Links for Keyword: Learning & Memory

Follow us on Facebook or subscribe to our mailing list, to receive news updates. Learn more.


Links 1 - 20 of 1244

By Laura Sanders Like all writers, I spend large chunks of my time looking for words. When it comes to the ultracomplicated and mysterious brain, I need words that capture nuance and uncertainties. The right words confront and address hard questions about exactly what new scientific findings mean, and just as importantly, why they matter. The search for the right words is on my mind because of recent research on COVID-19 and the brain. As part of a large brain-scanning study, researchers found that infections of SARS-CoV-2, the virus that causes COVID-19, were linked with less gray matter, tissue that’s packed with the bodies of brain cells. The results, published March 7 in Nature, prompted headlines about COVID-19 causing brain damage and shrinkage. That coverage, in turn, prompted alarmed posts on social media, including mentions of early-onset dementia and brain rotting. As someone who has reported on brain research for more than a decade, I can say those alarming words are not the ones that I would choose here. The study is one of the first to look at structural changes in the brain before and after a SARS-CoV-2 infection. And the study is meticulous. It was done by an expert group of brain imaging researchers who have been doing this sort of research for a very long time. As part of the UK Biobank project, 785 participants underwent two MRI scans. Between those scans, 401 people had COVID-19 and 384 people did not. By comparing the before and after scans, researchers could spot changes in the people who had COVID-19 and compare those changes with people who didn’t get the infection. © Society for Science & the Public 2000–2022.

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: 28246 - Posted: 03.19.2022

Yasemin Saplakoglu Imagine that while you are enjoying your morning bowl of Cheerios, a spider drops from the ceiling and plops into the milk. Years later, you still can’t get near a bowl of cereal without feeling overcome with disgust. Researchers have now directly observed what happens inside a brain learning that kind of emotionally charged response. In a new study published in January in the Proceedings of the National Academy of Sciences, a team at the University of Southern California was able to visualize memories forming in the brains of laboratory fish, imaging them under the microscope as they bloomed in beautiful fluorescent greens. From earlier work, they had expected the brain to encode the memory by slightly tweaking its neural architecture. Instead, the researchers were surprised to find a major overhaul in the connections. What they saw reinforces the view that memory is a complex phenomenon involving a hodgepodge of encoding pathways. But it further suggests that the type of memory may be critical to how the brain chooses to encode it — a conclusion that may hint at why some kinds of deeply conditioned traumatic responses are so persistent, and so hard to unlearn. “It may be that what we’re looking at is the equivalent of a solid-state drive” in the brain, said co-author Scott Fraser, a quantitative biologist at USC. While the brain records some types of memories in a volatile, easily erasable form, fear-ridden memories may be stored more robustly, which could help to explain why years later, some people can recall a memory as if reliving it, he said. Memory has frequently been studied in the cortex, which covers the top of the mammalian brain, and in the hippocampus at the base. But it’s been examined less often in deeper structures such as the amygdala, the brain’s fear regulation center. The amygdala is particularly responsible for associative memories, an important class of emotionally charged memories that link disparate things — like that spider in your cereal. While this type of memory is very common, how it forms is not well understood, partly because it occurs in a relatively inaccessible area of the brain. All Rights Reserved © 2022

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28241 - Posted: 03.16.2022

By Linda Searing Health-care workers and others who are exposed on the job to formaldehyde, even in low amounts, face a 17 percent increased likelihood of developing memory and thinking problems later on, according to research published in the journal Neurology. The finding adds cognitive impairment to already established health risks associated with formaldehyde. As the level of exposure increases, those risks range from eye, nose and throat irritation to skin rashes and breathing problems. At high levels of exposure, the chemical is considered a carcinogen, linked to leukemia and some types of nose and throat cancer. A strong-smelling gas, formaldehyde is used in making building materials and plastics and often as a component of disinfectants and preservatives. Materials containing formaldehyde can release it into the air as a vapor that can be inhaled, which is the main way people are exposed to it. The study, which included data from more than 75,000 people, found that the majority of those exposed were workers in the health-care sector — nurses, caregivers, medical technicians and those working in labs and funeral homes. Other study participants who had been exposed to formaldehyde included workers in textile, chemistry and metal industries; carpenters; and cleaners. At highest risk were those whose work had exposed them to formaldehyde for 22 years or more, giving them a 21 percent higher risk for cognitive problems than those who had not been exposed. Using a battery of standardized tests, the researchers found that formaldehyde exposure created higher risk for every type of cognitive function that was tested, including memory, attention, reasoning, word recall and other thinking skills.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28203 - Posted: 02.16.2022

