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Windows Installed in Skulls Help Doctors Study Damaged Brains

By Gina Kolata Tucker Marr’s life changed forever last October. He was on his way to a wedding reception when he fell down a steep flight of metal stairs, banging the right side of his head so hard he went into a coma. He’d fractured his skull, and a large blood clot formed on the left side of his head. Surgeons had to remove a large chunk of his skull to relieve pressure on his brain and to remove the clot. “Getting a piece of my skull taken out was crazy to me,” Mr. Marr said. “I almost felt like I’d lost a piece of me.” But what seemed even crazier to him was the way that piece was restored. Mr. Marr, a 27-year-old analyst at Deloitte, became part of a new development in neurosurgery. Instead of remaining without a piece of skull or getting the old bone put back, a procedure that is expensive and has a high rate of infection, he got a prosthetic piece of skull made with a 3-D printer. But it is not the typical prosthesis used in such cases. His prosthesis, which is covered by his skin, is embedded with an acrylic window that would let doctors peer into his brain with ultrasound. A few medical centers are offering such acrylic windows to patients who had to have a piece of skull removed to treat conditions like a brain injury, a tumor, a brain bleed or hydrocephalus. “It’s very cool,” Dr. Michael Lev, director of emergency radiology at Massachusetts General Hospital, said. But, “it is still early days,” he added. Advocates of the technique say that if a patient with such a window has a headache or a seizure or needs a scan to see if a tumor is growing, a doctor can slide an ultrasound probe on the patient’s head and look at the brain in the office. © 2023 The New York Times Company

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: 28914 - Posted: 09.16.2023

Biosensors Illuminate Talk Between Neurons

Neurotransmitters are the words our brain cells use to communicate with one another. For years, researchers relied on tools that provided limited temporal and spatial resolution to track changes in the fast chemical chat between neurons. But that started to change about ten years ago for glutamate—the most abundant excitatory neurotransmitter in vertebrates that plays an essential role in learning, memory, and information processing—when scientists engineered the first glutamate fluorescent reporter, iGluSnFR, which provided a readout of neurons’ fast glutamate release. In 2013, researchers at the Howard Hughes Medical Institute collaborated with scientists from other institutions to develop the first generation of iGluSnFR.1 To create the biosensor, the team combined a bacteria-derived glutamate binding protein, Gltl, a wedged fluorescent GFP protein, and a membrane-targeting protein that anchors the reporter to the surface of the cell. Upon glutamate binding, the Gltl protein changes its conformation, increasing the fluorescence intensity of GFP. In their first study, the team showcased the utility of the biosensor for monitoring glutamate levels by demonstrating selective activation by glutamate in cell cultures. By conducting experiments with brain cells from the C. elegans worm, zebrafish, and mice, they confirmed that the reporter also tracked glutamate in vivo, a finding that set iGluSnFR apart from existing glutamate sensors. The first iGluSnFR generation allowed researchers to study glutamate dynamics in different biological systems, but the indicator could not detect small amounts of the neurotransmitter or keep up with brain cells’ fast glutamate release bouts. Making improvements © 1986–2023 The Scientist.

Scientists Tried to Re-create an Entire Human Brain in a Computer. What Happened?

By Miryam Naddaf, It took 10 years, around 500 scientists and some €600 million, and now the Human Brain Project — one of the biggest research endeavours ever funded by the European Union — is coming to an end. Its audacious goal was to understand the human brain by modelling it in a computer. During its run, scientists under the umbrella of the Human Brain Project (HBP) have published thousands of papers and made significant strides in neuroscience, such as creating detailed 3D maps of at least 200 brain regions, developing brain implants to treat blindness and using supercomputers to model functions such as memory and consciousness and to advance treatments for various brain conditions. “When the project started, hardly anyone believed in the potential of big data and the possibility of using it, or supercomputers, to simulate the complicated functioning of the brain,” says Thomas Skordas, deputy director-general of the European Commission in Brussels. Advertisement Almost since it began, however, the HBP has drawn criticism. The project did not achieve its goal of simulating the whole human brain — an aim that many scientists regarded as far-fetched in the first place. It changed direction several times, and its scientific output became “fragmented and mosaic-like”, says HBP member Yves Frégnac, a cognitive scientist and director of research at the French national research agency CNRS in Paris. For him, the project has fallen short of providing a comprehensive or original understanding of the brain. “I don’t see the brain; I see bits of the brain,” says Frégnac. HBP directors hope to bring this understanding a step closer with a virtual platform — called EBRAINS — that was created as part of the project. EBRAINS is a suite of tools and imaging data that scientists around the world can use to run simulations and digital experiments. “Today, we have all the tools in hand to build a real digital brain twin,” says Viktor Jirsa, a neuroscientist at Aix-Marseille University in France and an HBP board member. But the funding for this offshoot is still uncertain. And at a time when huge, expensive brain projects are in high gear elsewhere, scientists in Europe are frustrated that their version is winding down. “We were probably one of the first ones to initiate this wave of interest in the brain,” says Jorge Mejias, a computational neuroscientist at the University of Amsterdam, who joined the HBP in 2019. Now, he says, “everybody’s rushing, we don’t have time to just take a nap”. Chequered past

