Chapter 9. Hearing, Balance, Taste, and Smell

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Jordana Cepelewicz Smell, rather than sight, reigns as the supreme sense for most animals. It allows them to find food, avoid danger and attract mates; it dominates their perceptions and guides their behavior; it dictates how they interpret and respond to the deluge of sensory information all around them. “How we as biological creatures interface with chemistry in the world is profoundly important for understanding who we are and how we navigate the universe,” said Bob Datta, a neurobiologist at Harvard Medical School. Yet olfaction might also be the least well understood of our senses, in part because of the complexity of the inputs it must reckon with. What we might label as a single odor — the smell of coffee in the morning, of wet grass after a summer storm, of shampoo or perfume — is often a mixture of hundreds of types of chemicals. For an animal to detect and discriminate between the many scents that are key to its survival, the limited repertoire of receptors on its olfactory sensory neurons must somehow recognize a vast number of compounds. So an individual receptor has to be able to respond to many diverse, seemingly unrelated odor molecules. That versatility is at odds with the traditional lock-and-key model governing how selective chemical interactions tend to work. “In high school biology, that’s what I learned about ligand-receptor interactions,” said Annika Barber, a molecular biologist at Rutgers University. “Something has to fit precisely in a site, and then it changes the [protein’s atomic arrangement], and then it works.” All Rights Reserved © 2021

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27869 - Posted: 06.23.2021

By Deborah Schoch Marcel Kuttab first sensed something was awry while brushing her teeth a year ago, several months after recovering from Covid-19. Her toothbrush tasted dirty, so she threw it out and got a new one. Then she realized the toothpaste was at fault. Onions and garlic and meat tasted putrid, and coffee smelled like gasoline — all symptoms of the once little-known condition called parosmia that distorts the senses of smell and taste. Dr. Kuttab, 28, who has a pharmacy doctoral degree and works for a drug company in Massachusetts, experimented to figure out what foods she could tolerate. “You can spend a lot of money in grocery stores and land up not using any of it,” she said. The pandemic has put a spotlight on parosmia, spurring research and a host of articles in medical journals. Membership has swelled in existing support groups, and new ones have sprouted. A fast-growing British-based Facebook parosmia group has more than 14,000 members. And parosmia-related ventures are gaining followers, from podcasts to smell training kits. Yet a key question remains unanswered: How long does Covid-linked parosmia last? Scientists have no firm timelines. Of five patients interviewed for this article, all of whom first developed parosmia symptoms in late spring and early summer of last year, none has fully regained normal smell and taste. Brooke Viegut, whose parosmia began in May 2020, worked for an entertainment firm in New York City before theaters were shuttered. She believes she caught Covid in March during a quick business trip to London, and, like many other patients, she lost her sense of smell. Before she regained it completely, parosmia set in, and she could not tolerate garlic, onions or meat. Even broccoli, she said at one point earlier this year, had a chemical smell. She still can’t stomach some foods, but she is growing more optimistic. “A lot of fruits taste more like fruit now instead of soap,” she said. And she recently took a trip without getting seriously nauseous. “So, I’d say that’s progress.” © 2021 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Neuroimmunology
Link ID: 27857 - Posted: 06.16.2021

Ed Yong Carl Schoonover and Andrew Fink are confused. As neuroscientists, they know that the brain must be flexible but not too flexible. It must rewire itself in the face of new experiences, but must also consistently represent the features of the external world. How? The relatively simple explanation found in neuroscience textbooks is that specific groups of neurons reliably fire when their owner smells a rose, sees a sunset, or hears a bell. These representations—these patterns of neural firing—presumably stay the same from one moment to the next. But as Schoonover, Fink, and others have found, they sometimes don’t. They change—and to a confusing and unexpected extent. Schoonover, Fink, and their colleagues from Columbia University allowed mice to sniff the same odors over several days and weeks, and recorded the activity of neurons in the rodents’ piriform cortex—a brain region involved in identifying smells. At a given moment, each odor caused a distinctive group of neurons in this region to fire. But as time went on, the makeup of these groups slowly changed. Some neurons stopped responding to the smells; others started. After a month, each group was almost completely different. Put it this way: The neurons that represented the smell of an apple in May and those that represented the same smell in June were as different from each other as those that represent the smells of apples and grass at any one time. This is, of course, just one study, of one brain region, in mice. But other scientists have shown that the same phenomenon, called representational drift, occurs in a variety of brain regions besides the piriform cortex. Its existence is clear; everything else is a mystery. Schoonover and Fink told me that they don’t know why it happens, what it means, how the brain copes, or how much of the brain behaves in this way. How can animals possibly make any lasting sense of the world if their neural responses to that world are constantly in flux? (c) 2021 by The Atlantic Monthly Group

