Chapter 17. Learning and Memory

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Links 1 - 20 of 1909

By Lara Lewington, It's long been known that our lifestyles can help to keep us healthier for longer. Now scientists are asking whether new technology can also help slow down the ageing process of our brains by keeping track of what happens to them as we get older. One sunny morning, 76-year-old Dutch-born Marijke and her husband Tom welcomed me in for breakfast at their home in Loma Linda, an hour east of Los Angeles. Oatmeal, chai seeds, berries, but no processed sugary cereal or coffee were served - a breakfast as pure as Loma Linda’s mission. Loma Linda has been identified as one of the world’s so-called Blue Zones, places where people have lengthier-than-average lifespans. In this case, it is the city’s Seventh-Day Adventist Church community who are living longer. They generally don’t drink alcohol or caffeine, stick to a vegetarian or even vegan diet and consider it a duty of their religion to look after their bodies as best they can. This is their “health message”, as they call it, and it has put them on the map - the city has been the subject of decades of research into why its residents live better for longer. Dr Gary Fraser from the University of Loma Linda told me members of the Seventh-Day Adventist community there can expect not only a longer lifespan, but an increased “healthspan” - that is, time spent in good health - of four to five years extra for women and seven years extra for men. Marijke and Tom had moved to the city later in life, but both were now firmly embedded in the community. Copyright 2024 BBC.

Keyword: Development of the Brain; Learning & Memory
Link ID: 29391 - Posted: 07.13.2024

Anna Bawden The idea that night owls who don’t go to bed until the early hours struggle to get anything done during the day may have to be revised. It turns out that staying up late could be good for our brain power as research suggests that people who identify as night owls could be sharper than those who go to bed early. Researchers led by academics at Imperial College London studied data from the UK Biobank study on more than 26,000 people who had completed intelligence, reasoning, reaction time and memory tests. They then examined how participants’ sleep duration, quality, and chronotype (which determines what time of day we feel most alert and productive) affected brain performance. They found that those who stay up late and those classed as “intermediate” had “superior cognitive function”, while morning larks had the lowest scores. Going to bed late is strongly associated with creative types. Artists, authors and musicians known to be night owls include Henri de Toulouse-Lautrec, James Joyce, Kanye West and Lady Gaga. But while politicians such as Margaret Thatcher, Winston Churchill and Barack Obama famously seemed to thrive on little sleep, the study found that sleep duration is important for brain function, with those getting between seven and nine hours of shut-eye each night performing best in cognitive tests. © 2024 Guardian News & Media Limited

Keyword: Biological Rhythms; Learning & Memory
Link ID: 29389 - Posted: 07.11.2024

By Shaena Montanari Five years ago, while working to develop a tool to label neurons active during seizures in mice, Quynh Anh Nguyen noticed something she had not seen before. “There was a particular region in the brain that seemed to light up really prominently,” she says. Nguyen, assistant professor of pharmacology at Vanderbilt University, had induced seizures in the animals by injecting kainic acid into the hippocampus—a common strategy to model temporal lobe epilepsy. The condition often involves hyperactivity in the anterior and middle regions of the hippocampus, but Nguyen’s mice also showed the activation in a tiny posterior part of the hippocampus that she was not familiar with. Nguyen brought the data to her then-supervisor Ivan Soltesz, professor of neurosciences and neurosurgery at Stanford University. Together they realized that these neurons were in an area called the fasciola cinereum—a subregion of the hippocampus so understudied, Soltesz says, that when Nguyen first asked him what it was, he had “no idea.” Despite the subregion’s obscurity, it looks to be an important and previously overlooked contributor to epilepsy in people who do not respond to anti-seizure medications or tissue ablation in the hippocampus, Nguyen and her colleagues say. Fasciola cinereum neurons were active during seizures in six people with drug-resistant epilepsy, the team reported in April. © 2024 Simons Foundation

