By Ann Gibbons As the parent of any teenager knows, humans need a long time to grow up: We take about twice as long as chimpanzees to reach adulthood. Anthropologists theorize that our long childhood and adolescence allow us to build comparatively bigger brains or learn skills that help us survive and reproduce. Now, a study of an ancient youth’s teeth suggests a slow pattern of growth appeared at least 1.8 million years ago, half a million years earlier than any previous evidence for delayed dental development. Researchers used state-of-the art x-ray imaging methods to count growth lines in the molars of a member of our genus, Homo, who lived 1.77 million years ago in what today is Dmanisi, Georgia. Although the youth developed much faster than children today, its molars grew as slowly as a modern human’s during the first 5 years of life, the researchers report today in Nature. The finding, in a group whose brains are hardly larger than chimpanzees, could provide clues to why humans evolved such long childhoods. “One of the main questions in paleoanthropology is to understand when this pattern of slow development evolves in [our genus] Homo,” says Alessia Nava, a bioarchaeologist at the Sapienza University of Rome who is not part of the study. “Now, we have an important hint.” Others caution that although the teeth of this youngster grew slowly, other individuals, including our direct ancestors, might have developed faster. Researchers have known since the 1930s that humans stay immature longer than other apes. Some posit our ancestors evolved slow growth to allow more time and energy to build bigger brains, or to learn how to adapt to complex social interactions and environments before they had children. To pin down when this slow pattern of growth arose, researchers often turn to teeth, especially permanent molars, because they persist in the fossil record and contain growth lines like tree rings. What’s more, the dental growth rate in humans and other primates correlates with the development of the brain and body.

Keyword: Evolution; Sexual Behavior
Link ID: 29562 - Posted: 11.16.2024

Ari Daniel The birds of today descended from the dinosaurs of yore. Researchers have known relatively little, however, about how the bird's brain took shape over tens of millions of years. "Birds are one of the most intelligent groups of living vertebrate animals," says Daniel Field, a vertebrate biologist at the University of Cambridge. "They really rival mammals in terms of their relative brain size and the complexity of their behaviors, social interactions, breeding displays." Now, a newly discovered fossil provides the most complete glimpse to date of the brains of the ancestral birds that once flew above the dinosaurs. The species was named Navaornis hestiae, and it's described in the journal Nature. Piecing together how bird brains evolved has been a challenge. First, most of the fossil evidence dates back to tens of millions of years before the end of the Cretaceous period when dinosaurs went extinct and birds diversified. In addition, the fossils of feathered dinosaurs that have turned up often have a key problem. "They're beautiful, but they're all like roadkill," says Luis Chiappe, a paleontologist and curator at the Natural History Museum of Los Angeles County. "They're all flattened and there are aspects that you're never going to be able to recover from those fossils." The shape and three-dimensional structure of the brain are among those missing aspects. But in 2016, Brazilian paleontologist William Nava discovered a remarkably well-preserved fossil in São Paulo state. It came from a prehistoric bird that fills in a crucial gap in understanding of how modern bird brains evolved. © 2024 npr

Keyword: Evolution; Development of the Brain
Link ID: 29561 - Posted: 11.16.2024

By Elena Renken Small may be mightier than we think when it comes to brains. This is what neuroscientist Marcella Noorman is learning from her neuroscientific research into tiny animals like fruit flies, whose brains hold around 140,000 neurons each, compared to the roughly 86 billion in the human brain. Nautilus Members enjoy an ad-free experience. Log in or Join now . In work published earlier this month in Nature Neuroscience, Noorman and colleagues showed that a small network of cells in the fruit fly brain was capable of completing a highly complex task with impressive accuracy: maintaining a consistent sense of direction. Smaller networks were thought to be capable of only discrete internal mental representations, not continuous ones. These networks can “perform more complex computations than we previously thought,” says Noorman, an associate at the Howard Hughes Medical Institute. The scientists monitored the brains of fruit flies as they walked on tiny rotating foam balls in the dark, and recorded the activity of a network of cells responsible for keeping track of head direction. This kind of brain network is called a ring attractor network, and it is present in both insects and in humans. Ring attractor networks maintain variables like orientation or angular velocity—the rate at which an object rotates—over time as we navigate, integrating new information from the senses and making sure we don’t lose track of the original signal, even when there are no updates. You know which way you’re facing even if you close your eyes and stand still, for example. After finding that this small circuit in fruit fly brains—which contains only about 50 neurons in the core of the network—could accurately represent head direction, Noorman and her colleagues built models to identify the minimum size of a network that could still theoretically perform this task. Smaller networks, they found, required more precise signaling between neurons. But hundreds or thousands of cells weren’t necessary for this basic task. As few as four cells could form a ring attractor, they found. © 2024 NautilusNext Inc.,

