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by Holly Barker By bloating brain samples and imaging them with a powerful microscope, researchers can reconstruct neurons across the entire mouse brain, according to a new preprint. The technique could help scientists uncover the neural circuits responsible for complex behaviors, as well as the pathways that are altered in neurological conditions. Tracking axons can help scientists understand how individual neurons and brain areas communicate over long distances. But tracing their path through the brain is tricky, says study investigator Adam Glaser, senior scientist at the Allen Institute for Neural Dynamics in Seattle, Washington. Axons, which are capable of spanning the entire brain, can be less than a micrometer in diameter, so mapping their route requires detailed imaging, he says. One existing approach involves a microscope that slices off an ultra-thin section of the brain and then scans it, repeating the process about 20,000 times to capture the entire mouse brain. Scientists then blend the images together to form a 3D reconstruction of neuronal pathways. But the process takes several days and is therefore more prone to complications — bubbles forming on the lens, say — than faster techniques, Glaser says. And slicing can distort the edges of the image, making it “challenging or impossible” to stitch them back together, says Paul Tillberg, principal scientist at the Howard Hughes Medical Institute’s Janelia Research Campus in Ashburn, Virginia, who was not involved in the study. “This is particularly an issue when reconstructing brain-wide axonal projections, where a single point of confusion can misalign an entire axonal arbor to the wrong neuron,” he says. © 2023 Simons Foundation

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28850 - Posted: 07.19.2023

Davide Castelvecchi The wrinkles that give the human brain its familiar walnut-like appearance have a large effect on brain activity, in much the same way that the shape of a bell determines the quality of its sound, a study suggests1. The findings run counter to a commonly held theory about which aspect of brain anatomy drives function. The study’s authors compared the influence of two components of the brain’s physical structure: the outer folds of the cerebral cortex — the area where most higher-level brain activity occurs — and the connectome, the web of nerves that links distinct regions of the cerebral cortex. The team found that the shape of the outer surface was a better predictor of brainwave data than was the connectome, contrary to the paradigm that the connectome has the dominant role in driving brain activity. “We use concepts from physics and engineering to study how anatomy determines function,” says study co-author James Pang, a physicist at Monash University in Melbourne, Australia. The results were published in Nature on 31 May1. ‘Exciting’ a neuron makes it fire, which sends a message zipping to other neurons. Excited neurons in the cerebral cortex can communicate their state of excitation to their immediate neighbours on the surface. But each neuron also has a long filament called an axon that connects it to a faraway region within or beyond the cortex, allowing neurons to send excitatory messages to distant brain cells. In the past two decades, neuroscientists have painstakingly mapped this web of connections — the connectome — in a raft of organisms, including humans. The authors wanted to understand how brain activity is affected by each of the ways in which neuronal excitation can spread: across the brain’s surface or through distant interconnections. To do so, the researchers — who have backgrounds in physics and neuroscience — tapped into the mathematical theory of waves.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 13: Memory and Learning
Link ID: 28811 - Posted: 06.03.2023

By Matteo Wong If you are willing to lie very still in a giant metal tube for 16 hours and let magnets blast your brain as you listen, rapt, to hit podcasts, a computer just might be able to read your mind. Or at least its crude contours. Researchers from the University of Texas at Austin recently trained an AI model to decipher the gist of a limited range of sentences as individuals listened to them—gesturing toward a near future in which artificial intelligence might give us a deeper understanding of the human mind. The program analyzed fMRI scans of people listening to, or even just recalling, sentences from three shows: Modern Love, The Moth Radio Hour, and The Anthropocene Reviewed. Then, it used that brain-imaging data to reconstruct the content of those sentences. For example, when one subject heard “I don’t have my driver’s license yet,” the program deciphered the person’s brain scans and returned “She has not even started to learn to drive yet”—not a word-for-word re-creation, but a close approximation of the idea expressed in the original sentence. The program was also able to look at fMRI data of people watching short films and write approximate summaries of the clips, suggesting the AI was capturing not individual words from the brain scans, but underlying meanings. The findings, published in Nature Neuroscience earlier this month, add to a new field of research that flips the conventional understanding of AI on its head. For decades, researchers have applied concepts from the human brain to the development of intelligent machines. ChatGPT, hyperrealistic-image generators such as Midjourney, and recent voice-cloning programs are built on layers of synthetic “neurons”: a bunch of equations that, somewhat like nerve cells, send outputs to one another to achieve a desired result. Yet even as human cognition has long inspired the design of “intelligent” computer programs, much about the inner workings of our brains has remained a mystery. Now, in a reversal of that approach, scientists are hoping to learn more about the mind by using synthetic neural networks to study our biological ones. It’s “unquestionably leading to advances that we just couldn’t imagine a few years ago,” says Evelina Fedorenko, a cognitive scientist at MIT. Copyright (c) 2023 by The Atlantic Monthly Group.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 15: Language and Lateralization
Link ID: 28802 - Posted: 05.27.2023

