Chapter 2. Neurophysiology: The Generation, Transmission, and Integration of Neural Signals

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By Rodrigo Pérez Ortega Was Tyrannosaurus rex as smart as a baboon? Scientists don’t like to compare intelligence between species (everyone has their own talents, after all), but a controversial new study suggests some dino brains were as densely packed with neurons as those of modern primates. If so, that would mean they were very smart—more than researchers previously thought—and could have achieved feats only humans and other very intelligent animals have, such as using tools. The findings, reported last week in the Journal of Comparative Neurology, are making waves among paleontologists on social media and beyond. Some are applauding the paper as a good first step toward better understanding dinosaur smarts, whereas others argue the neuron estimates are flawed, undercutting the study’s conclusions. Measuring dinosaur intelligence has never been easy. Historically, researchers have used something called the encephalization quotient (EQ), which measures an animal’s relative brain size, related to its body size. A T. rex, for example, had an EQ of about 2.4, compared with 3.1 for a German shepherd dog and 7.8 for a human—leading some to assume it was at least somewhat smart. EQ is hardly foolproof, however. In many animals, body size evolves independently from brain size, says Ashley Morhardt, a paleoneurologist at Washington University School of Medicine in St. Louis who wasn’t involved in the study. “EQ is a fraught metric, especially when studying extinct species.” Looking for a more trustworthy alternative, Suzana Herculano-Houzel, a neuroanatomist at Vanderbilt University, turned to a different measure: the density of neurons in the cortex, the wrinkly outer brain area critical to most intelligence-related tasks. She had previously estimated the number of neurons in many animal species, including humans, by making “brain soup”—dissolving brains in a detergent solution—and counting the neurons in different parts of the brain. © 2023 American Association for the Advancement of Science.

Keyword: Evolution
Link ID: 28627 - Posted: 01.12.2023

by Giorgia Guglielmi About five years ago, Catarina Seabra made a discovery that led her into uncharted scientific territory. Seabra, then a graduate student in Michael Talkowski’s lab at Harvard University, found that disrupting the autism-linked gene MBD5 affects the expression of other genes in the brains of mice and in human neurons. Among those genes, several are involved in the formation and function of primary cilia — hair-like protrusions on the cell’s surface that sense its external environment. “This got me intrigued, because up to that point, I had never heard of primary cilia in neurons,” Seabra says. She wondered if other researchers had linked cilia defects to autism-related conditions, but the scientific literature offered only sparse evidence, mostly in mice. Seabra, now a postdoctoral researcher in the lab of João Peça at the Center for Neuroscience and Cell Biology at the University of Coimbra in Portugal, is spearheading an effort to look for a connection in people: The Peça lab established a biobank of dental stem cells obtained from baby teeth of 50 children with autism or other neurodevelopmental conditions. And the team plans to look at neurons and brain organoids made from those cells to see if their cilia show any defects in structure or function. Other neuroscientists, too, are working to understand the role of cilia during neurodevelopment. Last September, for example, researchers working with tissue samples from mice discovered that cilia on the surface of neurons can form junctions, or synapses, with other neurons — which means cilia defects could, at least in theory, hinder the development of neural circuitry and activity. Other teams have connected several additional autism-related genes, beyond MBD5, to the tiny cell antennae. © 2023 Simons Foundation

