By Carl Zimmer The human brain is so complex that scientific brains have a hard time making sense of it. A piece of neural tissue the size of a grain of sand might be packed with hundreds of thousands of cells linked together by miles of wiring. In 1979, Francis Crick, the Nobel-prize-winning scientist, concluded that the anatomy and activity in just a cubic millimeter of brain matter would forever exceed our understanding. “It is no use asking for the impossible,” Dr. Crick wrote. Forty-six years later, a team of more than 100 scientists has achieved that impossible, by recording the cellular activity and mapping the structure in a cubic millimeter of a mouse’s brain — less than one percent of its full volume. In accomplishing this feat, they amassed 1.6 petabytes of data — the equivalent of 22 years of nonstop high-definition video. “This is a milestone,” said Davi Bock, a neuroscientist at the University of Vermont who was not involved in the study, which was published Wednesday in the journal Nature. Dr. Bock said that the advances that made it possible to chart a cubic millimeter of brain boded well for a new goal: mapping the wiring of the entire brain of a mouse. “It’s totally doable, and I think it’s worth doing,” he said. More than 130 years have passed since the Spanish neuroscientist Santiago Ramón y Cajal first spied individual neurons under a microscope, making out their peculiar branched shapes. Later generations of scientists worked out many of the details of how a neuron sends a spike of voltage down a long arm, called an axon. Each axon makes contact with tiny branches, or dendrites, of neighboring neurons. Some neurons excite their neighbors into firing voltage spikes of their own. Some quiet other neurons. Human thought somehow emerges from this mix of excitation and inhibition. But how that happens has remained a tremendous mystery, largely because scientists have been able to study only a few neurons at a time. In recent decades, technological advances have allowed scientists to start mapping brains in their entirety. In 1986, British researchers published the circuitry of a tiny worm, made up of 302 neurons. In subsequent years, researchers charted bigger brains, such as the 140,000 neurons in the brain of a fly. © 2025 The New York Times Company

Keyword: Brain imaging; Development of the Brain
Link ID: 29743 - Posted: 04.12.2025

Avram Holmes. Human thought and behavior emerge through complex and reciprocal interactions that link microscale molecular and cellular processes with macroscale functional patterns. Functional MRI (fMRI), one of the most common methods for studying the human brain, detects these latter patterns through the “blood oxygen level dependent,” or BOLD, signal, a composite measure of both neural and vascular signals that reflects an indirect measure of brain activity. Despite an enormous investment by scientific funders and the research community in the use of fMRI, though, researchers still don’t fully understand the underlying mechanisms that drive individual or population-level differences measured via in-vivo brain imaging, which limits our ability to interpret those data. For fMRI to meaningfully contribute to progress in neuroscience, we need to develop research programs that link phenomena across levels, from genes and molecules to cells, circuits, networks and behavior. Without a concerted effort in this direction, fMRI will remain a methodological spandrel, a byproduct of technological development rather than a tool explicitly designed to reveal neural mechanisms, generating isolated datapoints that are left unintegrated with broader scientific theory or progress. Recently, the human functional neuroimaging community has turned a critical eye toward its own methods and findings. These debates have led to field-wide initiatives calling for larger and more diverse study samples, better phenotypic reliability and findings that generalize across populations. But researchers have put relatively little emphasis on contextualizing the resulting work across levels of analysis or on deciphering the biological mechanism that may underpin changes to the BOLD signal across groups and individual people or over the lifespan. Appeals to better integrate the different levels of neuroscience are not new. But despite persuasive arguments, fMRI researchers have largely remained scientifically siloed, isolated by a nearly ubiquitous focus on a single level of analysis and a rigid adherence to a select set of imaging methods. Our work is typically presented inside of field-specific echo chambers—departmental or group seminars, topic-specific journals and society meetings—where our methodological and analytic choices go unchallenged. What progress can we expect to make if we remain isolated from other fields of study? © 2025 Simons Foundation