Keyword: Development of the Brain; Vision
Link ID: 29560 - Posted: 11.16.2024

By Tim Vernimmen Few people are fond of earwigs, with their menacing abdominal pincers — whether they’re skittering across your floor, getting comfy in the folds of your camping tent or minding their own business. Scientists, too, have given them short shrift, compared with the seemingly endless attention they have lavished on social insects like ants and bees. Yet there are a handful of exceptions. Some researchers have made conscious career decisions to dig into the hidden, underground world where earwigs reside, and have found the creatures to be surprisingly interesting and social, if still not exactly endearing. Work in the 1990s and early 2000s focused on earwig courtship. These often-intricate performances of attraction and repulsion — in which pincers and antennae play prominent roles — can last hours, and the mating itself as long as 20 hours, at least in one Papua New Guinea species, Tagalina papua. The females usually decide when they’ve had enough, though males of some species use their pincers to restrain the object of their desire. Males of the bone-house earwig Marava arachidis (often found in bone meal plants and slaughterhouses) are particularly coercive, says entomologist Yoshitaka Kamimura of Keio University in Japan, who has studied earwig mating for 25 years. “They bite the female’s antennae and use a little hook on their genitalia to lock them inside her reproductive tract.” Size matters

Keyword: Sexual Behavior; Evolution
Link ID: 29559 - Posted: 11.16.2024

By Angie Voyles Askham Engrams, the physical circuits of individual memories, consist of more than just neurons, according to a new study published today in Nature. Astrocytes, too, shape how some memories are stored and retrieved, the work shows. The results represent “a fundamental change” in how the neuroscience field should think about indexing memories, says lead researcher Benjamin Deneen, professor of neurosurgery at Baylor College of Medicine. “We need to reconsider the cellular, physical basis of how we store memories.” When mice form a new memory, a specific set of neurons becomes active and expresses the immediate early gene c-FOS, past work has found. Reactivating that ensemble of neurons, the engram, causes the mice to recall that memory. Interactions between neurons and astrocytes are critical for the formation of long-term memory, according to a spatial transcriptomics study from February, and both astrocytes and oligodendrocytes are involved in memory formation, other work has shown. Yet engram studies have largely ignored the activity of non-neuronal cells, says Sheena Josselyn, senior scientist at the Hospital for Sick Children, who was not involved in the new study. But astrocytes are also active alongside neurons as memories are formed and recalled, and disrupting the star-shaped cells’ function interferes with these processes, the new work reveals. The study does not dethrone neurons as the lead engram stars, according to Josselyn. “It really shows that, yes, neurons are important. But there are also other players that we’re just beginning to understand the importance of,” she says. “It’ll help broaden our focus.” © 2024 Simons Foundation

