Dustin Jones Researchers from Sweden and the United Kingdom teamed up to sniff out the answer to a question practically every person has pondered at one time or another: what is the best smell out there? They found that most people, despite coming from different cultures and backgrounds, find vanilla to be the most pleasant smell on the planet more often than not. Sour, stinky feet? Not so much. The collaborative study between Sweden's Karolinska Institutet and the University of Oxford found that people share similar preferences when it comes to smell, regardless of cultural background. And according to the results, vanilla is the most pleasing smell around, followed by ethyl butyrate, which smells like peaches. Artin Arshamian, researcher at Karolinska and one of the study's authors, said humans may have similar olfactory preferences because it helped early humans survive. Which may very well explain why stinky feet came in dead last as far as appealing odors are concerned. According to the study, the pleasantness of a smell can be attributed to the structure of an edible item's odor molecule 41% of the time. Simply put, humans likely enjoy many of the same smells, more often than not, because of a deep-rooted sense that an item is safe to eat. Sponsor Message "We wanted to examine if people around the world have the same smell perception and like the same types of [odor], or whether this is something that is culturally learned," Arshamian said. "Traditionally it has been seen as cultural, but we can show that culture has very little to do with it." © 2022 npr

Keyword: Chemical Senses (Smell & Taste)
Link ID: 28268 - Posted: 04.06.2022

By Pam Belluck Covid-19 may cause greater loss of gray matter and tissue damage in the brain than naturally occurs in people who have not been infected with the virus, a large new study found. The study, published Monday in the journal Nature, is believed to be the first involving people who underwent brain scans both before they contracted Covid and months after. Neurological experts who were not involved in the research said it was valuable and unique, but they cautioned that the implications of the changes were unclear and did not necessarily suggest that people might have lasting damage or that the changes might profoundly affect thinking, memory or other functions. The study, involving people aged 51 to 81, found shrinkage and tissue damage primarily in brain areas related to sense of smell; some of those areas are also involved in other brain functions, the researchers said. “To me, this is pretty convincing evidence that something changes in brains of this overall group of people with Covid,” said Dr. Serena Spudich, chief of neurological infections and global neurology at the Yale School of Medicine, who was not involved in the study. But, she cautioned: “To make a conclusion that this has some long-term clinical implications for the patients I think is a stretch. We don’t want to scare the public and have them think, ‘Oh, this is proof that everyone’s going to have brain damage and not be able to function.’” The study involved 785 participants in UK Biobank, a repository of medical and other data from about half a million people in Britain. The participants each underwent two brain scans roughly three years apart, plus some basic cognitive testing. In between their two scans, 401 participants tested positive for the coronavirus, all infected between March 2020 and April 2021. The other 384 participants formed a control group because they had not been infected with the coronavirus and had similar characteristics to the infected patients in areas like age, sex, medical history and socioeconomic status. With normal aging, people lose a tiny fraction of gray matter each year. For example, in regions related to memory, the typical annual loss is between 0.2 percent and 0.3 percent, the researchers said. © 2022 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Learning & Memory
Link ID: 28237 - Posted: 03.11.2022

By Roni Caryn Rabin Few of Covid-19’s peculiarities have piqued as much interest as anosmia, the abrupt loss of smell that has become a well-known hallmark of the disease. Covid patients lose this sense even without a stuffy nose; the loss can make food taste like cardboard and coffee smell noxious, occasionally persisting after other symptoms have resolved. Scientists are now beginning to unravel the biological mechanisms, which have been something of a mystery: The neurons that detect odors lack the receptors that the coronavirus uses to enter cells, prompting a long debate about whether they can be infected at all. Insights gleaned from new research could shed new light on how the coronavirus might affect other types of brain cells, leading to conditions like “brain fog,” and possibly help explain the biological mechanisms behind long Covid — symptoms that linger for weeks or months after the initial infection. The new work, along with earlier studies, settles the debate over whether the coronavirus infects the nerve cells that detect odors: It does not. But the virus does attack other supporting cells that line the nasal cavity, the researchers found. The infected cells shed virus and die, while immune cells flood the region to fight the virus. The subsequent inflammation wreaks havoc on smell receptors, proteins on the surface of the nerve cells in the nose that detect and transmit information about odors. The process alters the sophisticated organization of genes in those neurons, essentially short-circuiting them, the researchers reported. Their paper significantly advances the understanding of how cells critical to the sense of smell are affected by the virus, despite the fact that they are not directly infected, said Dr. Sandeep Robert Datta, an associate professor of neurobiology at Harvard Medical School, who was not involved in the study. © 2022 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 28232 - Posted: 03.05.2022