Jordana Cepelewicz We often think of memory as a rerun of the past — a mental duplication of events and sensations that we’ve experienced. In the brain, that would be akin to the same patterns of neural activity getting expressed again: Remembering a person’s face, for instance, might activate the same neural patterns as the ones for seeing their face. And indeed, in some memory processes, something like this does occur. But in recent years, researchers have repeatedly found subtle yet significant differences between visual and memory representations, with the latter showing up consistently in slightly different locations in the brain. Scientists weren’t sure what to make of this transformation: What function did it serve, and what did it mean for the nature of memory itself? Now, they may have found an answer — in research focused on language rather than memory. A team of neuroscientists created a semantic map of the brain that showed in remarkable detail which areas of the cortex respond to linguistic information about a wide range of concepts, from faces and places to social relationships and weather phenomena. When they compared that map to one they made showing where the brain represents categories of visual information, they observed meaningful differences between the patterns. And those differences looked exactly like the ones reported in the studies on vision and memory. The finding, published last October in Nature Neuroscience, suggests that in many cases, a memory isn’t a facsimile of past perceptions that gets replayed. Instead, it is more like a reconstruction of the original experience, based on its semantic content. All Rights Reserved © 2022

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 15: Language and Lateralization
Link ID: 28202 - Posted: 02.12.2022

ByRodrigo Pérez Ortega A good workout doesn’t just boost your mood—it also boosts the brain’s ability to create new neurons. But exactly how this happens has puzzled researchers for years. “It’s been a bit of a black box,” says Tara Walker, a neuroscientist at the University of Queensland’s Brain Institute. Now, Walker and her colleagues think they have found a key: the chemical element selenium. During exercise, mice produce a protein containing selenium that helps their brains grow new neurons, the team reports today. Scientists may also be able to harness the element to help reverse cognitive decline due to old age and brain injury, the authors say. It’s a “fantastic” study, says Bárbara Cardoso, a nutritional biochemist at Monash University’s Victorian Heart Institute. Her own research has shown selenium—which is found in Brazil nuts, grains, and some legumes—improves verbal fluency and the ability to copy drawings correctly in older adults. “We could start thinking about selenium as a strategy” to treat or prevent cognitive decline in those who cannot exercise or are more vulnerable to selenium deficiency, she says, such as older adults, and stroke and Alzheimer’s disease patients. In 1999, researchers reported that running stimulates the brain to make new neurons in the hippocampus, a region involved in learning and memory. But which molecules were released into the bloodstream to spark this “neurogenesis” remained unclear. So 7 years ago, Walker and her colleagues screened the blood plasma of mice that had exercised on a running wheel in their cages for 4 days, versus mice that had no wheel. The team identified 38 proteins whose levels increased after the workout. © 2022 American Association for the Advancement of Science.

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 5: The Sensorimotor System
Link ID: 28185 - Posted: 02.05.2022

Dan Robitzski As the coronavirus pandemic continues, scientists are racing to understand the underlying causes and implications of long COVID, the umbrella term for symptoms that persist for at least 12 weeks but often last even longer and affect roughly 30 percent of individuals who contract COVID-19. Evidence for specific risk factors such as diabetes and the presence of autoantibodies is starting to emerge, but throughout the pandemic, one assumption has been that an important indicator of whether a COVID-19 survivor is likely to develop long COVID is the severity of their acute illness. However, a preprint shared online on January 10 suggests that even mild SARS-CoV-2 infections may lead to long-term neurological symptoms associated with long COVID such as cognitive impairment and difficulties with attention and memory, a suite of symptoms often lumped together as “brain fog.” In the study, which has not yet been peer-reviewed, scientists led by Stanford University neurologist Michelle Monje identified a pathway in COVID-19–infected mice and humans that almost perfectly matches the inflammation thought to cause chemotherapy-related cognitive impairment (CRCI), also known as “chemo fog,” following cancer treatments. On top of that, the preprint shows that the neuroinflammation pathway can be triggered even without the coronavirus infecting a single brain cell. As far back as March 2020, Monje feared that cytokine storms caused by the immune response to SARS-CoV-2 would cause the same neuroinflammation and symptoms associated with CRCI, she tells The Scientist. But because her lab doesn’t study viral infections, she had no way to test her hypothesis until other researchers created the appropriate models. In the study, Monje and her colleagues used a mouse model for mild SARS-CoV-2 infections developed at the lab of Yale School of Medicine biologist and study coauthor Akiko Iwasaki as well as brain tissue samples taken from people who had COVID-19 when they died to demonstrate that mild infections can trigger inflammation in the brain. © 1986–2022 The Scientist.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28182 - Posted: 02.02.2022