Keyword: Learning & Memory; Glia
Link ID: 29558 - Posted: 11.13.2024

By Fred Schwaller Scott Imbrie still remembers the first time that physicians switched on the electrodes sitting on the surface of his brain. He felt a tingling, poking sensation in his hand, like “reaching into an evergreen bush”, he says. “It was like I was decorating a Christmas tree.” Back in 1985, a car crash shattered three of Imbrie’s vertebrae and severed 70% of his spinal cord, leaving him with very limited sensation or mobility in parts of his body. Now, thanks to an implanted brain–computer interface (BCI), Imbrie can operate a robotic arm, and receive sensory information related to what that arm is doing. Imbrie spends four days a week, three hours at a time, testing, refining and tuning the device with a team of researchers at the University of Chicago in Illinois. Scientists have been trying to restore mobility for people with missing or paralysed limbs for decades. The aim, historically, was to give people the ability to control prosthetics with commands from the nervous system. But this motor-first approach produced bionic limbs that were much less helpful than hoped: devices were cumbersome and provided only rudimentary control of a hand or leg. What’s more, they just didn’t feel like they were part of the body and required too much concentration to use. Scientists gradually began to realize that restoring full mobility meant restoring the ability to sense touch and temperature, says Robert Gaunt, a bioengineer at the University of Pittsburgh in Pennsylvania. Gaunt says that this realization has led to a revolution in the field. A landmark study1 came in 2016, when a team led by Gaunt restored tactile sensations in a person with upper-limb paralysis using a computer chip implanted in a region of the brain that controls the hand. Gaunt then teamed up with his Pittsburgh colleague, bioengineer Jennifer Collinger, to integrate a robotic arm with the BCI, allowing the individual to feel and manipulate objects. © 2024 Springer Nature Limited

Keyword: Robotics; Pain & Touch
Link ID: 29557 - Posted: 11.13.2024

Terry Gross We've all had bug bites, or dry scalp, or a sunburn that causes itch. But what if you felt itchy all the time — and there was no relief? Journalist Annie Lowrey suffers from primary biliary cholangitis (PBC), a degenerative liver disease in which the body mistakenly attacks cells lining the bile ducts, causing them to inflame. The result is a severe itch that doesn't respond to antihistamines or steroids. "It feels like being trapped inside your own body," Lowrey says of the disease. "I always describe it as being like a car alarm. Like, you can't stop thinking about it." PBC is impacts approximately 80,000 people in the U.S., the majority of whom are women. At its worst, Lowrey says, the itch caused her to dig holes in her skin and scalp. She's even fantasized about having limbs amputated to escape the itch. Lowrey writes about living with PBC in the Atlantic article, "Why People Itch and How to Stop It." She says a big part of her struggle is coming to terms with the fact that she may never feel fully at ease in her skin. "I talked to two folks who are a lot older than I was, just about like, how do you deal with it? How do you deal with the fact that you might itch and never stop itching? … And both of them were kind of like, 'You put up with it, stop worrying about it and get on with your life,'" she says. "I think I was mentally trapped ... and sometimes it's like, OK, ... go do something else. Life continues on. You have a body. It's OK." © 2024 npr

Keyword: Pain & Touch
Link ID: 29556 - Posted: 11.13.2024

By Kim Tingley There are two opposite paths to achievement in science. The first is straightforward: Identify a problem and set about solving it. The second is rather unscientific-sounding and perhaps more faith-based: Study in obscurity and hope serendipity strikes. In 1980, a young gastroenterologist named Jean-Pierre Raufman wound up taking the latter road through the digestive-diseases branch of the National Institutes of Health. His goal there was to gain research experience. While doing so, he chanced to meet the lead chemist of another laboratory, John Pisano, who had a passion for seeking out new and interesting examples of a specific kind of hormone, called a peptide, in animal venoms. Pisano regularly appealed to local insect and reptile enthusiasts in the classified pages of The Washington Post; in response, they would show up at his office door carrying plastic bags wriggling with possibility. Pisano offered some venom samples to Raufman for his meandering analyses. Over the following month, Raufman experimented with them to see if they stimulated pancreatic cells harvested from guinea pigs. The venom with the biggest effect by far came from a desert reptile that Raufman had never heard of: the Gila monster. Gila monsters — sluggish, thick-tailed ground dwellers — are native to southern Arizona and northern Mexico. They have blunt noses and bumpy black skin with tan, pink or orange squiggles. They spend 95 percent of their lives underground. Like their cousins to the south, Mexican beaded lizards, they are one of the very few lizard species that produces venom, which they excrete from mouth glands into grooves in their serrated teeth. The strength of their jaws is typically enough to subdue their prey (chicks, frogs, worms and the like). But if threatened and unable to escape or hide, they may bite a predator. Whenever they clamp down, piercing the skin, venom enters the victim’s bloodstream. This causes intense pain and can initiate a cascade of other symptoms that, in people, includes vomiting, dizziness, rapid heart rate, low blood pressure and, in rare circumstances, death. © 2024 The New York Times Company