Nicola Davis Science correspondent It may not yet feature in a West End musical but scientists say they have found an unexpected response to singin’ in the brain. Researchers say they have found particular groups of neurons that appear to respond selectively to the sound of singing. Writing in the journal Current Biology, a team of scientists in the US report how they made their discovery by recording electrical activity in the brains of 15 participants, each of whom had electrodes inserted inside their skulls to monitor epileptic seizures before undergoing surgery. The team recorded electrical activity in response to 165 different sounds, from pieces of instrumental music to speech and sounds such as dogs barking, and then processed them using an algorithm. They combined the results with data from fMRI brain scans previously collected from 30 different individuals to map the location of the patterns in the brain. Dr Samuel Norman-Haignere, a co-author of the study based at the University of Rochester, said the team decided to combine the data from the different approaches to overcome their respective weaknesses and combine their strengths. “fMRI is one of the workhorses of human cognitive neuroscience, but it is very coarse. Intracranial data is much more precise but has very poor spatial coverage,” he said. The results confirmed previous findings from fMRI scans that some neurons respond only to speech or respond more strongly to music. However, they also revealed populations of neurons that appear to respond selectively to the sound of singing, showing only very weak responses to other types of music or speech alone. © 2022 Guardian News & Media Limited

Keyword: Hearing; Attention
Link ID: 28217 - Posted: 02.23.2022

Jon Hamilton When Michael Schneider's anxiety and PTSD flare up, he reaches for the ukulele he keeps next to his computer. "I can't actually play a song," says Schneider, who suffered two serious brain injuries during nearly 22 years in the Marines. "But I can play chords to take my stress level down." It's a technique Schneider learned through Creative Forces, an arts therapy initiative sponsored by the National Endowment for the Arts, in partnership with the departments of Defense and Veterans Affairs. It's also an example of how arts therapies are increasingly being used to treat brain conditions including PTSD, depression, Parkinson's and Alzheimer's. But most of these treatments, ranging from music to poetry to visual arts, still have not undergone rigorous scientific testing. So artists and brain scientists have launched an initiative called the NeuroArts Blueprint to change that. A brain circuit tied to emotion may lead to better treatments for Parkinson's disease Shots - Health News A brain circuit tied to emotion may lead to better treatments for Parkinson's disease The initiative is the result of a partnership between the Johns Hopkins International Arts + Mind Lab Center for Applied Neuroaesthetics and the Aspen Institute's Health, Medicine and Society Program. Its leadership includes soprano Renée Fleming, actress and playwright Anna Deavere Smith, and Dr. Eric Nestler, who directs the Friedman Brain Institute at Mt. Sinai's Icahn School of Medicine. One goal of the NeuroArts initiative is to measure how arts therapies change the brains of people like Schneider. "I had a traumatic brain injury when I was involved in a helicopter incident on board a U.S. Naval vessel," he explains. That was in 2005. Article continues after sponsor message Later that same year, he experienced sudden decompression – the aviator's version of the bends — while training for high-altitude flights. The result was like a stroke. © 2022 npr

Keyword: Stress; Hearing
Link ID: 28212 - Posted: 02.19.2022

ByTess Joosse Bite into a lemon and you’ll likely experience a clashing rush of sensations: crushing sharpness, mouth-watering tanginess, and pleasant brightness. But despite its assertiveness—and its role as one of the five main taste profiles (along with sweet, salty, savory, and bitter)—scientists don’t know much about how our acidic taste evolved. Enter Rob Dunn. The North Carolina State University ecologist and his collaborators have spent years scanning the scientific literature in search of an answer. In a paper published this week in the Proceedings of the Royal Society B, the team reports some clues. Science chatted with Dunn about how, and why, humans like to pucker up. This interview has been edited for clarity and length. Rob Dunn Ecologist Rob DunnAmanda Ward Q: Do other animals like sour foods? A: With almost all the other tastes, species have lost them through evolution. Dolphins appear to have no taste receptors other than salty, and cats don’t have sweet taste receptors. That’s what we expected to see with sour. What we see instead is all the species that have been tested [about 60 so far] are able to detect acidity in their food. Of those animals, pigs and primates seem to really like acidic foods. For example, wild pigs (Sus scrofa) are really attracted to fermented corn, and gorillas (Gorilla gorilla) have shown a preference for acidic fruits in the ginger family. Q: Sweet taste gives us a reward for energy, and bitter alerts us to potential poisons. Why might we have evolved a taste for sour? A: Sour taste was likely present in ancient fish—they’re the earliest vertebrate animals that we know can sense sour. The origin in fish was likely not to taste food with their mouths, but to sense acidity in the ocean—basically fish “tasting” with the outside of their body. Variations in dissolved carbon dioxide can create acidity gradients in the water, which can be dangerous for fish. Being able to sense acidity would have been important. © 2022 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28198 - Posted: 02.12.2022