Keyword: Autism
Link ID: 28623 - Posted: 01.07.2023

Heidi Ledford Severe COVID-19 is linked to changes in the brain that mirror those seen in old age, according to an analysis of dozens of post-mortem brain samples1. The analysis revealed brain changes in gene activity that were more extensive in people who had severe SARS-CoV-2 infections than in uninfected people who had been in an intensive care unit (ICU) or had been put on ventilators to assist their breathing — treatments used in many people with serious COVID-19. The study, published on 5 December in Nature Aging, joins a bevy of publications cataloguing the effects of COVID-19 on the brain. “It opens a plethora of questions that are important, not only for understanding the disease, but to prepare society for what the consequences of the pandemic might be,” says neuropathologist Marianna Bugiani at Amsterdam University Medical Centers. “And these consequences might not be clear for years.” Maria Mavrikaki, a neurobiologist at the Beth Israel Deaconess Medical Center in Boston, Massachusetts, embarked on the study about two years ago, after seeing a preprint, later published as a paper2, that described cognitive decline after COVID-19. She decided to follow up to see whether she could find changes in the brain that might trigger the effects. She and her colleagues studied samples taken from the frontal cortex — a region of the brain closely tied to cognition — of 21 people who had severe COVID-19 when they died and one person with an asymptomatic SARS-CoV-2 infection at death. The team compared these with samples from 22 people with no known history of SARS-CoV-2 infection. Another control group comprised nine people who had no known history of infection but had spent time on a ventilator or in an ICU — interventions that can cause serious side effects. The team found that genes associated with inflammation and stress were more active in the brains of people who had had severe COVID-19 than in the brains of people in the control group. Conversely, genes linked to cognition and the formation of connections between brain cells were less active. © 2022 Springer Nature Limited

Keyword: Development of the Brain; Brain imaging
Link ID: 28584 - Posted: 12.06.2022

Darby Saxbe The time fathers devote to child care every week has tripled over the past 50 years in the United States. The increase in fathers’ involvement in child rearing is even steeper in countries that have expanded paid paternity leave or created incentives for fathers to take leave, such as Germany, Spain, Sweden and Iceland. And a growing body of research finds that children with engaged fathers do better on a range of outcomes, including physical health and cognitive performance. Despite dads’ rising participation in child care and their importance in the lives of their kids, there is surprisingly little research about how fatherhood affects men. Even fewer studies focus on the brain and biological changes that might support fathering. It is no surprise that the transition to parenthood can be transformative for anyone with a new baby. For women who become biological mothers, pregnancy-related hormonal changes help to explain why a new mother’s brain might change. But does fatherhood reshape the brains and bodies of men – who don’t experience pregnancy directly – in ways that motivate their parenting? We set out to investigate this question in our recent study of first-time fathers in two countries. Recent research has found compelling evidence that pregnancy can enhance neuroplasticity, or remodeling, in the structures of a woman’s brain. Using magnetic resonance imaging, researchers have identified large-scale changes in the anatomy of women’s brains from before to after pregnancy. In one study, researchers in Spain scanned first-time mothers before conceiving, and again at two months after they gave birth. Compared with childless women, the new mothers’ brain volume was smaller, suggesting that key brain structures actually shrank in size across pregnancy and the early postpartum period. The brain changes were so pronounced that an algorithm could easily differentiate the brain of a woman who had gone through a pregnancy from that of a woman with no children. Copyright © 2010–2022, The Conversation US, Inc.

Keyword: Sexual Behavior; Brain imaging
Link ID: 28576 - Posted: 12.03.2022

By Laura Sanders SAN DIEGO — Scientists have devised ways to “read” words directly from brains. Brain implants can translate internal speech into external signals, permitting communication from people with paralysis or other diseases that steal their ability to talk or type. New results from two studies, presented November 13 at the annual meeting of the Society for Neuroscience, “provide additional evidence of the extraordinary potential” that brain implants have for restoring lost communication, says neuroscientist and neurocritical care physician Leigh Hochberg. Some people who need help communicating can currently use devices that require small movements, such as eye gaze changes. Those tasks aren’t possible for everyone. So the new studies targeted internal speech, which requires a person to do nothing more than think. “Our device predicts internal speech directly, allowing the patient to just focus on saying a word inside their head and transform it into text,” says Sarah Wandelt, a neuroscientist at Caltech. Internal speech “could be much simpler and more intuitive than requiring the patient to spell out words or mouth them.” Neural signals associated with words are detected by electrodes implanted in the brain. The signals can then be translated into text, which can be made audible by computer programs that generate speech. That approach is “really exciting, and reinforces the power of bringing together fundamental neuroscience, neuroengineering and machine learning approaches for the restoration of communication and mobility,” says Hochberg, of Massachusetts General Hospital and Harvard Medical School in Boston, and Brown University in Providence, R.I. © Society for Science & the Public 2000–2022.

