Chapter 6. Hearing, Balance, Taste, and Smell

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By Kim Tingley Hearing loss has long been considered a normal, and thus acceptable, part of aging. It is common: Estimates suggest that it affects two out of three adults age 70 and older. It is also rarely treated. In the U.S., only about 14 percent of adults who have hearing loss wear hearing aids. An emerging body of research, however, suggests that diminished hearing may be a significant risk factor for Alzheimer’s disease and other forms of dementia — and that the association between hearing loss and cognitive decline potentially begins at very low levels of impairment. In November, a study published in the journal JAMA Otolaryngology — Head and Neck Surgery examined data on hearing and cognitive performance from more than 6,400 people 50 and older. Traditionally, doctors diagnose impairment when someone experiences a loss in hearing of at least 25 decibels, a somewhat arbitrary threshold. But for the JAMA study, researchers included hearing loss down to around zero decibels in their analysis and found that they still predicted correspondingly lower scores on cognitive tests. “It seemed like the relationship starts the moment you have imperfect hearing,” says Justin Golub, the study’s lead author and an ear, nose and throat doctor at the Columbia University Medical Center and NewYork-Presbyterian. Now, he says, the question is: Does hearing loss actually cause the cognitive problems it has been associated with and if so, how? Preliminary evidence linking dementia and hearing loss was published in 1989 by doctors at the University of Washington, Seattle, who compared 100 patients with Alzheimer’s-like dementia with 100 demographically similar people without it and found that those who had dementia were more likely to have hearing loss, and that the extent of that loss seemed to correspond with the degree of cognitive impairment. But that possible connection wasn’t rigorously investigated until 2011, when Frank Lin, an ear, nose and throat doctor at Johns Hopkins School of Medicine, and colleagues published the results of a longitudinal study that tested the hearing of 639 older adults who were dementia-free and then tracked them for an average of nearly 12 years, during which time 58 had developed Alzheimer’s or another cognitive impairment. They discovered that a subject’s likelihood of developing dementia increased in direct proportion to the severity of his or her hearing loss at the time of the initial test. The relationship seems to be “very, very linear,” Lin says, meaning that the greater the hearing deficit, the greater the risk a person will develop the condition. © 2020 The New York Times Company

Keyword: Hearing; Alzheimers
Link ID: 27057 - Posted: 02.20.2020

By Katherine Kornei Imagine a frog call, but with a metallic twang—and the intensity of a chainsaw. That’s the “boing” of a minke whale. And it’s a form of animal communication in danger of being drowned out by ocean noise, new research shows. By analyzing more than 42,000 minke whale boings, scientists have found that, as background noise intensifies, the whales are losing their ability to communicate over long distances. This could limit their ability to find mates and engage in important social contact with other whales. Tyler Helble, a marine acoustician at the Naval Information Warfare Center Pacific, and colleagues recorded minke whale boings over a 1200-square-kilometer swathe of the U.S. Navy’s Pacific Missile Range Facility near the Hawaiian island of Kauai from 2012 to 2017. By measuring when a single boing arrived at various underwater microphones, the team pinpointed whale locations to within 10 to 20 meters. The researchers then used these positions, along with models of how sound propagates underwater, to calculate the intensity of each boing when it was emitted. The team compared these measurements with natural ambient noise, including waves, wind, and undersea earthquakes (no military exercises were conducted nearby during the study period). They found that minke whale boings grew louder in louder conditions. That’s not surprising—creatures across the animal kingdom up their volume when there’s background noise. (This phenomenon, dubbed the Lombard effect, holds true for humans, too—think of holding a conversation at a loud concert.) © 2019 American Association for the Advancement of Science.