Keyword: Neurotoxins; Obesity
Link ID: 29555 - Posted: 11.13.2024

Denis Campbell Health policy editor Hundreds of thousands of smokers will be given a pill that increases people’s chances of quitting, in a move that NHS bosses believe will save thousands of lives. About 85,000 people a year in England will be offered the chance to use varenicline, a once-a-day tablet that experts say is as effective as vapes at helping people to kick the habit. Amanda Pritchard, the chief executive of NHS England, hailed the pill as a potential “gamechanger” in the fight to tackle smoking and the huge harm to health it causes. The drug helps people to quit by reducing their cravings for nicotine and ensuring that it cannot affect the brain in its usual way. It has also been found to reduce the side-effects smokers can experience when they stop using tobacco, such as trouble sleeping and irritability. The NHS in England will give varenicline as part of its efforts to keep driving down the number of people who smoke. A decline in smoking rates over the past 20 years means that only 11.6% of adults in England still have the habit – about 6 million people. Health service bosses hope its use will lead to 9,500 fewer smoking-related deaths over the next five years. The drug – known at the time as Champix – began being used in 2006 and was taken by about 85,800 people a year until July 2021. It then became unavailable after the Medicines and Healthcare products Regulatory Agency (MHRA), which regulates drugs, found impurities in it. That problem has now been addressed to the MHRA’s satisfaction and it has recently approved a generic version of the drug, which NHS England will use. It cited research by University College London that found it would save £1.65 in healthcare costs for every £1 it spent on the pill. © 2024 Guardian News & Media Limited

Keyword: Drug Abuse
Link ID: 29554 - Posted: 11.13.2024

By Christina Caron In high school, Sophie Didier started falling behind. She found it difficult to concentrate on her schoolwork, felt restless in class and often got in trouble for talking too much. “I had a teacher that used to give me suckers so that I would shut up,” she said. At 15, a doctor diagnosed her with attention deficit hyperactivity disorder. Medication helped, but she discovered that having a demanding schedule was also important. In both high school and college, her grades improved when she was juggling lacrosse and other extracurricular activities with her classes. Being so busy forced her to stick to a routine. “I felt more organized then,” recalled Ms. Didier, now 24 and living in Kansas City, Mo. “Like I had a better handle on things.” Research has shown that A.D.H.D. symptoms can change over time, improving and then worsening again or vice versa. And according to a recently published study, having additional responsibilities and obligations is associated with periods of milder A.D.H.D. This might mean that staying busy had been beneficial, researchers said. It could also just mean that people with milder symptoms had been able to handle more demands, they added. Oftentimes, people with A.D.H.D. “seem to do best when there’s an urgent deadline or when the stakes are high,” said Margaret Sibley, who is a professor of psychiatry and behavioral sciences at the University of Washington School of Medicine in Seattle and who led the study. The study, published online in October in the Journal of Clinical Psychiatry, tracked 483 patients in the United States and Canada who each had a combination of inattentive and hyperactive-impulsive A.D.H.D. symptoms. The researchers followed the participants for 16 years, starting at an average age of 8. They found that about three-quarters of the patients experienced fluctuations in their symptoms, generally beginning around age 12, which included either a full or partial remission of symptoms. © 2024 The New York Times Company