Keyword: Brain imaging; Language
Link ID: 28556 - Posted: 11.16.2022

By Elena Renken The brain’s lifeline, its network of blood vessels, is like a tree, says Mathieu Pernot, deputy director of the Physics for Medicine Paris Lab. The trunk begins in the neck with the carotid arteries, a pair of broad channels that then split into branches that climb into the various lobes of the brain. These channels fork endlessly into a web of tiny vessels that form a kind of canopy. The narrowest of these vessels are only wide enough for a single red blood cell to pass through, and in one important sense these vessels are akin to the tree’s leaves. “When you want to look at pathology, usually you don’t see the sickness in the tree, but in the leaves,” Pernot says. (You can identify Dutch Elm Disease when the tree’s leaves yellow and wilt.) Just like leaves, the tiniest blood vessels in the brain often register changes in neuron and synapse activity first, including illness, such as new growth in a cancerous brain tumor.1, 2 But only in the past decade or so have we developed the technology to detect these microscopic changes in blood flow: It’s called ultrafast ultrasound. Standard ultrasound is already popular in clinical imaging given that it is minimally invasive, low-cost, portable, and can generate images in real time.3 But until now, it has rarely been used to image the brain. That’s partly because the skull gets in the way—bone tends to scatter ultrasound waves—and the technology is too slow to detect blood flow in the smaller arteries that support most brain function. Neurologists have mostly used it in niche applications: to examine newborns, whose skulls have gaps between the bone plates, or to guide surgeons in some brain surgeries, where part of the skull is typically removed. Neuroscience researchers have also used it to study functional differences between the two hemispheres of the brain, based on imaging of the major cerebral arteries, by positioning the device over the temporal bone window, the thinnest area of the skull. © 2022 NautilusThink Inc,

Keyword: Brain imaging; Hearing
Link ID: 28536 - Posted: 11.02.2022

By Jan Claassen, Brian L. Edlow A medical team surrounded Maria Mazurkevich’s hospital bed, all eyes on her as she did … nothing. Mazurkevich was 30 years old and had been admitted to New York–Presbyterian Hospital at Columbia University on a blisteringly hot July day in New York City. A few days earlier, at home, she had suddenly fallen unconscious. She had suffered a ruptured blood vessel in her brain, and the bleeding area was putting tremendous pressure on critical brain regions. The team of nurses and physicians at the hospital’s neurological intensive care unit was looking for any sign that Mazurkevich could hear them. She was on a mechanical ventilator to help her breathe, and her vital signs were stable. But she showed no signs of consciousness. Mazurkevich’s parents, also at her bed, asked, “Can we talk to our daughter? Does she hear us?” She didn’t appear to be aware of anything. One of us (Claassen) was on her medical team, and when he asked Mazurkevich to open her eyes, hold up two fingers or wiggle her toes, she remained motionless. Her eyes did not follow visual cues. Yet her loved ones still thought she was “in there.” She was. The medical team gave her an EEG—placing sensors on her head to monitor her brain’s electrical activity—while they asked her to “keep opening and closing your right hand.” Then they asked her to “stop opening and closing your right hand.” Even though her hands themselves didn’t move, her brain’s activity patterns differed between the two commands. These brain reactions clearly indicated that she was aware of the requests and that those requests were different. And after about a week, her body began to follow her brain. Slowly, with minuscule responses, Mazurkevich started to wake up. Within a year she recovered fully without major limitations to her physical or cognitive abilities. She is now working as a pharmacist. © 2022 Scientific American,

