore brain cells impaired by a rare and life-threatening genetic disorder called Timothy syndrome. A type of drug known as an antisense oligonucleotide allowed clusters of human neurons to develop normally even though they carried the mutation responsible for Timothy syndrome, a team reports in the journal Nature. The approach may help researchers develop treatments for other genetic conditions, including some that cause schizophrenia, epilepsy, ADHD, and autism spectrum disorder. "It's immensely exciting because we now have the tools," says Dr. Sergiu Pasca, a professor of psychiatry and behavioral sciences at Stanford University and the study's senior author. "It's the beginning of a new era for many of these diseases that we first thought were untreatable," says Dr. Huda Zoghbi, a professor at Baylor College of Medicine who was not involved in the research. But most of these conditions involve multiple genes, not just one — and scientists don't yet know enough about these multiple gene disorders to effectively treat them with antisense oligonucleotides, Zoghbi says. Timothy Syndrome has been diagnosed in fewer than 100 people worldwide. Children born with it often have heart problems, autism, epilepsy, developmental delay, and intellectual disability. But because Timothy syndrome is caused by a mutation in a single gene, it offers scientists a way to study changes that affect brain development. "Rare syndromes that are very clearly defined genetically are sort of like windows, or Rosetta Stones, into understanding other, more common conditions," Pasca says. © 2024 npr

Keyword: Autism; Genes & Behavior
Link ID: 29277 - Posted: 04.30.2024

By Claire Cameron On Aug. 19, 2021, a humpback whale named Twain whupped back. Specifically, Twain made a series of humpback whale calls known as “whups” in response to playback recordings of whups from a boat of researchers off the coast of Alaska. The whale and the playback exchanged calls 36 times. On the boat was naturalist Fred Sharpe of the Alaska Whale Foundation, who has been studying humpbacks for over two decades, and animal behavior researcher Brenda McCowan, a professor at the University of California, Davis. The exchange was groundbreaking, Sharpe says, because it brought two linguistic beings—humans and humpback whales—together. “You start getting the sense that there’s this mutual sense of being heard.” In their 2023 published results, McGowan, Sharpe, and their coauthors are careful not to characterize their exchange with Twain as a conversation. They write, “Twain was actively engaged in a type of vocal coordination” with the playback recordings. To the paper’s authors, the interspecies exchange could be a model for perhaps something even more remarkable: an exchange with an extraterrestrial intelligence. Sharpe and McGowan are members of Whale SETI, a team of scientists at the SETI Institute, which has been scanning the skies for decades, listening for signals that may be indicative of extraterrestrial life. The Whale SETI team seeks to show that animal communication, and particularly, complex animal vocalizations like those of humpback whales, can provide scientists with a model to help detect and decipher a message from an extraterrestrial intelligence. And, while they’ve been trying to communicate with whales for years, this latest reported encounter was the first time the whales talked back. It all might sound far-fetched. But then again, Laurance Doyle, an astrophysicist who founded the Whale SETI team and has been part of the SETI Institute since 1987, is accustomed to being doubted by the mainstream science community. © 2024 NautilusNext Inc.,

Keyword: Animal Communication; Language
Link ID: 29276 - Posted: 04.30.2024

By Christina Caron Antidepressants are among the most prescribed medications in the United States. This is, in part, because the number of people diagnosed with depression and anxiety has been on the rise, and prescriptions jumped sharply among some age groups during the pandemic. Despite the prevalence of these medications, some patients have “significant misconceptions” about how the drugs work, said Dr. Andrew J. Gerber, a psychiatrist and the president and medical director of Silver Hill Hospital in New Canaan, Conn. About 80 percent of antidepressants are prescribed by primary care doctors who have not had extensive training in managing mental illness. Dr. Paul Nestadt, an associate professor of psychiatry at the Johns Hopkins School of Medicine, said patients tell him, “‘You know, Doc, I’ve tried everything.’” But often, he said, “they never got to a good dose, or they were only on it for a week or two.” Here are some answers to frequently asked questions about antidepressants. How do antidepressants work? There are many types of antidepressants, and they all work a bit differently. In general, they initiate a change in the way brain cells — and different regions of the brain — communicate with one another, said Dr. Gerard Sanacora, a professor of psychiatry at the Yale School of Medicine. Clinical trials have shown that antidepressants are generally more effective with moderate, severe and chronic depression than with mild depression. Even then, it’s a modest effect when compared with placebo. © 2024 The New York Times Company