Keyword: ADHD
Link ID: 29553 - Posted: 11.13.2024

By Erin Garcia de Jesús The first detailed structure of an infectious prion that causes chronic wasting disease, or CWD, reveals features that could help guide vaccine development or explain why the illness hasn’t yet made the leap to people, researchers report October 24 in Acta Neuropathologica. One such feature is a 180-degree twist between two sections of the prion. In versions engineered to infect rodents in order to study the disease, that twist doesn’t exist. Like the prion illness Creutzfeldt-Jakob disease in people, CWD prions in deer, elk and moose transform a healthy brain protein called PrP into misshapen versions that clump together and cause symptoms such as listlessness, drastic weight loss and lack of fear. While no person has contracted the disease and studies in mice and primates suggest that the risk to humans is extremely low, CWD’s spread among animals that people eat has raised concerns that it one day could jump to people (SN: 6/10/24). Understanding how deer prions misfold could help reveal why CWD doesn’t easily spread to humans. But “prions are messy,” says Byron Caughey, a biochemist at the National Institutes of Health’s Rocky Mountain Laboratories in Hamilton, Mont. Because the proteins “are very sticky and they tend to cling together,” researchers have a tough time getting a clear picture of what diseased prions look like. Previous studies looking at other prions, including rodent-adapted versions originally from sheep, showed that the proteins stack together like plates. Using hundreds of thousands of electron microscopy images, Caughey and colleagues found that a natural prion from the brain tissue of a white-tailed deer stacks in a similar way, but with some potentially key differences. © Society for Science & the Public 2000–2024.

Keyword: Prions
Link ID: 29552 - Posted: 11.13.2024

By Miryam Naddaf When a dog shakes water off its fur, the action is not just a random flurry of movements — nor a deliberate effort to drench anyone standing nearby. This instinctive reflex is shared by many furry mammals including mice, cats, squirrels, lions, tigers and bears. The move helps animals to remove water, insects or other irritants from hard-to-reach places. But underlying the shakes is a complex — and previously mysterious — neurological mechanism. Now, researchers have identified the neural circuit that triggers characteristic ‘wet dog’ shaking behaviour in mice — which involves a specific class of touch receptors, and neurons that connect the spinal cord to the brain. Their findings were published in Science on 7 November1. “The touch system is so complex and rich that [it] can distinguish a water droplet from a crawling insect from the gentle touch of a loved one,” says Kara Marshall, a neuroscientist at Baylor College of Medicine in Houston, Texas. “It’s really remarkable to be able to link a very specific subset of touch receptors to this familiar and understandable behaviour.” The hairy skin of mammals is packed with more than 12 types of sensory neuron, each with a unique function to detect and interpret various sensations. Study co-author Dawei Zhang, a neuroscientist then at Harvard Medical School in Boston, Massachusetts, and his colleagues focused on a type of ultra-sensitive touch detecting receptors called C-fibre low-threshold mechanoreceptors (C-LTMRs), which wrap around hair follicles. In humans, these receptors are associated with pleasant touch sensations, such as a soft hug or a soothing stroke. But in mice and other animals, they serve a protective role: alerting them to the presence of something on their skin, whether it’s water, dirt or a parasite. When these stimuli cause hairs on the skin to bend it activates the C-LTMRs, says Marshall, “extending the sensibility of the skin beyond just the surface”. © 2024 Springer Nature Limited

Keyword: Pain & Touch; Evolution
Link ID: 29551 - Posted: 11.09.2024

By Shaena Montanari In the Sterling Hall of Medicine at Yale University, a sign on a walk-in refrigerator door tells people to keep their voices down. Inside, about 250 ground squirrels are hibernating, each surrounded by shredded paper fluff and curled up in a clear plastic box. Shelves lined with these makeshift nests are bathed in red light that only the researchers can see, leaving the motionless animals in complete darkness. From about September to April—roughly the hibernation season for these thirteen-lined ground squirrels, which have stripes reminiscent of a chipmunk—the temperature inside the homemade hibernaculum is set at 4 degrees Celsius. The tiny rodents’ body temperature is the same as the chilly air, and their breathing and heart rates slow to just a handful of breaths and beats per minute—an energy-conserving response known as torpor. Scientists have studied this extreme physiological state for more than a century, says Elena Gracheva, whose bustling lab sits just outside the silent hibernaculum. But to date, they have focused mainly on physiological changes in individual peripheral organs that help an animal survive in cold temperatures. It is still unknown how the central nervous system regulates the process, she says. “We know a lot about physiology, but we don’t know the molecular basis.” Gracheva, professor of physiology and neuroscience at Yale University, is part of a small cadre of scientists who have set their sights on revealing those neural hibernation controls, using advanced tools to explore how the brain and other organ systems work together to maintain homeostasis. Their efforts are opening a “new era” in hibernation research, says Shona Wood, associate professor of Arctic chronobiology and physiology at the Arctic University of Norway. © 2024 Simons Foundation