By Marla Broadfoot In Alexandre Dumas’s classic novel The Count of Monte-Cristo, a character named Monsieur Noirtier de Villefort suffers a terrible stroke that leaves him paralyzed. Though he remains awake and aware, he is no longer able to move or speak, relying on his granddaughter Valentine to recite the alphabet and flip through a dictionary to find the letters and words he requires. With this rudimentary form of communication, the determined old man manages to save Valentine from being poisoned by her stepmother and thwart his son’s attempts to marry her off against her will. Dumas’s portrayal of this catastrophic condition — where, as he puts it, “the soul is trapped in a body that no longer obeys its commands” — is one of the earliest descriptions of locked-in syndrome. This form of profound paralysis occurs when the brain stem is damaged, usually because of a stroke but also as the result of tumors, traumatic brain injury, snakebite, substance abuse, infection or neurodegenerative diseases like amyotrophic lateral sclerosis (ALS). The condition is thought to be rare, though just how rare is hard to say. Many locked-in patients can communicate through purposeful eye movements and blinking, but others can become completely immobile, losing their ability even to move their eyeballs or eyelids, rendering the command “blink twice if you understand me” moot. As a result, patients can spend an average of 79 days imprisoned in a motionless body, conscious but unable to communicate, before they are properly diagnosed. The advent of brain-machine interfaces has fostered hopes of restoring communication to people in this locked-in state, enabling them to reconnect with the outside world. These technologies typically use an implanted device to record the brain waves associated with speech and then use computer algorithms to translate the intended messages. The most exciting advances require no blinking, eye tracking or attempted vocalizations, but instead capture and convey the letters or words a person says silently in their head. © 2023 Annual Reviews

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28791 - Posted: 05.21.2023

By Laura Sanders Like Dumbledore’s wand, a scan can pull long strings of stories straight out of a person’s brain — but only if that person cooperates. This “mind-reading” feat, described May 1 in Nature Neuroscience, has a long way to go before it can be used outside of sophisticated laboratories. But the result could ultimately lead to seamless devices that help people who can’t talk or otherwise communicate easily. The research also raises privacy concerns about unwelcome neural eavesdropping (SN: 2/11/21). “I thought it was fascinating,” says Gopala Anumanchipalli, a neural engineer at the University of California, Berkeley who wasn’t involved in the study. “It’s like, ‘Wow, now we are here already,’” he says. “I was delighted to see this.” As opposed to implanted devices that have shown recent promise, the new system requires no surgery (SN: 11/15/22). And unlike other external approaches, it produces continuous streams of words instead of having a more constrained vocabulary. For the new study, three people lay inside a bulky MRI machine for at least 16 hours each. They listened to stories, mostly from The Moth podcast, while functional MRI scans detected changes in blood flow in the brain. These changes are proxies for brain activity, albeit slow and imperfect measures. With this neural data in hand, computational neuroscientists Alexander Huth and Jerry Tang of the University of Texas at Austin and colleagues were able to match patterns of brain activity to certain words and ideas. The approach relied on a language model that was built with GPT, one of the forerunners that enabled today’s AI chatbots (SN: 4/12/23). © Society for Science & the Public 2000–2023.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 14: Attention and Higher Cognition
Link ID: 28769 - Posted: 05.03.2023

