Chapter 17. Learning and Memory

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Jon Hamilton People who have had a stroke appear to regain more hand and arm function if intensive rehabilitation starts two to three months after the injury to their brain. A study of 72 stroke patients suggests this is a "critical period," when the brain has the greatest capacity to rewire, a team reports in this week's journal PNAS. The finding challenges the current practice of beginning rehabilitation as soon as possible after a stroke and suggests intensive rehabilitation should go on longer than most insurance coverage allows, says Elissa Newport, a co-author of the study and director of the Center for Brain Plasticity and Recovery at Georgetown University Medical Center. Newport was speaking in place of the study's lead author, Dr. Alexander Dromerick, who died after the study was accepted but before it was published. If the results are confirmed with other larger studies, "the clinical protocol for the timing of stroke rehabilitation would be changed," says Li-Ru Zhao, a professor of neurosurgery at Upstate Medical University in Syracuse, N.Y., who was not involved in the research. The study involved patients treated at Medstar National Rehabilitation Hospital in Washington, D.C., most in their 50s and 60s. One of the study participants was Anthony McEachern, who was 45 when he had a stroke in 2017. Just a few hours earlier, McEachern had been imitating Michael Jackson dance moves with his kids. But at home that night he found himself unable stand up. © 2021 npr

Keyword: Stroke; Learning & Memory
Link ID: 28002 - Posted: 09.22.2021

David Kleinfeld My colleagues and I recently found that we were able to train mice to voluntarily increase the size and frequency of seemingly random dopamine impulses in their brains. Conventional wisdom in neuroscience has held that dopamine levels change solely in response to cues from the world outside of the brain. Our new research shows that increases in dopamine can also be driven by internally mediated changes within the brain. Dopamine is a small molecule found in the brains of mammals and is associated with feelings of reward and happiness. In 2014, my colleagues and I invented a new method to measure dopamine in real time in different parts of the brains of mice. Using this new tool, my former thesis student, Conrad Foo, found that neurons in the brains of mice release large bursts of dopamine – called impulses – for no easily apparent reason. This occurs at random times, but on average about once a minute. Pavlov was famously able to train his dogs to salivate at the sound of a bell, not the sight of food. Today, scientists believe that the bell sound caused a release of dopamine to predict the forthcoming reward. If Pavlov’s dogs could control their cue-based dopamine responses with a little training, we wondered if our mice could control their spontaneous dopamine impulses. To test this, our team designed an experiment that rewarded mice if they increased the strength of their spontaneous dopamine impulses. The mice were able to not only increase how strong these dopamine releases were, but also how often they occurred. When we removed the possibility of a reward, the dopamine impulses returned to their original levels. In the 1990s, neuroscientist Wolfram Schultz discovered that an animal’s brain will release dopamine if the animal expects a reward, not just when receiving a reward. This showed that dopamine can be produced in response to the expectation of a reward, not just the reward itself – the aforementioned modern version of Pavlov’s dog. © 2010–2021, The Conversation US, Inc.

Keyword: Drug Abuse; Learning & Memory
Link ID: 27993 - Posted: 09.15.2021

Sophie Fessl The hormone irisin is necessary for the cognitive benefits of exercise in healthy mice and can rescue cognitive decline associated with Alzheimer’s disease, according to a study published August 20 in Nature Metabolism. According to the authors, these results support the hypothesis that irisin undergirds the cognitive benefits of exercise—a link that has been long debated. In addition, this study has “paved the way for thinking whether irisin could be a therapeutic agent against Alzheimer’s disease,” says biologist Steffen Maak with the Leibniz Institute for Farm Animal Biology in Germany, who has been critical of the methods used to study irisin in the past and was not involved in the study. Many studies have found that exercise is good for the brain, but the molecular mechanisms responsible for the cognitive boost have remained elusive. During her postdoctoral studies, neuroscientist Christiane Wrann found that the gene that codes for irisin becomes highly expressed in the brain during exercise—one of the first studies linking irisin with the brain. See “Irisin Skepticism Goes Way Back” When she joined the faculties at Massachusetts General Hospital and Harvard Medical School, she decided to investigate the hormone further. Wrann, who holds a patent related to irisin and is academic cofounder and consultant for Aevum Therapeutics, a company developing drugs that harness the protective molecular mechanisms of exercise to treat neurodegenerative and neuromuscular disorders, began to investigate whether irisin mediates the positive effects of exercise on the brain. © 1986–2021 The Scientist.