By Hallie Levine If you have ever had a ringing or buzzing in one or both ears after a live concert, you have experienced tinnitus — defined as the perception of noise where no external noise is present, according to the American Tinnitus Association. Aside from loud sound, a variety of issues, like excess ear wax, infections and nasal congestion, can cause short-term tinnitus. After a loud event like a concert, the intrusive sounds usually fade within hours to days. But chronic tinnitus — where noise persistently waxes and wanes, or never disappears — affects about 11 percent of adults. In some cases, this can lead to trouble sleeping or concentrating, isolation, anxiety, depression and stress. A 2019 research letter published in JAMA Otolaryngology Head & Neck Surgery found that women with undiagnosed tinnitus were even at increased risk of suicide. Is there a covid-19 connection? During the pandemic, reports of tinnitus rose, especially in people with covid-19. A study published online last March in the International Journal of Audiology estimated that almost 15 percent of those with covid-19 said they had tinnitus, often early in the course of the virus. This typically lasted only a few days. But “there have been anecdotal reports from patients that they have experienced changes in hearing and tinnitus post-covid,” says Cleveland Clinic audiologist Sarah Sydlowski, president of the American Academy of Audiology. One theory is that the virus that causes covid-19 damages the auditory nerve at least temporarily, says Douglas Hildrew, an ear, nose, and throat (ENT) specialist at Yale Medicine.

Keyword: Hearing
Link ID: 28190 - Posted: 02.09.2022

ByWarren Cornwall Bats use sound to hunt a dizzying array of prey. Some zero in on flowers to sip nectar, whereas others find cattle and suck their blood. Many nab insects midflight. One species of bat senses small fish beneath the water and snatches them as osprey do. Now, scientists have discovered an anatomical quirk in the ears of some bats that could help explain how they evolved so many hunting specialties. “For me this is a huge revelation,” says Zhe-Xi Luo, a University of Chicago evolutionary biologist who has studied the origins of mammalian hearing and supervised the new research. “This is totally distinct and unique from all other hearing mammals.” Most bats use their ears to “see” the world around them: After a bat chirps, its ears sense shapes and movement as sound waves bounce off objects, much as ships use sonar. Bats’ ears were long thought to be just a finely tuned version of the ears of nearly all mammals. Then, in 2015, Benjamin Sulser, a University of Chicago biology student on the hunt for a thesis project, took detailed 3D images of the inner ear of a bat skull. But he couldn’t find a feature common in virtually all mammals—a bony tube that encases the nerve cells and connects the ear to the brain. Thinking he’d made a mistake, he and Luo imaged the skulls of two more related species using a computed tomography scanner, with similar results. The researchers realized they might have stumbled across an answer to a mystery that had bedeviled bat biologists for 2 decades—and an explanation for why some families of bats had such a diverse echolocation arsenal. © 2022 American Association for the Advancement of Science.

Keyword: Hearing
Link ID: 28175 - Posted: 01.29.2022

John Crimaldi Brian H. Smith Elizabeth Hong Nathan Urban A dog raises its nose in the air before chasing after a scent. A mosquito zigzags back and forth before it lands on your arm for its next meal. What these behaviors have in common is that they help these animals “see” their world through their noses. While humans primarily use their vision to navigate their environment, the vast majority of organisms on Earth communicate and experience the world through olfaction – their sense of smell. We are members of Odor2Action, an international network of over 50 scientists and students using olfaction to study brain function in animals. Our goal is to understand a fundamental question in neuroscience: How do animal brains translate information from their environments to changes in their behaviors? Here, we trace the interconnections between smells and behaviors – looking at how behavior influences odor detection, how the brain processes sensory information from smells and how this information triggers new behaviors. When the odor of a flower is released into the air, it takes the shape of a wind-borne cloud of molecules called a plume. It encounters physical obstacles and temperature differences as it flows through space. These interactions create turbulence that splits the odor plume into thin threads that spread out as the scent moves away from its source. These filaments eventually reach an animal’s nose or an insect’s antenna. © 2010–2022, The Conversation US, Inc.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 28173 - Posted: 01.26.2022