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27852 - Posted: 06.11.2021

Joanne Silberner Scientists once compared the abilities of humans versus canines in tracking a trail of chocolate essential oil laid down in an open field. Though the humans weren't nearly as proficient as the dogs, they did get better with practice. Vladimir Godnik/Getty Images/fStop About 25 years ago, after a particularly bad cold, I suddenly lost my sense of smell — I could no longer sense the difference between sweaty tennis shoes and a fragrant rose. Since then, my olfactory discernment comes and goes, and most of the time it's just gone. I always figured there wasn't much I could do about that, and it hasn't been terrible. My taste buds still work, and I adore fine chocolate. But when COVID-19 hit, the inability to detect odors and fragrances became a diagnostic symptom that upset a lot of COVID-19 sufferers, many of whom also lost their sense of taste. That got me thinking — what does it really mean to have a disordered sense of smell? Does it matter that with my eyes closed I can't tell if I'm in an overripe gym or a perfume store? And is there hope that I'll ever again be able to smell a wet dog or freesia or a gas leak or a raw onion? Scientists explain that when you put your nose in the way of steam rising from a hot cup of coffee, molecules called odorants rise up and land high up in your nose. And when you take a swig of that same joe, as the liquid goes down your throat, some molecules rise upward and hit that sweet spot. Nerve cells there have receptors that recognize specific molecules, and those nerve cells extend directly into the brain. "That's how you tell you're smelling coffee as opposed to pizza," says Pamela Dalton of the Monell Chemical Senses Center in Philadelphia, who studies how we perceive good smells and bad. When the coffee "odorants" connect with their nerve cells, she says, your brain knows that you've just enjoyed your morning brew. © 2021 npr

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27807 - Posted: 05.08.2021

Jon Hamilton A study of mice that hear imaginary sounds could help explain human disorders like schizophrenia, which produce hallucinations. D-Keine/Getty Images A technique that induces imaginary sounds in both mice and people could help scientists understand the brain circuits involved in schizophrenia and other disorders that cause hallucinations. The technique appears to offer "a way to study psychotic disorders in animals," says Adam Kepecs, a professor of neuroscience and psychiatry at Washington University School of Medicine in St. Louis. It also shows how levels of the brain chemical dopamine determine the likelihood that a mouse or a person will perceive something that isn't really there, Kepecs and a team report in this week's issue of the journal Science. Until now, scientists have had no good way to study precisely how hallucinations occur in the brain. "This study is valuable because it will allow us to use mice and dig into the cellular, molecular, physiological details," says Eleanor Simpson, a researcher at the New York State Psychiatric Institute. That's important, Simpson says, because it could lead to better treatments for disorders like schizophrenia. "We have drugs that treat hallucinations but they're not very good," she says. "They don't work for everybody and they have a lot of terrible side effects which prevent people from using them." The study came about because "a mouse can't tell you when it's hallucinating," Kepecs © 2021 npr

Keyword: Schizophrenia; Hearing
Link ID: 27758 - Posted: 04.03.2021

By Lisa Sanders, M.D. The dental hygienist greeted her longtime patient enthusiastically. Unexpectedly, the 68-year-old woman burst into tears. “I feel so bad,” she said, her voice cracking with emotion. “I’m worried I might be dying.” She was always tired, as if all her energy had been sucked out. And she felt a strange dread that something awful was happening to her. And if that weren’t enough, for the past couple of weeks she had lost much of her hearing in her right ear. She was sure she had a brain tumor — though none of her doctors thought so. After offering sympathy, the dental assistant realized she had something more to offer: “We have a dental CT scanner. Should we get a CT of your head?” The patient was amazed. Yes — she would very much like a CT scan of her head. It would cost her $150, the technician told her. At that point, it seemed like a bargain. And, just like that, it was done. And there was a mass. It wasn’t on the right side, where she thought her trouble lay. It was on the left. And it wasn’t in her ear, but in the sinus behind her cheek. That was confusing. She thanked the tech for the scan. She had an ENT and would send the images to him to see what he thought. That right ear had been giving the patient trouble for more than 20 years, she reminded her ear, nose and throat doctor in Prescott, Ariz., when she spoke with him. In her 40s she developed terrible vertigo. She was living in Atlanta then and saw an ENT there who told her she probably had Ménière’s disease, a disorder induced by increased pressure in the inner ear. The cause is unknown, though in some cases it appears to run in families. And it’s characterized by intermittent episodes of vertigo usually accompanied by a sensation of fullness in the ear, as well as tinnitus and hearing loss. These symptoms can be present from the start, but often develop over time. There’s no definitive test for the disease, though evidence of the increased pressure is sometimes visible on an M.R.I. © 2021 The New York Times Company