Keyword: Learning & Memory; Hormones & Behavior
Link ID: 27985 - Posted: 09.13.2021

By Nicholas Bakalar Many animals are known to use tools, but a bird named Bruce may be one of the most ingenious nonhuman tool inventors of all: He is a disabled parrot who has designed and uses his own prosthetic beak. Bruce is a kea, a species of parrot found only in New Zealand. He is about 9 years old, and when wildlife researchers found him as a baby, he was missing his upper beak, probably because it had been caught in a trap made for rats and other invasive mammals the country was trying to eliminate. This is a severe disability, as kea use their dramatically long and curved upper beaks for preening their feathers to get rid of parasites and to remove dirt and grime. But Bruce found a solution: He has taught himself to pick up pebbles of just the right size, hold them between his tongue and his lower beak, and comb through his plumage with the tip of the stone. Other animals use tools, but Bruce’s invention of his own prosthetic is unique. Researchers published their findings Friday in the journal Scientific Reports. Studies of animal behavior are tricky — the researchers have to make careful, objective observations and always be wary of bias caused by anthropomorphizing, or erroneously attributing human characteristics to animals. “The main criticism we received before publication was, ‘Well, this activity with the pebbles may have been just accidental — you saw him when coincidentally he had a pebble in his mouth,’” said Amalia P.M. Bastos, an animal cognition researcher at the University of Auckland and the study’s lead author. “But no. This was repeated many times. He drops the pebble, he goes and picks it up. He wants that pebble. If he’s not preening, he doesn’t pick up a pebble for anything else.” Dorothy M. Fragaszy, an emerita professor of psychology at the University of Georgia who has published widely on animal behavior but was unacquainted with Bruce’s exploits, praised the study as a model of how to study tool use in animals. © 2021 The New York Times Company

Keyword: Intelligence; Evolution
Link ID: 27984 - Posted: 09.11.2021

Jordana Cepelewicz Faced with a threat, the brain has to act fast, its neurons making new connections to learn what might spell the difference between life and death. But in its response, the brain also raises the stakes: As an unsettling recent discovery shows, to express learning and memory genes more quickly, brain cells snap their DNA into pieces at many key points, and then rebuild their fractured genome later. The finding doesn’t just provide insights into the nature of the brain’s plasticity. It also demonstrates that DNA breakage may be a routine and important part of normal cellular processes — which has implications for how scientists think about aging and disease, and how they approach genomic events they’ve typically written off as merely bad luck. The discovery is all the more surprising because DNA double-strand breaks, in which both rails of the helical ladder get cut at the same position along the genome, are a particularly dangerous kind of genetic damage associated with cancer, neurodegeneration and aging. It’s more difficult for cells to repair double-strand breaks than other kinds of DNA damage because there isn’t an intact “template” left to guide the reattachment of the strands. Yet it’s also long been recognized that DNA breakage sometimes plays a constructive role, too. When cells are dividing, double-strand breaks allow for the normal process of genetic recombination between chromosomes. In the developing immune system, they enable pieces of DNA to recombine and generate a diverse repertoire of antibodies. Double-strand breaks have also been implicated in neuronal development and in helping turn certain genes on. Still, those functions have seemed like exceptions to the rule that double-strand breaks are accidental and unwelcome. All Rights Reserved © 2021