Keyword: Brain imaging
Link ID: 29735 - Posted: 04.09.2025

Miryam Naddaf A brain-reading implant that translates neural signals into audible speech has allowed a woman with paralysis to hear what she intends to say nearly instantly. Researchers enhanced the device — known as a brain–computer interface (BCI) — with artificial intelligence (AI) algorithms that decoded sentences as the woman thought of them, and then spoke them out loud using a synthetic voice. Unlike previous efforts, which could produce sounds only after users finished an entire sentence, the current approach can simultaneously detect words and turn them into speech within 3 seconds. The findings, published in Nature Neuroscience on 31 March1, represent a big step towards BCIs that are of practical use. Older speech-generating BCIs are similar to “a WhatsApp conversation”, says Christian Herff, a computational neuroscientist at Maastricht University, the Netherlands, who was not involved with the work. “I write a sentence, you write a sentence and you need some time to write a sentence again,” he says. “It just doesn’t flow like a normal conversation.” BCIs that stream speech in real time are “the next level” in research because they allow users to convey the tone and emphasis that are characteristic of natural speech, he adds. The study participant, Ann, lost her ability to speak after a stroke in her brainstem in 2005. Some 18 years later, she underwent a surgery to place a paper-thin rectangle containing 253 electrodes on the surface of her brain cortex. The implant can record the combined activity of thousands of neurons at the same time. Researchers personalized the synthetic voice to sound like Ann’s own voice from before her injury, by training AI algorithms on recordings from her wedding video. During the latest study, Ann silently mouthed 100 sentences from a set of 1,024 words and 50 phrases that appeared on a screen. The BCI device captured her neural signals every 80 milliseconds, starting 500 milliseconds before Ann started to silently say the sentences. It produced between 47 and 90 words per minute (natural conversation happens at around 160 words per minute).

Keyword: Language; Robotics
Link ID: 29726 - Posted: 04.02.2025

By Veronique Greenwood Encased in the skull, perched atop the spine, the brain has a carefully managed existence. It receives only certain nutrients, filtered through the blood-brain barrier; an elaborate system of protective membranes surrounds it. That privileged space contains a mystery. For more than a century, scientists have wondered: If it’s so hard for anything to get into the brain, how does waste get out? The brain has one of the highest metabolisms of any organ in the body, and that process must yield by-products that need to be removed. In the rest of the body, blood vessels are shadowed by a system of lymphatic vessels. Molecules that have served their purpose in the blood move into these fluid-filled tubes and are swept away to the lymph nodes for processing. But blood vessels in the brain have no such outlet. Several hundred kilometers of them, all told, seem to thread their way through this dense, busily working tissue without a matching waste system. However, the brain’s blood vessels are surrounded by open, fluid-filled spaces. In recent decades, the cerebrospinal fluid, or CSF, in those spaces has drawn a great deal of interest. “Maybe the CSF can be a highway, in a way, for the flow or exchange of different things within the brain,” said Steven Proulx, who studies the CSF system at the University of Bern. A recent paper in Cell contains a new report about what is going on around the brain (opens a new tab) and in its hidden cavities. A team at the University of Rochester led by the neurologist Maiken Nedergaard (opens a new tab) asked whether the slow pumping of the brain’s blood vessels might be able to push the fluid around, among, and in some cases through cells, to potentially drive a system of drainage. In a mouse model, researchers injected a glowing dye into CSF, manipulated the blood vessel walls to trigger a pumping action, and saw the dye concentration increase in the brain soon after. They concluded that the movement of blood vessels might be enough to move CSF, and possibly the brain’s waste, over long distances. © 2025 Simons Foundation.

Keyword: Brain imaging; Sleep
Link ID: 29722 - Posted: 03.27.2025

Nora Bradford Scientists have created the first map of the crucial structures called mitochondria throughout the entire brain ― a feat that could help to unravel age-related brain disorders1. The results show that mitochondria, which generate the energy that powers cells, differ in type and density in different parts of the brain. For example, the evolutionarily oldest brain regions have a lower density of mitochondria than newer regions. The map, which the study’s authors call the MitoBrainMap, is “both technically impressive and conceptually groundbreaking”, says Valentin Riedl, a neurobiologist at Friedrich-Alexander University in Erlangen, Germany, who was not involved in the project. The brain’s mitochondria are not just bit-part players. “The biology of the brain, we know now, is deeply intertwined with the energetics of the brain,” says Martin Picard, a psychobiologist at Columbia University in New York City, and a co-author of the study. And the brain accounts for 20% of the human body’s energy usage2. Wielding a tool typically used for woodworking, the study’s authors divided a slice of frozen human brain ― from a 54-year-old donor who died of a heart attack ― into 703 tiny cubes. Each cube measured 3 × 3 × 3 millimetres, which is comparable to the size of the units that make up standard 3D images of the brain. “The most challenging part was having so many samples,” says Picard. The team used biochemical and molecular techniques to determine the density of mitochondria in each of the 703 samples. In some samples, the researchers also estimated the mitochondria’s efficiency at producing energy. To extend their findings beyond a single brain slab, the authors developed a model to predict the numbers and types of mitochondria across the entire brain. They fed it brain-imaging data and the brain-cube data. To check their model, they applied it to other samples of the frozen brain slice and found that it accurately predicted the samples’ mitochondrial make-up. © 2025 Springer Nature