Keyword: Sleep
Link ID: 29550 - Posted: 11.09.2024

By Lynne Peeples Living things began tracking the incremental passage of time long before the human-made clock lent its hands. As life grew in harmony with the sun’s daily march through the sky, and with the seasons, phases of the moon, tides, and other predictable environmental cycles, evolution ingrained biology with the timekeeping tools to keep a step ahead. It gifted an ability to anticipate changes, rather than respond to them, and an internal nudge to do things when most advantageous and to avoid doing things when not so advantageous. Of course, that optimal timing depended on a species’ niche on the 24-hour clock. When mammals first arose, for example, they were nocturnal — most active during the hours that the dinosaurs slept. Now mammals occupy both their choice territories on a spinning planet and their preferred space on a rotating clock. Timing is everything when it comes to seeking and digesting food, storing food, avoiding becoming food, dodging exposure to DNA-damaging ultraviolet radiation, and many more vital activities, such as navigating, migrating, and reproducing. Take the Eudyptula minor, a tiny penguin species that lives on Phillip Island in Australia. The slate-blue plumaged seabird speed waddles from the ocean to burrow home at the same “sun time” each day — just after sunset. Finding that precise window between day and night maximizes the penguins’ fishing time, allows them enough light to see their way to their burrows, and minimizes the chances they become visible food along the way for nighttime predators, such as orcas, seabirds, and feral cats. An internal clock off by just 10 minutes could prove fatal, one source told me. The island’s tourism industry capitalizes on this predictable “Penguin Parade.” A website lists approximate penguin arrival times for every month of the year and sells tickets to witness the spectacle. A higher ticket price grants visitors access to an underground viewing structure where they can watch the procession of waddlers at eye level. In October 2022, lucky visitors got to view a record-breaking 5,440 little penguins storm the shore and hurry home.

Keyword: Biological Rhythms
Link ID: 29549 - Posted: 11.09.2024

Andrew Gregory Health editor Doing more than an hour of moderate intensity exercise each week may reduce the severity of “baby blues” and almost halve the risk of new mothers developing major clinical depression, the largest analysis of evidence suggests. However, researchers behind the study acknowledged that finding the time amid so many new responsibilities and challenges would not be easy, and recovery from childbirth should be prioritised. New mothers could restart exercise with “gentle” walks, which they could do with their babies, and then increase to “moderate” activity when they were ready, they added. This moderate physical activity could include brisk walking, water aerobics, stationary cycling or resistance training, according to the team of academics in Canada. Maternal depression and anxiety are relatively common after giving birth and associated with reduced self-care and compromised infant caregiving and bonding, which could in turn affect the child’s cognitive, emotional and social development, the researchers said. Conventional treatments for depression and anxiety in the first weeks and months after giving birth mostly involve drugs and counselling, which are often associated with, respectively, side-effects and poor adherence, and lack of timely access and expense. Research has previously shown that physical activity is an effective treatment for depression and anxiety in general. But until now it has not been known whether it could reduce the severity of the baby blues in the first few weeks after giving birth or lower the risk of major postpartum depression several months later. © 2024 Guardian News & Media Limited