Keyword: Epilepsy
Link ID: 29360 - Posted: 06.15.2024

By Max Kozlov A crucial brain signal linked to long-term memory falters in rats when they are deprived of sleep — which might help to explain why poor sleep disrupts memory formation1. Even a night of normal slumber after a poor night’s sleep isn’t enough to fix the brain signal. These results, published today in Nature, suggest that there is a “critical window for memory processing”, says Loren Frank, a neuroscientist at the University of California, San Francisco, who was not involved with the study. “Once you’ve lost it, you’ve lost it.” In time, these findings could lead to targeted treatments to improve memory, says study co-author Kamran Diba, a computational neuroscientist at the University of Michigan Medical School in Ann Arbor. Neurons in the brain seldom act alone; they are highly interconnected and often fire together in a rhythmic or repetitive pattern. One such pattern is the sharp-wave ripple, in which a large group of neurons fire with extreme synchrony, then a second large group of neurons does the same and so on, one after the other at a particular tempo. These ripples occur in a brain area called the hippocampus, which is key to memory formation. The patterns are thought to facilitate communication with the neocortex, where long-term memories are later stored. One clue to their function is that some of these ripples are accelerated re-runs of brain-activity patterns that occurred during past events. For example, when an animal visits a particular spot in its cage, a specific group of neurons in the hippocampus fires in unison, creating a neural representation of that location. Later, these same neurons might participate in sharp-wave ripples — as if they were rapidly replaying snippets of that experience. © 2024 Springer Nature Limited

Keyword: Learning & Memory; Sleep
Link ID: 29358 - Posted: 06.13.2024

By Yasemin Saplakoglu György Buzsáki first started tinkering with waves when he was in high school. In his childhood home in Hungary, he built a radio receiver, tuned it to various electromagnetic frequencies and used a radio transmitter to chat with strangers from the Faroe Islands to Jordan. He remembers some of these conversations from his “ham radio” days better than others, just as you remember only some experiences from your past. Now, as a professor of neuroscience at New York University, Buzsáki has moved on from radio waves to brain waves to ask: How does the brain decide what to remember? By studying electrical patterns in the brain, Buzsáki seeks to understand how our experiences are represented and saved as memories. New studies from his lab and others have suggested that the brain tags experiences worth remembering by repeatedly sending out sudden and powerful high-frequency brain waves. Known as “sharp wave ripples,” these waves, kicked up by the firing of many thousands of neurons within milliseconds of each other, are “like a fireworks show in the brain,” said Wannan Yang, a doctoral student in Buzsáki’s lab who led the new work, which was published in Science in March. They fire when the mammalian brain is at rest, whether during a break between tasks or during sleep. Sharp wave ripples were already known to be involved in consolidating memories or storing them. The new research shows that they’re also involved in selecting them — pointing to the importance of these waves throughout the process of long-term memory formation. It also provides neurological reasons why rest and sleep are important for retaining information. Resting and waking brains seem to run different programs: If you sleep all the time, you won’t form memories. If you’re awake all the time, you won’t form them either. “If you just run one algorithm, you will never learn anything,” Buzsáki said. “You have to have interruptions.” © 2024 the Simons Foundation.

Keyword: Learning & Memory
Link ID: 29322 - Posted: 05.23.2024

By Lee Alan Dugatkin 1 The complexity of animal social behavior is astonishing I have studied animal behavior for more than 35 years, so I’m rarely surprised at just how nuanced, subtle, and complex the social behavior of nonhuman animals can be. But, every once in a while, that “my goodness, how astonishing!” feeling—which I felt so often in graduate school—returns. That’s how I felt when I read Kevin Oh and Alexander Badyaev’s work on sexual selection and social networks in house finches (Haemorhous mexicanus). The house finches in question, I learned while researching my book, live on the campus of the University of Arizona, where, in 2003, Oh was doing his graduate work and Badyaev was a young assistant professor. Using data on thousands of finches they banded over six years, these two researchers were able to map the social network the birds relied on during breeding season. This network was composed of 25 “neighborhoods” with an average of 30 finches per group. Females rarely left their neighborhoods to interact with birds in other neighborhoods. But how much males moved around from one neighborhood to the next depended on their coloring. Those with plenty of red coloration—which females tend to prefer as mating partners—generally remained put, just like females. But drabber colored males were more likely to socialize across many neighborhoods. The question was why? The answer was what rekindled my own sense of awe in the power of natural selection to shape animal social behavior. When Oh and Bedyaev mapped reproductive success in their house finches, they found that the most colorful males did well no matter what neighborhood they were in. Drab males, however, had greater reproductive success if they tried their luck all around town—essentially, this allowed them to find just the spot where their relative coloration was greatest and therefore most likely to score them a mate. In other words, they learned to play the field, restructuring social networks in a way that served their purposes best. 2 Technology is radically changing how scientists study the behavior of animals © 2024 NautilusNext Inc.,