Keyword: Brain imaging
Link ID: 29721 - Posted: 03.27.2025

Anna Bawden Health and social affairs correspondent Researchers have developed ultra-powerful scans that could enable surgery for previously treatment-resistant epilepsy. Globally, about 50 million people have epilepsy. In England, epileptic seizures are the sixth most common reason for hospital admission. About 360,000 people in the UK have focal epilepsy, which causes recurring seizures in a specific part of the brain. Many patients successfully treat their condition with medication but for more than 100,000 patients, their symptoms do not improve with drugs, leaving surgery as the only option. Finding brain lesions, a significant cause of epilepsy, can be tricky. Ultra-powerful MRI scanners are capable of identifying even tiny lesions in patients’ brains. These 7T MRI scanners produce much more detailed resolution on brain scans, enabling better detection of lesions. If surgeons can see the lesions on MRI scans, this can double the chances of the patient being free of seizures after surgery. But 7T scanners are also susceptible to “dark patches” known as signal dropouts. Now researchers in Cambridge and Paris have developed a new technique to overcome the problem. Scientists at the University of Cambridge’s Wolfson Brain Imaging Centre, and the Université Paris-Saclay, used eight transmitters around the brain, rather than the usual one, to “parallel transmit” MRI images, which significantly reduced the number of black spots. The first study to use this approach, doctors at Addenbrooke’s hospital, Cambridge, then trialled the technique with 31 drug-resistant epilepsy patients to see whether the parallel transmit 7T scanner was better than conventional 3T scanners at detecting brain lesions. The research, published in the journal Epilepsia, found that the parallel transmit 7T scanner identified previously unseen structural lesions in nine patients. © 2025 Guardian News & Media Limited

Keyword: Brain imaging; Epilepsy
Link ID: 29716 - Posted: 03.22.2025

Five years ago Italian researchers published a study on the eruption of Mount Vesuvius in A.D. 79. that detailed how one victim of the blast, a male presumed to be in his mid 20s, had been found nearby in the seaside settlement of Herculaneum. He was lying facedown and buried by ash on a wooden bed in the College of the Augustales, a public building dedicated to the worship of Emperor Augustus. Some scholars believe that the man was the center’s caretaker and was asleep at the time of the disaster. In 2018, one researcher discovered black, glossy shards embedded inside the caretaker’s skull. The paper, published in 2020, speculated that the heat of the explosion was so immense that it had fused the victim’s brain tissue into glass. Vesuvius Erupted, but When Exactly? March 2, 2025 Forensic analysis of the obsidian-like chips revealed proteins common in brain tissue and fatty acids found in human hair, while a chunk of charred wood unearthed near the skeleton indicated a thermal reading as high as 968 degrees Fahrenheit, roughly the dome temperature of a wood-fired Neapolitan pizza oven. It was the only known instance of soft tissue — much less any organic material — being naturally preserved as glass. On Thursday, a paper published in Nature verified that the fragments are indeed glassified brain. Using techniques such as electron microscopy, energy dispersive X-ray spectroscopy and differential scanning calorimetry, scientists examined the physical properties of samples taken from the glassy fragments and demonstrated how they were formed and preserved. “The unique finding implies unique processes,” said Guido Giordano, a volcanologist at the Roma Tre University and lead author of the new study. Foremost among those processes is vitrification, by which material is burned at a high heat until it liquefies. To harden into glass, the substance requires rapid cooling, solidifying at a temperature higher than its surroundings. This makes organic glass formation challenging, Dr. Giordano said, as vitrification entails very specific temperature conditions and the liquid form must cool fast enough to avoid being crystallized as it congeals. © 2025 The New York Times Company