Keyword: Animal Communication; Hearing
Link ID: 27051 - Posted: 02.19.2020

By Brian Platzer Three years ago I wrote an essay for Well about the chronic dizziness that had devastated my life. In response, I received thousands of letters, calls, tweets, emails and messages from Times readers who were grateful to see a version of their own story made public. Their symptoms varied. While some experienced a constant disequilibrium and brain fog that were similar to mine, others had become accustomed to a pattern of short periods of relative health alternating with longer periods of vertigo. Most of them, like me, felt that family and friends often didn’t understand how dizziness could be so debilitating. They told me that the combination of the loneliness and feelings of uselessness that come from an inability to work or spend time with family led to despair and depression. And, most commonly, they felt that the medical system made them feel responsible for their own suffering. “Doctors began to suggest that anxiety or depression were the cause of my symptoms,” a young woman from Connecticut wrote. “I eventually gave up on the quest for answers, as their attitudes added stress to an already stressful reality.” “Have been to so many doctors that keep saying, ‘It’s all in your head. There’s nothing wrong with you,’” wrote an older woman from Ohio. “Mostly been told there is nothing they can find,” wrote a middle-aged woman from Illinois. Her doctor told her it was probably just depression and anxiety. Dizziness is among the most common reasons people visit their doctor in the United States. When patients first experience prolonged dizziness, they may go to an emergency room or to see their primary care physician. That’s what I did. And I heard what most patients hear: “People get dizzy for all sorts of reasons, and it should resolve itself soon.” It’s true that dizziness often is a temporary symptom. The most common causes of dizziness are benign paroxysmal positional vertigo (caused by displaced pieces of small bone-like calcium in the inner ear), and vestibular neuritis (dizziness attributed to a viral infection or tiny stroke of the vestibular nerve), both of which typically last only weeks or months. © 2020 The New York Times Company

Keyword: Miscellaneous
Link ID: 27036 - Posted: 02.13.2020

John Henning Schumann As the owner of a yellow lab named Gus, author Maria Goodavage has had many occasions to bathe her pooch when he rolls around in smelly muck at the park. Nevertheless, her appreciation for his keen sense of smell has inspired her write best-selling books about dogs with special assignments in the military and the U.S. Secret Service. Her latest, Doctor Dogs: How Our Best Friends Are Becoming Our Best Medicine, highlights a vast array of special medical tasks that dogs can perform — from the laboratory to the bedside, and everywhere else a dog can tag along and sniff. Canines' incredible olfactory capacity — they can sniff in parts per trillion — primes them to detect disease, and their genius for observing our behavior helps them guide us physically and emotionally. Goodavage spoke with NPR contributor John Henning Schumann, a doctor and host of Public Radio Tulsa's #MedicalMonday about what she has learned about dogs in medicine What led you to look into dogs in medicine? I've been reading and writing about military dogs and Secret Service dogs for many years now, and it was sort of a natural next step. These are dogs on the cutting edge of medicine. They're either working in research or right beside someone to save their life every day. And really, doctor dogs are, for the most part, using their incredible sense of smell to detect diseases. And if they're paired with a person, they bond with that person to tell them something that will save their life. © 2020 npr

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26992 - Posted: 01.25.2020

By Bradley Berman The day is approaching when commuters stuck in soul-crushing traffic will be freed from the drudgery of driving. Companies are investing billions to devise sensors and algorithms so motorists can turn our attention to where we like it these days: our phones. But before the great promise of multitasking on the road can be realized, we need to overcome an age-old problem: motion sickness. “The autonomous-vehicle community understands this is a real problem it has to deal with,” said Monica Jones, a transportation researcher at the University of Michigan. “That motivates me to be very systematic.” So starting in 2017, Ms. Jones led a series of studies in which more than 150 people were strapped into the front seat of a 2007 Honda Accord. They were wired with sensors and set on a ride that included roughly 50 left-hand turns and other maneuvers. Each subject was tossed along the same twisty route for a second time but also asked to complete a set of 13 simple cognitive and visual tasks on an iPad Mini. About 11 percent of the riders got nauseated or, for other reasons, asked that the car be stopped. Four percent vomited. Ms. Jones takes no joy in documenting her subjects’ getting dizzy, hyperventilating or losing their lunch. She feels their pain. Ms. Jones, a chronic sufferer of motion sickness, has experienced those discomforts in car back seats all her life. “I don’t remember not experiencing it,” she said. “As I’m getting older, it’s getting worse.” It’s also getting worse for the legions of commuters hailing Ubers or taxis and hopping in, barely lifting their gaze from a screen in the process. © 2020 The New York Times Company

