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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.

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 8: Hormones and Sex
Link ID: 27985 - Posted: 09.13.2021

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

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 13: Memory and Learning
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.

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27974 - Posted: 09.01.2021

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

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 5: Hormones and the Brain
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 8: Hormones and Sex
Link ID: 27961 - 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

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27951 - Posted: 08.18.2021

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

Related chapters from BN: Chapter 6: Evolution of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
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

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 13: Memory and Learning
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.

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 4: Development of the Brain
Link ID: 27923 - Posted: 07.24.2021

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

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 13: Memory and Learning
Link ID: 27905 - Posted: 07.14.2021

By Carolyn Wilke Scientists have long sought to prevent sharp memories from dulling with age, but the problem remains stubborn. Now research published in Scientific Reports suggests virtual reality might help older people recall facts and events based on specific details. The study involved 42 healthy older adults from the San Francisco Bay Area. Half spent a dozen hours over four weeks playing a virtual-reality game called Labyrinth; they strapped on headsets and walked in place, roaming virtual neighborhoods while completing errands. The other half, in the control group, used electronic tablets to play games that did not require navigating or recalling details. After 15 sessions, the latter performed roughly the same as before on a long-term memory test based on picking out objects they had seen about an hour earlier. But the Labyrinth players' scores rose, and they were less frequently tricked by objects that resembled ones they had viewed. Those improvements “brought them back up to the level of another group of younger adults who did the same memory tests,” says cognitive neuroscientist Peter Wais of the University of California, San Francisco. He and his colleagues designed the VR game, which they say likely stimulates the hippocampus—a brain area important for long-term memory. The team did not observe improvement on two other tests, which measured autobiographical memory and spatial memory capability. © 2021 Scientific American,

Related chapters from BN: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 13: Memory and Learning
Link ID: 27853 - Posted: 06.16.2021

By Emily Underwood In the 1930s, neurosurgeon Wilder Penfield pioneered a daring new kind of cartography. As a stenographer took notes, he delicately touched an electrode to the exposed brains of his awake, consenting patients and asked what they felt as electrical current hit different areas. Penfield wanted to better predict which brain functions would be threatened when surgeons had to remove tumors or chunks of tissue that were triggering epileptic seizures. Stimulating adjacent brain regions, he found, produced sensations in corresponding body parts: hand, forearm, elbow. The result of his mapping was the iconic “homunculus”: a map on the brain’s wrinkled outer layer representing the surface of the body. Penfield then ventured into more mysterious territory. When he probed the insula, a deep fold of cortex, some patients felt nauseated or gassy; others belched or vomited. “My stomach is upset and I smell something like medicine,” one said. Penfield found those visceral signals harder to decipher than the brain’s map of the body’s surface. Brain regions responsible for different internal sensations seemed to overlap. Sensory regions were hard to distinguish from those that sent motor instructions such as telling the intestines to contract. Penfield once asked participants to swallow an electrode to detect changes in gut contractions while he stimulated their brains. But his map of the inner organs was blurry and ambiguous—and stayed that way for most of the next century. Decades later, scientists are starting to unravel how our wet, spongy, slippery organs talk to the brain and how the brain talks back. That two-way communication, known as interoception, encompasses a complex, bodywide system of nerves and hormones. Much recent exploration has focused on the vagus nerve: a massive, meandering network of more than 100,000 fibers that travel from nearly every internal organ to the base of the brain and back again. © 2021 American Association for the Advancement of Science.

Related chapters from BN: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 13: Memory and Learning
Link ID: 27850 - Posted: 06.11.2021

