Chapter 13. Memory and Learning

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By John Krakauer & Tamar Makin The human brain’s ability to adapt and change, known as neuroplasticity, has long captivated both the scientific community and the public imagination. It’s a concept that brings hope and fascination, especially when we hear extraordinary stories of, for example, blind individuals developing heightened senses that enable them to navigate through a cluttered room purely based on echolocation or stroke survivors miraculously regaining motor abilities once thought lost. For years, the notion that neurological challenges such as blindness, deafness, amputation or stroke lead to dramatic and significant changes in brain function has been widely accepted. These narratives paint a picture of a highly malleable brain that is capable of dramatic reorganization to compensate for lost functions. It’s an appealing notion: the brain, in response to injury or deficit, unlocks untapped potentials, rewires itself to achieve new capabilities and self-repurposes its regions to achieve new functions. This idea can also be linked with the widespread, though inherently false, myth that we only use 10 percent of our brain, suggesting that we have extensive neural reserves to lean on in times of need. But how accurate is this portrayal of the brain’s adaptive abilities to reorganize? Are we truly able to tap into reserves of unused brain potential following an injury, or have these captivating stories led to a misunderstanding of the brain’s true plastic nature? In a paper we wrote for the journal eLife, we delved into the heart of these questions, analyzing classical studies and reevaluating long-held beliefs about cortical reorganization and neuroplasticity. What we found offers a compelling new perspective on how the brain adapts to change and challenges some of the popularized notions about its flexible capacity for recovery. The roots of this fascination can be traced back to neuroscientist Michael Merzenich’s pioneering work, and it was popularized through books such as Norman Doidge’s The Brain That Changes Itself. Merzenich’s insights were built on the influential studies of Nobel Prize–winning neuroscientists David Hubel and Torsten Wiesel, who explored ocular dominance in kittens. © 2023 SCIENTIFIC AMERICAN,

Keyword: Learning & Memory; Regeneration
Link ID: 29019 - Posted: 11.22.2023

Claudia López Lloreda The idea that the nervous system passes messages from one nerve cell to another only through synapses — the points where the cells link up end to end — is changing. Two studies show how messages can pass between cells over longer distances, through a ‘wireless’ nerve network in the worm Caenorhabditis elegans. Researchers had not appreciated the extent of this wireless communication, which happens when a molecule called a neuropeptide is released by one neuron and intercepted by another some distance away. The new studies, published in Nature1 and in Neuron2, map out the entire network of neuropeptide communication in a model organism for the first time. “We knew that these chemical connections existed, but this is probably the most comprehensive study in an entire nervous system,” says Gáspár Jékely, a neuroscientist at Heidelberg University in Germany who was not involved in the work. And what the research shows, he adds, is that “it’s not all about the synapses”. Researchers had previously worked out anatomical wiring maps — connectomes — showing how all the neurons in the fruit fly (Drosophila melanogaster) and in C. elegans are linked by their synapses. However, William Schafer, a neuroscientist at the MRC Laboratory of Molecular Biology in Cambridge, UK, wondered about the role of neuropeptides, which had been considered merely helpers in nervous-system messaging. “When I first started talking about this,” he says, “some people wondered, ‘is it all just kind of a soup’” where neuropeptides randomly float from one neuron to the next, “or can you really think about it like a network?” He and his colleagues analysed which neurons in the C. elegans nervous system expressed genes for certain neuropeptides and which ones expressed genes for the receptors of those neuropeptides. Using this data, the team predicted which pairs of nerve cells might be communicating wirelessly. On the basis of these results, the researchers generated a potential map of wireless connections in the worm, finding dense connectivity that looks very different from the anatomical wiring diagram of C. elegans. They published their findings in Neuron2 last week. © 2023 Springer Nature Limited