Keyword: Consciousness; Brain imaging
Link ID: 28527 - Posted: 10.26.2022

McKenzie Prillaman A twist on functional magnetic resonance imaging (fMRI) offers a multi-fold improvement in its time sensitivity, better enabling it to unveil the fine-scale dynamics underlying mental processes. Researchers published the results on 13 October in Science1. Can brain scans reveal behaviour? Bombshell study says not yet A standard fMRI technique measures brain activity indirectly, by tracking increases in blood flow in regions where neurons are suddenly consuming more oxygen. This signal, however, can lag behind neuronal activity by 1 second, which dampens time sensitivity — the speedy cells take mere milliseconds to send messages to one another. Jang-Yeon Park, an MRI physicist at Sungkyunkwan University in Suwon, South Korea, set out to enhance fMRI’s temporal precision to track neuronal activity on the order of milliseconds. He and his colleagues accomplished this by changing the software of a high-intensity MRI scanner to acquire data every 5 milliseconds — about 8 times faster than what the standard technique can capture — and applying frequent, repetitive stimulation to animals they were testing. This suppressed the slower-paced blood oxygenation signal, making it possible to observe faster-paced brain activity. The researchers named their technique direct imaging of neuronal activity, or DIANA. In the study, an anaesthetized mouse inside an MRI scanner received a minor electric shock to its face every 200 milliseconds. Between shocks, the machine acquired data from one tiny region of the mouse’s brain every 5 milliseconds. It moved on to a new area after the next electric shock. After the software stitched everything together, the process produced a head-on image of one full slice of the brain, capturing neuronal activity over a 200-millisecond time period. (Spatial resolution was 0.22 millimetres, which is standard for high-intensity MRI.) During the scan, the facial stimulation activated a part of the brain that processes sensory inputs, causing the region to light up with a signal. The researchers found that this ‘DIANA response’ happened at the same time that neurons fired off signals, or ‘spiked’ — activity that was measured separately, using a surgically inserted probe. Furthermore, the team was able to trace the DIANA signal through a brain circuit as groups of neurons sequentially triggered each other. © 2022 Springer Nature Limited

Keyword: Brain imaging
Link ID: 28515 - Posted: 10.15.2022

By Greg Miller If you’re lucky enough to live to 80, you’ll take up to a billion breaths in the course of your life, inhaling and exhaling enough air to fill about 50 Goodyear blimps or more. We take about 20,000 breaths a day, sucking in oxygen to fuel our cells and tissues, and ridding the body of carbon dioxide that builds up as a result of cellular metabolism. Breathing is so essential to life that people generally die within minutes if it stops. It’s a behavior so automatic that we tend to take it for granted. But breathing is a physiological marvel — both extremely reliable and incredibly flexible. Our breathing rate can change almost instantaneously in response to stress or arousal and even before an increase in physical activity. And breathing is so seamlessly coordinated with other behaviors like eating, talking, laughing and sighing that you may have never even noticed how your breathing changes to accommodate them. Breathing can also influence your state of mind, as evidenced by the controlled breathing practices of yoga and other ancient meditative traditions. In recent years, researchers have begun to unravel some of the underlying neural mechanisms of breathing and its many influences on body and mind. In the late 1980s, neuroscientists identified a network of neurons in the brainstem that sets the rhythm for respiration. That discovery has been a springboard for investigations into how the brain integrates breathing with other behaviors. At the same time, researchers have been finding evidence that breathing may influence activity across wide swaths of the brain, including ones with important roles in emotion and cognition. “Breathing has a lot of jobs,” says Jack L. Feldman, a neuroscientist at the University of California, Los Angeles, and coauthor of a recent article on the interplay of breathing and emotion in the Annual Review of Neuroscience. “It’s very complicated because we’re constantly changing our posture and our metabolism, and it has to be coordinated with all these other behaviors.” © 2022 Annual Reviews

Keyword: ADHD
Link ID: 28508 - Posted: 10.08.2022

By Claudia Lopez Lloreda If you look at parts of the circulatory system of whales and dolphins, you might think that you are looking at a Jackson Pollock painting, not blood vessels. These cetaceans have especially dense, complex networks of blood vessels mainly associated with the brain and spine, but scientists didn’t know why. A new analysis suggests that the networks protect cetaceans’ brains from the pulses of blood pressure that the animals endure while diving deep in the ocean, researchers report in the Sept. 23 Science. Whales and dolphins “have gone through these really amazing vascular adaptations to support their brain,” says Ashley Blawas, a marine scientist at the Duke University Marine Lab in Beaufort, N.C., who was not involved with the research. Called retia mirabilia, which means “wonderful nets,” the blood vessel networks are present in some other animals besides cetaceans, including giraffes and horses. But the networks aren’t found in other aquatic vertebrates that move differently from whales, such as seals. So scientists had suspected that the cetaceans’ retia mirabilia play a role in controlling blood pressure surges. When whales and dolphins dive, they move their tail up and down in an undulating manner, which creates surges in blood pressure. Land animals that experience similar surges, like galloping horses, are able to release some of this pressure by exhaling. But some cetaceans hold their breath to dive for long periods of time (SN: 9/23/20). Without a way to relieve that pressure, those blasts could tear blood vessels and harm other organs, including the brain. In the new study, biomechanics researcher Margo Lillie of the University of British Columbia in Vancouver and colleagues used data on the morphology of 11 cetacean species to create a computational model that can simulate the animals’ retia mirabilia. It revealed that the arteries and veins in this tangle of blood vessels are really close and may even sometimes be joined. As a result, the retia mirabilia could equalize the differences in blood pressure generated by diving, perhaps by redistributing the blood pulses from arteries to veins and vice versa. This way, the networks get rid of, or at least weaken, huge blood pressure surges that might otherwise reach and devastate the brain. © Society for Science & the Public 2000–2022.