Keyword: Brain imaging
Link ID: 29690 - Posted: 03.05.2025

By Holly Barker Hunched over a microscope more than a century ago, Santiago Ramón y Cajal discovered that distinct types of neurons favor different brain regions. Looking at tissue from a pigeon’s cerebellum, he drew Purkinje cells, their dendrites outspread and twisted like a ravaged oak. And drawing from another sample—the first cortical layer of a newborn rabbit’s brain—he traced the tentacled nerve cells that would later bear his name. But the brain’s cellular organization is even more ordered than Ramón y Cajal could have imagined, a new study suggests. Different functional networks—measured using functional MRI—involve distinct blends of cell types, identified from their transcriptional profiles. And a machine-learning tool trained on cell distributions in postmortem tissue can identify functional networks based on these cellular “fingerprints,” the researchers found. The findings could address the gulf between neuroimaging and cell-based research, says the study’s principal investigator, Avram Holmes, associate professor of psychiatry at Rutgers University. “In-vivo imaging studies are almost never linked back to the underlying biological cascades that give rise to the phenotypes,” he says. But the new approach “lets you jump between fields of study—that was very difficult to do in the past.” Using bulk gene-expression data from postmortem human brain tissue—obtained from the Allen Human Brain Atlas—Holmes and his colleagues classified 24 different types of cells. They then mapped the cells’ spatial distribution to two features of large-scale brain organization derived from a popular fMRI atlas: networks, and those networks’ position in the cortical gradient, which is based on location, style of information processing and connectivity pattern. Unimodal sensorimotor networks—those that perceive stimuli and act on them—anchor one end of the gradient, and the other end is occupied by transmodal systems, such as the default mode network, that integrate multiple information streams across the cortex. The remaining networks are parked between these two extremes. © 2025 Simons Foundation

Keyword: Brain imaging
Link ID: 29689 - Posted: 03.01.2025

By Heidi Ledford A slimy barrier lining the brain’s blood vessels could hold the key to shielding the organ from the harmful effects of ageing, according to a study in mice. The study showed that this oozy barrier deteriorates with time, potentially allowing harmful molecules into brain tissue and sparking inflammatory responses. Gene therapy to restore the barrier reduced inflammation in the brain and improved learning and memory in aged mice. The work was published today in Nature1. The finding shines a spotlight on a cast of poorly understood molecules called mucins that coat the interior of blood vessels throughout the body and give mucus its slippery texture, says Carolyn Bertozzi, a Nobel-prizewinning chemist at Stanford University in California and a lead author of the study. “Mucins play a lot of interesting roles in the body,” she says. “But until recently, we didn’t have the tools to study them. They were invisible.” Snotty barrier Mucins are large proteins decorated with carbohydrates that form linkages with one another, creating a water-laden, gel-like substance. They are crucial constituents of the blood–brain barrier, a system that restricts the movement of some molecules from the blood into the brain. Researchers have long sought ways to sneak medicines past this barrier to treat diseases of the brain. Previous work also showed that the integrity of the barrier erodes with age2, suggesting that it could be an important target for therapies to combat diseases associated with ageing, such as Alzheimer’s disease. But scientists knew little about the contribution of mucins to these changes, until Sophia Shi, a graduate student at Stanford, decided to focus on a mucin-rich layer called the glycocalyx, which lines blood vessels. Shi and her colleagues looked at what happens to the glycocalyx in the brain as mice age. “The mucins on the young blood vessels were thick and juicy and plump,” says Bertozzi. “In the old mice, they were thin and lame and patchy.” © 2025 Springer Nature Limited

Keyword: Brain Injury/Concussion; Brain imaging
Link ID: 29688 - Posted: 03.01.2025