Keyword: Miscellaneous
Link ID: 26976 - Posted: 01.21.2020

By Tina Hesman Saey Some hairy cells in the nose may trigger sneezing and allergies to dust mites, mold and other substances, new work with mice suggests. When exposed to allergens, these “brush cells” make chemicals that lead to inflammation, researchers report January 17 in Science Immunology. Only immune cells previously were thought to make such inflammatory chemicals — fatty compounds known as lipids. The findings may provide new clues about how people develop allergies. Brush cells are shaped like teardrops topped by tufts of hairlike projections. In people, mice and other animals, these cells are also found in the linings of the trachea and the intestines, where they are known as tuft cells (SN: 4/13/18). However, brush cells are far more common in the nose than in other tissues, and may help the body identify when pathogens or noxious chemicals have been inhaled, says Lora Bankova, an allergist and immunologist at Brigham and Women’s Hospital in Boston. Bankova and her colleagues discovered that, when exposed to certain molds or dust mite proteins, brush cells in mice’s noses churn out inflammation-producing lipids, called cysteinyl leukotrienes. The cells also made the lipids when encountering ATP, a chemical used by cells for energy that also signals when nearby cells are damaged, as in an infection. Mice exposed to allergens or ATP developed swelling of their nasal tissues. But mice that lacked brush cells suffered much less inflammation. Such inflammation may lead to allergies in some cases. The researchers haven’t yet confirmed that brush cells in human noses respond to allergens in the same way as these cells do in mice. © Society for Science & the Public 2000–2020

Keyword: Chemical Senses (Smell & Taste); Neuroimmunology
Link ID: 26974 - Posted: 01.21.2020

By Jane E. Brody Every now and then I write a column as much to push myself to act as to inform and motivate my readers. What follows is a prime example. Last year in a column entitled “Hearing Loss Threatens Mind, Life and Limb,” I summarized the current state of knowledge about the myriad health-damaging effects linked to untreated hearing loss, a problem that afflicts nearly 38 million Americans and, according to two huge recent studies, increases the risk of dementia, depression, falls and even cardiovascular diseases. Knowing that my own hearing leaves something to be desired, the research I did for that column motivated me to get a proper audiology exam. The results indicated that a well-fitted hearing aid could help me hear significantly better in the movies, theater, restaurants, social gatherings, lecture halls, even in the locker room where the noise of hair dryers, hand dryers and swimsuit wringers often challenges my ability to converse with my soft-spoken friends. That was six months ago, and I’ve yet to go back to get that recommended hearing aid. Now, though, I have a new source of motivation. A large study has documented that even among people with so-called normal hearing, those with only slightly poorer hearing than perfect can experience cognitive deficits. That means a diminished ability to get top scores on standardized tests of brain function, like matching numbers with symbols within a specified time period. But while you may never need or want to do that, you most likely do want to maximize and maintain cognitive function: your ability to think clearly, plan rationally and remember accurately, especially as you get older. While under normal circumstances, cognitive losses occur gradually as people age, the wisest course may well be to minimize and delay them as long as possible and in doing so, reduce the risk of dementia. Hearing loss is now known to be the largest modifiable risk factor for developing dementia, exceeding that of smoking, high blood pressure, lack of exercise and social isolation, according to an international analysis published in The Lancet in 2017. © 2019 The New York Times Company

Keyword: Hearing
Link ID: 26923 - Posted: 12.30.2019

By Carolyn Gramling Exceptionally preserved skulls of a mammal that lived alongside the dinosaurs may be offering scientists a glimpse into the evolution of the middle ear. The separation of the three tiny middle ear bones — known popularly as the hammer, anvil and stirrup — from the jaw is a defining characteristic of mammals. The evolutionary shift of those tiny bones, which started out as joints in ancient reptilian jaws and ultimately split from the jaw completely, gave mammals greater sensitivity to sound, particularly at higher frequencies (SN: 3/20/07). But finding well-preserved skulls from ancient mammals that can help reveal the timing of this separation is a challenge. Now, scientists have six specimens — four nearly complete skeletons and two fragmented specimens — of a newly described, shrew-sized critter dubbed Origolestes lii that lived about 123 million years ago. O. lii was part of the Jehol Biota, an ecosystem of ancient wetlands-dwellers that thrived between 133 million and 120 million years ago in what’s now northeastern China. The skulls on the nearly complete skeletons were so well-preserved that they were able to be examined in 3-D, say paleontologist Fangyuan Mao of the Chinese Academy of Sciences in Beijing and colleagues. That analysis suggests that O. lii’s middle ear bones were fully separated from its jaw, the team reports online December 5 in Science. Fossils from an older, extinct line of mammals have shown separated middle ear bones, but this newfound species would be the first of a more recent lineage to exhibit this evolutionary advance. © Society for Science & the Public 2000–2019