Veronique Greenwood In the moment between reading a phone number and punching it into your phone, you may find that the digits have mysteriously gone astray — even if you’ve seared the first ones into your memory, the last ones may still blur unaccountably. Was the 6 before the 8 or after it? Are you sure? Maintaining such scraps of information long enough to act on them draws on an ability called visual working memory. For years, scientists have debated whether working memory has space for only a few items at a time, or if it just has limited room for detail: Perhaps our mind’s capacity is spread across either a few crystal-clear recollections or a multitude of more dubious fragments. The uncertainty in working memory may be linked to a surprising way that the brain monitors and uses ambiguity, according to a recent paper in Neuron from neuroscience researchers at New York University. Using machine learning to analyze brain scans of people engaged in a memory task, they found that signals encoded an estimate of what people thought they saw — and the statistical distribution of the noise in the signals encoded the uncertainty of the memory. The uncertainty of your perceptions may be part of what your brain is representing in its recollections. And this sense of the uncertainties may help the brain make better decisions about how to use its memories. The findings suggests that “the brain is using that noise,” said Clayton Curtis, a professor of psychology and neuroscience at NYU and an author of the new paper. All Rights Reserved © 2022

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28163 - Posted: 01.19.2022

Nicola Davis It’s a cold winter’s day, and I’m standing in a room watching my dog stare fixedly at two flower pots. I’m about to get an answer to a burning question: is my puppy a clever girl? Dogs have been our companions for millennia, domesticated sometime between 15,000 and 30,000 years ago. And the bond endures: according to the latest figures from the Pet Food Manufacturers Association 33% of households in the UK have a dog. But as well as fulfilling roles from Covid detection to lovable family rogue, scientists investigating how dogs think, express themselves and communicate with humans say dogs can also teach us about ourselves. And so I am here at the dog cognition centre at the University of Portsmouth with Calisto, the flat-coated retriever, and a pocket full of frankfurter sausage to find out how. We begin with a task superficially reminiscent of the cup and ballgame favoured by small-time conmen. Amy West, a PhD student at the centre, places two flower pots a few metres in front of Calisto, and appears to pop something under each. However, only one actually contains a tasty morsel. West points at the pot under which the sausage lurks, and I drop Calisto’s lead. The puppy makes a beeline for the correct pot. But according to Dr Juliane Kaminski, reader in comparative psychology at the University of Portsmouth, this was not unexpected. “A chimpanzee is our closest living relative – they ignore gestures like these coming from humans entirely,” she says. “But dogs don’t.” © 2022 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: 28162 - Posted: 01.19.2022

Sophie Fessl Mice raised in an enriched environment are better able to adapt and change than mice raised in standard cages, but why they show this higher brain plasticity has not been known. Now, a study published January 11 in Cell Reports finds that the environment could act indirectly: living in enriched environments changes the animals’ gut microbiota, which appears to modulate plasticity. The study “provides very interesting new insights into possible beneficial effects of environmental enrichment on the brain that might act via the gut,” writes Anthony Hannan, a neuroscientist at the Florey Institute of Neuroscience and Mental Health in Australia who was not involved in the study, in an email to The Scientist. “This new study has implications for how we might understand the beneficial effects of environmental enrichment, and its relevance to cognitive training and physical activity interventions in humans.” In previous studies, mice raised in what scientists call an enriched environment—one in which they have more opportunities to explore, interact with others, and receive sensory stimulation than they would in standard laboratory enclosures—have been better able to modify their neuronal circuits in response to external stimuli than mice raised in smaller, plainer cages. Paola Tognini, a neuroscientist at the University of Pisa and lead author of the new study, writes in an email to The Scientist that she “wondered if endogenous factors (signals coming from inside our body instead of the external world), such as the signals coming from the intestine, could also influence brain plasticity.” © 1986–2022 The Scientist.