By Oliver Whang Think of the words whirling around in your head: that tasteless joke you wisely kept to yourself at dinner; your unvoiced impression of your best friend’s new partner. Now imagine that someone could listen in. On Monday, scientists from the University of Texas, Austin, made another step in that direction. In a study published in the journal Nature Neuroscience, the researchers described an A.I. that could translate the private thoughts of human subjects by analyzing fMRI scans, which measure the flow of blood to different regions in the brain. Already, researchers have developed language-decoding methods to pick up the attempted speech of people who have lost the ability to speak, and to allow paralyzed people to write while just thinking of writing. But the new language decoder is one of the first to not rely on implants. In the study, it was able to turn a person’s imagined speech into actual speech and, when subjects were shown silent films, it could generate relatively accurate descriptions of what was happening onscreen. “This isn’t just a language stimulus,” said Alexander Huth, a neuroscientist at the university who helped lead the research. “We’re getting at meaning, something about the idea of what’s happening. And the fact that that’s possible is very exciting.” The study centered on three participants, who came to Dr. Huth’s lab for 16 hours over several days to listen to “The Moth” and other narrative podcasts. As they listened, an fMRI scanner recorded the blood oxygenation levels in parts of their brains. The researchers then used a large language model to match patterns in the brain activity to the words and phrases that the participants had heard. © 2023 The New York Times Company

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 14: Attention and Higher Cognition
Link ID: 28768 - Posted: 05.03.2023

Sara Reardon The little voice inside your head can now be decoded by a brain scanner — at least some of the time. Researchers have developed the first non-invasive method of determining the gist of imagined speech, presenting a possible communication outlet for people who cannot talk. But how close is the technology — which is currently only moderately accurate — to achieving true mind-reading? And how can policymakers ensure that such developments are not misused? Most existing thought-to-speech technologies use brain implants that monitor activity in a person’s motor cortex and predict the words that the lips are trying to form. To understand the actual meaning behind the thought, computer scientists Alexander Huth and Jerry Tang at the University of Texas at Austin and their colleagues combined functional magnetic resonance imaging (fMRI), a non-invasive means of measuring brain activity, with artificial intelligence (AI) algorithms called large language models (LLMs), which underlie tools such as ChatGPT and are trained to predict the next word in a piece of text. In a study published in Nature Neuroscience on 1 May, the researchers had 3 volunteers lie in an fMRI scanner and recorded the individuals’ brain activity while they listened to 16 hours of podcasts each1. By measuring the blood flow through the volunteers’ brains and integrating this information with details of the stories they were listening to and the LLM’s ability to understand how words relate to one another, the researchers developed an encoded map of how each individual’s brain responds to different words and phrases. Next, the researchers recorded the participants’ fMRI activity while they listened to a story, imagined telling a story or watched a film that contained no dialogue. Using a combination of the patterns they had previously encoded for each individual and algorithms that determine how a sentence is likely to be constructed based on other words in it, the researchers attempted to decode this new brain activity. The video below shows the sentences produced from brain recordings taken while a study participant watched a clip from the animated film Sintel about a girl caring for a baby dragon. © 2023 Springer Nature Limited

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 14: Attention and Higher Cognition
Link ID: 28767 - Posted: 05.03.2023

By McKenzie Prillaman Cracking the code to brain cancer treatment might start with cracking the brain’s protective shield. Nearly impenetrable walls of jam-packed cells line most of the brain’s blood vessels. Although this blood-brain barrier protects the organ from harmful invaders, it also prevents many medications from reaching the brain. Now, scientists can get a powerful chemotherapy drug into the human brain by temporarily opening its protective shield with ultrasound and tiny bubbles. The early-stage clinical trial, described May 2 in the Lancet Oncology, could lead to new treatments for those with brain cancer. Better treatments are especially needed for glioblastoma, a common and aggressive type of brain tumor. Even after surgical removal, another mass tends to grow in its place. “There’s really no established treatment for when the tumors come back,” says neurosurgeon Adam Sonabend of the Northwestern University Feinberg School of Medicine in Chicago. Patients with recurrent glioblastomas “don’t have any meaningful therapeutic options, so we were exploring new ways of treating them.” After the initial tumor has been removed, patients typically receive a relatively weak chemotherapy drug that can bypass the brain’s barricade. More potent drugs could help destroy any lingering disease — if the medicines could break through the barrier. © Society for Science & the Public 2000–2023.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28763 - Posted: 05.03.2023