Chloe Tenn Humans have a sugar sense. Animals and humans prefer sugar over artificial sweeteners in experiments, and that could be because a specific gut sensor cell triggers one of two separate neural pathways depending on which it detects, researchers suggest in a January 13 study in Nature Neuroscience. “It has been known for decades that animals prefer sugar to non-caloric sweeteners and that this preference relies on feedback from the gut,” Lisa Beutler, a Northwestern University endocrinologist who researches the connection between the gut and brain and was not affiliated with the new work, writes in an email to The Scientist. “This study is among the first to provide insight at the molecular level into how the gut knows the difference between sugar and non-caloric sweeteners, and how this drives preference.” The study builds on previous research from the lab of Duke University gut-brain neuroscientist Diego Bohórquez. In 2015, Bohórquez established that endocrine cells, which were previously thought to only communicate with the nervous system indirectly through hormone secretion, can in fact have direct contact with neurons, evidenced by a video. Then, in 2018, the Bohórquez Lab found that the gut has similar cells to those that allow for taste on the tongue and smell in the nose, and that these sensors also have direct contact with neurons. “If they are connected to neurons, they must be connected to the brain,” Bohórquez tells The Scientist. “When we ingest sugar, it stimulates cells in the gut, and these cells release glutamate and activate the vagus nerve,” Bohórquez explains of his prior research. The vagus nerve is a cranial nerve that plays a regulatory role in internal organ functions such as digestion. His team observed that these gut sensor cells, which the team dubbed “neuropods,” transmit the chemosensory information mere milliseconds after detecting sugar. © 1986–2022 The Scientist.

Keyword: Chemical Senses (Smell & Taste); Obesity
Link ID: 28170 - Posted: 01.26.2022

By Erin Garcia de Jesús For many people, one of the fastest tip-offs that they have COVID-19 is the loss of taste or smell. Now researchers have pinpointed some genetic variants in people that may make it more likely that the coronavirus might rob them of these senses. A study of nearly 70,000 adults with COVID-19 found that individuals with certain genetic tweaks on chromosome 4 were 11 percent more likely to lose the ability to smell or taste than people without the changes, researchers report January 17 in Nature Genetics. The data come from people who’d had their DNA analyzed by genetic testing company 23andMe and self-reported a case of COVID-19. Two genes, UGT2A1 and UGT2A2, that help people smell reside in the region of chromosome 4 linked to sensory loss during infection, epidemiologist Janie Shelton of 23andMe and colleagues found. Both genes make enzymes that metabolize substances called odorants, which produce distinctive smells. Sign up for e-mail updates on the latest coronavirus news and research Studies suggest that loss of smell, a hallmark symptom of COVID-19, stems from infections taking hold in smell-supporting cells called sustentacular cells (SN: 6/12/20). It’s possible that the genetic variants near UGT2A1 and UGT2A2 could affect how the two genes are turned on or off to somehow mess with smell during an infection, Shelton says. © Society for Science & the Public 2000–2022.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 28160 - Posted: 01.19.2022