Keyword: Depression
Link ID: 29275 - Posted: 04.30.2024

By Laura Sanders What does it feel like to be a rat? We will never know, but some very unusual mice may now have an inkling. In a series of new experiments, bits of rat brain grew inside the brains of mice. Donor stem cells from rats formed elaborate — and functional — neural structures in mice’s brains, despite being from a completely different species, researchers report in two papers published April 25 in Cell. The findings are “remarkable,” says Afsaneh Gaillard, a neuroscientist at INSERM and the University of Poitiers in France. “The ability to generate specific neuronal cells that can successfully integrate into the brain may provide a solution for treating a variety of brain diseases associated with neuronal loss.” These chimeric mice are helping to reveal just how flexible brain development can be (SN: 3/29/23). And while no one is suggesting that human brains could be grown in another animal, the results may help clarify biological details relevant to interspecies organ transplants, the researchers say. The success of these rat-mouse hybrids depended on timing: The rat and mouse cells had to grow into brains together from a very young stage. Stem cells from rats that had the potential to mature into several different cell types were injected into mouse embryos. From there, these rat cells developed alongside mice cells in the growing brain, though researchers couldn’t control exactly where the rat cells ended up. In one set of experiments, researchers first cleared the way for these rat cells to develop in the young mouse brains. Stem cell biologist Jun Wu and colleagues used a form of the genetic tool CRISPR to inactivate a mouse gene that instructs their brain cells to build a forebrain, a large region involved in learning, remembering and sensing the world. This left the mice without forebrains — normally, a lethal problem. © Society for Science & the Public 2000–2024.

Keyword: Development of the Brain; Neurogenesis
Link ID: 29274 - Posted: 04.26.2024

Sofia Quaglia Noise pollution from traffic stunts growth in baby birds, even while inside the egg, research has found. Unhatched birds and hatchlings that are exposed to noise from city traffic experience long-term negative effects on their health, growth and reproduction, the study found. “Sound has a much stronger and more direct impact on bird development than we knew before,” said Dr Mylene Mariette, a bird communication expert at Deakin University in Australia and a co-author of the study, published in the journal Science. “It would be wise to work more to reduce noise pollution.” A growing body of research has suggested that noise pollution causes stress to birds and makes communication harder for them. But whether birds are already distressed at a young age because they are affected by noise, or by how noise disrupts their environment and parental care, was still unclear. Mariette’s team routinely exposed zebra finch eggs for five days to either silence, soothing playbacks of zebra finch songs, or recordings of city traffic noises such as revving motors and cars driving past. They did the same with newborn chicks for about four hours a night for up to 13 nights, without exposing the birds’ parents to the sounds. They noticed that the bird eggs were almost 20% less likely to hatch if exposed to traffic noise. The chicks that did hatch were more than 10% smaller and almost 15% lighter than the other hatchlings. When the team ran analyses on their red blood cells and their telomeres – a piece of DNA that shortens with stress and age – they were more eroded and shorter than their counterparts’. The effects continued even after the chicks were no longer exposed to noise pollution, and carried over into their reproductive age four years later. The birds disturbed by noise during the early stages of their lives produced fewer than half as many offspring as their counterparts. © 2024 Guardian News & Media Limited