Keyword: Hearing; Evolution
Link ID: 26880 - Posted: 12.07.2019

By Jade Wu What do the sounds of whispering, crinkling paper, and tapping fingernails have in common? What about the sight of soft paint brushes on skin, soap being gently cut to pieces, and hand movements like turning the pages of a book? Well, if you are someone who experiences the autonomous sensory meridian response—or ASMR, for short—you may recognize these seemingly ordinary sounds and sights as “triggers” for the ASMR experience. No idea what I’m talking about? Don’t worry, you’re actually in the majority. Most people, myself included, aren’t affected by these triggers. But what happens to those who are? What is the ASMR experience? It’s described as a pleasantly warm and tingling sensation that starts on the scalp and moves down the neck and spine. ASMR burst onto the Internet scene in 2007, according to Wikipedia, when a woman with the username “okaywhatever” described her experience of ASMR sensations in an online health discussion forum. At the time, there was no name for this weird phenomenon. But by 2010, someone called Jennifer Allen had named the experience, and from there, ASMR became an Internet sensation. Today, there are hundreds of ASMR YouTubers who collectively post over 200 videos of ASMR triggers per day, as reported by a New York Times article in April, 2019. Some ASMR YouTubers have become bona fide celebrities with ballooning bank accounts, millions of fans, and enough fame to be stopped on the street for selfies. There’s been some controversy. Some people doubt whether this ASMR experience is “real,” or just the result of recreational drugs or imagined sensations. Some have chalked the phenomenon up to a symptom of loneliness among Generation Z, who get their dose of intimacy from watching strangers pretend to do their makeup without having to interact with real people. Some people are even actively put off by ASMR triggers. One of my listeners, Katie, said that most ASMR videos just make her feel agitated. But another listener, Candace, shared that she has been unknowingly chasing ASMR since she was a child watching BBC. © 2019 Scientific American

Keyword: Hearing; Emotions
Link ID: 26873 - Posted: 12.05.2019

Jon Hamilton When we hear a sentence, or a line of poetry, our brains automatically transform the stream of sound into a sequence of syllables. But scientists haven't been sure exactly how the brain does this. Now, researchers from the University of California, San Francisco, think they've figured it out. The key is detecting a rapid increase in volume that occurs at the beginning of a vowel sound, they report Wednesday in Science Advances. "Our brain is basically listening for these time points and responding whenever they occur," says Yulia Oganian, a postdoctoral scholar at UCSF. The finding challenges a popular idea that the brain monitors speech volume continuously to detect syllables. Instead, it suggests that the brain periodically "samples" spoken language looking for specific changes in volume. The finding is "in line" with a computer model designed to simulate the way a human brain decodes speech, says Oded Ghitza, a research professor in the biomedical engineering department at Boston University who was not involved in the study. Detecting each rapid increase in volume associated with a syllable gives the brain, or a computer, an efficient way to deal with the "stream" of sound that is human speech, Ghitza says. And syllables, he adds, are "the basic Lego blocks of language." Oganian's study focused on a part of the brain called the superior temporal gyrus. "It's an area that has been known for about 150 years to be really important for speech comprehension," Oganian says. "So we knew if you can find syllables somewhere, it should be there." The team studied a dozen patients preparing for brain surgery to treat severe epilepsy. As part of the preparation, surgeons had placed electrodes over the area of the brain involved in speech. © 2019 npr

Keyword: Language; Hearing
Link ID: 26841 - Posted: 11.21.2019

By Neuroskeptic | Many people may be living life without a particular brain region – and not suffering any ill-effects. In a new paper in Neuron, neuroscientists Tali Weiss and colleagues discuss five women who appear to completely lack olfactory bulbs (OB). According to most neuroscience textbooks, no OB should mean no sense of smell, because the OB is believed to be a key relay point for olfactory signals. As Wikipedia puts it: The olfactory bulb transmits smell information from the nose to the brain, and is thus necessary for a proper sense of smell. Scent molecules activate olfactory receptors and signals travel up the olfactory nerves to the olfactory bulb, and then on to the rest of the brain via the olfactory tract. From Wikipedia. However, remarkably, Weiss et al.’s five women seem to have entirely normal sense of smell despite lacking any visible OBs on brain MRI scans. On both subjective and objective measures of olfactory function, these women showed no abnormalities. MRIs showing normal development of olfactory bulbs (A) compared to two women with no visible olfactory bulbs but normal sense of smell (B) & (D) and one woman with no sense of smell (C). From Weiss et al. Fig 1 Weiss et al. came across two of the women serendipitously while carrying out MRI scans for an unrelated project. The other 3 were found among healthy controls in the Human Connectome Project MRI dataset.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26825 - Posted: 11.18.2019