Keyword: Hearing
Link ID: 27753 - Posted: 03.31.2021

By Christina Caron When Laura Drager contracted Covid-19 in July, it was as though someone had suddenly muted her olfactory system. One morning she was sipping her favorite Gatorade (the yellow one), and two hours later the drink was completely flavorless. She immediately lit a candle and blew it out, but she couldn’t smell the smoke. Her sense of smell had disappeared. Now, she said, “everything either tastes like bleach or tastes like nothing.” Over the past few months she has lost 19 pounds. “I don’t have that ‘I’m hungry’ feeling,” said Ms. Drager, 41, who lives in Sevierville, Tenn., about 45 minutes from Knoxville. “I think you forget how much smell and taste is a part of your life until it goes away.” As the coronavirus continues to spread, there are increasing numbers of people who have either lost their senses of smell after contracting Covid or are struggling with parosmia, a disturbing disorder that causes previously normal odors to develop a new, often unpleasant aroma. One meta-analysis published in September found that as many as 77 percent of those who had Covid were estimated to have some form of smell loss as a result of their infections. The recommended treatment for these conditions is smell training. But how exactly do you do it, and why should you bother? © 2021 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27745 - Posted: 03.27.2021

By Alyson Krueger Samantha LaLiberte, a social worker in Nashville, thought she had made a full recovery from Covid-19. But in mid-November, about seven months after she’d been sick, a takeout order smelled so foul that she threw it away. When she stopped by the house of a friend who was cooking, she ran outside and vomited on the front lawn. “I stopped going places, even to my mom’s house or to dinner with friends, because anything from food to candles smelled so terrible,” Ms. LaLiberte, 35, said. “My relationships are strained.” She is dealing with parosmia, a distortion of smell such that previously enjoyable aromas — like that of fresh coffee or a romantic partner — may become unpleasant and even intolerable. Along with anosmia, or diminished sense of smell, it is a symptom that has lingered with some people who have recovered from Covid-19. The exact number of people experiencing parosmia is unknown. One recent review found that 47 percent of people with Covid-19 had smell and taste changes; of those, about half reported developing parosmia. “That means that a rose might smell like feces,” said Dr. Richard Doty, director of the Smell and Taste Center at the University of Pennsylvania. He noted that people typically recover their smell within months. Right now, Ms. LaLiberte can’t stand the scent of her own body. Showering is no help; the smell of her body wash, conditioner and shampoo made her sick. What’s more, she detected the same odor on her husband of eight years. “There is not a whole lot of intimacy right now,” she said. “And it’s not because we don’t want to.” “It’s a much bigger issue than people give it credit for,” said Dr. Duika Burges Watson, who leads the Altered Eating Research Network at Newcastle University in England and submitted a journal research paper on the topic. “It is something affecting your relationship with yourself, with others, your social life, your intimate relationships.” © 2021 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 27742 - Posted: 03.23.2021

By Jake Buehler You might be able to do a mean celebrity impression or two, but can you imitate an entire film’s cast at the same time? A male superb lyrebird (Menura novaehollandiae) can, well almost. During courtship and even while mating, the birds pull off a similar feat, mimicking the calls and wingbeat noises of many bird species at once, a new study shows. The lyrebirds appear to be attempting to recreate the specific ecological soundscape associated with the arrival of a predator, researchers report February 25 in Current Biology. Why lyrebirds do this isn’t yet clear, but the finding is the first time that an individual bird has been observed mimicking the sounds of multiple bird species simultaneously. The uncanny acoustic imitation of multispecies flocks adds a layer of complexity to the male lyrebird’s courtship song yet unseen in birds and raises questions about why its remarkable vocal mimicry skills, which include sounds like chainsaws and camera shutters, evolved in the first place. Superb lyrebirds — native to forested parts of southeastern Australia — have a flair for theatrics. The males have exceptionally long, showy tail feathers that are shaken extensively in elaborate mating dances (SN: 6/6/13). The musical accompaniment to the dance is predominantly a medley of greatest hits of the songs of other bird species, the function of which behavioral ecologist Anastasia Dalziell was studying via audio and video recordings of the rituals.