Keyword: Hormones & Behavior
Link ID: 29017 - Posted: 11.22.2023

Lilly Tozer By analysing more than one million people’s genomes, researchers have identified stretches of DNA that could be linked to cannabis addiction. They also found that some of the same regions in the genome are associated with other health conditions, such as lung cancer and schizophrenia. The findings are evidence that cannabis addiction “could have substantial public-health risks if the usage increases”, says Daniel Levey, a medical neuroscientist at Yale University in New Haven, Connecticut, and a co-author of the study, published today in Nature Genetics1. Taking cannabis recreationally is legal in at least 8 countries, and 48 countries have legalized medicinal use of the drug for conditions including chronic pain, cancer and epilepsy. But one-third of people who take cannabis end up becoming addicted, or using the drug in a way that is damaging to their health. Previous studies have suggested that there is a genetic component, and have shown links between problematic cannabis use and some cancers and psychiatric disorders. Weighing the dangers of cannabis Drug taking and addiction can be influenced both by people’s genes and by their environment, which makes them extremely difficult to study, says Levey. But the team was able to build on data from previous work2 by including genetic information from additional sources, predominantly the Million Veteran Program — a US-based biobank with a large genetic database that aims to improve health care for former military service members. The analysis encompassed multiple ethnic groups, a first for a genetic study looking at cannabis misuse. As well as identifying regions of the genome that might be involved, the researchers saw a bi-directional link between excessive cannabis use and schizophrenia, meaning that the two conditions can influence each other. This finding is intriguing, says Marta Di Forti, a psychiatrist-scientist at King’s College London. Cannabis use “is the most preventable risk factor” for schizophrenia, she says, adding that the type of genetic data examined in the study could be used in future to identify and support people at increased risk of developing psychiatric disorders through cannabis use. © 2023 Springer Nature Limited

Keyword: Drug Abuse; Genes & Behavior
Link ID: 29015 - Posted: 11.22.2023

By Laura Sanders WASHINGTON — Brain scans could be used to predict how teenagers’ mental health will fare during a stressful time, an analysis that spanned the COVID-19 pandemic suggests. The findings, presented November 13 in a news briefing at the annual meeting of the Society for Neuroscience, may help explain why some people succumb to stress while others are more resilient. For a lot of research, “the study happens, and you report on the results, and that’s about it,” says Margot Wagner, a bioengineer at the University of California, San Diego who was not involved in the new work. But this research followed hundreds of teenagers over time, a study design that “means you can intervene and help way sooner than otherwise,” Wagner says. The pandemic was particularly tough for many teenagers, as isolation, worry and upheaval of daily routines affected them in ways that scientists are just now starting to see (SN: 1/3/23). A record number of young people are struggling with depression and anxiety, a mental health crisis that some scientists are calling “the second pandemic” (SN: 6/30/23). While many teenagers struggled during the pandemic, others did OK. Computational neuroscientist Caterina Stamoulis of Harvard Medical School and Boston Children’s Hospital investigated why responses differed using data collected as part of the Adolescent Brain Cognitive Development, or ABCD, study. That larger study — involving scientists at 21 research sites across the United States — aims to figure out how teenagers’ brains grow over the years. “This is the first time in history we’re looking at thousands of participants and getting these measures over time,” Wagner says. “It’s truly remarkable.” The ABCD study, begun in 2015, was well under way when COVID hit, so researchers possessed brain scans from before the pandemic. “Without the pandemic, we would not have been able to understand the impact of a long-lasting adverse event” that deeply affected the participants’ lives, changing their interactions with their family and friends, Stamoulis says. © Society for Science & the Public 2000–2023.

Keyword: Development of the Brain; Stress
Link ID: 29012 - Posted: 11.18.2023

By Carl Zimmer Sign up for Science Times Get stories that capture the wonders of nature, the cosmos and the human body. Get it sent to your inbox. If a troop of baboons encounters another troop on the savanna, they may keep a respectful distance or they may get into a fight. But human groups often do something else: They cooperate. Tribes of hunter-gatherers regularly come together for communal hunts or to form large-scale alliances. Villages and towns give rise to nations. Networks of trade span the planet. Human cooperation is so striking that anthropologists have long considered it a hallmark of our species. They have speculated that it emerged thanks to the evolution of our powerful brains, which enable us to use language, establish cultural traditions and perform other complex behaviors. But a new study, published in Science on Thursday, throws that uniqueness into doubt. It turns out that two groups of apes in Africa have regularly mingled and cooperated with each other for years. “To have extended, friendly, cooperative relationships between members of other groups who have no kinship ties is really quite extraordinary,” said Joan Silk, a primatologist at Arizona State University who was not involved in the study. The new research comes from long-term observations of bonobos, an ape species that lives in the forests of the Democratic Republic of Congo. A century ago, primatologists thought bonobos were a slender subspecies of chimpanzee. But the two species are genetically distinct and behave in some remarkably different ways. Among chimpanzees, males hold a dominant place in society. They can be extremely violent, even killing babies. In bonobo groups, however, females dominate, and males have never been observed to commit infanticide. Bonobos often defuse conflict with sex, a strategy that primatologists have not observed among chimpanzees. Scientists made most of their early observations of bonobos in zoos. But in recent years they’ve conducted long-term studies of the apes in the wild. © 2023 The New York Times Company