Keyword: Brain imaging
Link ID: 28499 - Posted: 10.05.2022

by Angie Voyles Askham / Brain connectivity patterns in people with autism and other neuropsychiatric conditions are more closely related to genetics than to phenotypic traits, according to two new studies. The findings highlight why a single brain biomarker for autism has remained elusive, the researchers say. The condition’s genetic heterogeneity has hampered the search for a shared brain signature: More than 100 genes have been identified as strongly linked to autism, and multiple copy number variations (CNVs) — deleted or duplicated stretches of genetic code — can increase a person’s likelihood of the condition. Autism also often overlaps with other conditions, such as schizophrenia and attention-deficit/hyperactivity disorder (ADHD), making autism-specific markers difficult to disentangle. Common variants tied to autism overlap strongly with those linked to schizophrenia and high IQ, for example, whereas rare autism-linked variants track with low IQ. According to the new papers, however, autism’s genetic heterogeneity corresponds to similarly disparate maps of ‘functional connectivity’ — a measure of which brain areas activate in sync while the brain is at rest. “What we’re seeing is that these groups of variants have specific functional connectivity signatures,” says lead investigator Sébastien Jacquemont, associate professor of pediatrics at the University of Montreal in Canada. The findings need to be replicated, says Aaron Alexander-Bloch, assistant professor of psychiatry at the University of Pennsylvania and the Children’s Hospital of Philadelphia, who was not involved in the work, but they point to the importance of subgrouping study participants based on their underlying genetics. © 2022 Simons Foundation

Keyword: Autism; Brain imaging
Link ID: 28490 - Posted: 09.28.2022

Sascha Pare Homer Simpson may not be the only one with a region of the brain dedicated to doughnuts: researchers have found that images of food appear to trigger a specific set of neurons. Previous research found that similar regions of the brain are highly specialised to identify and remember faces, places, bodies and words. The team, based at the Massachusetts Institute of Technology (MIT), say they stumbled upon the food-sensitive neurons by accident – and they could have evolved due to the evolutionary and cultural importance of food for humans. “Our most novel result is the discovery of a new neural response that has not been reported previously for the ventral visual pathway and that is highly selective for images of food,” the scientists wrote in the journal Current Biology. The researchers examined brain scans of eight participants taken as they viewed 10,000 images. Pictures of food appeared to trigger a population of neurons in the ventral visual cortex, which processes visual information. “We were quite puzzled by this because food is not a visually homogenous category,” said Meenakshi Khosla, one of the lead authors of the study. “Things like apples and corn and pasta all look so unlike each other, yet we found a single population that responds similarly to all these diverse food items.” Cooked meals such as a cheesy slice of pizza provoked a slightly stronger reactions than raw fruit and vegetables, the researchers noted. To test whether this was due to warmer colours in prepared food, they compared participants’ reactions with cool-toned images of food and richly coloured non-food objects. They found food caused a sharper signal. © 2022 Guardian News & Media Limited