Hate eating certain vegetables? It could be down to your genes, say US scientists who have done some new research. Inheriting two copies of the unpleasant taste gene provides a "ruin-your-day level of bitterness" to foods like broccoli and sprouts, they say. It could explain why some people find it difficult to include enough vegetables in their diet, they suggest. The gene may also make beer, coffee and dark chocolate taste unpleasant. In evolutionary terms, being sensitive to bitter taste may be beneficial - protecting humans from eating things that could be poisonous. But Dr Jennifer Smith and colleagues from the University of Kentucky School of Medicine say it can also mean some people struggle to eat their recommended five-a-day of fresh fruit and veg. Everyone inherits two copies of a taste gene called TAS2R38. It encodes for a protein in the taste receptors on the tongue which allows us to taste bitterness. People who inherit two copies of a variant of the gene TAS2R38, called AVI, are not sensitive to bitter tastes from certain chemicals. Those with one copy of AVI and another called PAV perceive bitter tastes of these chemicals, but not to such an extreme degree as individuals with two copies of PAV, often called "super-tasters", who find the same foods exceptionally bitter. The scientists studied 175 people and found those with two copies of the bitter taste PAV version of the gene ate only small amounts of leafy green vegetables, which are good for the heart. Dr Smith told medics at a meeting of the American Heart Association: "You have to consider how things taste if you really want your patient to follow nutrition guidelines." © 2019 BBC.

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 26814 - Posted: 11.12.2019

By Veronique Greenwood When a bird preens its feathers, it uses a little of nature’s own pomade: an oil made by glands just above the tail. This oil helps clean and protect the bird’s plumage, but also contains a delicate bouquet of scents. To other birds — potential mates or would-be rivals — these smells carry many messages, not unlike the birdsongs and fancy feathers that are more obvious to human observers. These scents may signal that a bird would be dangerous to encounter or might be ready to mate, or any number of other cues. However, new research using dark-eyed juncos, a common North American bird, suggests that these odoriferous messages may not be entirely of the bird’s own making. In a study published last month in the Journal of Experimental Biology, biologists reported that microbes living peacefully on the birds’ oil glands may play an important role in making the scent molecules involved. That implies that the birds’ microbiomes may influence both the smell and the behavior it provokes in other birds. Birds’ scented messages are the focus of the research of Danielle Whittaker, managing director of the Beacon Center for the Study of Evolution in Action at Michigan State University and an author of the paper. Some years ago, after she gave a talk, Kevin Theis, a colleague who studied scent-producing bacteria living on hyenas and who is a co-author of the new paper, asked her whether she had ever looked at the birds’ microbes. “I had never thought about bacteria at all,” said Dr. Whittaker. “But all the compounds I was describing were known byproducts of bacterial metabolism.” Dr. Whittaker took samples of bacteria living on the oil glands of 10 captive dark-eyed juncos and then injected the glands with an antibiotic. When she compared the microbes before and after the treatment, the results seemed to show that two groups of bacteria in particular had taken a hit from the treatment. Furthermore, when she compared the scent molecules in the oil before and after the treatment, there were significant differences. © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26812 - Posted: 11.11.2019

Adam Miller · CBC News · New research is shedding light on how the brain interacts with music. It also highlights how challenging it is to study the issue effectively due to the highly personalized nature of how we interpret it. "Music is very subjective," says Dr. Daniel Levitin, a professor of neuroscience and music at McGill University in Montreal and author of the bestselling book This is Your Brain on Music. "People have their own preferences and their own experience and to some extent baggage that they bring to all of this — it is challenging." Levitin says there are more researchers studying the neurological effects of music now than ever before. From 1998 to 2008 there were only four media reports of evidence-based uses of music in research, while from 2009 to 2019 there were 185, Levitin said in a recent paper for the journal Music and Medicine. It's a "great time for music and brain research" because more people are well-trained and skilled at conducting rigorous experiments, according to Levitin. Emerging research reveals challenges A new study by researchers in Germany and Norway used artificial intelligence to analyze levels of "uncertainty" and "surprise" in 80,000 chords from 745 commercially successful pop songs on the U.S. Billboard charts. The research, published Thursday in Current Biology, found that chords provided more pleasure to the listener both when there is uncertainty in anticipating what comes next, and from the surprise the music elicits when the chords deviate from expectations. ©2019 CBC/Radio-Canada