By Winston Choi-Schagrin SOUTH ST. PAUL, Minn. — Chuck McGinley, a chemical engineer, stepped out of his car, eyed the smokestack of an animal processing plant rising above the treetops, and inhaled deeply. At first he smelled nothing except the faint, sweet fragrance of the nearby trees. Suddenly, the wind picked up. “We have an oh-my-God smell!” Mr. McGinley exclaimed. Immediately one of his colleagues pressed a Nasal Ranger to his nose. The 14-inch-long smell-measuring device, which looks like a cross between a radar gun and a bugle, is one of Mr. McGinley’s most significant inventions. Using terms from one of Mr. McGinley’s other standard tools, an odor wheel, a chart akin to an artist’s color wheel that he has been fine-tuning for decades, the team described the stink. “Sour,” one person said. “Decay, with possibly some petroleum,” said another. Then, as quickly as it had arrived, the smell disappeared. “The wind decided it was going to gift us only a short sniff,” Mr. McGinley said. “To tease us.” Intuitively, humans know to avoid bad smells. Yet for a half-century, Mr. McGinley, 76, has returned again and again to society’s stinkiest sites, places very much like this one, in order to measure, describe and demystify smell. Climate Fwd There’s an ongoing crisis — and tons of news. Our newsletter keeps you up to date. Get it sent to your inbox. From his unconventional lab in a Minnesota suburb (it actually feels more like a ski lodge) Mr. McGinley and his son Mike have established an outsize influence over the measurement and understanding of odor. They have equipped scientists around the world with tools the elder Mr. McGinley invented, advised governments on odor regulations and empowered communities near smelly places to find a vocabulary for their complaints and a way to measure what their noses are telling them. In many ways, the growing demand for Mr. McGinley’s services and instruments signals society’s heightened awareness of the power of odor and its potential to make people physically ill or diminish their quality of life. His inventions have taken on a powerful role in a movement to recognize odor as a pollutant, not merely an annoyance, worthy of closer study and perhaps tighter regulation. © 2022 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 28153 - Posted: 01.15.2022

By Judith Graham The reports from coronavirus patients are disconcerting. Only a few hours before, they were enjoying a cup of pungent coffee or the fragrance of flowers in a garden. Then, as if a switch had been flipped, those smells disappeared. F Young and old alike are affected — more than 80 to 90 percent of those diagnosed with the virus, according to some estimates. While most people recover in a few months, 16 percent take half a year or longer to do so, research has found. According to new estimates, up to 1.6 million Americans have chronic smell problems because of covid-19, the disease caused by the coronavirus. Seniors are especially vulnerable, experts say. “We know that many older adults have a compromised sense of smell to begin with. Add to that the insult of covid, and it made these problems worse,” said Jayant Pinto, a professor of surgery and a specialist in sinus and nasal diseases at the University of Chicago Medical Center. Advertisement Recent data highlights the interaction between covid-19, advanced age and loss of smell. When Italian researchers evaluated 101 patients who had been hospitalized for mild to moderate covid-19, 50 showed objective signs of smell impairment six months later. Those 65 or older were nearly twice as likely to be impaired; those 75 or older were more than 2½ times as likely. Most people aren’t aware of the extent to which smell can be diminished in later life. More than half of 65-to-80-year-olds have some degree of smell loss, or olfactory dysfunction, as it’s known in the scientific literature. That rises to as high as 80 percent for those even older. People affected often report concerns about safety, less enjoyment eating and an impaired quality of life. But because the ability to detect, identify and discriminate among odors declines gradually, most older adults — up to 75 percent of those with some degree of smell loss — don’t realize they’re affected.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 28151 - Posted: 01.12.2022

Stephen Wooding The sweetness of sugar is one of life’s great pleasures. People’s love for sweet is so visceral, food companies lure consumers to their products by adding sugar to almost everything they make: yogurt, ketchup, fruit snacks, breakfast cereals and even supposed health foods like granola bars. Schoolchildren learn as early as kindergarten that sweet treats belong in the smallest tip of the food pyramid, and adults learn from the media about sugar’s role in unwanted weight gain. It’s hard to imagine a greater disconnect between a powerful attraction to something and a rational disdain for it. How did people end up in this predicament? I’m an anthropologist who studies the evolution of taste perception. I believe insights into our species’ evolutionary history can provide important clues about why it’s so hard to say no to sweet. The basic activities of day-to-day life, such as raising the young, finding shelter and securing enough food, all required energy in the form of calories. Individuals more proficient at garnering calories tended to be more successful at all these tasks. They survived longer and had more surviving children – they had greater fitness, in evolutionary terms. One contributor to success was how good they were at foraging. Being able to detect sweet things – sugars – could give someone a big leg up. In nature, sweetness signals the presence of sugars, an excellent source of calories. So foragers able to perceive sweetness could detect whether sugar was present in potential foods, especially plants, and how much. © 2010–2022, The Conversation US, Inc.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 28146 - Posted: 01.12.2022