Keyword: Obesity; Brain imaging
Link ID: 28452 - Posted: 08.27.2022

By Fionna M. D. Samuels, Liz Tormes Experiencing art, whether through melody or oil paint, elicits in us a range of emotions. This speaks to the innate entanglement of art and the brain: Mirror neurons can make people feel like they are physically experiencing a painting. And listening to music can change their brain chemistry. For the past 11 years, the Netherlands Institute for Neuroscience in Amsterdam has hosted the annual Art of Neuroscience Competition and explored this intersection. This year’s competition received more than 100 submissions, some created by artists inspired by neuroscience and others by neuroscientists inspired by art. The top picks explore a breadth of ideas—from the experience of losing consciousness to the importance of animal models in research—but all of them tie back to our uniquely human brain. In the moment between wakefulness and sleep, we may feel like we are losing ourself to the void of unconsciousness. This is the moment Daniela de Paulis explores with her interdisciplinary project Mare Incognito. “I always had a fascination for the moment of falling asleep,” she says. “Since I was a very small child, I always found this moment as quite transformative, also quite frightening in a way.” The winning Art of Neuroscience submission is the culmination of her project: a film that recorded de Paulis falling asleep among the silver, treelike antennas of the Square Kilometer Array at the Mullard Radio Observatory in Cambridge, England, while her brain activity was converted into radio waves and transmitted directly into space. “We combined the scientific interest with my poetic fascination in this idea of losing consciousness,” she says. In the clip above, Tristan Bekinschtein, a neuroscientist at the University of Cambridge, explains the massive change humans and their brain experience when they drift from consciousness into sleep. As someone falls asleep, their brain activity slows down in stages until they are fully out. Then bursts of activity light up their gray matter as their brain switches over to rapid eye movement (REM) sleep, and they begin to dream. © 2022 Scientific American,

Keyword: Vision; Brain imaging
Link ID: 28446 - Posted: 08.27.2022

By Eduardo Medina An infection caused by a brain-eating amoeba killed a child who swam in a Nebraska river over the weekend, health officials said Friday. It was the first such death in the state’s history and the second in the Midwest this summer. The child, whose name was not released by officials, contracted the infection, known as primary amebic meningoencephalitis, while swimming with family in a shallow part of the Elkhorn River in eastern Nebraska on Sunday, according to the Douglas County Health Department. At a news conference on Thursday, health officials said the typically fatal infection is caused by Naegleria fowleri, also known as brain-eating amoeba, and most likely led to the child’s death. The Centers for Disease Control and Prevention confirmed Friday that it had found Naegleria fowleri in the child’s cerebrospinal fluid. Last month, a person in Missouri died because of the same amoeba infection, according to the Missouri Department of Health and Senior Services. The person had been swimming at the beach at Lake of Three Fires State Park in Iowa. Out of precaution, the Iowa Department of Public Health closed the lake’s beach for about three weeks. The brain-eating amoebas, which are single-cell organisms, usually thrive in warm freshwater lakes, rivers, canals and ponds, though they can also be present in soil. They enter the body through the nose and then move into the brain. People usually become infected while swimming in lakes and rivers, according to the C.D.C. Infections from brain-eating amoeba are extremely rare: From 2012 to 2021, only 31 cases were reported in the U.S., according to the C.D.C. An infection, however, almost always leads to death. In the United States, there were 143 infections from 1962 through 2017. All but four of them were fatal, the C.D.C. said. More than half of the infections occurred in Texas and Florida, where the climate is warm and water activities are popular. © 2022 The New York Times Company

Keyword: Miscellaneous
Link ID: 28437 - Posted: 08.20.2022

Scientists know both a lot and very little about the brain. With billions of neurons and trillions of connections among them, and the experimental limitations of examining the seat of consciousness and bodily function, studying the human brain is a technical, theoretical and ethical challenge. And one of the biggest challenges is perhaps one of the most fundamental – seeing what it looks like in action. The U.S. Brain Research Through Advancing Innovative Neurotechnologies (BRAIN) Initiative is a collaboration among the National Institutes of Health, Defense Advanced Research Projects Agency, National Science Foundation, Food and Drug Administration and Intelligence Advanced Research Projects Activity and others. Since its inception in 2013, its goal has been to develop and use new technologies to examine how each neuron and neural circuit comes together to “record, process, utilize, store, and retrieve vast quantities of information, all at the speed of thought.” Just as genomic sequencing enabled the creation of a comprehensive map of the human genome, tools that elucidate the connection between brain structure and function could help researchers answer long-standing questions about how the brain works, both in sickness and in health. These five stories from our archives cover research that has been funded by or advances the goals of the BRAIN Initiative, detailing a slice of what’s next in neuroscience. Attempts to map the structure of the brain date back to antiquity, when philosophers and scholars had only the unaided eye to map anatomy to function. New visualization techniques in the 20th century led to the discovery that, just like all the other organs of the body, the brain is composed of individual cells – neurons. © 2010–2022, The Conversation US, Inc.