Keyword: Hearing
Link ID: 26807 - Posted: 11.09.2019

By Sofie Bates Some people may be able to smell even without key structures that relay odor information from the nose to the brain. Researchers used brain scans to identify two women who appear to be missing their olfactory bulbs, the only parts of the brain known to receive signals about smell sensations from the nose and send them to other parts of the brain for processing. Both individuals performed similarly to other women with olfactory bulbs on several tests to identify and differentiate odors, the scientists report November 6 in Neuron. The findings challenge conventional views of the olfactory system, and may lead to treatments for people with no sense of smell (SN: 7/2/07). “I’m not sure that our textbook view of how the [olfactory] system works is right,” says Noam Sobel, a neuroscientist at the Weizmann Institute of Science in Rehovot, Israel. MRI scans of the women’s brains revealed that where most people have two olfactory bulbs, these two appeared to have cerebrospinal fluid instead. To the researchers, this indicated that the women didn’t have olfactory bulbs. But Jay Gottfried, a neuroscientist at the University of Pennsylvania who was not involved in the study, says “I am not convinced that the women are indeed missing their bulbs.” Some evidence for olfactory bulbs may be undetectable with MRI, like microscopic structures or olfactory tissue that could be found with antibodies, he says. © Society for Science & the Public 2000–2019

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26800 - Posted: 11.07.2019

By Jon Cohen On a lightly snowing Sunday evening, a potential participant in Denis Rebrikov’s controversial plans to create gene-edited babies meets with me at a restaurant in a Moscow suburb. She does not want to be identified beyond her patronymic, Yevgenievna. We sit at a corner table in an empty upstairs section of the restaurant while live Georgian music plays downstairs. Yevgenievna, in her late 20s, cannot hear it—or any music. She has been deaf since birth. But with the help of a hearing aid that’s linked to a wireless microphone, which she places on the table, she can hear some sounds, and she is adept at reading lips. She speaks to me primarily in Russian, through a translator, but she is also conversant in English. Yevgenievna and her husband, who is partially deaf, want to have children who will not inherit hearing problems. There is nothing illicit about our discussion: Russia has no clear regulations prohibiting Rebrikov’s plan to correct the deafness mutation in an in vitro fertilization (IVF) embryo. But Yevgenievna is uneasy about publicity. “We were told if we become the first couple to do this experiment we’ll become famous, and HBO already tried to reach me,” Yevgenievna says. “I don’t want to be well known like an actor and have people bother me.” She is also deeply ambivalent about the procedure itself, a pioneering and potentially risky use of the CRISPR genome editor. The couple met on vk.com, a Russian Facebook of sorts, in a chat room for people who are hearing impaired. Her husband could hear until he was 15 years old, and still gets by with hearing aids. They have a daughter—Yevgenievna asks me not to reveal her age—who failed a hearing test at birth. Doctors initially believed it was likely a temporary problem produced by having a cesarean section, but 1 month later, her parents took her to a specialized hearing clinic. “We were told our daughter had zero hearing,” Yevgenievna says. “I was shocked, and we cried.” © 2019 American Association for the Advancement of Science.

Keyword: Hearing; Genes & Behavior
Link ID: 26732 - Posted: 10.22.2019

By Kelly Servick The brain has a way of repurposing unused real estate. When a sense like sight is missing, corresponding brain regions can adapt to process new input, including sound or touch. Now, a study of blind people who use echolocation—making clicks with their mouths to judge the location of objects when sound bounces back—reveals a degree of neural repurposing never before documented. The research shows that a brain area normally devoted to the earliest stages of visual processing can use the same organizing principles to interpret echoes as it would to interpret signals from the eye. In sighted people, messages from the retina are relayed to a region at the back of the brain called the primary visual cortex. We know the layout of this brain region corresponds to the layout of physical space around us: Points that are next to each other in our environment project onto neighboring points on the retina and activate neighboring points in the primary visual cortex. In the new study, researchers wanted to know whether blind echolocators used this same type of spatial mapping in the primary visual cortex to process echoes. The researchers asked blind and sighted people to listen to recordings of a clicking sound bouncing off an object placed at different locations in a room while they lay in a functional magnetic resonance imaging scanner. The researchers found that expert echolocators—unlike sighted people and blind people who don’t use echolocation—showed activation in the primary visual cortex similar to that of sighted people looking at visual stimuli. © 2019 American Association for the Advancement of Science.