By Elizabeth Landau In a narrow medical school hallway, Matt Stewart opened a large cabinet to reveal dozens of shelves stacked with wooden boxes and trays, some at least 100 years old. Stewart, tall and silver-haired, pulled out one of the trays and showed off its contents: Thin slices of human skull bones and the organs of hearing and balance they contain, stained shades of pink. Affixed to microscope slides, the anatomical bits resembled abstract rubber stamp art, no bigger than thumbprints. “Our Johns Hopkins history,” he said, referring to the university’s collection of specimens from more than 5,000 patients. Stewart’s research team at Johns Hopkins University in Baltimore had a long, complicated journey to make slides like these in 2021. The researchers need these specimens, sliced from the portion of skull that houses the inner ear, to ask a fundamental question about the novel coronavirus, SARS-CoV-2: Does it directly invade the cells of tissues that enable hearing and balance? Ear surgeon Matt Stewart leads a research team at Johns Hopkins University that is investigating how SARS-CoV-2 might infect ear cells that enable hearing and balance. Data on ear problems as they relate to Covid-19, the disease caused by SARS-CoV-2, is spotty. To date, case reports and small studies have found that some Covid-19 patients experience significant and rapid hearing loss, ringing in the ears called tinnitus, or balance issues. Estimates vary on the prevalence of these symptoms, but because the coronavirus has infected hundreds of millions of people, even a few percent of Covid patients experiencing hearing loss would add up to a large increase globally. Yet no causal link has been drawn between the novel coronavirus and auditory symptoms. Hearing problems aren’t even on lists of Covid-19 symptoms, short or long-term, published by the Centers for Disease Control and Prevention.

Keyword: Hearing
Link ID: 28139 - Posted: 01.05.2022

By Ariana Remmel Scientists have finally sniffed out the molecules behind marijuana’s skunky aroma. The heady bouquet that wafts off of fresh weed is actually a cocktail of hundreds of fragrant compounds. The most prominent floral, citrusy and piney overtones come from a common class of molecules called terpenes, says analytical chemist Iain Oswald of Abstrax Tech, a private company in Tustin, Calif., that develops terpenes for cannabis products (SN: 4/30/18). But the source of that funky ganja note has been hard to pin down. Now, an analysis is the first to identify a group of sulfur compounds in cannabis that account for the skunklike scent, researchers report November 12 in ACS Omega. Oswald and colleagues had a hunch that the culprit may contain sulfur, a stinky element found in hops and skunk spray. So the team started by rating the skunk factor of flowers harvested from more than a dozen varieties of Cannabis sativa on a scale from zero to 10, with 10 being the most pungent. Next, the team created a “chemical fingerprint” of the airborne components that contributed to each cultivar’s unique scent using gas chromatography, mass spectroscopy and a sulfur chemiluminescence detector. As suspected, the researchers found small amounts of several fragrant sulfur compounds lurking in the olfactory profiles of the smelliest cultivars. The most dominant was a molecule called prenylthiol, or 3-methyl-2-butene-1-thiol, that gives “skunked beer” its notorious flavor (SN: 11/27/05). © Society for Science & the Public 2000–2021

Keyword: Chemical Senses (Smell & Taste); Drug Abuse
Link ID: 28092 - Posted: 12.01.2021

ByEmily Underwood Scientists have argued for decades over whether humans have pheromones, chemical compounds that trigger aggression and mating in insects and other animals. Although the notion has great popular appeal—search Amazon for “pheromone” and you’ll get the idea—there’s scant evidence for this kind of signal in our species. A new study could change that. Researchers have identified an odorless compound emitted by people—and in particular babies—called hexadecanal, or HEX, that appears to foster aggressive behavior in women and blunt it in men. “We cannot say that this is a pheromone,” says study author Noam Sobel, a neuroscientist at the Weizmann Institute of Science. “But we can say that it’s a molecule expressed by the human body that influences human behavior, specifically aggressive behavior, in a predicted manner.” Humans emit HEX from their skin, saliva, and feces, and it’s among the most abundant molecules babies emit from their heads. When researchers isolated the odorless compound and piped it into mouse cages, it had a relaxing effect on the animals, says Sobel, who studies the role of scent in human interactions. To test how HEX affects people, Eva Mishor, who earned her Ph.D. in Sobel’s lab, created a series of computer games designed to evoke intense frustration—and a measurable response to it—in 126 human participants. Half of the volunteers wore a HEX-infused adhesive strip on their upper lips while they played, whereas the other half wore strips that smelled identical but were HEX-free. In one task, participants negotiated with an unseen partner to divvy up a sum of virtual money. The participants thought they were playing with another person, but they were actually playing against computers. If a player offered their “partner” anything less than 90% of the whole amount, the computer rejected their proposals with a bright red “NO!” preventing them from earning any money. © 2021 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Aggression
Link ID: 28086 - Posted: 11.20.2021