Keyword: Evolution; Aggression
Link ID: 29011 - Posted: 11.18.2023

Max Kozlov Researchers have sifted through genomes from thousands of individuals in an effort to identify genes linked to Alzheimer’s disease. But these scientists have faced a serious obstacle: it’s hard to know for certain which of those people have Alzheimer’s. There’s no foolproof blood test for the disease, and dementia, a key symptom of Alzheimer’s, is also caused by other disorders. Early-stage Alzheimer’s might cause no symptoms at all. Now, researchers have developed artificial intelligence (AI)-based approaches that could help. One algorithm efficiently sorts through large numbers of brain images and picks out those that include characteristics of Alzheimer’s. A second machine-learning method identifies important structural features of the brain — an effort that could eventually help scientists to spot new signs of Alzheimer’s in brain scans. The goal is to use people’s brain images as visual ‘biomarkers’ of Alzheimer’s. Applying the method to large databases that also include medical information and genetic data, such as the UK Biobank, could allow scientists to pinpoint genes that contribute to the disease. In turn, this work could aid the creation of treatments and of models that predict who’s at risk of developing the disease. Combining genomics, brain imaging and AI is allowing researchers to “find brain measures that are tightly linked to a genomic driver”, says Paul Thompson, a neuroscientist at the University of Southern California in Los Angeles, who is spearheading efforts to develop these algorithms. Thompson and others described the new AI techniques on 4 November at the annual conference of the American Society of Human Genetics in Washington DC. Overwhelmed with data © 2023 Springer Nature Limited

Keyword: Alzheimers; Robotics
Link ID: 29004 - Posted: 11.13.2023

by Grace Huckins In 1961, the late psychiatrist Daniel Freedman made what would become one of the most replicated — and most mysterious — discoveries in the history of autism research. Comparing blood levels of the neurotransmitter serotonin in 4 non-autistic and 23 autistic children, he found significantly higher levels among the latter group. Since then, researchers have repeatedly identified this trait, called hyperserotonemia, in about a third of autistic people tested. It’s not difficult to theorize how hyperserotonemia might be linked to a range of autism traits. Neurons that release serotonin extend into practically every part of the brain, where they modulate signals sent among other neurons. Selective serotonin reuptake inhibitors (SSRIs), drugs that raise levels of serotonin in the brain’s synapses, treat psychiatric conditions, such as anxiety and obsessive-compulsive disorder, that can co-occur with autism. And serotonin prompts the gut to contract and facilitate digestion, which is often impaired in autistic people. So when Edwin Cook, professor of psychiatry at the University of Illinois at Chicago, began to study the biology of autism in the 1980s, hyperserotonemia seemed like an obvious place to start. “We didn’t have much [else],” he says. “There were plenty of mothers of older patients I saw who had been labeled refrigerator mothers,” a term that refers to the discredited idea that unaffectionate mothers cause autism. The serotonin finding offered a tangible, biological clue. Even today, with decades more autism research to look back on, the hyperserotonemia result stands out. “It’s one of the few robust biological clues that we’ve had in autism,” says Jeremy Veenstra-VanderWeele, professor of psychiatry at Columbia University and a former advisee of Cook’s. But so far, it has escaped explanation. Nor have researchers been able to definitively link hyperserotonemia to specific genetic, anatomical or behavioral traits in autistic people. This apparent lack of progress has led some to disregard work on the neurotransmitter, according to serotonin researcher Georgianna Gould, associate professor of physiology at the University of Texas Health Science Center at San Antonio. “I’ve actually seen reviews come back that say that serotonin has nothing to do with autism,” she says. © 2023 Simons Foundation