By Nora Bradford The classical view of how the human brain controls voluntary movement might not tell the whole story. That map of the primary motor cortex — the motor homunculus — shows how this brain region is divided into sections assigned to each body part that can be controlled voluntarily (SN: 6/16/15). It puts your toes next to your ankle, and your neck next to your thumb. The space each part takes up on the cortex is also proportional to how much control one has over that part. Each finger, for example, takes up more space than a whole thigh. A new map reveals that in addition to having regions devoted to specific body parts, three newfound areas control integrative, whole-body actions. And representations of where specific body parts fall on this map are organized differently than previously thought, researchers report April 19 in Nature. Research in monkeys had hinted at this. “There is a whole cohort of people who have known for 50 years that the homunculus isn’t quite right,” says Evan Gordon, a neuroscientist at Washington University School of Medicine in St. Louis. But ever since pioneering brain-mapping work by neurosurgeon Wilder Penfield starting in the 1930s, the homunculus has reigned supreme in neuroscience. Gordon and his colleagues study synchronized activity and communication between different brain regions. They noticed some spots in the primary motor cortex were linked to unexpected areas involved in action control and pain perception. Because that didn’t fit with the homunculus map, they wrote it off as a result of imperfect data. “But we kept seeing it, and it kept bugging us,” Gordon says. So the team gathered functional MRI data on volunteers as they performed various tasks. Two participants completed simple movements like moving just their eyebrows or toes, as well as complex tasks like simultaneously rotating their wrist and moving their foot from side to side. The fMRI data revealed which parts of the brain activated at the same time as each task was done, allowing the researchers to trace which regions were functionally connected to one another. Seven more participants were recorded while not doing any particular task in order to look at how brain areas communicate during rest. © Society for Science & the Public 2000–2023.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 5: The Sensorimotor System
Link ID: 28748 - Posted: 04.22.2023

Max Kozlov The bizarre-looking ‘homunculus’ is one of neuroscience’s most fundamental diagrams. Found in countless textbooks, it depicts a deformed constellation of body parts mapped onto a narrow strip of the brain, showing the corresponding brain regions that control each part. But a study published in Nature1 on 19 April reveals that this brain strip, called the primary motor cortex, is much more complex than the famous diagram suggests. It might coordinate complex movements involving multiple muscles through connections to brain regions responsible for critical thinking, maintaining the body’s physiology and planning actions. The new results could help scientists better understand and treat brain injuries. “This study is very interesting and very important,” says Michael Graziano, a neuroscientist at Princeton University in New Jersey. It’s becoming clear that the primary motor cortex isn’t “just a simple roster of muscles down the brain that control the toes to the tongue”, he says. Little man in the brain The idea of the homunculus dates to the late nineteenth century, when researchers noticed that electrically stimulating the primary motor cortex corresponded to specific body parts twitching. Later work found that some body parts, such as the hands, feet and mouth, took up a disproportionate amount of space in the primary motor cortex compared with the rest of the body. In 1937, these findings culminated with the first publication of the motor homunculus, which translates to ‘little man’ in Latin. Neurosurgeon Wilder Penfield’s 1948 diagram of the motor homunculus (left) shows the areas of the primary motor cortex that control each body part. A new study redraws the diagram (right), adding regions connected to brain areas responsible for coordinating complex movements.Credit: E. Gordon et al./Nature © 2023 Springer Nature Limited

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 5: The Sensorimotor System
Link ID: 28747 - Posted: 04.22.2023