Keyword: Learning & Memory; Epigenetics
Link ID: 27975 - Posted: 09.01.2021

Virginia Morell Goffin’s cockatoos (Cacatua goffiniana) are so smart they’ve been compared to 3-year-old humans. But what 3-year-old has made their own cutlery set? Scientists have observed wild cockatoos, members of the parrot family, crafting the equivalent of a crowbar, an ice pick, and a spoon to pry open one of their favorite fruits. This is the first time any bird species has been seen creating and using a set of tools in a specific order—a cognitively challenging behavior previously known only in humans, chimpanzees, and capuchin monkeys. The work “supports the idea that parrots have a general [type of] intelligence that allows them to innovate creative solutions to the problems they run into in nature,” says Alex Taylor, a biologist who studies New Caledonian crows at the University of Auckland. “[It] establishes this species as one of the avian family’s most proficient wild tool users.” The discovery happened serendipitously when behavioral ecologist Mark O’Hara was working with wild but captive birds in a research aviary on Yamdena Island in Indonesia. “I’d just turned away, and when I looked back, one of the birds was making and using tools,” says O’Hara, of the Messerli Research Institute. “I couldn’t believe my eyes!” The Goffin’s cockatoo is known for being a clever and innovative social learner. In captivity, the birds have solved complex puzzle boxes and invented rakelike tools to retrieve objects. Several other birds, including hyacinth macaws and New Caledonian crows, make and use tools in the wild, often to extract food, but none seems to make a set of tools. For the new study, O’Hara and his colleagues traveled to this cockatoo’s home on Indonesia’s Tanimbar Islands. The birds live high in the tropical forest canopy, making them difficult to observe. The scientists spent almost 900 hours looking up to watch wild cockatoos feed, but didn’t witness tool use.

Keyword: Learning & Memory; Intelligence
Link ID: 27974 - Posted: 09.01.2021

Terry Gross Human beings are programmed to approach pleasure and avoid pain. It's an instinct that dates back millions of years, to a time when people needed to actively seek food, clothing and shelter every day, or risk death. But psychiatrist Anna Lembke says that in today's world, such basic needs are often readily available — which changes the equation. "Living in this modern age is very challenging. ... We're now having to cope with: How do I live in a world in which everything is provided?" Lembke says. "And if I consume too much of it — which my reflexes compel me to do — I'm going to be even more unhappy." Lembke is the medical director of addiction medicine at Stanford University and chief of the Stanford Addiction Medicine Dual Diagnosis Clinic. Her new book, Dopamine Nation, explores the interconnection of pleasure and pain in the brain and helps explain addictive behaviors — not just to drugs and alcohol, but also to food, sex and smart phones. Lembke says that her patients who are struggling with substance abuse often believe their addictions are fueled by depression, anxiety and insomnia. But she maintains that the reverse is often true: Addictions can become the cause of pain — not the relief from it. That's because the behavior triggers, among other things, an initial response of the neurotransmitter dopamine, which floods the brain with pleasure. But once the dopamine wears off, a person is often left feeling worse than before. "They start out using the drug in order to feel good or in order to experience less pain," Lembke says. "Over time, with repeated exposure, that drug works less and less well. But they find themselves unable to stop, because when they're not using, then they're in a state of a dopamine deficit." © 2021 npr