Keyword: Depression; Hormones & Behavior
Link ID: 29548 - Posted: 11.09.2024

By Sara Reardon Elephants love showering to cool off, and most do so by sucking water into their trunks and spitting it over their bodies. But an elderly pachyderm named Mary has perfected the technique by using a hose as a showerhead, much in the way humans do. The behavior is a remarkable example of sophisticated tool use in the animal kingdom. But the story doesn’t end there. Mary’s long, luxurious baths have drawn so much attention that an envious elephant at the Berlin Zoo has figured out how to shut the water off on her supersoaking rival—a type of sabotage rarely seen among animals. Both behaviors, reported today in Current Biology, further cement elephants as complex thinkers, says Lucy Bates, a behavioral ecologist at the University of Portsmouth not involved in the study. The work, she says, “suggests problem solving or even ‘insight.’” Many elephants enjoy playing with hoses, probably because they remind them of trunks, says Michael Brecht, a computational neuroscientist at Humboldt University of Berlin. But Mary takes the activity to another level. Using her trunk, the 54-year-old Asian elephant (Elephas maximus)—a senior citizen, given the average captive life span of her species of 48 years—holds a hose over her head and waves it back and forth. She also changes her grip on the hose to spray different parts of her body and swings it like a lasso to throw water over her back. Brecht’s graduate student, Lena Kaufmann, noticed Mary’s hose use while studying other types of behavior in the zoo’s elephants; the zookeepers told her Mary did this frequently. So Kaufman and her colleagues started to record the showering on video over the course of a year, testing how Mary reacted to changes in the setup.

Keyword: Learning & Memory; Evolution
Link ID: 29547 - Posted: 11.09.2024

By Tamlyn Hunt The neuron, the specialized cell type that makes up much of our brains, is at the center of today’s neuroscience. Neuroscientists explain perception, memory, cognition and even consciousness itself as products of billions of these tiny neurons busily firing their tiny “spikes” of voltage inside our brain. These energetic spikes not only convey things like pain and other sensory information to our conscious mind, but they are also in theory able to explain every detail of our complex consciousness. At least in principle. The details of this “neural code” have yet to be worked out. While neuroscientists have long focused on spikes travelling throughout brain cells, “ephaptic” field effects may really be the primary mechanism for consciousness and cognition. These effects, resulting from the electric fields produced by neurons rather than their synaptic firings, may play a leading role in our mind’s workings. In 1943 American scientists first described what is known today as the neural code, or spike code. They fleshed out a detailed map of how logical operations can be completed with the “all or none” nature of neural firing—similar to how today’s computers work. Since then neuroscientists around the world have engaged in a vast endeavor to crack the neural code in order to understand the specifics of cognition and consciousness. To little avail. “The most obvious chasm in our understanding is in all the things we did not meet on our journey from your eye to your hand,” confessed neuroscientist Mark Humphries in 2020’s The Spike, a deep dive into this journey: “All the things of the mind I’ve not been able to tell you about, because we know so little of what spikes do to make them.” © 2024 SCIENTIFIC AMERICAN

Keyword: Consciousness
Link ID: 29546 - Posted: 11.09.2024

By Heidi Ledford To unlock the secrets of human ageing, researchers might do better to look to the pet napping on their couch than to a laboratory mouse. As cats age, their brains show signs of atrophy and cognitive decline that more closely resemble the deterioration seen in ageing humans than do the changes in the brains of ageing mice, according to findings presented last month at the Lake Conference on Comparative and Evolutionary Neurobiology near Seattle, Washington. The results are part of a large project, called Translating Time, that compares brain development across more than 150 mammal species, and is now expanding to include data on aging. The hope is that the data will aid researchers trying to crack the causes of age-related diseases, particularly conditions that affect the brain, such as Alzheimer’s disease. “To address challenges in human medicine, we need to draw from a wide range of model systems,” says Christine Charvet, a comparative neuroscientist at Auburn University College of Veterinary Medicine in Alabama, who presented the work. “Cats, lemurs, mice are all useful. We shouldn’t focus all our efforts on one.” The Translating Time project started in the 1990s as a tool for developmental biologists1. Project scientists compiled data on how long it takes for the brain to reach a range of developmental milestones in a variety of mammals and used these data to graph the relative development of two species over time. This can help researchers to link observations of animal development to the corresponding human age. Over the years, however, as Charvet presented these data at conferences, researchers kept asking her to extend the database to include not only early development, but also how the brain changes as animals age. © 2024 Springer Nature Limited