Keyword: Learning & Memory; Evolution
Link ID: 29305 - Posted: 05.14.2024

By Gayathri Vaidyanathan An orangutan in Sumatra surprised scientists when he was seen treating an open wound on his cheek with a poultice made from a medicinal plant. It’s the first scientific record of a wild animal healing a wound using a plant with known medicinal properties. The findings were published this week in Scientific Reports1. “It shows that orangutans and humans share knowledge. Since they live in the same habitat, I would say that’s quite obvious, but still intriguing to realize,” says Caroline Schuppli, a primatologist at the Max Planck Institute of Animal Behavior in Konstanz, Germany, and a co-author of the study. In 2009, Schuppli’s team was observing Sumatran orangutans (Pongo abelii) in the Gunung Leuser National Park in South Aceh, Indonesia, when a young male moved into the forest. He did not have a mature male’s big cheek pads, called flanges, and was probably around 20 years old, Schuppli says. He was named Rakus, or ‘greedy’ in Indonesian, after he ate all the flowers off a gardenia bush in one sitting. In 2021, Rakus underwent a growth spurt and became a mature flanged male. The researchers observed Rakus fighting with other flanged males to establish dominance and, in June 2022, a field assistant noted an open wound on his face, possibly made by the canines of another male, Schuppli says. Days later, Rakus was observed eating the stems and leaves of the creeper akar kuning (Fibraurea tinctoria), which local people use to treat diabetes, dysentery and malaria, among other conditions. Orangutans in the area rarely eat this plant. In addition to eating the leaves, Rakus chewed them without swallowing and used his fingers to smear the juice on his facial wound over seven minutes. Some flies settled on the wound, whereupon Rakus spread a poultice of leaf-mash on the wound. He ate the plant again the next day. Eight days after his injury, his wound was fully closed. © 2024 Springer Nature Limited

Keyword: Learning & Memory; Evolution
Link ID: 29290 - Posted: 05.03.2024

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 Diana Kwon Overall, people in U.S. live longer than they did a hundred years ago. The growing number of people reaching old age has meant an increased proportion are at risk of developing dementia or Alzheimer’s disease, illnesses that typically strike later in life. However, researchers have found that, in the U.S. and elsewhere, dementia risk may actually be decreasing, at least in a subset of the population. A new study provides a potential explanation for this trend: Human brains may be getting larger—and thus more resilient to degeneration—over time. Several large population studies in countries including the U.S. and Great Britain have found that, in recent decades, the number of new cases, or incidence, of dementia has declined. Among these is the Framingham Heart Study, which has been collecting data from individuals living in Framingham, Massachusetts since 1948. Now accommodating a third generation of participants, the study includes data from more than 15,000 people. In 2016, Sudha Seshadri, a neurologist at UT Health San Antonio and her colleagues published findings revealing that while the prevalence—the total number of people with dementia—had increased, the incidence had declined since the late 1970s. “That was a piece of hopeful news,” Seshadri says. “It suggested that over 30 years, the average age at which somebody became symptomatic had gone up.” These findings left the team wondering: What was the cause of this reduced dementia risk? While the cardiovascular health of the Framingham residents and their descendants—which can influence the chances of developing dementia—had also improved over the decades, this alone could not fully explain the decline. On top of that, the effect only appeared in people who had obtained a high school diploma, which, according to Seshadri, pointed to the possibility that greater resilience against dementia may result from changes that occur in early life. © 2024 SCIENTIFIC AMERICAN,

Keyword: Development of the Brain; Learning & Memory
Link ID: 29265 - Posted: 04.20.2024

By Bob Holmes Like many of the researchers who study how people find their way from place to place, David Uttal is a poor navigator. “When I was 13 years old, I got lost on a Boy Scout hike, and I was lost for two and a half days,” recalls the Northwestern University cognitive scientist. And he’s still bad at finding his way around. The world is full of people like Uttal — and their opposites, the folks who always seem to know exactly where they are and how to get where they want to go. Scientists sometimes measure navigational ability by asking someone to point toward an out-of-sight location — or, more challenging, to imagine they are someplace else and point in the direction of a third location — and it’s immediately obvious that some people are better at it than others. “People are never perfect, but they can be as accurate as single-digit degrees off, which is incredibly accurate,” says Nora Newcombe, a cognitive psychologist at Temple University who coauthored a look at how navigational ability develops in the 2022 Annual Review of Developmental Psychology. But others, when asked to indicate the target’s direction, seem to point at random. “They have literally no idea where it is.” While it’s easy to show that people differ in navigational ability, it has proved much harder for scientists to explain why. There’s new excitement brewing in the navigation research world, though. By leveraging technologies such as virtual reality and GPS tracking, scientists have been able to watch hundreds, sometimes even millions, of people trying to find their way through complex spaces, and to measure how well they do. Though there’s still much to learn, the research suggests that to some extent, navigation skills are shaped by upbringing. Nurturing navigation skills