Keyword: Hearing; Learning & Memory
Link ID: 26663 - Posted: 10.02.2019

By Shraddha Chakradhar, Rockefeller University neuroscientist Vanessa Ruta was just named a member of the latest class of MacArthur “Genius” grant winners. The fellowship offers a five-year grant of $625,000 to individuals “who show exceptional creativity in their work and the prospect for still more in the future,” according to the MacArthur Foundation. Fortuitously, or perhaps by design, creativity has been a guiding principle for Ruta, 45, and her work. Both her parents were visual artists, and Ruta herself grew up as a ballet dancer—and at one point considered it a career path. After making the switch to science, however, she says that creativity—and the freedom that comes with it—still plays a big part in how she goes about her work. Her research now involves better understanding how the nervous system takes in external cues such as smell and processes these stimuli to inspire various behaviors. Advertisement STAT spoke with Ruta to learn more about her life and work. This interview has been lightly edited and condensed. Both your parents were artists. Did they influence how you work? I was strongly influenced by their creative process, which is parallel to how scientists work. There’s a kind of honing in your craft. It’s obvious in the artistic endeavors, whether it’s practicing dancing or something else. But it’s also there in the sciences—you have to be disciplined about pushing through with your experiments. © 2019 Scientific American

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26654 - Posted: 09.28.2019

Emily Makowski When we eat sour food, we instantaneously react due to a taste-sensing circuit between the tongue and the brain. Two papers published today (September 19)—one in Cell and the other in Current Biology—show that the otopetrin-1 proton channel in the tongue’s sour taste receptors is one of the components responsible for sour taste sensing in mice. These findings add to the body of sour taste research “from the molecular level, of how these protons are transported, up to the level of how the mice are able to taste it,” says Lucie Delemotte, a computational biophysicist at KTH Royal Institute of Technology who was not involved with either study. On the tongue, each taste bud contains a cluster of taste receptor cells innervated by a gustatory nerve network. The tips of these cells have a variety of taste molecule-capturing proteins and, in the case of sour detection, proteins that are called proton channels that sense pH. A team led by Charles Zuker at Columbia University Medical Center identified a potential sour taste receptor for the first time in 2006, and he and other researchers have continued to work on clarifying the mechanics and function of that receptor along with other possible sour taste receptors. A breakthrough occurred last year when Emily Liman of the University of Southern California’s lab discovered that otopetrin-1 (also referred to as OTOP1) was a proton channel also implicated in detecting sour tastes. But the researchers stopped short of demonstrating that OTOP1 was required for sour taste sensing in an actual animal—until now. © 1986–2019 The Scientist

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26631 - Posted: 09.21.2019

Nicola Davis Squirrels eavesdrop on the chatter of songbirds to work out whether the appearance of a predator is cause for alarm, researchers have found. Animals including squirrels have previously been found to tune in to cries of alarm from other creatures, while some take note of “all-clear” signals from another species with which they co-exist to assess danger. But the latest study suggests animals may also keep an ear out for everyday chitchat among other species as a way to gauge whether there is trouble afoot. “This study suggests that eavesdropping on public information about safety is more widespread and broader than we originally thought,” said Prof Keith Tarvin, co-author of the study from Oberlin College, Ohio. “It may not require tight ecological relationships that allow individuals to carefully learn the cues provided by other species,” he added, noting that the grey squirrels and songbirds in the study moved from place to place without regard for the other. Writing in the journal Plos One, Tarvin and colleagues reported on how they made their discovery by observing 67 grey squirrels as they pottered about different areas in the parks and residential regions of Oberlin. After 30 seconds of observing a squirrel, researchers played it a recording of the call of a red-tailed hawk, which lasted a couple of seconds – and their behaviour in the next 30 seconds was monitored. © 2019 Guardian News & Media Limited

Keyword: Animal Communication; Hearing
Link ID: 26573 - Posted: 09.05.2019