Keyword: Autism; Obesity
Link ID: 28998 - Posted: 11.11.2023

By Catherine Offord Close your eyes and picture yourself running an errand across town. You can probably imagine the turns you’d need to take and the landmarks you’d encounter. This ability to conjure such scenarios in our minds is thought to be crucial to humans’ capacity to plan ahead. But it may not be uniquely human: Rats also seem to be able to “imagine” moving through mental environments, researchers report today in Science. Rodents trained to navigate within a virtual arena could, in return for a reward, activate the same neural patterns they’d shown while navigating—even when they were standing still. That suggests rodents can voluntarily access mental maps of places they’ve previously visited. “We know humans carry around inside their heads representations of all kinds of spaces: rooms in your house, your friends’ houses, shops, libraries, neighborhoods,” says Sean Polyn, a psychologist at Vanderbilt University who was not involved in the research. “Just by the simple act of reminiscing, we can place ourselves in these spaces—to think that we’ve got an animal analog of that very human imaginative act is very impressive.” Researchers think humans’ mental maps are encoded in the hippocampus, a brain region involved in memory. As we move through an environment, cells in this region fire in particular patterns depending on our location. When we later revisit—or simply think about visiting—those locations, the same hippocampal signatures are activated. Rats also encode spatial information in the hippocampus. But it’s been impossible to establish whether they have a similar capacity for voluntary mental navigation because of the practical challenges of getting a rodent to think about a particular place on cue, says study author Chongxi Lai, who conducted the work while a graduate student and later a postdoc at the Howard Hughes Medical Institute’s Janelia Research Campus. In their new study, Lai, along with Janelia neuroscientist Albert Lee and colleagues, found a way around this problem by developing a brain-machine interface that rewarded rats for navigating their surroundings using only their thoughts.

Keyword: Learning & Memory; Attention
Link ID: 28989 - Posted: 11.04.2023

By Clay Risen William E. Pelham Jr., a child psychologist who challenged how his field approached attention deficit hyperactivity disorder in children, arguing for a therapy-based regimen that used drugs like Ritalin and Adderall as an optional supplement, died on Oct. 21 in Miami. He was 75. His son, William E. Pelham III, who is also a child psychologist, confirmed the death, in a hospital, but did not provide a cause. Dr. Pelham began his career in the mid-1970s, when the modern understanding of mental health was emerging and psychologists were only just beginning to understand A.D.H.D. — and with it a new generation of medication to treat it. Through the 1980s and ’90s, doctors and many parents embraced A.D.H.D. drugs like Ritalin and Adderall as miracle medications, though some, including Dr. Pelham, raised concerns about their efficacy and side effects. Dr. Pelham was not opposed to medication. He recognized that drugs were effective at rapidly addressing the symptoms of A.D.H.D., like fidgeting, impulsiveness and lack of concentration. But in a long string of studies and papers, he argued that for most children, behavioral therapy, combined with parental intervention techniques, should be the first line of attack, followed by low doses of drugs, if necessary. And yet, as he pointed out repeatedly, the reality was far different: The Centers for Disease Control and Prevention reported in 2016 that while six in 10 children diagnosed with A.D.H.D. were on medication, fewer than half received behavioral therapy. In one major study, which he published in 2016 along with Susan Murphy, a statistician at the University of Michigan, he demonstrated the importance of treatment sequencing — that behavioral therapy should come first, then medication. He and Dr. Murphy split a group of 146 children with A.D.H.D., from ages 5 to 12, into two groups. One group received a low dose of generic Ritalin; the other received nothing, but their parents were given instruction in behavioral-modification techniques. After two months, children from both groups who showed no improvement were arranged into four new groups: The children given generic Ritalin received either more medication or behavioral modification therapy, and the children given behavioral modification therapy received either more intense therapy or a dose of medication. © 2023 The New York Times Company

Keyword: ADHD; Drug Abuse
Link ID: 28984 - Posted: 11.04.2023

By Jake Buehler A fruit bat hanging in the corner of a cave stirs; it is ready to move. It scans the space to look for a free perch and then takes flight, adjusting its membranous wings to angle an approach to a spot next to one of its fuzzy fellows. As it does so, neurological data lifted from its brain is broadcast to sensors installed in the cave’s walls. This is no balmy cave along the Mediterranean Sea. The group of Egyptian fruit bats is in Berkeley, California, navigating an artificial cave in a laboratory that researchers have set up to study the inner workings of the animals’ minds. The researchers had an idea: that as a bat navigates its physical environment, it’s also navigating a network of social relationships. They wanted to know whether the bats use the same or different parts of their brain to map these intersecting realities. In a new study published in Nature in August, the scientists revealed that these maps overlap. The brain cells informing a bat of its own location also encode details about other bats nearby — not only their location, but also their identities. The findings raise the intriguing possibility that evolution can program those neurons for multiple purposes to serve the needs of different species. The neurons in question are located in the hippocampus, a structure deep within the mammalian brain that is involved in the creation of long-term memories. A special population of hippocampal neurons, known as place cells, are thought to create an internal navigation system. First identified in the rat hippocampus in 1971 by the neuroscientist John O’Keefe, place cells fire when an animal is in a particular location; different place cells encode different places. This system helps animals determine where they are, where they need to go and how to get from here to there. In 2014, O’Keefe was awarded the Nobel Prize for his discovery of place cells, and over the last several decades they have been identified in multiple primate species, including humans. However, moving from place to place isn’t the only way an animal can experience a change in its surroundings. In your home, the walls and furniture mostly stay the same from day to day, said Michael Yartsev, who studies the neural basis of natural behavior at the University of California, Berkeley and co-led the new work. But the social context of your living space could change quite regularly. © 2023 An editorially independent publication supported by the Simons Foundation.