Keyword: Learning & Memory
Link ID: 29255 - Posted: 04.13.2024

By Nicole Rust We readily (and reasonably) accept that the causes of memory dysfunction, including Alzheimer’s disease, reside in the brain. The same is true for many problems with seeing, hearing and motor control. We acknowledge that understanding how the brain supports these functions is important for developing treatments for their corresponding dysfunctions, including blindness, deafness and Parkinson’s disease. Applying the analogous assertion to mood—that understanding how the brain supports mood is crucial for developing more effective treatments for mood disorders, such as depression—is more controversial. For brain researchers unfamiliar with the controversy, it can be befuddling. You might hear, “Mental disorders are psychological, not biological,” and wonder, what does that mean, exactly? Experts have diverse opinions on the matter, with paper titles ranging from “Brain disorders? Not really,” to “Brain disorders? Precisely.” Even though a remarkable 21 percent of adults in the United States will experience a mood disorder at some point in their lives, we do not fully understand what causes them, and existing treatments do not work for everyone. How can we best move toward an impactful understanding of mood and mood disorders, with the longer-term goal of helping these people? What, if anything, makes mood fundamentally different from, say, memory? The answer turns out to be complex and nuanced—here, I hope to unpack it. I also ask brain and mind researchers with diverse perspectives to chime in. Among contemporary brain and mind researchers, I have yet to find any whose position is driven by the notion that some force in the universe beyond the brain, like a nonmaterial soul, gives rise to mood. Rather, the researchers generally agree that our brains mediate all mental function. If everyone agrees that both memory and mood disorders follow from things that happen in the brain, why would the former but not the latter qualify as “brain disorders”? © 2024 Simons Foundation

Keyword: Depression; Learning & Memory
Link ID: 29251 - Posted: 04.11.2024

By Markham Heid The human hand is a marvel of nature. No other creature on Earth, not even our closest primate relatives, has hands structured quite like ours, capable of such precise grasping and manipulation. But we’re doing less intricate hands-on work than we used to. A lot of modern life involves simple movements, such as tapping screens and pushing buttons, and some experts believe our shift away from more complex hand activities could have consequences for how we think and feel. “When you look at the brain’s real estate — how it’s divided up, and where its resources are invested — a huge portion of it is devoted to movement, and especially to voluntary movement of the hands,” said Kelly Lambert, a professor of behavioral neuroscience at the University of Richmond in Virginia. Dr. Lambert, who studies effort-based rewards, said that she is interested in “the connection between the effort we put into something and the reward we get from it” and that she believes working with our hands might be uniquely gratifying. In some of her research on animals, Dr. Lambert and her colleagues found that rats that used their paws to dig up food had healthier stress hormone profiles and were better at problem solving compared with rats that were given food without having to dig. She sees some similarities in studies on people, which have found that a whole range of hands-on activities — such as knitting, gardening and coloring — are associated with cognitive and emotional benefits, including improvements in memory and attention, as well as reductions in anxiety and depression symptoms. These studies haven’t determined that hand involvement, specifically, deserves the credit. The researchers who looked at coloring, for example, speculated that it might promote mindfulness, which could be beneficial for mental health. Those who have studied knitting said something similar. “The rhythm and repetition of knitting a familiar or established pattern was calming, like meditation,” said Catherine Backman, a professor emeritus of occupational therapy at the University of British Columbia in Canada who has examined the link between knitting and well-being. © 2024 The New York Times Company