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: 28159 - Posted: 01.19.2022

Don Arnold All memory storage devices, from your brain to the RAM in your computer, store information by changing their physical qualities. Over 130 years ago, pioneering neuroscientist Santiago Ramón y Cajal first suggested that the brain stores information by rearranging the connections, or synapses, between neurons. Since then, neuroscientists have attempted to understand the physical changes associated with memory formation. But visualizing and mapping synapses is challenging to do. For one, synapses are very small and tightly packed together. They’re roughly 10 billion times smaller than the smallest object a standard clinical MRI can visualize. Furthermore, there are approximately 1 billion synapses in the mouse brains researchers often use to study brain function, and they’re all the same opaque to translucent color as the tissue surrounding them. A new imaging technique my colleagues and I developed, however, has allowed us to map synapses during memory formation. We found that the process of forming new memories changes how brain cells are connected to one another. While some areas of the brain create more connections, others lose them. Mapping new memories in fish Previously, researchers focused on recording the electrical signals produced by neurons. While these studies have confirmed that neurons change their response to particular stimuli after a memory is formed, they couldn’t pinpoint what drives those changes. © 2010–2022, The Conversation US, Inc.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28149 - Posted: 01.12.2022

By Maria Temming It might seem like a fish needs a car like — well, like a fish needs a bicycle. But a new experiment suggests that fish actually make pretty good drivers. In the experiment, several goldfish learned to drive what is essentially the opposite of a submarine — a tank of water on wheels — to destinations in a room. That these fish could maneuver on land suggests that fishes’ understanding of space and navigation is not limited to their natural environment — and perhaps has something in common with landlubber animals’ internal sense of direction, researchers report in the Feb. 15 Behavioural Brain Research. Researchers at Ben-Gurion University of the Negev in Beer-Sheva, Israel taught six goldfish to steer a motorized water tank. The fishmobile was equipped with a camera that continually tracked a fish driver’s position and orientation inside the tank. Whenever the fish swam near one of the tank’s walls, facing outward, the vehicle trundled off in that direction. This goldfish knows how to use its wheels. Successfully navigating in a tank on land suggests that the animals understand space and direction in a way that lets them explore even in unfamiliar habitats. Fish were schooled on how to drive during about a dozen 30-minute sessions. The researchers trained each fish to drive from the center of a small room toward a pink board on one wall by giving the fish a treat whenever it reached the wall. During their first sessions, the fish averaged about 2.5 successful trips to the target. During their final sessions, fish averaged about 17.5 successful trips. By the end of driver’s ed, the animals also took faster, more direct routes to their goal. © Society for Science & the Public 2000–2022.

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28148 - Posted: 01.12.2022

By Abdulrahman Olagunju How does our brain know that “this” follows “that”? Two people meet, fall in love and live happily ever after—or sometimes not. The sequencing of events that takes place in our head—with one thing coming after another—may have something to do with so-called time cells recently discovered in the human hippocampus. The research provides evidence for how our brain knows the start and end of memories despite time gaps in the middle. As these studies continue, the work could lead to strategies for memory restoration or enhancement. The research has focused on “episodic memory,” the ability to remember the “what, where and when” of a past experience, such as the recollection of what you did when you woke up today. It is part of an ongoing effort to identify how the organ creates such memories. A team led by Leila Reddy, a neuroscience researcher at the French National Center for Scientific Research, sought to understand how human neurons in the hippocampus represent temporal information during a sequence of learning steps to demystify the functioning of time cells in the brain. In a study published this summer in the Journal of Neuroscience, Reddy and her colleagues found that, to organize distinct moments of experience, human time cells fire at successive moments during each task. The study provided further confirmation that time cells reside in the hippocampus, a key memory processing center. They switch on as events unfold, providing a record of the flow of time in an experience. “These neurons could play an important role in how memories are represented in the brain,” Reddy says. “Understanding the mechanisms for encoding time and memory will be an important area of research.” © 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: 28133 - Posted: 12.31.2021