Keyword: Drug Abuse; Learning & Memory
Link ID: 27964 - Posted: 08.28.2021

By Gretchen Reynolds An intriguing new study shows how exercise may bolster brain health. The study was in mice, but it found that a hormone produced by muscles during exercise can cross into the brain and enhance the health and function of neurons, improving thinking and memory in both healthy animals and those with a rodent version of Alzheimer’s disease. Earlier research shows that people produce the same hormone during exercise, and together the findings suggest that moving could alter the trajectory of memory loss in aging and dementia. We have plenty of evidence already that exercise is good for the brain. Studies in both people and animals show that exercise prompts the creation of new neurons in the brain’s memory center and then helps those new cells survive, mature and integrate into the brain’s neural network, where they can aid in thinking and remembering. Large-scale epidemiological studies also indicate that active people tend to be far less likely to develop Alzheimer’s disease and other forms of dementia than people who rarely exercise. But how does working out affect the inner workings of our brains at a molecular level? Scientists have speculated that exercise might directly change the biochemical environment inside the brain, without involving muscles. Alternatively, the muscles and other tissues might release substances during physical activity that travel to the brain and jump-start processes there, leading to the subsequent improvements in brain health. But in that case, the substances would have to be able to pass through the protective and mostly impermeable blood-brain barrier that separates our brains from the rest of our bodies. Those tangled issues were of particular interest a decade ago to a large group of scientists at Harvard Medical School and other institutions. In 2012, some of these researchers, led by Bruce M. Spiegelman, the Stanley J. Korsmeyer Professor of Cell Biology and Medicine at the Dana-Farber Cancer Institute and Harvard Medical School, identified a previously unknown hormone produced in the muscles of lab rodents and people during exercise and then released into the bloodstream. They named the new hormone irisin, after the messenger god Iris in Greek mythology. © 2021 The New York Times Company

Keyword: Learning & Memory; Muscles
Link ID: 27961 - Posted: 08.25.2021

By Paula Span Learning your odds of eventually developing dementia — a pressing concern for many, especially those with a family history of it — requires medical testing and counseling. But what if everyday behavior, like overlooking a couple of credit card payments or habitually braking while driving, could foretell your risk? A spate of experiments is underway to explore that possibility, reflecting the growing awareness that the pathologies underlying dementia can begin years or even decades before symptoms emerge. “Early detection is key for intervention, at the stage when that would be most effective,” said Sayeh Bayat, the lead author of a driving study funded by the National Institutes of Health and conducted at Washington University in St. Louis. Such efforts could help identify potential volunteers for clinical trials, researchers say, and help protect older people against financial abuse and other dangers. In recent years, many once-promising dementia drugs, particularly for Alzheimer’s disease, have failed in trials. One possible reason, researchers say, is that the drugs are administered too late to be helpful. Identifying risks earlier, when the brain has sustained less damage, could create a pool of potential participants with “preclinical” Alzheimer’s disease, who could then test preventive measures or treatments. It could also bring improvements in daily life. “We could support people’s ability to drive longer, and have safer streets for everyone,” Ms. Bayat offered as an example. © 2021 The New York Times Company

Keyword: Alzheimers; Learning & Memory
Link ID: 27959 - Posted: 08.25.2021

Natalie Grover Cuttlefish have one of the largest brains among invertebrates and can remember what, where, and when specific things happened right up to their final days of life, according to new research. The cephalopods – which have three hearts, eight arms, blue-green blood, regenerating limbs, and the ability to camouflage and exert self-control – only live for roughly two years. As they get older, they show signs of declining muscle function and appetite, but it appears that no matter their age they can remember what they ate, where and when, and use this to guide their future feeding decisions, said the lead study author, Dr Alexandra Schnell from the University of Cambridge. This is in contrast to humans, who gradually lose the ability to remember experiences that occurred at a particular time and place with age – for instance, what you ate for lunch last Wednesday. This “episodic memory” and its deterioration is linked to the hippocampus, a seahorse-shaped organ in the part of the brain near our ears. Cuttlefish, meanwhile, do not have a hippocampus, but a “vertical lobe” associated with learning and memory. In the study, Schnell and her colleagues conducted memory tests in 24 cuttlefish. Half were 10-12 months old (not quite adults) while the rest were 22-24 months old (the equivalent of a human in their 90s), according to the paper, published in the journal Proceedings of the Royal Society B. In one experiment, both groups of cuttlefish were first trained to approach a specific location in their tank, marked with a flag, and learn that two different foods would be provided at different times. At one spot, the flag was waved and the less-preferred king prawn was provided every hour. Grass shrimp, which they like more, was provided at a different spot where another flag was waved – but only every three hours. This was done for about four weeks, until they learned that waiting for longer meant that they could get their preferred food. © 2021 Guardian News & Media Limited