By Ben Guarino and Frances Stead Sellers In the coronavirus pandemic’s early weeks, in neuropathology departments around the world, scientists wrestled with a question: Should they cut open the skulls of patients who died of covid-19 and extract their brains? Autopsy staff at Columbia University in New York were hesitant. Sawing into bone creates dust, and the Centers for Disease Control and Prevention had issued a warning about the bodies of covid patients — airborne debris from autopsies could be an infectious hazard. But as more patients were admitted and more began to die, researchers decided to “make all the efforts we could to start collecting the brain tissue,” Columbia neuropathologist Peter D. Canoll said. In March 2020, in an insolation room, the Columbia team extracted a brain from a patient who had died of severe covid-19, the illness caused by the coronavirus. During the next months, they would examine dozens more. Saw met skull elsewhere, too. In Germany, scientists autopsied brains — even though medical authorities recommended against doing that. Researchers were searching the brain for damage — and for the virus itself. At the pandemic’s start, understanding how the virus affected the nervous system was largely a mystery. S. Andrew Josephson, chair of neurology at the University of California at San Francisco and editor in chief of the academic journal JAMA Neurology, said, “We had hundreds of submissions of ‘I saw one case of X.’” It was difficult to understand whether single cases has any relationship to covid at all. Patients reported visual and auditory disturbances, vertigo and tingling sensations, among other perplexing symptoms. Some lost their sense of smell, or their vision became distorted. Weeks or months after the initial onset of symptoms, some remain convinced after even a mild bout of the coronavirus of persistent “brain fog.”

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 14: Attention and Higher Cognition
Link ID: 27845 - Posted: 06.08.2021

By Jason S. Tsukahara, Alexander P. Burgoyne, Randall W. Engle It has been said that “the eyes are the window to the soul,” but new research suggests that they may be a window to the brain as well. Our pupils respond to more than just the light. They indicate arousal, interest or mental exhaustion. Pupil dilation is even used by the FBI to detect deception. Now work conducted in our laboratory at the Georgia Institute of Technology suggests that baseline pupil size is closely related to individual differences in intelligence. The larger the pupils, the higher the intelligence, as measured by tests of reasoning, attention and memory. In fact, across three studies, we found that the difference in baseline pupil size between people who scored the highest on the cognitive tests and those who scored the lowest was large enough to be detected by the unaided eye. We first uncovered this surprising relationship while studying differences in the amount of mental effort people used to complete memory tasks. We used pupil dilations as an indicator of effort, a technique psychologist Daniel Kahneman popularized in the 1960s and 1970s. When we discovered a relationship between baseline pupil size and intelligence, we weren’t sure if it was real or what it meant. Advertisement Intrigued, we conducted several large-scale studies in which we recruited more than 500 people aged 18 to 35 from the Atlanta community. We measured participants’ pupil size using an eye tracker, a device that captures the reflection of light off the pupil and cornea using a high-powered camera and computer. We measured participants’ pupils at rest while they stared at a blank computer screen for up to four minutes. All the while, the eye tracker was recording. Using the tracker, we then calculated each participant’s average pupil size. © 2021 Scientific American

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 14: Attention and Higher Cognition
Link ID: 27844 - Posted: 06.08.2021

By Jackie Rocheleau It’s an attractive idea: By playing online problem-solving, matching and other games for a few minutes a day, people can improve such mental abilities as reasoning, verbal skills and memory. But whether these games deliver on those promises is up for debate. “For every study that finds some evidence, there’s an equal number of papers that find no evidence,” says Bobby Stojanoski, a cognitive neuroscientist at Western University in Ontario (SN: 3/8/17; SN: 5/9/17). Now, in perhaps the biggest real-world test of these programs, Stojanoski and colleagues pitted more than 1,000 people who regularly use brain trainers against around 7,500 people who don’t do the mini brain workouts. There was little difference between how both groups performed on a series of tests of their thinking abilities, suggesting that brain training doesn’t live up to its name, the scientists report in the April Journal of Experimental Psychology: General. “They put brain training to the test,” says Elizabeth Stine-Morrow, a cognitive aging scientist at the University of Illinois at Urbana-Champaign. While the study doesn’t show why brain trainers aren’t seeing benefits, it does show there is no link “between the amount of time spent with the brain training programs and cognition,” Stine-Morrow says. “That was pretty cool.” © Society for Science & the Public 2000–2021

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 14: Attention and Higher Cognition
Link ID: 27830 - Posted: 05.27.2021