Keyword: Brain imaging; Development of the Brain
Link ID: 28421 - Posted: 08.06.2022

R. Douglas Fields Neuroscientists, being interested in how brains work, naturally focus on neurons, the cells that can convey elements of sense and thought to each other via electrical impulses. But equally worthy of study is a substance that’s between them — a viscous coating on the outside of these neurons. Roughly equivalent to the cartilage in our noses and joints, the stuff clings like a fishing net to some of our neurons, inspiring the name perineuronal nets (PNNs). They’re composed of long chains of sugar molecules attached to a protein scaffolding, and they hold neurons in place, preventing them from sprouting and making new connections. Given this ability, this little-known neural coating provides answers to some of the most puzzling questions about the brain: Why do young brains absorb new information so easily? Why are the fearful memories that accompany post-traumatic stress disorder (PTSD) so difficult to forget? Why is it so hard to stop drinking after becoming dependent on alcohol? And according to new research from the neuroscientist Arkady Khoutorsky and his colleagues at McGill University, we now know that PNNs also explain why pain can develop and persist so long after a nerve injury. Neural plasticity is the ability of neural networks to change in response to experiences in life or to repair themselves after brain injury. Such opportunities for effortless change are known as critical periods when they occur early in life. Consider how easily babies pick up language, but how difficult it is to learn a foreign language as an adult. In a way, this is what we’d want: After the intricate neural networks that allow us to understand our native language are formed, it’s important for them to be locked down, so the networks remain relatively undisturbed for the rest of our lives. All Rights Reserved © 2022

Keyword: Pain & Touch; Glia
Link ID: 28415 - Posted: 07.30.2022

Bill Chappell Its name alone is terrifying. Add the fact that it kills most people it infects — and that while infections are rare, the parasite is fairly common — it's not surprising that a confirmed case of Naegleria fowleri infection in a swimmer in Iowa is drawing attention. Iowa officials closed the beach at Lake of Three Fires State Park on Thursday after confirming that a person who swam there was infected with Naegleria fowleri, an amoeba that causes a disease called primary amebic meningoencephalitis (PAM). It's both extremely rare — and extremely deadly. "The fatality rate is over 97%," the Centers for Disease Control and Prevention says of PAM infections. "Only four people out of 154 known infected individuals in the United States from 1962 to 2021 have survived." Details about the Iowa case have not yet been released. The person was visiting from Missouri, which is just over the border from the park in Iowa's southwest. Iowa's Department of Health and Human Services says it's working with the CDC to confirm whether Naegleria fowleri is present in the lake — a process that takes several days. The state agency is also in contact with the Missouri Department of Health, an Iowa representative told NPR. "It's strongly believed by public health experts that the lake is a likely source," Missouri's health department said on Friday. But it added, "Additional public water sources in Missouri are being tested." © 2022 npr