Keyword: Learning & Memory; Evolution
Link ID: 27951 - Posted: 08.18.2021

Jordana Cepelewicz An understanding of numbers is often viewed as a distinctly human faculty — a hallmark of our intelligence that, along with language, sets us apart from all other animals. But that couldn’t be further from the truth. Honeybees count landmarks when navigating toward sources of nectar. Lionesses tally the number of roars they hear from an intruding pride before deciding whether to attack or retreat. Some ants keep track of their steps; some spiders keep track of how many prey are caught in their web. One species of frog bases its entire mating ritual on number: If a male calls out — a whining pew followed by a brief pulsing note called a chuck — his rival responds by placing two chucks at the end of his own call. The first frog then responds with three, the other with four, and so on up to around six, when they run out of breath. Practically every animal that scientists have studied — insects and cephalopods, amphibians and reptiles, birds and mammals — can distinguish between different numbers of objects in a set or sounds in a sequence. They don’t just have a sense of “greater than” or “less than,” but an approximate sense of quantity: that two is distinct from three, that 15 is distinct from 20. This mental representation of set size, called numerosity, seems to be “a general ability,” and an ancient one, said Giorgio Vallortigara, a neuroscientist at the University of Trento in Italy. Now, researchers are uncovering increasingly more complex numerical abilities in their animal subjects. Many species have displayed a capacity for abstraction that extends to performing simple arithmetic, while a select few have even demonstrated a grasp of the quantitative concept of “zero” — an idea so paradoxical that very young children sometimes struggle with it. All Rights Reserved © 2021

Keyword: Intelligence; Evolution
Link ID: 27944 - Posted: 08.11.2021

Nicola Davis Science correspondent It’s been used to detect eye diseases, make medical diagnoses, and spot early signs of oesophageal cancer. Now it has been claimed artificial intelligence may be able to diagnose dementia from just one brain scan, with researchers starting a trial to test the approach. The team behind the AI tool say the hope is that it will lead to earlier diagnoses, which could improve outcomes for patients, while it may also help to shed light on their prognoses. Dr Timothy Rittman, a senior clinical research associate and consultant neurologist at the University of Cambridge, who is leading the study, told the BBC the AI system is a “fantastic development”. “These set of diseases are really devastating for people,” he said. “So when I am delivering this information to a patient, anything I can do to be more confident about the diagnosis, to give them more information about the likely progression of the disease to help them plan their lives is a great thing to be able to do.” It is expected that in the first year of the trial the AI system, which uses algorithms to detect patterns in brain scans, will be tested in a “real-world” clinical setting on about 500 patients at Addenbrooke’s hospital in Cambridge and other memory clinics across the country. “If we intervene early, the treatments can kick in early and slow down the progression of the disease and at the same time avoid more damage,” Prof Zoe Kourtzi, of Cambridge University and a fellow of national centre for AI and data science the Alan Turing Institute, told the BBC. “And it’s likely that symptoms occur much later in life or may never occur.” © 2021 Guardian News & Media Limited

Keyword: Alzheimers; Development of the Brain
Link ID: 27941 - Posted: 08.11.2021

By Annie Roth As anyone who has ever tried to eat french fries on a beach will attest, stealing is not an uncommon behavior among birds. In fact, many birds are quite skilled at bold and brazen theft. Scientists have documented several species of birds, including magpies, bowerbirds, and black kites, looting everything from discarded plastic to expensive jewelry to decorate their nests. And then there are birds who want hair, and will go to great lengths to get their beaks on it. Hair from dogs, raccoons and even humans has been found in the nests of birds, which scientists believe makes the nests better insulated. For a long time, scientists assumed that birds had to collect hair that had been shed or scavenge it from mammal carcasses. However, a new study, published last week in the journal Ecology, shows that several species of bird, including chickadees and titmice, don’t just scavenge hair, they steal it. The study, based largely on analysis of YouTube videos, shows numerous examples of birds pulling tufts of hair from living mammals, including humans. This phenomenon, which the study’s authors have dubbed “kleptotrichy,” has been well-documented by birders on the web, but this is the first time scientists have formally recognized it. “This is just another example of something that was overlooked in the scientific literature but was common knowledge in the bird watching and bird feeding community,” said Henry Pollock, a postdoctoral researcher in ornithology at the University of Illinois and co-author of the new study. Last spring, Dr. Pollock was participating in his university’s annual spring bird count when a tufted titmouse caught his eye. It was flitting near a raccoon sleeping soundly on a tree branch, inching closer and closer to it. Then, to Dr. Pollock’s amusement, the tiny bird began plucking tufts of the raccoon’s fur. The titmouse managed to steal over 20 beak-fulls of the raccoon’s fur without waking it. © 2021 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 27937 - Posted: 08.07.2021