By Elizabeth Preston A person trying to learn the way around a new neighborhood might spend time studying a map. You would probably not benefit from being carried rapidly through the air, upside-down in the dark. Yet that’s how some baby bats learn to navigate, according to a study published last month in Current Biology. As their mothers tote them on nightly trips between caves and certain trees, the bat pups gain the skills they need to get around when they grow up. Mothers of many bat species carry their young while flying, said Aya Goldshtein, a behavioral ecologist at the Max Planck Institute of Animal Behavior in Konstanz, Germany. Egyptian fruit bats, for example, are attached to their mothers continuously for the first three weeks of life. While a mother searches for food, her pup clings to her body with two feet and its jaw, latching its teeth around her nipple. Mothers can still be seen flying with older pups that weigh 40 percent of what they do. It hadn’t been clear why the moms go to this length, instead of leaving pups in the cave where they roost, as some other species do. Dr. Goldshtein worked with Lee Harten, a behavioral ecologist at Tel Aviv University in Israel, where both she and Dr. Goldshtein were graduate students at the time in the lab of Yossi Yovel, a study co-author, to make sense of this maternal mystery. The researchers captured Egyptian fruit bat mothers and pups from a cave just outside Tel Aviv. They attached a tag holding a radio transmitter and miniature GPS device to each bat’s fur that would drop off after a couple of weeks. Then, the researchers brought the bats back to their cave. To track the bats, Dr. Harten held an antenna while standing on the roof of a 10-story building with a view of the cave. She directed Dr. Goldshtein, who was on foot or in a car with her own antenna, to follow the radio signals of bat pairs as they flew out at night. But again and again, there was a problem: The pup’s movement would suddenly stop, while the mother’s signal disappeared. “At the beginning we thought that we were doing our job wrong, and just losing the bats,” Dr. Harten said. © 2021 The New York Times Company

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 8: Hormones and Sex
Link ID: 28102 - Posted: 12.08.2021

Alison Abbott There Is Life After the Nobel Prize Eric Kandel Columbia Univ. Press (2021) In 1996, Denise Kandel warned her husband that were he to win the Nobel prize for his pioneering work on memory, then it should be later rather than sooner. Laureates too often turn into socialites, she warned, and stop contributing to the intellectual life of science. Just four years later, Eric Kandel shared the 2000 Nobel Prize in Physiology or Medicine. He was then 71, an age when he could legitimately have rested on his laurels. But resting is not among Kandel’s many strengths. His new book, There Is Life After the Nobel Prize, outlines his achievements of the past couple of decades — numerous enough to dispel Denise’s fears, he writes. It is hard to disagree. The volume adds to Kandel’s respected literary oeuvre, which ranges from neuroscience textbooks to highly original popular science. But it is slight, and feels like a coda. In it, he summarises his post-Nobel research (on learning and memory deficits in addiction, schizophrenia and ageing), writing and public outreach. And he acknowledges colleagues and sponsors of his long career, particularly the Howard Hughes Medical Institute in Chevy Chase, Maryland, and Columbia University in New York City, where he remains a professor and institute director. A fuller and more poignant autobiography can be found in Kandel’s 2006 book In Search of Memory. There, he explains why his traumatic childhood in Austria drew him to study the mechanisms of memory. That book also presents a marvellous history of neuroscience. Making sense Kandel was born in 1929 in Vienna. His family was Jewish and owned a toy shop. When Hitler annexed Austria in 1938, his parents began their year-long effort to emigrate. They finally arrived in New York shortly before the outbreak of World War II, physically unharmed but psychologically traumatized. © 2021 Springer Nature Limited

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28100 - Posted: 12.08.2021

By Pam Belluck AURORA, Ill. — There is sobering evidence of Samantha Lewis’s struggle with long Covid on her bathroom mirror. Above the sink, she has posted a neon pink index card scrawled with nine steps (4. Wet brush 5. Toothpaste) reminding her how to brush and floss her teeth. It is one of many strategies Ms. Lewis, 34, has learned from “cognitive rehab,” an intensive therapy program for Covid-19 survivors whose lives have been upended by problems like brain fog, memory lapses, dizziness and debilitating fatigue. Nearly two years into the pandemic, advances have been made in treating Covid itself, but long Covid — a constellation of lingering health problems that some patients experience — remains little understood. Post-Covid clinics around the country are trying different approaches to help patients desperate for answers, but there is little data on outcomes so far, and doctors say it is too soon to know what might work, and for which patients. While some physical symptoms of long Covid, like shortness of breath or nausea, can be addressed with medication, cognitive issues are more challenging. Few drugs exist, and while some deficits can rebound with time, they can also be exacerbated by resuming activities too soon or intensively. Over several months, The New York Times visited Ms. Lewis, interviewed her doctors, attended her therapy sessions and read her medical records. Before she was infected with the coronavirus in October 2020, experiencing a modest initial illness that did not require hospitalization, she was successfully juggling a demanding, detail-oriented job while raising a child with autism and attention deficit hyperactivity disorder. But this summer, she scored 25 on a 30-point assessment, placing her in a pre-dementia category called mild cognitive impairment. © 2021 The New York Times Company