By Lydia Denworth When Mala Murthy and Sebastian Seung of Princeton University saw high-resolution 2D electron microscope images in a 2018 Cell paper, they decided to try to build a fruit fly connectome with that dataset. Funded by the U.S. National Institutes of Health BRAIN Initiative, Murthy and Seung used the electron microscopy data to launch the work that resulted in FlyWire, a nine-paper package published in Nature in October 2024. The work made international headlines for its novelty and ambition. Not long ago, the length of the author list on the flagship FlyWire paper also would have been newsworthy: 46 researchers, including Murthy, Seung and first author Sven Dorkenwald. Neuroscience research has long been driven by individual labs and individual investigators, but today it is increasingly becoming a team sport similar to the FlyWire work—a 2024 preprint describing a study of hundreds of thousands of neuroscience papers published worldwide between 2001 and 2022 found a consistent rise in the number of authors per paper in nearly every country examined. There were 66 Nature Neuroscience papers in 2023 that had double-digit author counts, with the longest author list for that year comprising 209 names. The causes of this shift are related to technology breakthroughs that have allowed for the generation of massive datasets, as well as the general maturation of neuroscience, which is catching up with the large-scale, collaborative efforts put forth in other fields. The dual landmark papers in 2001 revealing the first draft of the Human Genome Project boasted 249 authors (in Nature) and 274 authors (in Science), and a fruit fly genome paper published in 2015 had more than 1,000. In physics, a 2015 paper providing an estimate of the mass of the Higgs boson listed more than 5,000 authors, thought to be a record. But researchers say long author lists are also raising questions about what kind of work is most productive for neuroscience and how to best parcel out credit. A stack of author names can diffuse “responsibility for what’s in the paper,” says neuroscientist J. Anthony Movshon of New York University. “We’re going to a place where it’s very hard to establish whose work you’re actually reading.” © 2025 Simons Foundation

Keyword: Miscellaneous
Link ID: 29682 - Posted: 02.26.2025

By Fred Schwaller Andrea West remembers the first time she heard about a new class of migraine medication that could end her decades of pain. It was 2021 and she heard a scientist on the radio discussing the promise of gepants, a class of drug that for the first time seemed to prevent migraine attacks. West followed news about these drugs closely, and when she heard last year that atogepant was approved for use in the United Kingdom, she went straight to her physician. West had endured migraines for 70 years. Since she started taking the drug, she hasn’t had one. “It’s marvellous stuff. It’s genuinely changed my life,” she says. For ages, the perception of migraine has been one of suffering with little to no relief. In ancient Egypt, physicians strapped clay crocodiles to people’s heads and prayed for the best. And as late as the seventeenth century, surgeons bored holes into people’s skulls — some have suggested — to let the migraine out. The twentieth century brought much more effective treatments, but they did not work for a significant fraction of the roughly one billion people who experience migraine worldwide. Now there is a new sense of progress running through the field, brought about by developments on several fronts. Medical advances in the past few decades — including the approval of gepants and related treatments — have redefined migraine as “a treatable and manageable condition”, says Diana Krause, a neuropharmacologist at the University of California, Irvine. At the same time, research is leading to a better understanding about the condition — and pointing to directions for future work. Studies have shown, for example, that migraine is a broad phenomenon that originates in the brain and can manifest in many debilitating symptoms, including light sensitivities and aura, brain fog and fatigue. “I used to think that disability travels with pain, and it’s only when the pain gets severe that people are impaired. That’s not only false, but we have treatments to do something about it,” says Richard Lipton, a neurologist at the Albert Einstein College of Medicine in New York City. © 2025 Springer Nature Limited

Keyword: Pain & Touch
Link ID: 29681 - Posted: 02.22.2025

By Tina Hesman Saey After nearly 350 years, a depiction of a bee’s brain is getting some buzz. A manuscript created in the mid-1670s contains the oldest known depiction of an insect’s brain, historian of science Andrea Strazzoni of the University of Turin in Italy reports January 29 in Royal Society Notes and Records. Handwritten by Dutch biologist and microscopist Johannes Swammerdam, the manuscript contains a detailed description and drawing of a honeybee drone’s brain. The illustration, based on his own dissections, was just one of Swammerdam’s firsts. In 1658, he was also the first to see and describe red blood cells. Since no one had previously reported dissecting a bee brain, Swammerdam based his descriptions on what was known about the brain anatomy of humans and other mammals. “He knew what to expect from or to imagine in his observations: in particular, the pineal gland and the cerebellum,” Strazzoni writes. Bees have neither of those parts but have brain structures that the 17th century scientist mistook for them. But Swammerdam deserves some slack, Strazzoni suggests. He was working with single-lens microscopes and developing new techniques for dissecting and observing insects’ internal organs. Even with those crude instruments, he was able to identify some nerves and describe how parts of the brain connected. © Society for Science & the Public 2000–2025.