Keyword: Hearing; Development of the Brain
Link ID: 29273 - Posted: 04.26.2024

By Carl Zimmer Earlier this month, millions of Americans looked up at the sky to witness a total eclipse. Now, another cyclical marvel has arrived, this time at our feet. Trillions of noisy, red-eyed insects called cicadas are emerging from the earth after more than a decade of feeding on tree roots. The United States is home to 15 cicada broods, and in most years at least one of them emerges. This spring, Brood XIX, known as the Great Southern Brood, and Brood XIII, or the Northern Illinois Brood, are emerging simultaneously. Cicada watchers have spotted the first insects coming out of the ground, reporting their sightings to apps such as iNaturalist and Cicada Safari. The Great Southern Brood, which emerges across the South and the Midwest every 13 years, has been seen at sites scattered from North Carolina to Georgia. The Northern Illinois Brood, which appears every 17 years in the Midwest, is expected to appear in the next month, as temperatures there warm. How cicadas manage to rise en masse after spending so long underground remains largely a mystery. “There’s surprisingly little information about cicadas that you’d like to know,” said Raymond Goldstein, a physicist at the University of Cambridge. Once a brood climbs out of the ground, the cicadas crawl up trees to mate, and the females lay eggs in tree branches. After hatching, the young insects drop to earth and burrow into the soil. Then, each cicada spends the next 13 or 17 years underground before emerging to mate and repeat the cycle. That means that trillions of insects have to track the passage of time in the soil. It’s possible that they detect annual changes in tree roots. But how can cicadas add up those changes to divine when 13 or 17 years have passed? Scientists cannot say. © 2024 The New York Times Company

Keyword: Biological Rhythms
Link ID: 29272 - Posted: 04.26.2024

By Sara Reardon Researchers have hailed organoids — 3D clusters of cells that mimic aspects of human organs — as a potential way to test drugs and even eliminate some forms of animal experimentation. Now, in two studies published on 24 April in Nature1,2, biologists have developed gut and brain organoids that could improve understanding of colon cancer and help to develop treatments for a rare neurological disorder. “In the last ten years, people spent a lot of time to develop and understand how to make organoids,” says Shuibing Chen, a chemical biologist at Weill Cornell Medical College in New York City. “But this is the time now to think more about how to use” the models. Organoids — particularly those made from human stem cells — sometimes reveal things that animal models can’t, says Sergiu Pașca, a neuroscientist at Stanford University in California and a co-author of one of the studies1. Pașca’s group studies Timothy syndrome: a genetic disorder involving autism, neurological problems and heart conditions that affects only a few dozen people in the world. Timothy syndrome is caused by a single mutation in a gene called CACNA1C, which encodes a channel through which calcium ions enter cells including neurons. Pașca says that there are no good animal models for Timothy syndrome because the underlying mutation doesn’t always cause the same symptoms in rodents. “It became very clear to us we’d need to find a way of testing in vivo,” he says. © 2024 Springer Nature Limited

Keyword: Development of the Brain
Link ID: 29271 - Posted: 04.26.2024

By Shaena Montanari The sympathetic nervous system may have originated in jawless fish—not tens of millions of years later as previously thought, according to a study published today in Nature. Anatomical work dating back to the 19th century suggested that the sympathetic nervous system was present only in jawed vertebrates. Yet the sea lamprey, the new findings reveal, sports clusters of sympathetic neurons along its trunk and expresses several genes involved in the “fight-or-flight” system, the response that kicks into gear when an animal perceives a threat. “Whenever new research causes troves of textbooks to need corrections, that’s always surprising,” says Tyler Square, assistant professor of molecular genetics at the University of Florida, who was not involved in the study. The team behind the new work decided to re-examine conventional wisdom after a postdoctoral researcher in the lab produced microscopy images of lamprey embryos stained for neurons in the animals’ gut. The stain highlighted some “small sort of concentrations of cells” that looked a lot like sympathetic neurons, recalls lead investigator Marianne Bronner, professor of biology at the California Institute of Technology. “I said, ‘Oh, those shouldn’t be there.’ So then we decided to delve deeper into it.” The unexpected neurons express several key genes—specifically ASCL1, PHOX2 and HAND—involved in the sympathoadrenal system, the team discovered using a suite of techniques, including immunohistochemistry, in situ hybridization chain reaction and RNA sequencing. These are “all transcription factors that are known to be important in sympathetic neuron differentiation in mammals,” Bronner says. © 2024 Simons Foundation