Keyword: Sexual Behavior; Animal Communication
Link ID: 27715 - Posted: 02.28.2021

By William Weir There are a few ways we perceive food, and not all are particularly well-understood. We know that much of it happens in the olfactory bulb, a small lump of tissue between the eyes and behind the nose, but how the stimuli arrive at this part of the brain is still being worked out. How these stimuli are processed in the brain plays a major role in our daily life. Fully understanding how our perceptions of food are formed is critical, Fahmeed Hyder said, but getting a clear picture of what our brains do when we smell has been tricky. “Knowing which exact pathways are affected and teaching our brain to appreciate and acknowledge both modes of perception in understanding the flavor is a part of our culture that we haven’t fully exploited yet,” he said. A better understanding of how smells get to our brain would not only tell us a lot about our eating habits, he said, it could even potentially help patients of certain diseases. Hyder, professor of biomedical engineering and radiology & biomedical imaging, has taken a detailed look at the function of the olfactory bulb. It may not be one of the most talked-about regions of the brain, but it helps us make sense of the outside world by taking in molecules from food — known as food volatiles — and then sending these signals further into the brain. It serves a pivotal role as the gateway for chemical stimuli to the rest of the brain — specifically the piriform cortex, amygdala, and hippocampus. To see exactly how it does that, Hyder and his team mapped the activity in the entire olfactory bulb. It’s the first time that this has ever been done for the two independent routes of odor delivery — that is, the orthonasal and retronasal routes. The results were published in NeuroImage. Copyright © 2021 Yale University

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27691 - Posted: 02.15.2021

By Carolyn Gramling The fin whale’s call is among the loudest in the ocean: It can even penetrate into Earth’s crust, a new study finds. Echoes in whale songs recorded by seismic instruments on the ocean floor reveal that the sound waves pass through layers of sediment and underlying rock. These songs can help probe the structure of the crust when more conventional survey methods are not available, researchers report in the Feb. 12 Science. Six songs, all from a single whale that sang as it swam, were analyzed by seismologists Václav Kuna of the Czech Academy of Sciences in Prague and John Nábělek of Oregon State University in Corvallis. They recorded the songs, lasting from 2.5 to 4.9 hours, in 2012 and 2013 with a network of 54 ocean-bottom seismometers in the northeast Pacific Ocean. The songs of fin whales (Balaenoptera physalus) can be up to 189 decibels, as noisy as a large ship. Seismic instruments detect the sound waves of the song, just like they pick up pulses from earthquakes or from air guns used for ship-based surveys. The underwater sounds can also produce seismic echoes: When sound waves traveling through the water meet the ground, some of the waves’ energy converts into a seismic wave (SN: 9/17/20). Those seismic waves can help scientists “see” underground: As the penetrating waves bounce off different rock layers, researchers can estimate the thickness of the layers. Changes in the waves’ speed can also reveal what types of rocks the waves traveled through. © Society for Science & the Public 2000–2021.

Keyword: Hearing; Animal Communication
Link ID: 27686 - Posted: 02.13.2021

By Brooke Jarvis Danielle Reed stopped counting after the 156th email arrived in a single afternoon. It was late March, and her laboratory at the Monell Chemical Senses Center in Philadelphia had abruptly gone into Covid-19 lockdown. For weeks, there had been little to do. Reed, who is famous in her field for helping to discover a new family of receptors that perceive bitter flavors, had spent years studying the way human genetics affect the way we experience smell and taste. It was important but niche science that seemingly had little to do with a dangerous respiratory virus spreading around the globe. And then one Saturday, she checked her email. Reed watched in amazement as the messages proliferated. It wasn’t how many threads there were, though that was overwhelming, but the way they seemed to grow like Hydras, sprouting in all directions. Recipients copied other people they thought might be interested in the discussion, who added more people, who added still others, across a huge range of countries and disciplines. The cascading emails were all responding to the same rather obscure news alert, meant for ear, nose and throat doctors based in Britain. It was titled: “Loss of smell as marker of Covid-19 infection.” The week before, Claire Hopkins, the president of the British Rhinological Society and an author of the alert, was seeing patients in her clinic in London when she noticed something odd. Hopkins, who specializes in nose and sinus diseases, especially nasal polyps, was accustomed to seeing the occasional patient — usually about one per month — whose sense of smell disappeared after a viral infection. Most of the time, such losses were fairly self-explanatory: A stuffy, inflamed nose keeps odorants from reaching the smell receptors at the top of the airway. Sometimes these receptors are also damaged by inflammation and need time to recover. But patients were now arriving with no blockage or swelling, no trouble breathing, no notable symptoms, other than the sudden and mysterious disappearance of their ability to smell. And there were nine of them. © 2021 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27672 - Posted: 01.30.2021