Keyword: Learning & Memory
Link ID: 28982 - Posted: 11.01.2023

By Paula Span A year ago, the Food and Drug Administration announced new regulations allowing the sale of over-the-counter hearing aids and setting standards for their safety and effectiveness. That step — which was supposed to take three years but required five — portended cheaper, high-quality hearing aids that people with mild to moderate hearing loss could buy online or at local pharmacies and big stores. So how’s it going? It’s a mixed picture. Manufacturers and retailers have become serious about making hearing aids more accessible and affordable. Yet the O.T.C. market remains confusing, if not downright chaotic, for the mostly older consumers the new regulations were intended to help. The past year also brought renewed focus on the importance of treating hearing loss, which affects two-thirds of people over age 70. Researchers at Johns Hopkins University published the first randomized clinical trial showing that hearing aids could help reduce the pace of cognitive decline. Some background: In 2020, the influential Lancet Commission on Dementia Prevention, Intervention and Care identified hearing loss as the greatest potentially modifiable risk factor for dementia. Previous studies had demonstrated a link between hearing loss and cognitive decline, said Dr. Frank Lin, an otolaryngologist and epidemiologist at Johns Hopkins and lead author of the new research. “What remained unanswered was, If we treat hearing loss, does it actually reduce cognitive loss?” he said. The ACHIEVE study (for Aging and Cognitive Health Evaluation in Elders) showed that, at least for a particular group of older adults, it could. Of nearly 1,000 people ages 70 to 84 with untreated mild to moderate hearing loss, half received hearing assessments from audiologists, were fitted with midpriced hearing aids and were counseled on how to use them for several months. The control group participated in a health education program. Over three years, the study found that hearing-aid use had scant effect on healthy volunteers at low risk of cognitive loss. But among participants who were older and less affluent, hearing aids reduced the rate of cognitive decline by 48 percent, compared with the control group, a difference the researchers deemed “clinically meaningful.” © 2023 The New York Times Company

Keyword: Hearing; Alzheimers
Link ID: 28979 - Posted: 11.01.2023

Anil Oza Scientists once considered sleep to be like a shade getting drawn over a window between the brain and the outside world: when the shade is closed, the brain stops reacting to outside stimuli. A study published on 12 October in Nature Neuroscience1 suggests that there might be periods during sleep when that shade is partially open. Depending on what researchers said to them, participants in the study would either smile or frown on cue in certain phases of sleep. “You’re not supposed to be able to do stuff while you sleep,” says Delphine Oudiette, a cognitive scientist at the Paris Brain Institute in France and a co-author of the study. Historically, the definition of sleep is that consciousness of your environment halts, she adds. “It means you don’t react to the external world.” Dream time A few years ago, however, Oudiette began questioning this definition after she and her team conducted an experiment in which they were able to communicate with people who are aware that they are dreaming while they sleep — otherwise known as lucid dreamers. During these people’s dreams, experimenters were able to ask questions and get responses through eye and facial-muscle movements2. Karen Konkoly, who was a co-author on that study and a cognitive scientist at Northwestern University in Evanston, Illinois, says that after that paper came out, “it was a big open question in our minds whether communication would be possible with non-lucid dreamers”. So Oudiette continued with the work. In her latest study, she and her colleagues observed 27 people with narcolepsy — characterized by daytime sleepiness and a high frequency of lucid dreams — and 22 people without the condition. While they were sleeping, participants were repeatedly asked to frown or smile. All of them responded accurately to at least 70% of these prompts. © 2023 Springer Nature Limited