By Nicholas Bakalar Long-term exposure to air pollution has many health consequences, including accelerating brain aging and increasing the risk for dementia. Now new research suggests that short-term exposure to polluted air, even at levels generally considered “acceptable,” may impair mental ability in the elderly. Scientists studied 954 men, average age 69, living in the greater Boston area. The men were tested at the start of the study and several times over the next 28 days using the Mini-Mental State Examination, or MMSE, a widely used test of cognitive ability. The test includes simple questions like “What year is this?” and “What season is it?,” and requires tasks like counting backward by sevens from 100. Correctly answering fewer than 25 of its 30 questions suggests mild dementia. Over the month, the researchers measured air levels of what’s known as PM 2.5, particles of soot and other fine particulate matter with a diameter of up to 2.5 microns, small enough to enter the lungs and move into bloodstream. There is no safe level of PM 2.5, but the Environmental Protection Agency considers air acceptable when it is under 12 micrograms per cubic meter. During the testing period, PM 2.5 levels in Boston averaged 10.77. Higher PM 2.5 was consistently associated with lower test scores. In weeks with the highest levels of air pollution, the men were 63 percent more likely to score below 25 on the MMSE than in weeks with the lowest levels. The study, in Nature Aging, adjusted for age, B.M.I., coronary heart disease, diabetes, alcohol consumption, smoking, high blood pressure and other factors. Dr. Andrea A. Baccarelli, the senior author and a professor of environmental science at the Columbia Mailman School of Public Health, said that these short-term effects may be reversible. “When air pollution goes down,” he said, “the brain reboots and goes back to normal. However, if repeated, these episodes produce long-term damage to the brain.” © 2021 The New York Times Company

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 14: Attention and Higher Cognition
Link ID: 27823 - Posted: 05.19.2021

Jordana Cepelewicz During every waking moment, we humans and other animals have to balance on the edge of our awareness of past and present. We must absorb new sensory information about the world around us while holding on to short-term memories of earlier observations or events. Our ability to make sense of our surroundings, to learn, to act and to think all depend on constant, nimble interactions between perception and memory. But to accomplish this, the brain has to keep the two distinct; otherwise, incoming data streams could interfere with representations of previous stimuli and cause us to overwrite or misinterpret important contextual information. Compounding that challenge, a body of research hints that the brain does not neatly partition short-term memory function exclusively into higher cognitive areas like the prefrontal cortex. Instead, the sensory regions and other lower cortical centers that detect and represent experiences may also encode and store memories of them. And yet those memories can’t be allowed to intrude on our perception of the present, or to be randomly rewritten by new experiences. A paper published recently in Nature Neuroscience may finally explain how the brain’s protective buffer works. A pair of researchers showed that, to represent current and past stimuli simultaneously without mutual interference, the brain essentially “rotates” sensory information to encode it as a memory. The two orthogonal representations can then draw from overlapping neural activity without intruding on each other. The details of this mechanism may help to resolve several long-standing debates about memory processing. To figure out how the brain prevents new information and short-term memories from blurring together, Timothy Buschman, a neuroscientist at Princeton University, and Alexandra Libby, a graduate student in his lab, decided to focus on auditory perception in mice. They had the animals passively listen to sequences of four chords over and over again, in what Buschman dubbed “the worst concert ever.” All Rights Reserved © 2021

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27778 - Posted: 04.17.2021

Natalie Grover Few species in the animal kingdom can change the size of their brain. Fewer still can change it back to its original size. Now researchers have found the first insect species with that ability: Indian jumping ants. They are like catnip to researchers in the field. In contrast to their cousins, Indian jumping ants colonies do not perish once their queen dies. Instead, “chosen” workers take her place – with expanded ovaries and shrunken brains – to produce offspring. But, if a worker’s “pseudo-queen” status is somehow revoked, their bodies can bounce back, the research suggests. Typically, whether an ant will be a worker or a queen is decided at the larval stage. If fed generously and given the right hormones, the ant has the chance to become a big queen. If not, then it is stuck with a career as a sterile worker deprived of the opportunity to switch – unless it’s part of a species such as the Indian jumping ant. “They have this ability to completely transform themselves at the adult stage, and that makes them interesting to try to understand,” said lead author Dr Clint Penick from US-based Kennesaw State University. Social insects such as ants typically inhabit a caste-based society – the queen reigns as the sole reproducer by secreting pheromones that thwart female worker ants from laying eggs. The other ants work hard: foraging and hunting for food, cleaning, caring for the young and defending the nest. But unlike typical colonies that wither away on the death of their queen, Indian jumping ant colonies are functionally immortal. © 2021 Guardian News & Media Limited