How — and why — scientists created a see-through squid

Jon Hamilton Scientists have genetically engineered a squid that is almost as transparent as the water it's in. The squid will allow researchers to watch brain activity and biological processes in a living animal. Sponsor Message ARI SHAPIRO, HOST: For most of us, it would take magic to become invisible, but for some lucky, tiny squid, all it took was a little genetic tweaking. As part of our Weekly Dose of Wonder series, NPR's Jon Hamilton explains how scientists created a see-through squid. JON HAMILTON, BYLINE: The squid come from the Marine Biological Laboratory in Woods Hole, Mass. Josh Rosenthal is a senior scientist there. He says even the animal's caretakers can't keep track of them. JOSH ROSENTHAL: They're really hard to spot. We know we put it in this aquarium, but they might look for a half-hour before they can actually see it. They're that transparent. HAMILTON: Almost invisible. Carrie Albertin, a fellow at the lab, says studying these creatures has been transformative. CARRIE ALBERTIN: They are so strikingly see-through. It changes the way you interpret what's going on in this animal, being able to see completely through the body. HAMILTON: Scientists can watch the squid's three hearts beating in synchrony or see its brain cells at work. And it's all thanks to a gene-editing technology called CRISPR. A few years ago, Rosenthal and Albertin decided they could use CRISPR to create a special octopus or squid for research. ROSENTHAL: Carrie and I are highly biased. We both love cephalopods - right? - and we have for our entire careers. HAMILTON: So they focused on the hummingbird bobtail squid. It's smaller than a thumb and shaped like a dumpling. Like other cephalopods, it has a relatively large and sophisticated brain. Rosenthal takes me to an aquarium to show me what the squid looks like before its genes are altered. ROSENTHAL: Here is our hummingbird bobtail squid. You can see him right there in the bottom, just kind of sitting there hunkered down in the sand. At night, it'll come out and hunt and be much more mobile. © 2023 npr

Related chapters from BN: Chapter 2: Functional Neuroanatomy: The Cells and Structure of the Nervous System; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 2: Neurophysiology: The Generation, Transmission, and Integration of Neural Signals
Link ID: 28883 - Posted: 08.26.2023

The quest to map the mouse brain

Diana Kwon Santiago Ramón y Cajal revolutionized neurobiology in the late nineteenth century with his exquisitely detailed illustrations of neural tissues. Created through years of meticulous microscopy work, the Spanish physician-scientist’s drawings revealed the unique cellular morphology of the brain. “With Cajal’s work, we saw that the cells of the brain don’t look like the cells of every other part of the body — they have incredible morphologies that you just don’t see elsewhere,” says Evan Macosko, a neuroscientist at the Broad Institute of MIT and Harvard in Cambridge, Massachusetts. Ramón y Cajal’s drawings provided one of the first clues that the keys to understanding how the brain governs its many functions, from regulating blood pressure and sleep to controlling cognition and mood, might lie at the cellular level. Still, when it comes it comes to the brain, crucial information remained — and indeed, remains — missing. “In order to have a fundamental understanding of the brain, we really need to know how many different types of cells there are, how are they organized, and how they interact with each other,” says Xiaowei Zhuang, a biophysicist at Harvard University in Cambridge. What neuroscientists require, Zhuang explains, is a way to systematically identify and map the many categories of brain cells. Now researchers are closing in on such a resource, at least in mice. By combining high-throughput single-cell RNA sequencing with spatial transcriptomics — methods for determining which genes are expressed in individual cells, and where those cells are located — they are creating some of the most comprehensive atlases of the mouse brain so far. The crucial next steps will be working out what these molecularly defined cell types do, and bringing the various brain maps together to create a unified resource that the broader neuroscience community can use. © 2023 Springer Nature Limited