By James Gorman You’ve heard of trash pandas: Raccoons raiding the garbage. How about trash parrots? Sulfur-crested cockatoos, which may sound exotic to Americans and Europeans, are everywhere in suburban areas of Sydney. They have adapted to the human environment, and since they are known to be clever at manipulating objects it’s not entirely surprising that they went after a rich food source. But you might say that the spread of their latest trick, to open trash cans, blows the lid off social learning and cultural evolution in animals. Not only do the birds acquire the skill by imitating others, which is social learning. But the details of technique evolve to differ in different groups as the innovation spreads, a mark of animal culture. Barbara C. Klump, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Germany, and the first author of a report on the cockatoo research in the journal Science, said, “It’s actually quite a complex behavior because it has multiple steps.” Dr. Klump and her colleagues broke the behavior down into five moves. First a bird uses its bill to pry the lid from the container. Then, she said, “they open it and then they hold it and then they walk along one side and then they flip it over. And at each of these stages, there is variation.” Some birds walk left, some right, they step differently or hold their heads differently. The process is similar to the spread and evolution of human cultural innovations like language, or a classic example of animal culture, bird song, which can vary from region to region in the same species. Dr. Klump and her colleagues in Germany and Australia plotted the spread of the behavior in greater Sydney over the course of two years. The behavior became more common, but it didn’t pop up in random locations as it might if different birds were figuring out the trash bin technique on their own. It spread outward from its origin, indicating that the cockatoos were learning how to do it from each other. © 2021 The New York Times Company

Keyword: Learning & Memory; Evolution
Link ID: 27928 - Posted: 07.28.2021

Christie Wilcox One of the most well-studied synapses in the brain continues to surprise neuroscientists. According to a May 18 study in Nature Communications, mossy fiber synapses, so named because their terminals look a bit like moss growing on the axons, have an unexpected way of regulating the flow of information in the hippocampus: the postsynaptic cells that receive neurotransmitter signals can release their own glutamate to tamp down the transmission from the cell on the presynaptic side. This so-called retrograde signaling was totally unexpected and depends on calcium influx to the postsynaptic cell, meaning researchers might have to rethink the results of past experiments that used in vitro conditions with different calcium availability. The findings are “a big deal” for neuroscientists, says Chris McBain, a synaptic physiologist at the National Institutes of Health who was not involved in the study. “Retrograde glutamatergic signaling is a really rare occurrence in the central nervous system,” he notes, and to find it in mossy fibers “adds another layer of complexity onto one of the most complex synapses.” The researchers behind the new paper, led by neurophysiologist Peter Jonas of the Institute of Science and Technology Austria, were investigating the plasticity of hippocampal neurons, the dynamic changes in connections between cells that contribute to the functioning of neural circuits and that ultimately underlie learning, memory, and other cognitive abilities. János Szabadics, a neurophysiologist at the Institute of Experimental Medicine, Budapest, puts it quite simply: “Without synaptic plasticity, the brain would be just a bag of wires,” he says. © 1986–2021 The Scientist.