Keyword: Sleep; Learning & Memory
Link ID: 28968 - Posted: 10.25.2023

By Carl Zimmer An international team of scientists has mapped the human brain in much finer resolution than ever before. The brain atlas, a $375 million effort started in 2017, has identified more than 3,300 types of brain cells, an order of magnitude more than was previously reported. The researchers have only a dim notion of what the newly discovered cells do. The results were described in 21 papers published on Thursday in Science and several other journals. Ed Lein, a neuroscientist at the Allen Institute for Brain Science in Seattle who led five of the studies, said that the findings were made possible by new technologies that allowed the researchers to probe millions of human brain cells collected from biopsied tissue or cadavers. “It really shows what can be done now,” Dr. Lein said. “It opens up a whole new era of human neuroscience.” Still, Dr. Lein said that the atlas was just a first draft. He and his colleagues have only sampled a tiny fraction of the 170 billion cells estimated to make up the human brain, and future surveys will certainly uncover more cell types, he said. Biologists first noticed in the 1800s that the brain was made up of different kinds of cells. In the 1830s, the Czech scientist Jan Purkinje discovered that some brain cells had remarkably dense explosions of branches. Purkinje cells, as they are now known, are essential for fine-tuning our muscle movements. Later generations developed techniques to make other cell types visible under a microscope. In the retina, for instance, researchers found cylindrical “cone cells” that capture light. By the early 2000s, researchers had found more than 60 types of neurons in the retina alone. They were left to wonder just how many kinds of cells were lurking in the deeper recesses of the brain, which are far harder to study. © 2023 The New York Times Company

Keyword: Brain imaging; Development of the Brain
Link ID: 28963 - Posted: 10.14.2023

By Laura Sanders A new look at the human brain is beginning to reveal the inner lives of its cellular residents. The human brain holds a dizzying collection of diverse cells, and no two brains are the same, cellularly speaking. Those are the prevailing conclusions of an onslaught of 21 papers published online October 12 in Science, Science Advances and Science Translational Medicine. The results just start to scratch the surface of understanding the mysteries of the brain. Still, they provide the most intimate look yet at the cells that build the brain, and offer clues about how the brain enables thoughts, actions and memories. The collection of data may also guide researchers in their hunt for the causes of brain disorders such as schizophrenia, Alzheimer’s disease and depression. The new brain map is a result of a coordinated international research effort called the National Institutes of Health’s Brain Initiative Cell Census Network, or BICCN, which ramped up in 2017. Many of the studies in the collection are based on a powerful technology called single-cell genomics. The method reveals which genes are active inside of a single cell, information that provides clues about the cell’s identity and job. As part of the BICCN, researchers examined all sorts of brains. One project detailed the cells in small pieces of live brain tissue taken from 75 people undergoing surgery for tumors or epilepsy, an approach that’s been used on smaller scales before (SN: 8/7/19). Another looked at samples taken from the brains of 17 deceased children. Still another looked at brain tissue from seven people, seven chimpanzees, four gorillas, three rhesus macaques and three marmosets. © Society for Science & the Public 2000–2023.

Keyword: Development of the Brain; Brain imaging
Link ID: 28962 - Posted: 10.14.2023

By Benjamin Mueller Once their scalpels reach the edge of a brain tumor, surgeons are faced with an agonizing decision: cut away some healthy brain tissue to ensure the entire tumor is removed, or give the healthy tissue a wide berth and risk leaving some of the menacing cells behind. Now scientists in the Netherlands report using artificial intelligence to arm surgeons with knowledge about the tumor that may help them make that choice. The method, described in a study published on Wednesday in the journal Nature, involves a computer scanning segments of a tumor’s DNA and alighting on certain chemical modifications that can yield a detailed diagnosis of the type and even subtype of the brain tumor. That diagnosis, generated during the early stages of an hourslong surgery, can help surgeons decide how aggressively to operate, the researchers said. In the future, the method may also help steer doctors toward treatments tailored for a specific subtype of tumor. “It’s imperative that the tumor subtype is known at the time of surgery,” said Jeroen de Ridder, an associate professor in the Center for Molecular Medicine at UMC Utrecht, a Dutch hospital, who helped lead the study. “What we have now uniquely enabled is to allow this very fine-grained, robust, detailed diagnosis to be performed already during the surgery.” A brave new world. A new crop of chatbots powered by artificial intelligence has ignited a scramble to determine whether the technology could upend the economics of the internet, turning today’s powerhouses into has-beens and creating the industry’s next giants. Here are the bots to know: ChatGPT. ChatGPT, the artificial intelligence language model from a research lab, OpenAI, has been making headlines since November for its ability to respond to complex questions, write poetry, generate code, plan vacations and translate languages. GPT-4, the latest version introduced in mid-March, can even respond to images (and ace the Uniform Bar Exam). © 2023 The New York Times Company