BySara Reardon Anyone who’s ever owned a telescope has probably tried looking through the wrong end to see whether it works in reverse—that is, like a microscope. Spoiler alert: It doesn’t. Now, a team of researchers inspired by the strange eyes of a sea creature has figured out a way to do it. By flipping the mirrors and lenses used in certain types of telescopes, they have created a new kind of microscope that can be used to image samples floating in any type of liquid—even the insides of transparent organs—while retaining enough light to allow for high magnification. The design could help scientists achieve high enough magnification to study tiny structures such as the long, skinny axons that connect neurons in the brain or individual proteins or RNA molecules inside cells. “It’s nice to see even something as basic as a lens could still bring interest and there's still room there to do some work that would help a lot of people,” says Kimani Touissant, an electrical engineer at Brown University. He says the design could be useful in his work, in which he uses lasers to etch patterns into gels that mimic collagen and act as scaffolds for cells. At very high magnification, light trained on a sample can scatter around it, blurring and dimming the image. To get around that problem, scientists using traditional, lens-based microscopes cover their sample with a thin layer of oil or water, then dip their device’s lens into the liquid, minimizing the degree of light scattering. But this technique requires instruments to have different lenses for different types of liquid, making it an expensive, finicky process and limiting the ways that samples can be prepared. Enter Fabian Voigt, a molecular biologist at Harvard University and inventor of the new design. He was reading a book about animal vision when he encountered the odd case of scallops’ eyes. Unlike most animals, whose eyes feature retinas that send images to the brain, scallops have mantles covered with hundreds of tiny blue dots, each of which contains a curved mirror at its back. As light passes through each eye’s lens, its inner mirror reflects the light back onto the creature’s photoreceptors to create an image that then allows the scallop to respond to its environment.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28742 - Posted: 04.18.2023

By Z Paige L’Erario New Research Points to Causes for Brain Disorders with No Obvious Injury A picture of a human brain taken by a positron emission tomography scanner, also called PET scan, is seen on a screen on January 9, 2019, at the Regional and University Hospital Center of Brest in France. Credit: Fred Tanneau/Getty Images “Stop faking!” Imagine hearing those words moments after your doctor diagnosed you with, say, a stroke or a brain tumor. That sounds absurd but for many people diagnosed with a condition called functional neurological disorder (FND), this is exactly what happens. Although the disorder is not well known to many people, FND is actually one of the most common conditions that neurologists like myself encounter. In it, abnormal brain functioning causes symptoms to appear. FND comes in many forms, with symptoms that can include seizures, feelings of weakness and movement disorders. People may lose consciousness or their ability to move or walk. Or they may experience abnormal tremors or tics. It can be highly disabling and just as costly as structural neurological conditions such as amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig’s disease, multiple sclerosis and Parkinson’s disease. Although men can develop FND, young to middle-aged women receive this diagnosis most frequently. And during the first two years of the COVID pandemic, FND briefly made international headlines when functional tic-like behaviors spread with social media usage, particularly among adolescent girls.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 28725 - Posted: 04.01.2023

By Nora Bradford For the first time, scientists have recorded brain waves from freely moving octopuses. The data reveal some unexpected patterns, though it’s too early to know how octopus brains control the animals’ behavior, researchers report February 23 in Current Biology. “Historically, it’s been so hard to do any recordings from octopuses, even if they’re sedated,” says neuroscientist Robyn Crook of San Francisco State University, who was not involved in the study. “Even when their arms are not moving, their whole body is very pliable,” making attaching recording equipment tricky. Octopuses also tend to be feisty and clever. That means they don’t usually put up with the uncomfortable equipment typically used to record brain waves in animals, says neuroethologist Tamar Gutnick of the University of Naples Federico II in Italy. To work around these obstacles, Gutnick and colleagues adapted portable data loggers typically used on birds, and surgically inserted the devices into three octopuses. The researchers also placed recording electrodes inside areas of the octopus brain that deal with learning and memory. The team then recorded the octopuses for 12 hours while the cephalopods went about their daily lives — sleeping, swimming and self-grooming — in tanks. Some brain wave patterns emerged across all three octopuses in the 12-hour period. For instance, some waves resembled activity in the human hippocampus, which plays a crucial role in memory consolidation. Other brain waves were similar to those controlling sleep-wake cycles in other animals. © Society for Science & the Public 2000–2023.