Keyword: Brain imaging; Evolution
Link ID: 29644 - Posted: 01.29.2025

By Shaena Montanari For evolutionary neuroanatomists who compare diverse animal brains, access to a gold mine of 500,000 histological sections and whole mounts is now only a mouse-click away. The R. Glenn Northcutt Collection of Comparative Vertebrate Neuroanatomy and Embryology at Harvard University—which comprises 33,000 slides of tissue samples from more than 240 vertebrate genera—is one of the world’s largest and most diverse collections of its kind. Northcutt, a prolific comparative vertebrate neuroanatomist and emeritus professor of neurosciences at the University of California, San Diego, amassed the collection over the course of five decades. Since 2021, James Hanken, research professor of biology at Harvard University and curator at the Museum of Comparative Zoology, has led an effort to digitize it. The scanning process is still ongoing and may take another two years to complete, Hanken says, but more than 8,000 slides are already publicly available in two online data repositories: MCZBase and MorphoSource. A comprehensive inventory of the entire collection appears in a paper Hanken and his colleagues published last week in the Bulletin of the Museum of Comparative Zoology. It provides researchers with an in-depth guide for using the collection, Hanken says. Few other resources of this type are available online to researchers interested in evolutionary biology and brain anatomy, says Andrew Iwaniuk, professor of neuroscience at the University of Lethbridge. For example, neither the Welker Comparative Anatomy Collection nor the Starr Collection, both housed at the U.S. National Museum of Health and Medicine in Silver Spring, Maryland, are available online. To access slide collections such as these, scientists have had to travel to see them in person, which can be difficult for those outside the United States, Iwaniuk adds. © 2025 Simons Foundation

Keyword: Brain imaging; Evolution
Link ID: 29642 - Posted: 01.25.2025

By Smriti Mallapaty For the first time, scientists have tracked microplastics moving through the bodies of mice in real time1. The tiny plastic particles are gobbled up by immune cells, travel through the bloodstream and eventually become lodged in blood vessels in the brain. It’s not clear whether such obstructions occur in people, say researchers, but they did seem to affect the mice’s movement. Microplastics are specks of plastic, less than 5 millimetres long, that can be found everywhere, from the deep ocean to Antarctic ice. They are in the air we breathe, the water we drink and the food we eat. They can even enter our bloodstreams directly through plastic medical devices. Studies show that microplastics, and smaller nanoplastics, have made their way into humans’ brains, livers and kidneys, but researchers are just beginning to understand what happens to these plastic intruders and their effect on human health. One study last year, for example, found that people with micro- and nano-plastics in fatty deposits in their main artery were more likely to experience a heart attack, stroke or death2. In the latest study, published in Science Advances today, Haipeng Huang, a biomedical researcher at Peking University in Beijing, and his colleagues wanted to better understand how microplastics affect the brain. They used a fluorescence imaging technique called miniature two-photon microscopy to observe what was happening in mouse brains through a transparent window surgically implanted into the animal’s skull. The imaging technique can trace microplastics as they move through the bloodstream, says Eliane El Hayek, an environmental-health researcher at University of New Mexico in Albuquerque. “It’s very interesting, and very helpful.” © 2025 Springer Nature Limited

Keyword: Neurotoxins; Stroke
Link ID: 29641 - Posted: 01.25.2025

Hannah Devlin Science correspondent A groundbreaking NHS trial will attempt to boost patients’ mood using a brain-computer-interface that directly alters brain activity using ultrasound. The device, which is designed to be implanted beneath the skull but outside the brain, maps activity and delivers targeted pulses of ultrasound to “switch on” clusters of neurons. Its safety and tolerability will be tested on about 30 patient in the £6.5m trial, funded by the UK’s Advanced Research and Invention Agency (Aria). In future, doctors hope the technology could revolutionise the treatment of conditions such as depression, addiction, OCD and epilepsy by rebalancing disrupted patterns of brain activity. Jacques Carolan, Aria’s programme director, said: “Neurotechnologies can help a much broader range of people than we thought. Helping with treatment resistant depression, epilepsy, addiction, eating disorders, that is the huge opportunity here. We are at a turning point in both the conditions we hope we can treat and the new types of technologies emerging to do that.” The trial follows rapid advances in brain-computer-interface (BCI) technology, with Elon Musk’s company Neuralink launching a clinical trial in paralysis patients last year and another study restoring communication to stroke patients by translating their thoughts directly into speech. However, the technologies raise significant ethical issues around the ownership and privacy of data, the possibility of enhancement and the risk of neuro-discrimination, whereby brain data might be used to judge a person’s suitability for employment or medical insurance. © 2025 Guardian News & Media Limited