Keyword: Learning & Memory
Link ID: 27923 - Posted: 07.24.2021

By Linda Searing Keeping your brain active later in life may delay by as much as five years the onset of Alzheimer’s disease, the most common type of dementia. Research published in the journal Neurology found that cognitively stimulating activities that involve seeking or processing information — such as reading books, magazines or newspapers, writing letters, playing card games, board games or checkers, and doing puzzles — seemed to add dementia-free time to older people’s lives. The research involved 1,903 people (average age was 80), none of whom had dementia at the start of the study and who were tracked and tested for up to 22 years. In that time, 457 participants developed Alzheimer’s. That occurred on average at age 94 for people who did the most brain-stimulating activities later in life, compared with developing Alzheimer’s at age 89 for those with the least amount of cognitive activity. Alzheimer’s, considered a degenerative brain disease, affects memory, thinking and behavior, with symptoms eventually becoming severe enough to interfere with once-routine daily tasks. Today, about 6.2 million Americans 65 and older have the disease, two-thirds of them women, according to the Alzheimer’s Association. That number is expected to reach nearly 13 million by 2050, unless ways are discovered to prevent, cure or slow the disease. The researchers found that neither education nor cognitive activity early in life were associated with the age at which a person developed Alzheimer’s. Rather, it’s what you do later in life that seems to make a difference. And, as the lead author of the story said, “It’s never too late to start doing the kinds of inexpensive, accessible activities” tracked in the study, “even in your 80s.”

Keyword: Alzheimers; Learning & Memory
Link ID: 27914 - Posted: 07.21.2021

By Jaime Chambers Wiggles and wobbles and a powerful pull toward people — that’s what 8-week-old puppies are made of. From an early age, dogs outpace wolves at engaging with and interpreting cues from humans, even if the dogs have had less exposure to people, researchers report online July 12 in Current Biology. The result suggests that domestication has reworked dogs’ brains to make the pooches innately drawn to people — and perhaps to intuit human gestures. Compared with human-raised wolf pups, dog puppies that had limited exposure to people were still 30 times as likely to approach a strange human, and five times as likely to approach a familiar person. “I think that is by far the clearest result in the paper, and is powerful and meaningful,” says Clive Wynne, a canine behavioral scientist at Arizona State University in Tempe who was not involved in the study. Wolf pups are naturally less entranced by people than dogs are. “When I walked into the [wolf] pen for the first time, they would all just run into the corner and hide,” says Hannah Salomons, an evolutionary anthropologist studying dog cognition at Duke University. Over time, Salomons says, most came to ignore her, “acting like I was a piece of furniture.” But dogs can’t seem to resist humans’ allure (SN: 7/19/17). They respond much more readily to people, following where a person points, for example. That ability may seem simple, but it’s a skill even chimpanzees — humans’ close relatives — don’t show. Human babies don’t learn how to do it until near their first birthday. © Society for Science & the Public 2000–2021

Keyword: Evolution; Learning & Memory
Link ID: 27906 - Posted: 07.14.2021

By Gretchen Reynolds Exercise can freshen and renovate the white matter in our brains, potentially improving our ability to think and remember as we age, according to a new study of walking, dancing and brain health. It shows that white matter, which connects and supports the cells in our brains, remodels itself when people become more physically active. In those who remain sedentary, on the other hand, white matter tends to fray and shrink. The findings underscore the dynamism of our brains and how they constantly transform themselves — for better and worse — in response to how we live and move. The idea that adult brains can be malleable is a fairly recent finding, in scientific terms. Until the late 1990s, most researchers believed human brains were physically fixed and inflexible after early childhood. We were born, it was thought, with most of the brain cells we would ever have and could not make more. In this scenario, the structure and function of our brains would only decline with age. But science advanced, thankfully, and revised that gloomy forecast. Complex studies using specialized dyes to identify newborn cells indicated that some parts of our brains create neurons deep into adulthood, a process known as neurogenesis. Follow-up studies then established that exercise amplifies neurogenesis. When rodents run, for example, they pump out three or four times as many new brain cells as inactive animals, while in people, beginning a program of regular exercise leads to greater brain volume. In essence, this research shows, our brains retain lifelong plasticity, changing as we do, including in response to how we exercise. These past studies of brain plasticity generally focused on gray matter, though, which contains the celebrated little gray cells, or neurons, that permit and create thoughts and memories. Less research has looked at white matter, the brain’s wiring. Made up mostly of fat-wrapped nerve fibers known as axons, white matter connects neurons and is essential for brain health. But it can be fragile, thinning and developing small lesions as we age, dilapidations that can be precursors of cognitive decline. Worryingly, it also has been considered relatively static, with little plasticity, or ability to adapt much as our lives change. © 2021 The New York Times Company