Keyword: Development of the Brain
Link ID: 29545 - Posted: 11.06.2024

By Angie Voyles Askham Keeping track of social hierarchies is crucial for any animal. Primates in particular must adapt their behaviors based on the status of those around them, or risk losing their own rank. “True, smart social behavior in humans and in monkeys is dependent on a full adjustment to the context,” says Katalin Gothard, professor of physiology and neuroscience at the University of Arizona. Multiple brain areas keep track of social information. Among them, the amygdala—known for processing emotions—responds to faces, facial expressions and social status, and activates as people learn social hierarchies. But the brain adapts this information for different social settings, a new study reveals: Neurons in the macaque amygdala encode knowledge about social status in a context-specific way, Gothard and her colleagues discovered. Just like people, macaques can infer social standing from videos, and the activity of amygdala cells captures information about both the identity of the individual they are watching and how that animal relates to others in the scene. These findings help explain how primates process information about social position, says Ralph Adolphs, professor of psychology and neuroscience at California Institute of Technology, who was not involved in the work. And because the monkeys could successfully learn this information from videos, the results open up a new avenue for studying how the primate brain encodes these relationships in a complex and dynamic way, he adds. “That’s a big step forward.” Like people, macaques have no physical traits that directly convey dominance, Gothard says. “The status of these individuals is inferred.” So she and her colleagues tested two macaques’ ability to understand a hierarchy that the team invented among four unfamiliar monkeys in a series of videos. Each clip simulated status-appropriate interactions between two of the four monkeys on a split screen to convey those two animals’ relative positions: a scene of a higher-ranked animal acting aggressive juxtaposed with one of a lower-ranked monkey smacking its lips in appeasement, for example. © 2024 Simons Foundation

Keyword: Emotions; Attention
Link ID: 29544 - Posted: 11.06.2024

By Elle Hunt The first time Nick (not his real name) tried ketamine, he felt as if he’d entered another dimension. Though he smoked marijuana regularly and had experimented with other drugs, Nick had never even heard of ketamine. But when his friend pulled out a bag of white powder, “I did what anybody else would do at 20 years old. I tried it,” he says. “And I found it really fun, to be honest.” The floaty feeling, like he’d been lifted out of his own body, was “euphoric”, he says. “Like you’re in a fairy world.” Sixteen years later, reality is biting hard. Nick, now 36, has spent the past three months in recovery for ketamine addiction after more than a decade of heavy use. His bladder is a fifth of the size it should be, he says. It’s “more than likely” that it will have to be removed and replaced with a urostomy bag. That’s setting aside all the other “brutal things” he’s gone through as a consequence of ketamine addiction – from being bed-bound by pain to embarrassing bladder failures. Now six months clean, Nick still cannot last half an hour without needing to use the toilet. “I am now a disabled person, having been such a fit lad,” he says. Nick is sharing his story to warn others of the dangers of ketamine, which is rapidly emerging as gen Z’s recreational drug of choice. Widely used in human and veterinary medicine as an anaesthetic, in illicit use the class B substance is typically snorted for its dissociative effects. According to the most recent government figures, use in England and Wales has more than doubled since 2016; among 16- to 24-year-olds, it has more than tripled, and there are stories of addicts as young as 12 or 13. The story is similar elsewhere. In Australia, recreational use of ketamine was reported to have reached a record high last year. In the US, seizures of illicit ketamine grew by 349% between 2017 and 2022. The death of Friends actor Matthew Perry at the age of 54 from “acute effects” of ketamine raised awareness of the risks of addiction. © 2024 Guardian News & Media Limited o

Keyword: Drug Abuse
Link ID: 29543 - Posted: 11.06.2024