Katherine J. Wu In a perfect world, the entrance to every office, restaurant and school would offer a coronavirus test — one with absolute accuracy, and able to instantly determine who was virus-free and safe to admit and who, positively infected, should be turned away. That reality does not exist. But as the nation struggles to regain a semblance of normal life amid the uncontrolled spread of the virus, some scientists think that a quick test consisting of little more than a stinky strip of paper might at least get us close. The test does not look for the virus itself, nor can it diagnose disease. Rather, it screens for one of Covid-19’s trademark signs: the loss of the sense of smell. Since last spring, many researchers have come to recognize the symptom, which is also known as anosmia, as one of the best indicators of an ongoing coronavirus infection, capable of identifying even people who don’t otherwise feel sick. A smell test cannot flag people who contract the coronavirus and never develop any symptoms at all. But in a study that has not yet been published in a scientific journal, a mathematical model showed that sniff-based tests, if administered sufficiently widely and frequently, might detect enough cases to substantially drive transmission down. Daniel Larremore, an epidemiologist at the University of Colorado, Boulder, and the study’s lead author, stressed that his team’s work was still purely theoretical. Although some smell tests are already in use in clinical and research settings, the products tend to be expensive and laborious to use and are not widely available. And in the context of the pandemic, there is not yet real-world data to support the effectiveness of smell tests as a frequent screen for the coronavirus. Given the many testing woes that have stymied pandemic control efforts so far, some experts have been doubtful that smell tests could be distributed widely enough, or made sufficiently cheat-proof, to reduce the spread of infection. © 2021 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27656 - Posted: 01.20.2021

Michael Marshall One treatment for survivors of COVID-19 who have lost their sense of smell is 'smell training', in which they relearn prescribed scents, such as those of roses and lemons.Credit: Christine E. Kelly Early in the COVID-19 pandemic, it emerged that many people infected with the SARS-CoV-2 virus were losing their sense of smell — even without displaying other symptoms. Researchers also discovered that infected people could lose their sense of taste and their ability to detect chemically triggered sensations such as spiciness, called chemesthesis. Almost a year later, some still haven’t recovered these senses, and for a proportion of people who have, odours are now warped: unpleasant scents have taken the place of normally delightful ones. Nature surveys the science behind this potentially long-lasting and debilitating phenomenon. How many people with COVID-19 lose their sense of smell? The exact percentage varies between studies, but most suggest that smell loss is a common symptom. One review published last June1 compiled data from 8,438 people with COVID-19, and found that 41% had reported experiencing smell loss. In another study, published in August2, a team led by researcher Shima T. Moein at the Institute for Research in Fundamental Sciences in Tehran, Iran, administered a smell-identification test to 100 people with COVID-19 in which the subjects sniffed odours and identified them on a multiple-choice basis. Ninety-six per cent of the participants had some olfactory dysfunction, and 18% had total smell loss (otherwise known as anosmia). © 2021 Springer Nature Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27649 - Posted: 01.15.2021