Keyword: Robotics; Intelligence
Link ID: 28958 - Posted: 10.12.2023

By Mark Johnson Using a host of high-tech tools to simulate brain development in a lab dish, Stanford University researchers have discovered several dozen genes that interfere with crucial steps in the process and may lead to autism, a spectrum of disorders that affects about one in every 36 Americans, impairing their ability to communicate and interact with others. The results of a decade of work, the findings published in the journal Nature may one day pave the way for scientists to design treatments that allow these phases of brain development to proceed unimpaired. The study delves into a 20-year-old theory that suggests one cause of autism may be a disruption of the delicate balance between two types of nerve cells found in the brain’s cerebral cortex, the area responsible for higher-level processes such as thought, emotion, decision-making and language. Some nerve cells in this region of the brain excite other nerve cells, encouraging them to fire; other cells, called interneurons, do the opposite. Too much excitation can impair focus in the brain and cause epilepsy, a seizure disorder that is more common in people with autism than in the general population. Scientists therefore believe a proper balance requires more of the inhibiting interneurons. In the developing fetus, these nerve cells start out deep in the brain in a region called the subpallium, then migrate slowly to the cerebral cortex. The process begins mid-gestation and ends in the infant’s second year of life, said Sergiu Pasca, a Stanford University professor of psychiatry and behavioral sciences who led the study. Pasca’s team, which included researchers from the University of California at San Francisco and the Icahn School of Medicine at Mount Sinai, tested 425 genes that have been linked to neurodevelopmental disorders to determine which ones interfere with the generation and migration of interneurons. Genes linked to autism were among those identified in the study. “What’s really cool about this paper is that autism is a collection of different behaviors, but we don’t have [an] understanding of how those behaviors are connected to differences in the brain,” said James McPartland, a professor of child psychiatry and psychology at the Yale School of Medicine, who was not involved in the study. The new work advances research into autism by “beginning to create a fundamental understanding of the building blocks of brain development,” he said.

Keyword: Autism; Genes & Behavior
Link ID: 28947 - Posted: 10.07.2023

Jon Hamilton A team of researchers has developed a new way to study how genes may cause autism and other neurodevelopmental disorders: by growing tiny brain-like structures in the lab and tweaking their DNA. These "assembloids," described in the journal Nature, could one day help researchers develop targeted treatments for autism spectrum disorder, intellectual disability, schizophrenia, and epilepsy. "This really accelerates our effort to try to understand the biology of psychiatric disorders," says Dr. Sergiu Pașca, a professor of psychiatry and behavioral sciences at Stanford University and an author of the study. The research suggests that someday "we'll be able to predict which pathways we can target to intervene" and prevent these disorders, adds Kristen Brennand, a professor of psychiatry at Yale who was not involved in the work. The study comes after decades of work identifying hundreds of genes that are associated with autism and other neurodevelopmental disorders. But scientists still don't know how problems with these genes alter the brain. "The challenge now is to figure out what they're actually doing, how disruptions in these genes are actually causing disease," Pașca says. "And that has been really difficult." For ethical reasons, scientists can't just edit a person's genes to see what happens. They can experiment on animal brains, but lab animals like rodents don't really develop anything that looks like autism or schizophrenia. So Pașca and a team of scientists tried a different approach, which they detailed in their new paper. The team did a series of experiments using tiny clumps of human brain cells called brain organoids. These clumps will grow for a year or more in the lab, gradually organizing their cells much the way a developing brain would. And by exposing an organoid to certain growth factors, scientists can coax it into resembling tissue found in brain areas including the cortex and hippocampus. © 2023 npr