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28098 - Posted: 12.04.2021

Allison Whitten Every time a human or machine learns how to get better at a task, a trail of evidence is left behind. A sequence of physical changes — to cells in a brain or to numerical values in an algorithm — underlie the improved performance. But how the system figures out exactly what changes to make is no small feat. It’s called the credit assignment problem, in which a brain or artificial intelligence system must pinpoint which pieces in its pipeline are responsible for errors and then make the necessary changes. Put more simply: It’s a blame game to find who’s at fault. AI engineers solved the credit assignment problem for machines with a powerful algorithm called backpropagation, popularized in 1986 with the work of Geoffrey Hinton, David Rumelhart and Ronald Williams. It’s now the workhorse that powers learning in the most successful AI systems, known as deep neural networks, which have hidden layers of artificial “neurons” between their input and output layers. And now, in a paper published in Nature Neuroscience in May, scientists may finally have found an equivalent for living brains that could work in real time. A team of researchers led by Richard Naud of the University of Ottawa and Blake Richards of McGill University and the Mila AI Institute in Quebec revealed a new model of the brain’s learning algorithm that can mimic the backpropagation process. It appears so realistic that experimental neuroscientists have taken notice and are now interested in studying real neurons to find out whether the brain is actually doing it. Simons Foundation All Rights Reserved © 2021

Related chapters from BN: Chapter 17: Learning and Memory; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 13: Memory and Learning; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28044 - Posted: 10.20.2021

Jordana Cepelewicz Leaping, scurrying, flying and swimming through their natural habitats, animals compile a mental map of the world around them — one that they use to navigate home, find food and locate other points of vital interest. Neuroscientists have chiseled away at the problem of how animals do this for decades. A crucial piece of the solution is an elegant neural code that researchers uncovered by monitoring the brains of rats in laboratory settings. That landmark discovery was awarded a Nobel Prize in 2014, and many scientists think the code could be a key component of how the brain handles other abstract forms of information. Yet lab animals in a box with a flat floor only need to navigate through two dimensions, and researchers are now finding that extending the lessons of that situation to the real world is full of challenges and pitfalls. In a pair of studies recently published in Nature and Nature Neuroscience, scientists working with bats and rats showed — to their surprise — that the brain encodes 3D spaces very differently from 2D ones, employing a mechanism that they are still struggling to describe and understand. “We expected something else entirely,” said Nachum Ulanovsky, a neurobiologist at the Weizmann Institute of Science in Israel who led the work in Nature and has studied neural representations of 3D spaces for more than 10 years. “We had to reboot our thinking.” The findings suggest that neuroscientists might need to reconsider what they thought they knew about how the brain encodes natural environments and how animals navigate those spaces. The work also hints at the possibility that other cognitive processes, including memory, might operate very differently than researchers have come to believe. Simons Foundation All Rights Reserved © 2021

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28041 - Posted: 10.16.2021

by Charles Q. Choi Chronic electrical stimulation of the fornix, a bundle of nerve fibers deep in the brain, rescues learning and memory deficits in mice with mutations of the autism-linked gene CDKL5, according to new research. The results support previous work in mice suggesting that electrical jolts to this fiber tract, which links brain regions involved in memory, could help address cognitive problems in multiple models of neurodevelopmental conditions. These animal studies all use deep brain stimulation (DBS), in which electrodes are placed chronically or, in some cases, permanently in specific neuroanatomical regions. In people, severe cognitive impairment, including memory and learning deficits, is a central feature of cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder, which results from mutations that impair production of the CDKL5 protein. Other characteristics include autism traits and epileptic seizures. “Our hope is to help CDKL5 deficiency patients with at least some aspects of their problems — for example, intellectual disability,” says lead investigator Jianrong Tang, associate professor of pediatrics at the Baylor College of Medicine in Houston, Texas. Little is known about how the loss of CDKL5 affects brain circuitry. In the new study, Tang and his colleagues analyzed the brain’s memory center, the hippocampus, in mice with CDKL5 mutations. The connections between neurons there were less flexible, they found, which likely contributed to the animals’ deficits in learning and memory. The mutations also strengthened inhibitory signals in the dentate gyrus, a part of the hippocampus that helps form new memories. © 2021 Simons Foundation

Related chapters from BN: Chapter 17: Learning and Memory
Related chapters from MM:Chapter 13: Memory and Learning
Link ID: 28038 - Posted: 10.16.2021

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.

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