By Roni Caryn Rabin Until March, when everything started tasting like cardboard, Katherine Hansen had such a keen sense of smell that she could recreate almost any restaurant dish at home without the recipe, just by recalling the scents and flavors. Then the coronavirus arrived. One of Ms. Hansen’s first symptoms was a loss of smell, and then of taste. Ms. Hansen still cannot taste food, and says she can’t even tolerate chewing it. Now she lives mostly on soups and shakes. “I’m like someone who loses their eyesight as an adult,” said Ms. Hansen, a realtor who lives outside Seattle. “They know what something should look like. I know what it should taste like, but I can’t get there.” A diminished sense of smell, called anosmia, has emerged as one of the telltale symptoms of Covid-19, the illness caused by the coronavirus. It is the first symptom for some patients, and sometimes the only one. Often accompanied by an inability to taste, anosmia occurs abruptly and dramatically in these patients, almost as if a switch had been flipped. Most regain their senses of smell and taste after they recover, usually within weeks. But in a minority of patients like Ms. Hansen, the loss persists, and doctors cannot say when or if the senses will return. Scientists know little about how the virus causes persistent anosmia or how to cure it. But cases are piling up as the coronavirus sweeps across the world, and some experts fear that the pandemic may leave huge numbers of people with a permanent loss of smell and taste. The prospect has set off an urgent scramble among researchers to learn more about why patients are losing these essential senses, and how to help them. “Many people have been doing olfactory research for decades and getting little attention,” said Dr. Dolores Malaspina, professor of psychiatry, neuroscience, genetics and genomics at Icahn School of Medicine at Mount Sinai in New York. “Covid is just turning that field upside down.” © 2021 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27642 - Posted: 01.09.2021

By Matthew Hutson Somehow, even in a room full of loud conversations, our brains can focus on a single voice in something called the cocktail party effect. But the louder it gets—or the older you are—the harder it is to do. Now, researchers may have figured out how to fix that—with a machine learning technique called the cone of silence. Computer scientists trained a neural network, which roughly mimics the brain’s wiring, to locate and separate the voices of several people speaking in a room. The network did so in part by measuring how long it took for the sounds to hit a cluster of microphones in the room’s center. When the researchers tested their setup with extremely loud background noise, they found that the cone of silence located two voices to within 3.7º of their sources, they reported this month at the online-only Conference on Neural Information Processing Systems. That compares with a sensitivity of only 11.5º for the previous state-of-the-art technology. When the researchers trained their new system on additional voices, it managed the same trick with eight voices—to a sensitivity of 6.3º—even if it had never heard more than four at once. Such a system could one day be used in hearing aids, surveillance setups, speakerphones, or laptops. The new technology, which can also track moving voices, might even make your Zoom calls easier, by separating out and silencing background noise, from vacuum cleaners to rambunctious children. © 2020 American Association for the Advancement of Science.

Keyword: Hearing
Link ID: 27628 - Posted: 12.19.2020

By Paula Span By now, we were supposed to be swiftly approaching the day when we could walk into a CVS or Walgreens, a Best Buy or Walmart, and walk out with a pair of quality, affordable hearing aids approved by the Food and Drug Administration. Hearing aids, a widely needed but dauntingly expensive investment, cost on average $4,700 a pair. (Most people need two.) So in 2017, Congress passed legislation allowing the devices to be sold directly to consumers, without a prescription from an audiologist. The next step was for the F.D.A. to issue draft regulations to establish safety and effectiveness benchmarks for these over-the-counter devices. Its deadline: August 2020. A public comment period would follow, and then — right about now — the agency would be preparing its final rule, to take effect in May 2021. So by next summer, people with what is known as “perceived mild to moderate hearing loss” might need to spend only one-quarter of today’s price or less, maybe far less. And then we could have turned down the TV volume and stopped making dinner reservations for 5:30 p.m., when restaurants are mostly empty and conversations are still audible. “These regulations are going to help a lot of people,” said Dr. Vinay Rathi, an otolaryngologist at Massachusetts Eye and Ear. “There could be great potential for innovation.” So, where are the new rules? This long-sought alternative to the current state of hearing aid services has been delayed, perhaps one more victim of the pandemic. Of course, the agency has other crucial matters to address just now. Although the office charged with hearing aid regulations is not the one assessing Covid-19 vaccines, an F.D.A. spokesman said via email that it was dealing with “an unprecedented volume of emergency use authorizations” for diagnostics, ventilators and personal protective equipment. © 2020 The New York Times Company