Worm Brains, Decoded like Never Before, Could Shed Light on Our Own Mind

By Lauren Leffer When a nematode wriggles around a petri dish, what’s going on inside a tiny roundworm’s even tinier brain? Neuroscientists now have a more detailed answer to that question than ever before. As with any experimental animal, from a mouse to a monkey, the answers may hold clues about the contents of more complex creatures’ noggin, including what resides in the neural circuitry of our own head. A new brain “atlas” and computer model, published in Cell on Monday, lays out the connections between the actions of the nematode species Caenorhabditis elegans and this model organism’s individual brain cells. With the findings, researchers can now observe a C. elegans worm feeding or moving in a particular way and infer activity patterns for many of the animal’s behaviors in its specific neurons. Through establishing those brain-behavior links in a humble roundworm, neuroscientists are one step closer to understanding how all sorts of animal brains, even potentially human ones, encode action. “I think this is really nice work,” says Andrew Leifer, a neuroscientist and physicist who studies nematode brains at Princeton University and was not involved in the new research. “One of the most exciting reasons to study how a worm brain works is because it holds the promise of being able to understand how any brain generates behavior,” he says. “What we find in the worm forms hypotheses to look for in other organisms.” Biologists have been drawn to the elegant simplicity of nematode biology for many decades. South African biologist Sydney Brenner received a Nobel Prize in Physiology or Medicine in 2002 for pioneering work that enabled C. elegans to become an experimental animal for the study of cell maturation and organ development. C. elegans was the first multicellular organism to have its entire genome and nervous system mapped. The first neural map, or “connectome,” of a C. elegans brain was published in 1986. In that research, scientists hand drew connections using colored pencils and charted each of the 302 neurons and approximately 5,000 synapses inside the one-millimeter-long animal’s transparent body. Since then a subdiscipline of neuroscience has emerged—one dedicated to plotting out the brains of increasingly complex organisms. Scientists have compiled many more nematode connectomes, as well as brain maps of a marine annelid worm, a tadpole, a maggot and an adult fruit fly. Yet these maps simply serve as a snapshot in time of a single animal. They can tell us a lot about brain structure but little about how behaviors relate to that structure. © 2023 Scientific American

Mind-reading machines are coming — how can we keep them in check?

Liam Drew Scientific advances are rapidly making science-fiction concepts such as mind-reading a reality — and raising thorny questions for ethicists, who are considering how to regulate brain-reading techniques to protect human rights such as privacy. On 13 July, neuroscientists, ethicists and government ministers discussed the topic at a Paris meeting organized by UNESCO, the United Nations scientific and cultural agency. Delegates plotted the next steps in governing such ‘neurotechnologies’ — techniques and devices that directly interact with the brain to monitor or change its activity. The technologies often use electrical or imaging techniques, and run the gamut from medically approved devices, such as brain implants for treating Parkinson’s disease, to commercial products such as wearables used in virtual reality (VR) to gather brain data or to allow users to control software. How to regulate neurotechnology “is not a technological discussion — it’s a societal one, it’s a legal one”, Gabriela Ramos, UNESCO’s assistant director-general for social and human sciences, told the meeting. Advances in neurotechnology include a neuroimaging technique that can decode the contents of people’s thoughts, and implanted brain–computer interfaces (BCIs) that can convert people’s thoughts of handwriting into text1. The field is growing fast — UNESCO’s latest report on neurotechnology, released at the meeting, showed that, worldwide, the number of neurotechnology-related patents filed annually doubled between 2015 and 2020. Investment rose 22-fold between 2010 and 2020, the report says, and neurotechnology is now a US$33-billion industry. One area in need of regulation is the potential for neurotechnologies to be used for profiling individuals and the Orwellian idea of manipulating people’s thoughts and behaviour. Mass-market brain-monitoring devices would be a powerful addition to a digital world in which corporate and political actors already use personal data for political or commercial gain, says Nita Farahany, an ethicist at Duke University in Durham, North Carolina, who attended the meeting. © 2023 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: 28859 - Posted: 07.27.2023

Repurposed electronics lens spies neurons across entire mouse brain

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

The human brain’s characteristic wrinkles help to drive how it works

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.

AI Is Unlocking the Human Brain’s Secrets

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.

Reading the mind with machines

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

Neuroscientists decoded people’s thoughts using brain scans

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.

A.I. Is Getting Better at Mind-Reading

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

Mind-reading machines are here: is it time to worry?

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

Ultrasound allows a chemotherapy drug to enter the human brain

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.

The classic map of how the human brain manages movement gets an update

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

Famous ‘homunculus’ brain map redrawn to include complex movements

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

Inspired by the sea and the sky, a biologist invents a new kind of microscope

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.

fMRI Points to Causes for Brain Disorders with No Obvious Injury

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.

Scientists have now recorded brain waves from freely moving octopuses

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

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