Keyword: Depression; Brain imaging
Link ID: 29637 - Posted: 01.22.2025

By Mitch Leslie Scientists think sleep is the brain’s rinse cycle, when fluid percolating through the organ flushes out chemical waste that accumulated while we were awake. But what propels this circulation has been uncertain. A study of mice, reported today in Cell, suggests regular contractions of blood vessels in the brain, stimulated by the periodic release of a chemical cousin of adrenaline, push the fluid along. “This is excellent science,” says neuroscientist Suzana Herculano-Houzel of Vanderbilt University, who wasn’t connected to the study. “They put a number of pieces of evidence together that tell a pretty compelling story.” The scientists also found that the sleep drug zolpidem, better known as Ambien, impedes the blood vessel oscillations and the fluid flow they promote, implying it could hamper cleansing. The finding could help researchers create new sleep aids that preserve this brain-scrubbing function. The brain lacks the lymphatic vessels that collect and move fluid in other parts of the body. But in 2012, neuroscientist Maiken Nedergaard of the University of Rochester Medical Center and colleagues identified an alternative drainage system in which cerebrospinal fluid, the liquid bathing the brain, seeps through the organ via tiny passages alongside blood vessels, sweeping away metabolic refuse and other unwanted molecules. Fluid flow through this so-called glymphatic system ramps up during sleep, they also reported. Studies from 
Nedergaard’s group and others suggest vigorous glymphatic clearance is beneficial: Circulation falters in Alzheimer’s disease and other neurodegenerative illnesses. Some researchers have challenged parts of this picture, however; a 2024 study, for example, suggested waste clearance is actually faster during waking than during sleep. In the new research, Nedergaard and her team wanted to pin down what keeps cerebrospinal fluid moving through the brain. But studying the mouse glymphatic system often involves anesthetizing the rodents, she says, which is very different from natural sleep. To avoid this problem, the scientists surgically implanted mice with electrodes and fiber optic filaments. Although the rodents are tethered to a set of cables, they can fall asleep normally while researchers track blood volume, electrical activity, and chemical levels and use light transmitted through the fiber optic lines to activate certain groups of neurons.

Keyword: Sleep
Link ID: 29626 - Posted: 01.11.2025

By McKenzie Prillaman A peek into living tissue from human hippocampi, a brain region crucial for memory and learning, revealed relatively few cell-to-cell connections for the vast number of nerve cells. But signals sent via those sparse connections proved extremely reliable and precise, researchers report December 11 in Cell. One seahorse-shaped hippocampus sits deep within each hemisphere of the mammalian brain. In each hippocampus’s CA3 area, humans have about 1.7 million nerve cells called pyramidal cells. This subregion is thought to be the most internally connected part of the brain in mammals. But much information about nerve cells in this structure has come from studies in mice, which have only 110,000 pyramidal cells in each CA3 subregion. Previously discovered differences between mouse and human hippocampi hinted that animals with more nerve cells may have fewer connections — or synapses — between them, says cellular neuroscientist Peter Jonas of the Institute of Science and Technology Austria in Klosterneuburg. To see if this held true, he and his colleagues examined tissue taken with consent from eight patients who underwent brain surgery to treat epilepsy. Recording electrical activity from human pyramidal cells in the CA3 area suggested that about 10 synapses existed for every 800 cell pairs tested. In mice, that concentration roughly tripled. Despite the relatively scant nerve cell connections in humans, those cells showed steady and robust activity when sending signals to one another — unlike mouse pyramidal cells. © Society for Science & the Public 2000–2025