Keyword: Miscellaneous
Link ID: 28392 - Posted: 07.12.2022

By Christina Caron In recent years, the vagus nerve has become an object of fascination, especially on social media. The vagal nerve fibers, which run from the brain to the abdomen, have been anointed by some influencers as the key to reducing anxiety, regulating the nervous system and helping the body to relax. TikTok videos with the hashtag “#vagusnerve” have been viewed more than 64 million times and there are nearly 70,000 posts with the hashtag on Instagram. Some of the most popular ones feature simple hacks to “tone” or “reset” the vagus nerve, in which people plunge their faces into ice water baths or lie on their backs with ice packs on their chests. There are also neck and ear massages, eye exercises and deep-breathing techniques. Now, wellness companies have capitalized on the trend, offering products like “vagus massage oil,” vibrating bracelets and pillow mists, that claim to stimulate the nerve, but that have not been endorsed by the scientific community. Researchers who study the vagus nerve say that stimulating it with electrodes can potentially help improve mood and alleviate symptoms in those who suffer from treatment-resistant depression, among other ailments. But are there other ways to activate the vagus nerve? Who would benefit most from doing so? And what exactly is the vagus nerve, anyway? Here’s a look at what we know so far. The term “vagus nerve” is actually shorthand for thousands of fibers. They are organized into two bundles that run from the brain stem down through each side of the neck and into the torso, branching outward to touch our internal organs, said Dr. Kevin J. Tracey, a neurosurgeon and president of the Feinstein Institutes for Medical Research, Northwell Health’s research center in New York. Imagine something akin to a tree, whose limbs interact with nearly every organ system in the body. (The word “vagus” means “wandering” in Latin.) The vagus nerve picks up information about how the organs are functioning and also sends information from the brain stem back to the body, helping to control digestion, heart rate, voice, mood and the immune system. For those reasons, the vagus nerve — the longest of the 12 cranial nerves — is sometimes referred to as an “information superhighway.” Dr. Tracey compared it to a trans-Atlantic cable. “It’s not a mishmash of signals,” he said. “Every signal has a specific job.” © 2022 The New York Times Company

Keyword: Depression; Stress
Link ID: 28361 - Posted: 06.09.2022

by Rachel Zamzow Inflammation may inflate or thin out brain regions tied to autism and schizophrenia, researchers report in a new study. The findings add nuance to the long-held hypothesis that immune activation elevates the risk for neurodevelopmental conditions. Autism, for example, is associated with prenatal exposure to infection, previous studies show. Taking a different approach, the new work focuses on how a genetic predisposition to inflammation affects brain development in the general population, says John Williams, research fellow at the University of Birmingham in the United Kingdom, who conducted the work with lead researcher Rachel Upthegrove, professor of psychiatry and youth mental health at the university. By pinpointing where inflammation leaves its mark in the brain, the findings serve as a guidepost for future studies of people with neuropsychiatric conditions, he says. “We think that it points to something that’s fairly transdiagnostic.” For their analyses, the team drew on brain imaging and genetic data from 10,828 women and 9,860 men in the general population who participated in the UK Biobank. They explored how 1,436 possible structural changes in the brain track with having single-nucleotide variants previously shown to increase circulating levels of five inflammatory molecules — interleukin 1 (IL-1), IL-2, IL-6, C-reactive protein and brain-derived neurotrophic factor. Three variants thought to boost IL-6 were associated with 33 structural changes, most notably increased volume in the middle temporal gyrus and fusiform gyrus, and decreased cortical thickness in the superior frontal gyrus — all brain areas implicated in autism. Variants associated with other inflammatory molecules did not track with brain changes, the researchers found. © 2022 Simons Foundation

Keyword: Autism; Genes & Behavior
Link ID: 28317 - Posted: 05.07.2022

By Monique Brouillette Neuroscientists have long aspired to understand the intangible properties of the mind. Our most treasured cerebral qualities, like the ability to think, write poetry, fall in love and even envision a higher spiritual realm, are all generated in the brain. But how the squishy, pinkish-gray, wrinkled mass of the physical brain gives rise to these impalpable experiences remains a mystery. Some neuroscientists think the key to cracking that mystery is a better map of the brain’s circuitry. Nearly 40 years ago, scientists achieved a milestone by completing a wiring diagram that traced all the connections of the 302 neurons of the roundworm Caenorhabditis elegans. They were traced by hand on printed sheets of electron microscope images, a meticulous and herculean task that took years to complete. The project marked the first-ever complete connectome — a comprehensive map of the neuronal connections in an animal’s nervous system. Today, thanks to advances in computing and image analysis algorithms, it can take less than a month to map a roundworm’s connectome. These technological improvements mean that scientists can set their sights on larger animals. They are closing in on the connectome of fruit fly larvae, with more than 9,000 cells, and adult flies, with 100,000 neurons. Next, they hope to map the brain of a developing fish and, perhaps within the next decade, a mouse, with roughly 70 million neurons — a project nearly a thousand times more ambitious than any done so far. And they have already started to map small pieces of the human brain, an unfathomable quest when the worm connectome was initially mapped. © 2022 Annual Reviews

Keyword: Brain imaging
Link ID: 28308 - Posted: 04.30.2022