Keyword: Epilepsy; Autism
Link ID: 28940 - Posted: 10.03.2023

By Stephanie Pappas If you’ve ever awoken from a vivid dream only to find that you can’t remember the details by the end of breakfast, you’re not alone. People forget most of the dreams they have—though it is possible to train yourself to remember more of them. Dreaming happens mostly (though not always exclusively) during rapid eye movement (REM) sleep. During this sleep stage, brain activity looks similar to that in a waking brain, with some very important differences. Key among them: during REM sleep, the areas of the brain that transfer memories into long-term storage—as well as the long-term storage areas themselves—are relatively deactivated, says Deirdre Barrett, a dream researcher at Harvard Medical School and author of the book The Committee of Sleep (Oneiroi Press, 2001). This may be a side effect of REM’s role in memory consolidation, according to a 2019 study on mice in the journal Science. Short-term memory areas are active during REM sleep, but those only hang on to memories for about 30 seconds. “You have to wake up from REM sleep, generally, to recall a dream,” Barrett says. If, instead, you pass into the next stage of sleep without rousing, that dream will never enter long-term memory. REM sleep occurs about every 90 minutes, and it lengthens as the night drags on. The first REM cycle of the night is typically just a few minutes long, but by the end of an eight-hour night of sleep, a person has typically been in the REM stage for a good 20 minutes, Barrett says. That’s why the strongest correlation between any life circumstance and your memory of dreams is the number of hours you’ve slept. If you sleep only six hours, you’re getting less than half of the dream time of an eight-hour night, she says. Those final hours of sleep are the most important for dreaming. And people tend to remember the last dream of the night—the one just before waking. © 2023 Scientific American

Keyword: Sleep; Learning & Memory
Link ID: 28939 - Posted: 10.03.2023

Sara Reardon Scientists have identified two types of brain cell linked to a reduced risk of dementia in older people — even those who have brain abnormalities that are hallmarks of Alzheimer’s disease1. The finding could eventually lead to new ways to protect these cells before they die. The results were published in Cell on 28 September. The most widely held theory about Alzheimer’s attributes the disease to a build-up of sticky amyloid proteins in the brain. This leads to clump-like ‘plaques’ of amyloid that slowly kill neurons and eventually destroy memory and cognitive ability. But not everyone who develops cognitive impairment late in life has amyloid clumps in their brain, and not everyone with amyloid accumulation develops Alzheimer’s. Neurobiologist Hansruedi Mathys at the University of Pittsburgh School of Medicine in Pennsylvania and neuroscientist Li-Huei Tsai and computer scientist Manolis Kellis at the Massachusetts Institute of Technology in Cambridge and their colleagues decided to investigate this disconnect. To do so, they used data from a massive study that tracks cognitive and motor skills in thousands of people throughout old age. The researchers examined tissue samples from 427 brains from participants who had died. Some of those participants had dementia typical of advanced Alzheimer’s disease, some had mild cognitive impairment and the remainder had no sign of impairment. The researchers isolated cells from each participant’s prefrontal cortex, the region involved in higher brain function. To classify the cells, they sequenced all the active genes in each one. This allowed them to create an atlas of the brain showing where the different cell types occur. The scientists identified two key cell types that had a specific genetic marker. One had active genes coding for reelin, a protein associated with brain disorders such as schizophrenia, and the other had active genes that code for somatostatin, a hormone that regulates processes throughout the body. © 2023 Springer Nature Limited

Keyword: Alzheimers; Genes & Behavior
Link ID: 28938 - Posted: 09.29.2023

By Clay Risen Endel Tulving, whose insights into the structure of human memory and the way we recall the past revolutionized the field of cognitive psychology, died on Sept. 11 in Mississauga, Ontario. He was 96. His daughters, Linda Tulving and Elo Tulving-Blais, said his death, at an assisted living home, was caused by complications of a stroke. Until Dr. Tulving began his pathbreaking work in the 1960s, most cognitive psychologists were more interested in understanding how people learn things than in how they retain and recall them. When they did think about memory, they often depicted it as one giant cerebral warehouse, packed higgledy-piggledy, with only a vague conception of how we retrieved those items. This, they asserted, was the realm of “the mind,” an untestable, almost philosophical construct. Dr. Tulving, who spent most of his career at the University of Toronto, first made his name with a series of clever experiments and papers, demonstrating how the mind organizes memories and how it uses contextual cues to retrieve them. Forgetting, he posited, was less about information loss than it was about the lack of cues to retrieve it. He established his legacy with a chapter in the 1972 book “Organization of Memory,” which he edited with Wayne Donaldson. In that chapter, he argued for a taxonomy of memory types. He started with two: procedural memory, which is largely unconscious and involves things like how to walk or ride a bicycle, and declarative memory, which is conscious and discrete. © 2023 The New York Times Company

Keyword: Learning & Memory
Link ID: 28934 - Posted: 09.29.2023