Keyword: Learning & Memory; Stress
Link ID: 29231 - Posted: 04.02.2024

By Marta Zaraska The renowned Polish piano duo Marek and Wacek didn’t use sheet music when playing live concerts. And yet onstage the pair appeared perfectly in sync. On adjacent pianos, they playfully picked up various musical themes, blended classical music with jazz and improvised in real time. “We went with the flow,” said Marek Tomaszewski, who performed with Wacek Kisielewski until Wacek’s death in 1986. “It was pure fun.” The pianists seemed to read each other’s minds by exchanging looks. It was, Marek said, as if they were on the same wavelength. A growing body of research suggests that might have been literally true. Dozens of recent experiments studying the brain activity of people performing and working together — duetting pianists, card players, teachers and students, jigsaw puzzlers and others — show that their brain waves can align in a phenomenon known as interpersonal neural synchronization, also known as interbrain synchrony. “There’s now a lot of research that shows that people interacting together display coordinated neural activities,” said Giacomo Novembre, a cognitive neuroscientist at the Italian Institute of Technology in Rome, who published a key paper on interpersonal neural synchronization last summer. The studies have come out at an increasing clip over the past few years — one as recently as last week — as new tools and improved techniques have honed the science and theory. They’re finding that synchrony between brains has benefits. It’s linked to better problem-solving, learning and cooperation, and even with behaviors that help others at a personal cost. What’s more, recent studies in which brains were stimulated with an electric current hint that synchrony itself might cause the improved performance observed by scientists. © 2024 the Simons Foundation.

Keyword: Attention
Link ID: 29229 - Posted: 03.30.2024

By Jake Buehler Much like squirrels, black-capped chickadees hide their food, keeping track of many thousands of little treasures wedged into cracks or holes in tree bark. When a bird returns to one of their many food caches, a particular set of nerve cells in the memory center of their brains gives a brief flash of activity. When the chickadee goes to another stash, a different combination of neurons lights up. These neural combinations act like bar codes, and identifying them may give key insights into how episodic memories — accounts of specific past events, like what you did on your birthday last year or where you’ve left your wallet — are encoded and recalled in the brain, researchers report March 29 in Cell. This kind of memory is challenging to study in animals, says Selmaan Chettih, a neuroscientist at Columbia University. “You can’t just ask a mouse what memories it formed today.” But chickadees’ very precise behavior provides a golden opportunity for researchers. Every time a chickadee makes a cache, it represents a single, well-defined moment logged in the hippocampus, a structure in the vertebrate brain vital for memory. To study the birds’ episodic memory, Chettih and his colleagues built a special arena made of 128 small, artificial storage sites. The team inserted small probes into five chickadees’ brains to track the electrical activity of individual neurons, comparing that activity with detailed recordings of the birds’ body positions and behaviors. A black-capped chickadee stores sunflower seeds in an artificial arena made of 128 different perches and pockets. These birds excel at finding their hidden food stashes. The aim of the setup was to see how their brain stores and retrieves the memory of each hidey-hole. Researchers closely observed five chickadees, comparing their caching behavior with the activity from nerve cells in their hippocampus, the brain’s memory center. © Society for Science & the Public 2000–2024.

Keyword: Learning & Memory
Link ID: 29228 - Posted: 03.30.2024

By Angie Voyles Askham For Christopher Zimmerman, it was oysters: After a bout of nausea on a beach vacation, he could hardly touch the mollusks for months. For others, that gut-lurching trigger is white chocolate, margaritas or spicy cinnamon candy. Whatever the taste, most people know the feeling of not being able to stomach a food after it has caused—or seemed to cause—illness. That response helps us learn which foods are safe, making it essential for survival. But how the brain links an unpleasant gastric event to food consumed hours prior has long posed a mystery, says Zimmerman, who is a postdoctoral fellow in Ilana Witten’s lab at Princeton University. The time scale for this sort of conditioned food aversion is an order of magnitude different from other types of learning, which involve delays of only a few seconds, says Peter Dayan, director of computational neuroscience at the Max Planck Institute for Biological Cybernetics, who was not involved in the work. “You need to have something that bridges that gap in time” between eating and feeling ill, he says. A newly identified neuronal circuit can do just that. Neurons in the mouse brainstem that respond to drug-induced nausea reactivate a specific subset of cells in the animals’ central amygdala that encode information about a recently tasted food. And that reactivation happens with novel—but not familiar—flavors, according to work that Zimmerman presented at the annual COSYNE meeting in Lisbon last month. With new flavors, animals seem primed to recall a recent meal if they get sick, Zimmerman says. As he put it in his talk, “it suggests that the common phrase we associate with unexpected nausea, that ‘it must be something I ate,’ is literally built into the brain in the form of this evolutionarily hard-wired prior.” © 2024 Simons Foundation