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27772 - Posted: 04.14.2021

Sarah DeGenova Ackerman The human brain is made up of billions of neurons that form complex connections with one another. Flexibility at these connections is a major driver of learning and memory, but things can go wrong if it isn’t tightly regulated. For example, in people, too much plasticity at the wrong time is linked to brain disorders such as epilepsy and Alzheimer’s disease. Additionally, reduced levels of the two neuroplasticity-controlling proteins we identified are linked to increased susceptibility to autism and schizophrenia. Similarly, in our fruit flies, removing the cellular brakes on plasticity permanently impaired their crawling behavior. While fruit flies are of course different from humans, their brains work in very similar ways to the human brain and can offer valuable insight. One obvious benefit of discovering the effect of these proteins is the potential to treat some neurological diseases. But since a neuron’s flexibility is closely tied to learning and memory, in theory, researchers might be able to boost plasticity in a controlled way to enhance cognition in adults. This could, for example, allow people to more easily learn a new language or musical instrument. A colorful microscope image of a developing fruit fly brain. In this image showing a developing fruit fly brain on the right and the attached nerve cord on the left, the astrocytes are labeled in different colors showing their wide distribution among neurons. Sarah DeGenova Ackerman, CC BY-ND © 2010–2021, The Conversation US, Inc.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27770 - Posted: 04.14.2021

By Rachel Aviv Elizabeth Loftus was in Argentina, giving talks about the malleability of memory, in October, 2018, when she learned that Harvey Weinstein, who had recently been indicted for rape and sexual assault, wanted to speak with her. She couldn’t figure out how to receive international calls in her hotel room, so she asked if they could talk in three days, once she was home, in California. In response, she got a series of frantic e-mails saying that the conversation couldn’t wait. But, when Weinstein finally got through, she said, “basically he just wanted to ask, ‘How can something that seems so consensual be turned into something so wrong?’ ” Loftus, a professor at the University of California, Irvine, is the most influential female psychologist of the twentieth century, according to a list ­compiled by the Review of General Psychology. Her work helped usher in a paradigm shift, rendering obsolete the archival model of memory—the idea, dominant for much of the twentieth century, that our memories exist in some sort of mental library, as literal representations of past events. According to Loftus, who has published twenty-four books and more than six hundred papers, memories are reconstructed, not replayed. “Our representation of the past takes on a living, shifting reality,” she has written. “It is not fixed and immutable, not a place way back there that is preserved in stone, but a living thing that changes shape, expands, shrinks, and expands again, an amoeba-­like creature.” George A. Miller, one of the founders of cognitive psychology, once said in a speech to the American Psychological Association that the way to advance the field was “to give psychology away.” Loftus, who is seventy-six, adopts a similar view, seizing any opportunity to elaborate on what she calls the “flimsy curtain that separates our imagination and our memory.” In the past forty-five years, she has testified or consulted in more than three hundred cases, on behalf of people wrongly accused of robbery and murder, as well as for high-profile defendants like Bill Cosby, Jerry Sandusky, and the Duke lacrosse players accused of rape, in 2006. “If the MeToo movement had an office, Beth’s picture would be on the ten-most-wanted list,” her brother Robert told me. © 2021 Condé Nast.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27754 - Posted: 03.31.2021

The Physics arXiv Blog One of the best-studied networks in neuroscience is the brain of a fruit fly, in particular, a part called the mushroom body. This analyzes sensory inputs such as odors, temperature, humidity and visual data so that the fly can learn to distinguish friendly stimuli from dangerous ones. Neuroscientists have long known how this section of the brain is wired. It consists of a set of cells called projection neurons that transmit the sensory information to a population of 2,000 neurons called Kenyon cells. The Kenyon cells are wired together to form a neural network capable of learning. This is how fruit flies learn to avoid potentially hazardous sensory inputs — such as dangerous smells and temperatures — while learning to approach foodstuffs, potential mates, and so on. But the power and flexibility of this relatively small network has long raised a curious question for neuroscientists: could it be re-programmed to tackle other tasks? Now they get an answer thanks to the work of Yuchan Liang at the Rensselaer Polytechnic Institute, the MIT-IBM Watson AI Lab, and colleagues. This team has hacked the fruit fly brain network to perform other tasks, such as natural language processing. It's the first time a naturally occurring network has been commandeered in this way. And this biological brain network is no slouch. Liang and the team says it matches the performance of artificial learning networks while using far fewer computational resources. © 2021 Kalmbach Media Co.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 27671 - Posted: 01.30.2021