Jon Hamilton Headaches, nausea, dizziness, and confusion are among the most common symptoms of a concussion. But researchers say a blow to the head can also make it hard to understand speech in a noisy room. "Making sense of sound is one of the hardest jobs that we ask our brains to do," says Nina Kraus, a professor of neurobiology at Northwestern University. "So you can imagine that a concussion, getting hit in the head, really does disrupt sound processing." About 15% to 20% of concussions cause persistent sound-processing difficulties, Kraus says, which suggests that hundreds of thousands of people are affected each year in the U.S. The problem is even more common in the military, where many of the troops who saw combat in Iraq and Afghanistan sustained concussions from roadside bombs. From ear to brain Our perception of sound starts with nerve cells in the inner ear that transform pressure waves into electrical signals, Kraus says. But it takes a lot of brain power to transform those signals into the auditory world we perceive. Article continues after sponsor message The brain needs to compare the signals from two ears to determine the source of a sound. Then it needs to keep track of changes in volume, pitch, timing and other characteristics. Kraus's lab, called Brainvolts, is conducting a five-year study of 500 elite college athletes to learn how a concussion can affect the brain's ability to process the huge amount of auditory information it receives. And she devotes an entire chapter to concussion in her 2021 book, Of Sound Mind: How Our Brain Constructs a Meaningful Sonic World. © 2021 npr

Keyword: Brain Injury/Concussion; Hearing
Link ID: 28064 - Posted: 11.06.2021

Jordana Cepelewicz Hearing is so effortless for most of us that it’s often difficult to comprehend how much information the brain’s auditory system needs to process and disentangle. It has to take incoming sounds and transform them into the acoustic objects that we perceive: a friend’s voice, a dog barking, the pitter-patter of rain. It has to extricate relevant sounds from background noise. It has to determine that a word spoken by two different people has the same linguistic meaning, while also distinguishing between those voices and assessing them for pitch, tone and other qualities. According to traditional models of neural processing, when we hear sounds, our auditory system extracts simple features from them that then get combined into increasingly complex and abstract representations. This process allows the brain to turn the sound of someone speaking, for instance, into phonemes, then syllables, and eventually words. But in a paper published in Cell in August, a team of researchers challenged that model, reporting instead that the auditory system often processes sound and speech simultaneously and in parallel. The findings suggest that how the brain makes sense of speech diverges dramatically from scientists’ expectations, with the signals from the ear branching into distinct brain pathways at a surprisingly early stage in processing — sometimes even bypassing a brain region thought to be a crucial stepping-stone in building representations of complex sounds.

Keyword: Language; Hearing
Link ID: 28058 - Posted: 10.30.2021

Bill Chappell People with mild or moderate hearing loss could soon be able to buy hearing aids without a medical exam or special fitting, under a new rule being proposed by the Food and Drug Administration. The agency says 37.5 million American adults have difficulty hearing. "Today's move by FDA takes us one step closer to the goal of making hearing aids more accessible and affordable for the tens of millions of people who experience mild to moderate hearing loss," Health and Human Services Secretary Xavier Becerra said as he announced the proposed rule on Tuesday. There is no timeline yet for when consumers might be able to buy an FDA-regulated over-the-counter (OTC) hearing aid. The proposed rule is now up for 90 days of public comment. The Hearing Loss Association of America, a consumer advocacy group, welcomed the proposal. "This is one step closer to seeing OTC hearing devices on the market," Barbara Kelley, the group's executive director, said in an email to NPR. "We hope adults will be encouraged to take that important first step toward good hearing health." Advocates and lawmakers have been calling for OTC hearing aids for years, including in a big push in 2017, when Sen. Elizabeth Warren, D-Mass., and co-sponsor Sen. Chuck Grassley, R-Iowa, introduced the bipartisan Over-the-Counter Hearing Aid Act. The legislators are now praising the FDA's move. © 2021 npr

Keyword: Hearing
Link ID: 28042 - Posted: 10.20.2021