Keyword: Learning & Memory; Evolution
Link ID: 29226 - Posted: 03.30.2024

By Max Kozlov Neurons (shown here in a coloured scanning electron micrograph) mend broken DNA during memory formation. Credit: Ted Kinsman/Science Photo Library When a long-term memory forms, some brain cells experience a rush of electrical activity so strong that it snaps their DNA. Then, an inflammatory response kicks in, repairing this damage and helping to cement the memory, a study in mice shows. The findings, published on 27 March in Nature1, are “extremely exciting”, says Li-Huei Tsai, a neurobiologist at the Massachusetts Institute of Technology in Cambridge who was not involved in the work. They contribute to the picture that forming memories is a “risky business”, she says. Normally, breaks in both strands of the double helix DNA molecule are associated with diseases including cancer. But in this case, the DNA damage-and-repair cycle offers one explanation for how memories might form and last. It also suggests a tantalizing possibility: this cycle might be faulty in people with neurodegenerative diseases such as Alzheimer’s, causing a build-up of errors in a neuron’s DNA, says study co-author Jelena Radulovic, a neuroscientist at the Albert Einstein College of Medicine in New York City. This isn’t the first time that DNA damage has been associated with memory. In 2021, Tsai and her colleagues showed that double-stranded DNA breaks are widespread in the brain, and linked them with learning2. To better understand the part these DNA breaks play in memory formation, Radulovic and her colleagues trained mice to associate a small electrical shock with a new environment, so that when the animals were once again put into that environment, they would ‘remember’ the experience and show signs of fear, such as freezing in place. Then the researchers examined gene activity in neurons in a brain area key to memory — the hippocampus. They found that some genes responsible for inflammation were active in a set of neurons four days after training. Three weeks after training, the same genes were much less active. © 2024 Springer Nature Limited

Keyword: Learning & Memory; Genes & Behavior
Link ID: 29223 - Posted: 03.28.2024

By Ingrid Wickelgren You see a woman on the street who looks familiar—but you can’t remember how you know her. Your brain cannot attach any previous experiences to this person. Hours later, you suddenly recall the party at a friend’s house where you met her, and you realize who she is. In a new study in mice, researchers have discovered the place in the brain that is responsible for both types of familiarity—vague recognition and complete recollection. Both, moreover, are represented by two distinct neural codes. The findings, which appeared on February 20 in Neuron, showcase the use of advanced computer algorithms to understand how the brain encodes concepts such as social novelty and individual identity, says study co-author Steven Siegelbaum, a neuroscientist at the Mortimer B. Zuckerman Mind Brain Behavior Institute at Columbia University. The brain’s signature for strangers turns out to be simpler than the one used for old friends—which makes sense, Siegelbaum says, given the vastly different memory requirements for the two relationships. “Where you were, what you were doing, when you were doing it, who else [was there]—the memory of a familiar individual is a much richer memory,” Siegelbaum says. “If you’re meeting a stranger, there’s nothing to recollect.” The action occurs in a small sliver of a brain region called the hippocampus, known for its importance in forming memories. The sliver in question, known as CA2, seems to specialize in a certain kind of memory used to recall relationships. “[The new work] really emphasizes the importance of this brain area to social processing,” at least in mice, says Serena Dudek, a neuroscientist at the National Institute of Environmental Health Sciences, who was not involved in the study. © 2024 SCIENTIFIC AMERICAN,