Keyword: Hearing
Link ID: 27626 - Posted: 12.15.2020

Sam Wollaston A single-storey building in a lonely rural business park, a few miles from Milton Keynes on a grey autumn day. It looks like a location for a bleak thriller: where a kidnap victim is held, perhaps, or the scene of a final shootout. Inside, though, something kind of cool is happening. In a brightly lit room, four inverted metal cups have been placed on the red carpet, each containing a small glass jar. One of these contains a smell: a “training odour”. Into the room bursts Billy, followed by Jess. Billy is a labrador, and Jess his human trainer. Billy bounces about the place, clearly super excited. He sniffs at everything – furniture, people, the cups – wagging ferociously. When he sniffs at the cup that contains the smell, another trainer, Jayde, indicates success with a clicking noise. Billy is rewarded with his favourite toy, a well-chewed rubber ball, and a chorus of “good boy”. So far, so unremarkable. Dogs have excellent noses, everyone knows that. They are estimated to be at least 10,000 times better than ours. It’s not immediately clear just how good Billy is. Did he really find the smell, or did Jayde just click when he sniffed the right cup? To be fair to Billy, he’s young, 18 months old, and this is only his second session. The trainers – Jess, Jayde and Mark – have high hopes for him. And after a couple more goes, it becomes clear that he is definitely finding the right cup, quickly. He is also clearly enjoying the game. What Billy lacks in refinement, he makes up for in youthful enthusiasm and exuberance, and he learns fast. Which is good news: this is just the first stage for Billy, who is on a fast-track training course to learn to sniff out Covid-19. He’s not working with the actual virus, of course, but a training sample, which will teach him to do that job. © 2020 Guardian News & Media Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27622 - Posted: 12.12.2020

By Jason Castro To be an expectant mother, or the anxious partner of one, is to be keenly, even agonizingly aware of how chemicals affect a developing life. The basic advice is well known, and obsessively followed: Alcohol in strict moderation, and no nicotine at all. Don’t mess with mercury. Folic acid is your friend. More protein and less caffeine. Stay away from BPA, PBCs and PFA, and generally make an enemy of the unpronounceable. But, if we take the results of a provocative recent paper seriously, there may be another important, and deeply underappreciated chemical influence at work: a man’s odor. The research, by a team headed by Noam Sobel of the Weizmann Institute of Science, suggests that there is a relationship between women’s response to “social odors” contained in male sweat and the heartbreaking condition of unexplained repeated pregnancy loss (uRPL). Specifically, in blind smell-tests, these scientists observed that women who had experienced uRPL were significantly better at identifying their spouse’s odor than age-matched controls. Additionally, their brains responded differently to nonspouse odors and they displayed unique olfactory neuroanatomy. Taken in the context of a large body of literature on chemosignaling in nonhuman animals, these results make it conceivable that the human nose could also communicate with the womb and may even influence a pregnancy. So far, the results are strictly correlative, and in no way point to male odor as some kind of pheromonal smoking gun that explains pregnancy loss. Hypothetically, it could also be true that women experiencing uRPL have, on average, larger middle toes, larger whites of their eyes, thinner wrists and a proclivity for wearing purple socks. None of these would give one pause or prompt a serious search for some kind of causal link to pregnancy loss. Yet this particular link between smell and pregnancy loss is intriguing because of how prevalent and robust it is in other mammals, including primates. Many miscarriages still have unexplained causes, which makes any lead, correlative or not, a particularly interesting and worthwhile area of research. © 2020 Scientific American

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 27619 - Posted: 12.09.2020

David Cox Seven years ago, rhinology surgeon Peter Andrews found himself performing an operation that would go on to change the course of his career. Andrews was operating on a patient who had broken his nose many decades earlier after being struck by a cricket ball. The procedure was delicate: straightening the septum – the thin wall of cartilage that separates the nostrils – and in the process improving his breathing, which had become more laboured in later life. But it had a surprising outcome. As well being able to breathe more freely, Andrews’s patient found he could smell again for the first time in 40 years, a remarkable turn of events that provided the medical community with a new insight into our sense of smell, and its capacity to regenerate. Being able to smell is actually a result of a complex neurological process. Smell-specific nerve cells known as olfactory neurons, located high in the nasal cavity, detect molecules in the air such as those released by a perfume, or smoke particles from something burning. They then convey this information via a long nerve fibre running up through the skull, to a part of the brain that makes sense of it all. This network is one of the most adaptable in the entire central nervous system. To keep functioning, it completely regenerates every six weeks, shedding existing olfactory neurons, and creating new ones from scratch. “That’s quite a feat in itself, because those neurons then have to reconnect up into the brain tissue,” says Andrews. But sometimes things can happen that impair its ability to regenerate. An estimated 5% of the general population is believed to have anosmia, the medical term for temporary or permanent smell loss. Anosmia can occur as part of the ageing process, but also in those of all ages due to factors ranging from broken noses to viral infections. © 2020 Guardian News & Media Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27618 - Posted: 12.09.2020