Keyword: Learning & Memory; Alzheimers
Link ID: 27905 - Posted: 07.14.2021

By Veronique Greenwood Captive cuttlefish require entertainment when they eat. Dinner and a show — if they can’t get live prey, then they need some dancing from a dead shrimp on a stick in their tank. When the food looks alive, the little cephalopods, which look like iridescent footballs with eight short arms and two tentacles, are more likely to eat it. Because a person standing before them has to jiggle it, the animals start to recognize that mealtime and a looming human-shaped outline go together. As soon as a person walks into the room, “they all swim to the front of the tank saying, give me food!” said Trevor Wardill, a biologist at the University of Minnesota who studies cuttlefish vision. You may get a squirt of water from a cuttlefish’s siphon if you don’t feed them, though. Alexandra Schnell, a comparative psychologist at the University of Cambridge, recalled some who sprayed her if she was even a little slow with the treats. It’s the kind of behavior that researchers who’ve worked with cuttlefish sometimes remark on: The critters have character. But they do not have the name recognition of their cousins — the octopus and the squid. Even Tessa Montague, a neuroscientist who today studies cuttlefish at Columbia University, hadn’t really heard of them until an aquarium visit during graduate school. “Octopus are obviously part of lots of children’s story books,” she notes. Cuttlefish were not present. During the last week of a course at the Marine Biological Laboratory in Woods Hole, Mass., though, she heard a talk by Bret Grasse, whom she called a “cephalopod guru.” “He said they have three hearts, green blood and one of the largest brains among invertebrates,” she said. “And they can regenerate their limbs, they can camouflage. Within about 30 seconds, I had basically planned out my entire life. That lunchtime I went to the facility where he was culturing all these animals. My entire scientific career flashed in front of me. I was like, this is it, this is what I’ve been looking for.” © 2021 The New York Times Company

Keyword: Evolution; Intelligence
Link ID: 27903 - Posted: 07.10.2021

Elena Renken For decades, neuroscientists have treated the brain somewhat like a Geiger counter: The rate at which neurons fire is taken as a measure of activity, just as a Geiger counter’s click rate indicates the strength of radiation. But new research suggests the brain may be more like a musical instrument. When you play the piano, how often you hit the keys matters, but the precise timing of the notes is also essential to the melody. “It’s really important not just how many [neuron activations] occur, but when exactly they occur,” said Joshua Jacobs, a neuroscientist and biomedical engineer at Columbia University who reported new evidence for this claim last month in Cell. For the first time, Jacobs and two coauthors spied neurons in the human brain encoding spatial information through the timing, rather than rate, of their firing. This temporal firing phenomenon is well documented in certain brain areas of rats, but the new study and others suggest it might be far more widespread in mammalian brains. “The more we look for it, the more we see it,” Jacobs said. Abstractions navigates promising ideas in science and mathematics. Journey with us and join the conversation. Some researchers think the discovery might help solve a major mystery: how brains can learn so quickly. The phenomenon is called phase precession. It’s a relationship between the continuous rhythm of a brain wave — the overall ebb and flow of electrical signaling in an area of the brain — and the specific moments that neurons in that brain area activate. A theta brain wave, for instance, rises and falls in a consistent pattern over time, but neurons fire inconsistently, at different points on the wave’s trajectory. In this way, brain waves act like a clock, said one of the study’s coauthors, Salman Qasim, also of Columbia. They let neurons time their firings precisely so that they’ll land in range of other neurons’ firing — thereby forging connections between neurons. All Rights Reserved © 2021

Keyword: Brain imaging
Link ID: 27898 - Posted: 07.08.2021