Keyword: Learning & Memory
Link ID: 29616 - Posted: 01.08.2025

By Yasemin Saplakoglu Bacteria are in, around and all over us. They thrive in almost every corner of the planet, from deep-sea hydrothermal vents to high up in the clouds, to the crevices of your ears, mouth, nose and gut. But scientists have long assumed that bacteria can’t survive in the human brain. The powerful blood-brain barrier, the thinking goes, keeps the organ mostly free from outside invaders. But are we sure that a healthy human brain doesn’t have a microbiome of its own? Over the last decade, initial studies have presented conflicting evidence. The idea has remained controversial, given the difficulty of obtaining healthy, uncontaminated human brain tissue that could be used to study possible microbial inhabitants. Recently, a study published in Science Advances provided the strongest evidence yet (opens a new tab) that a brain microbiome can and does exist in healthy vertebrates — fish, specifically. Researchers at the University of New Mexico discovered communities of bacteria thriving in salmon and trout brains. Many of the microbial species have special adaptations that allow them to survive in brain tissue, as well as techniques to cross the protective blood-brain barrier. Matthew Olm (opens a new tab), a physiologist who studies the human microbiome at the University of Colorado, Boulder and was not involved with the study, is “inherently skeptical” of the idea that populations of microbes could live in the brain, he said. But he found the new research convincing. “This is concrete evidence that brain microbiomes do exist in vertebrates,” he said. “And so the idea that humans have a brain microbiome is not outlandish.” While fish physiology is, in many ways, similar to humans’, there are some key differences. Still, “it certainly puts another weight on the scale to think about whether this is relevant to mammals and us,” said Christopher Link (opens a new tab), who studies the molecular basis of neurodegenerative disease at the University of Colorado, Boulder and was also not involved in the work. © 2024 Simons Foundation

Keyword: Obesity; Brain imaging
Link ID: 29588 - Posted: 12.04.2024

' By Sofia Quaglia Flip open any neuroscience textbook and the depiction of a neuron will be roughly the same: a blobby, amoebalike cell body shooting out a long, thick strand. That strand is the axon, which conducts electrical signals to terminals where the cell communicates with other neurons. Axons have long been depicted as smooth and cylindrical, but a new study of mouse neurons challenges that view. Instead, it suggests their natural shape is more like a string of pearls. Even more provocatively, the authors propose those pearly bumps serve as control knobs, influencing how quickly and precisely the cell fires its signals. The study, published today in Nature Neuroscience, should “100%” change how we’ve been thinking about neurons and their signals, says senior author Shigeki Watanabe, a molecular neuroscientist at John Hopkins University. Some outsiders agree. The findings are “highly significant and I think have been overlooked for quite some time,” says evolutionary biologist Pawel Burkhardt of the University of Bergen, who recently spotted similar pearl structures in neurons from tiny marine invertebrates known as comb jellies. Yet several experts in the field contest the findings. Some cite potential confounding effects of the preparation and freezing method used to preserve cells before imaging. And some doubt the work totally upends what’s known about the true shape of the axon. “I think it’s true that [the axon is] not a perfect tube, but it’s not also just this kind of accordion that they show,” says neuroscientist Christophe Leterrier from Aix-Marseille University, who calls the study “a controversial addition to the literature.” Since the mid-1960s, microscopists have seen that axons can scrunch up to form beads when they are diseased or under other stress. Leterrier has called these temporary beads “stress balls for the brain” and found evidence that they prevent cellular damage from spreading. Other studies suggest even normal axons bulge temporarily when cargo traveling to and from the cell nucleus forms a traffic jam, like the elephant bulging inside the body of a boa in the children’s book The Little Prince.

Keyword: Brain imaging
Link ID: 29586 - Posted: 12.04.2024

By Claudia López Lloreda For decades, researchers have considered the brain “immune privileged”—protected from the vagaries of the body’s immune system. But building evidence suggests that the brain may be more immunologically active than previously thought, well beyond its own limited immune response. The choroid plexus in particular—the network of blood vessels and cerebrospinal-fluid (CSF)-producing epithelial cells that line the organ’s ventricles—actively recruits immune cells from both the periphery and the CSF, according to a new study in mice. The epithelial layer of the choroid plexus shields the rest of the brain from toxic substances, pathogens and other molecules that circulate in the blood. Dysfunction and neuroinflammation in the choroid plexus is associated with aging and many neurological conditions, such as amyotrophic lateral sclerosis and Alzheimer’s disease. Even in the absence of inflammation, the choroid plexus harbors immune cells, some of which reside in the space between the vessels and the epithelial layer, and some on the epithelial surface. During an immune response, it also contains recruited cells, such as macrophages and other leukocytes, and pro-inflammatory signals, previous research has shown. But those findings offered only a snapshot of the cells’ locations, says Maria Lehtinen, professor of pathology at Harvard Medical School, who led the new work. “Just because [the cell] is in the tissue doesn’t mean it’s necessarily crossing or has gone in the direction that you anticipate that it would be going in.” How the choroid plexus gatekeeps immune cells remains a big question in the field, says Michal Schwartz, a neuroimmunologist at the Weizmann Institute of Science, who was not involved with the new work. © 2024 Simons Foundation

Keyword: Neuroimmunology
Link ID: 29571 - Posted: 11.23.2024