Keyword: Attention; Learning & Memory
Link ID: 29222 - Posted: 03.28.2024

By Holly Barker Our understanding of memory is often summed up by a well-worn mantra: Neurons that fire together wire together. Put another way, when two brain cells simultaneously send out an impulse, their synapses strengthen, whereas connections between less active neurons slowly diminish. But there may be more to it, a new preprint suggests: To consolidate memories, synapses may also influence neighboring neurons by using a previously unknown means of communication. When synapses strengthen, they release a virus-like particle that weakens the surrounding cells’ connections, the new work shows. This novel form of plasticity may aid memory by helping some synapses to shout above the background neuronal hubbub, the researchers say. The mechanism involves the neuronal gene ARC, which is known to contribute to learning and memory and encodes a protein that assembles into virus-like capsids—protein shells that viruses use to package and spread their genetic material. ARC capsids enclose ARC messenger RNA and transfer it to nearby neurons, according to a 2018 study. This leads to an increase in ARC protein and, in turn, a decrease in the number of excitatory AMPA receptors at those cells’ synapses, the preprint shows. “ARC has this crazy virus-like biology,” says Jason Shepherd, associate professor of neurobiology at the University of Utah, who led the 2018 study and the new work. But how ARC capsids form and eject from neurons was unclear, he says. As it turns out, synaptic strengthening spurs ARC capsid release, according to the preprint. When neuronal connections strengthen, ARC capsids are packaged into vesicles, which then bubble out of neurons through their interactions with a protein called IRSp53. Surrounding cells absorb the vesicles containing ARC, which tamps down their synapses, the new work suggests. © 2024 Simons Foundation

Keyword: Learning & Memory
Link ID: 29209 - Posted: 03.23.2024

By Shaena Montanari When Nacho Sanguinetti-Scheck came across a seal study in Science in 2023, he saw it as confirmation of the “wild” research he had recently been doing himself. In the experiment, the researchers had attached portable, noninvasive electroencephalogram caps, custom calibrated to sense brain waves through blubber, to juvenile northern elephant seals. After testing the caps on five seals in an outdoor pool, the team attached the caps to eight seals free-swimming in the ocean. The results were striking: In the pool, the seals slept for six hours a day, but in the open ocean, they slept for just about two. And when seals were in REM sleep in the ocean, they flipped belly up and slowly spiraled downward, hundreds of meters below the surface. It was “one of my favorite papers of the past years,” says Sanguinetti-Scheck, a Harvard University neuroscience postdoctoral researcher who studies rodent behavior in the wild. “It’s just beautiful.” It was also the kind of experiment that needed to be done beyond the confines of a lab setting, he says. “You cannot see that in a pool.” Sanguinetti-Scheck is part of a growing cadre of researchers who champion the importance of studying animal behavior in the wild. Studying animals in the environment in which they evolved, these researchers say, can provide neuroscientific insight that is truly correlated with natural behavior. But not everyone agrees. In February, a group of about two dozen scientists and philosophers gathered in snowy, mountainous Terzolas, Italy, to wrestle with what, exactly, “natural behavior” means. “People don’t really think, ‘Well, what does it mean?’” says Mateusz Kostecki, a doctoral student at Nencki Institute of Experimental Biology in Poland. He helped organize the four-day workshop as “a good occasion to think critically about this trend.” © 2024 Simons Foundation

Keyword: Evolution; Sleep
Link ID: 29205 - Posted: 03.21.2024

By Claudia López Lloreda Loss of smell, headaches, memory problems: COVID-19 can bring about a troubling storm of neurological symptoms that make everyday tasks difficult. Now new research adds to the evidence that inflammation in the brain might underlie these symptoms. Not all data point in the same direction. Some new studies suggest that SARS-CoV-2, the virus that causes COVID-19, directly infects brain cells. Those findings bolster the hypothesis that direct infection contributes to COVID-19-related brain problems. But the idea that brain inflammation is key has gotten fresh support: one study, for example, has identified specific brain areas prone to inflammation in people with COVID-191. “The whole body of literature is starting to come together a little bit more now and give us some more concrete answers,” says Nicola Fletcher, a neurovirologist at University College Dublin. Immunological storm When researchers started looking for a culprit for the brain problems caused by COVID-19, inflammation quickly became a key suspect. That’s because inflammation — the flood of immune cells and chemicals that the body releases against intruders — has been linked to the cognitive symptoms caused by other viruses, such as HIV. SARS-CoV-2 stimulates a strong immune response throughout the body, but it was unclear whether brain cells themselves contributed to this response and, if so, how. Helena Radbruch, a neuropathologist at the Charité – Berlin University Medicine, and her colleagues looked at brain samples from people who’d died of COVID-19. They didn’t find any cells infected with SARS-CoV-2. But they did find these people had more immune activity in certain brain areas than did people who died from other causes. This unusual activity was noticeable in regions such as the olfactory bulb, which is involved in smell, and the brainstem, which controls some bodily functions, such as breathing. It was seen only in the brains of people who had died soon after catching the virus. © 2024 Springer Nature Limited

Keyword: Learning & Memory; Attention
Link ID: 29202 - Posted: 03.21.2024