Keyword: Stress; Evolution
Link ID: 29270 - Posted: 04.26.2024

By Lilly Tozer How the brain processes visual information — and its perception of time — is heavily influenced by what we’re looking at, a study has found. In the experiment, participants perceived the amount of time they had spent looking at an image differently depending on how large, cluttered or memorable the contents of the picture were. They were also more likely to remember images that they thought they had viewed for longer. The findings, published on 22 April in Nature Human Behaviour1, could offer fresh insights into how people experience and keep track of time. “For over 50 years, we’ve known that objectively longer-presented things on a screen are better remembered,” says study co-author Martin Wiener, a cognitive neuroscientist at George Mason University in Fairfax, Virginia. “This is showing for the first time, a subjectively experienced longer interval is also better remembered.” Research has shown that humans’ perception of time is intrinsically linked to our senses. “Because we do not have a sensory organ dedicated to encoding time, all sensory organs are in fact conveying temporal information” says Virginie van Wassenhove, a cognitive neuroscientist at the University of Paris–Saclay in Essonne, France. Previous studies found that basic features of an image, such as its colours and contrast, can alter people’s perceptions of time spent viewing the image. In the latest study, researchers set out to investigate whether higher-level semantic features, such as memorability, can have the same effect. © 2024 Springer Nature Limited

Keyword: Attention; Vision
Link ID: 29269 - Posted: 04.24.2024

By Bill Wasik and Monica Murphy What makes a desert tortoise happy? Before you answer, we should be more specific: We’re talking about a Sonoran desert tortoise, one of a few species of drab, stocky tortoises native to North America’s most arid landscapes. Adapted to the rocky crevices that striate the hills from western Arizona to northern Mexico, this long-lived reptile impassively plods its range, browsing wildflowers, scrub grasses and cactus paddles during the hours when it’s not sheltering from the brutal heat or bitter cold. Sonoran desert tortoises evolved to thrive in an environment so different from what humans find comfortable that we can rarely hope to encounter one during our necessarily short forays — under brimmed hats and layers of sunblock, carrying liters of water and guided by GPS — into their native habitat. This past November, in a large, carpeted banquet room on the University of Wisconsin’s River Falls campus, hundreds of undergraduate, graduate and veterinary students silently considered the lived experience of a Sonoran desert tortoise. Perhaps nine in 10 of the participants were women, reflecting the current demographics of students drawn to veterinary medicine and other animal-related fields. From 23 universities in the United States and Canada, and one in the Netherlands, they had traveled here to compete in an unusual test of empathy with a wide range of creatures: the Animal Welfare Assessment Contest. That morning in the banquet room, the academics and experts who organize the contest (under the sponsorship of the American Veterinary Medical Association, the nation’s primary professional society for vets) laid out three different fictional scenarios, each one involving a binary choice: Which animals are better off? One scenario involved groups of laying hens in two different facilities, a family farm versus a more corporate affair. Another involved bison being raised for meat, some in a smaller, more managed operation and others ranging more widely with less hands-on human contact. © 2024 The New York Times Company

Keyword: Animal Rights; Emotions
Link ID: 29268 - Posted: 04.24.2024

By Angie Voyles Askham The ability of amphibians to metamorphosize and, in some cases, regenerate limbs and even brain tissue raises puzzling yet fundamental questions about how a nervous system wires itself up. For example, if a frog’s legs don’t exist when its brain begins to develop—those limbs later replace its tadpole tail—how are the neural connections maintained such that, once the legs take shape, a frog can move them? “How many connections are there between the spinal cord and the brain? How do they change over metamorphosis?” asks Lora Sweeney, assistant professor at the Institute of Science and Technology Austria. To find out, Sweeney and her colleagues decided to screen a panel of adeno-associated viruses (AAVs) in two species of frog and a newt. These viruses are commonly used to genetically manipulate brain cells in rodents and monkeys, but they have not been proven useful in amphibian experiments. With the right techniques, most common AAVs can deliver genes to amphibian cells through a process called transduction, according to Sweeney’s unpublished results, though the most effective viruses vary by species. These amphibian-friendly AAVs can be used to trace neuronal connections and track groups of neurons born at the same time, the new work shows. And a subset of these same AAVs can also transduce cells in axolotls, newts’ fuzzy-gilled Mexican cousins, according to another preprint from an independent team. Both preprints were posted on bioRxiv in February. “It’s a big game-changer,” says Helen Willsey, assistant professor of psychiatry at the University of California, San Francisco, who was not involved in either study but works with amphibian models. “It opens up a lot of doors for new experiments.” Other researchers had previously tried to get AAVs to transduce cells in frogs and fish, with little success. © 2024 Simons Foundation

Keyword: Brain imaging; Evolution
Link ID: 29267 - Posted: 04.24.2024