Related chapters from BN: Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28716 - Posted: 03.25.2023

By McKenzie Prillaman The wiring of one insect’s brain no longer contains much uncharted territory. All of the nerve cells — and virtually every connection between them — in a larval fruit fly brain have now been mapped, researchers report in the March 10 Science. It’s the most complex whole brain wiring diagram yet created. Previously, just three organisms — a sea squirt and two types of worm — had their brain circuitry fully diagrammed to this resolution. But the brains of those creatures have only a few hundred neurons. The scientists who conducted the new study wanted to understand much more complicated brains. Fruit flies (Drosophila melanogaster) share a wide range of behaviors with humans, including integrating sensory information and learning. Larvae perform nearly all the same actions as adult flies — except for some, like flying and mating — but have smaller brains, making data collection much faster (SN: 7/19/18). The idea for this project came 12 years ago, says neuroscientist Marta Zlatic of the MRC Laboratory of Molecular Biology in Cambridge, England. At that time, she and her colleagues captured electron microscope images of the entire larval fruit fly brain. They then stitched those images together in a computer and manually traced each neuron to create a 3-D rendering of the cells. Finally, the team found the connections where information gets passed between the cells, and even determined the sending and receiving ends. Neurons transmit information to one another in circuits. Exploring the neurons’ connectivity patterns — not just directly linked partners, but also the links of linked cells and so on — revealed 93 different types of neurons. The classes were consistent with preexisting groupings characterized by shape and function. And nearly 75 percent of the most well-connected neurons were tied to the brain’s learning center, indicating the importance of learning in animals. © Society for Science & the Public 2000–2023.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 13: Memory and Learning
Link ID: 28697 - Posted: 03.11.2023

By Sidney Perkowitz In 2019, Edward Chang, a neurosurgeon at the University of California, San Francisco, opened the skull of a 36-year-old man, nicknamed “Pancho,” and placed a thin sheet of electrodes on the surface of his brain.1 The electrodes gather electrical signals from the motor neurons that control the movement of the mouth, larynx, and other body parts to produce speech. A small port, implanted on top of Pancho’s head, relayed the brain signals to a computer. This “brain-computer interface,” or BCI, solved an intractable medical problem. In 2003, Pancho, a field worker in California’s vineyards, was involved in a car crash. Days after undergoing surgery, he suffered a brainstem stroke, reported the New York Times Magazine.2 The stroke robbed Poncho of the power of speech. He could communicate only by laboriously spelling out words one letter at a time with a pointing device. After training with the computer outfitted with deep-learning algorithms that interpreted his brain activity, Pancho could think the words that he wanted to say, and they would appear on the computer screen. Scientists called the results “groundbreaking”; Pancho called them “life-changing.” The clinical success of BCIs (there are other stories to go along with Pancho’s) appear to vindicate the futurists who claim that BCIs may soon enhance the brains of healthy people. Most famously, Ray Kurzweil, author of The Singularity Is Near, has asserted that exponentially rapid developments in neuroscience, bioscience, nanotechnology, and computation will coalesce and allow us to transcend the limitations of our bodies and brains. A major part of this huge shift will be the rise of artificial intelligences that are far more capable than human brains. It is an inevitability of human evolution, Kurzweil thinks, that the two kinds of intelligence will merge to form powerful hybrid brains, which will define the future of humanity. This, he predicted, would happen by 2045. While futuristic scenarios like Kurzweil’s are exciting to ponder, they are brought back down to Earth by the technological capabilities of brain-computer hybrids as they exist today. BCIs are impressive, but the path from helping stroke victims to giving people superpowers is neither direct nor inevitable. © 2022 NautilusThink Inc,

Related chapters from BN: Chapter 11: Motor Control and Plasticity; Chapter 3: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 3: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 28570 - Posted: 11.30.2022

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.

Related chapters from BN: Chapter 19: Language and Lateralization; Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 15: Language and Lateralization; Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
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,

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 28536 - Posted: 11.02.2022

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

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28515 - Posted: 10.15.2022

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.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 28499 - Posted: 10.05.2022

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.

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals; Chapter 13: Memory and Learning
Link ID: 28421 - Posted: 08.06.2022