Chapter 9. Hearing, Vestibular Perception, Taste, and Smell

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By C. Claiborne Ray Q. Our dog escaped from the car. How did he find his way home the next day from nearly three miles away? A. What took so long? Dogs are well known for their ability to backtrack to a beloved home — or person. Most animal behavior experts attribute their navigating ability largely to a hypersensitive sense of smell. Three miles is not a great distance, compared with some of the epic homeward journeys that dogs have occasionally made, and a three-mile radius would be rich in odor guideposts. The theory is that a dog creates a map of scents from odiferous sites like a food store or fertilized garden — or even just a hint of an owner’s scent in the ground or air. Dogs are especially sensitive to the odor of the humans in their lives. One study used MRI imaging to study activity in the caudate nucleus, a brain area associated with the expectation of a reward. Dogs of varying breeds were exposed to their own scent or that of a familiar dog, a strange dog, a strange human or a familiar human. By far the strongest activation followed exposure to the scent of a familiar person. Another navigational clue may come from dogs’ suspected sensitivity to differences in magnetic orientation. A study of dozens of dogs found that they usually preferred to defecate with their bodies aligned in a north-south orientation, a preference that disappeared when the magnetic field was disturbed. © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26144 - Posted: 04.16.2019

/ By Jed Gottlieb In 1983, The New York Times published a bombshell report about President Ronald Reagan: Starkey Laboratories had fitted the President, then 72, with a hearing aid. The news was welcomed by health professionals who reckoned it could help to reduce the stigma associated with hearing loss. At the time, one in three people over the age of 60 was thought to have hearing problems, though only around 20 percent who needed hearing aids used them. “The way I do the math, a third of all adults have unaddressed hearing issues. That’s lot of people.” Indeed, Reagan’s handlers knew too well that the revelation risked making the president look like a feeble old man — and worse, someone ill-equipped to run the most powerful nation on earth. “Among Presidential advisers,” The New York Times noted, “Mr. Reagan’s use of a hearing aid revived speculation on whether his age would be an issue if he seeks re-election next year.” Reagan won re-election, of course, but nearly 40 years later, negative perceptions persist — and health advocates are more concerned than ever. Hearing loss, they say, is not just a functional disability affecting a subset of aging adults. With population growth and a boom in the global elderly population, the World Health Organization (WHO) now estimates that by 2050, more than 900 million people will have disabling hearing loss. A 2018 study of 3,316 children aged nine to 11 meanwhile, found that 14 percent already had signs of hearing loss themselves. While not conclusive, the study linked the loss to the rise of portable music players. Copyright 2019 Undark

Keyword: Hearing
Link ID: 26124 - Posted: 04.09.2019

By Jamie Lauren Keiles When Jennifer Allen watched videos of space, she sometimes felt this peculiar sensation: a tingling that spread through her scalp as the camera pulled back to show the marble of the earth. It came in a wave, like a warm effervescence, making its way down the length of her spine and leaving behind a sense of gratitude and wholeness. Allen loved this feeling, but she didn’t know what caused it. It was totally distinct from anything she’d experienced before. Every two years or so she’d take to Google. She tried searching things like “tingling head and spine” or “brain orgasm.” For nine years, the search didn’t turn up anything. Then, around 2009, it did. As always, Allen typed her phrases into Google, but this time she got a result on a message board called SteadyHealth. The post was titled WEIRD SENSATION FEELS GOOD: i get this sensation sometimes. theres no real trigger for it. it just happens randomly. its been happening since i was a kid and i’m 21 now. some examples of what it seems has caused it to happen before are as a child while watching a puppet show and when i was being read a story to. as a teenager when a classmate did me a favor and when a friend drew on the palm of my hand with markers. sometimes it happens for no reason at all The poster went on to demand an explanation. In the discussion, nobody had one, but many described a similar feeling — a “silvery sparkle” inside the head, a euphoric “brain-gasm” or a feeling like goose bumps in the scalp that faded “in and out in waves of heightened intensity.” Many people agreed that the sensation was euphoric. (“Aside from an actual orgasm, it’s probably the most enjoyable sensation possible,” one user wrote.) Its triggers were as varied as watching someone fill out a form, listening to whispering sounds or seeing Bob Ross paint landscapes on TV. Allen scrolled through pages and pages of discussion. Oh my gosh, she remembers thinking. These people are talking about exactly what I experience. © 2019 The New York Times Company

Keyword: Pain & Touch; Hearing
Link ID: 26114 - Posted: 04.04.2019

Nell Greenfieldboyce Mosquitoes searching for a meal of blood use a variety of clues to track down humans, including our body heat and the carbon dioxide in our breath. Now, research shows that a certain olfactory receptor in their antennae also serves as a detector of humans, responding to smelly chemicals in our sweat. Targeting this receptor might offer a new way to foil blood-seeking mosquitoes and prevent the transmission of diseases including malaria, Zika virus and dengue, according to the study published Thursday in the journal Current Biology. "We found a receptor for human sweat, and we found that acidic volatiles that come off of us are really key for mosquitoes to find us," says Matthew DeGennaro, a neurogeneticist at Florida International University in Miami. "I think what's exciting about it is that finally we have evidence that there is some sort of pathway, in the sense of smell, that is required for mosquitoes to like us," says Lindy McBride, a scientist at Princeton University who studies mosquito behavior and was not part of the research team. It's long been known that mosquitoes rely on multiple clues to target humans. First, a mosquito will sense exhaled carbon dioxide from a distance that can be more than 30 feet. "After the carbon dioxide," DeGennaro explains, "then it begins to sense human odor." © 2019 npr

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26092 - Posted: 03.29.2019

By James Gallagher Health and science correspondent, BBC News French scientists say they have proof that dogs can pick up the smell of an epileptic seizure. The University of Rennes team hope the findings could lead to ways to predict when people will have a seizure. These could include dogs or "electronic noses" that pick up the precise odour being given off during a seizure. Dogs have previously been shown to be able to sniff out diseases including cancers, Parkinson's, malaria and diabetes. Some people with epilepsy already rely on the animals. One sleeping in a child's bedroom can alert family members of a seizure in the middle of the night. The latest study, in the journal Scientific Reports, trained five dogs from Medical Mutts, in the US, to recognise the smell of sweat taken from a patient having a seizure. They were then given a choice of seven sweat samples taken from other patients while they were either relaxing, exercising or having a seizure. Two of the dogs found the seizure sample about two-thirds of the time and the other three were 100% accurate The report says: "The results are extremely clear and constitute a first step towards identifying a seizure-specific odour." © 2019 BBC

Keyword: Chemical Senses (Smell & Taste); Epilepsy
Link ID: 26091 - Posted: 03.29.2019

By Richard Klasco, M.D. Q. I have completely lost my sense of smell and can taste only a few things. I have seen doctors and taken tests, but no answers. I know I’m not the only one with this problem. Any ideas? A. Humans are able to perceive an astounding one trillion odors. But our sense of smell is fragile. About a quarter of adults, and more than half of those over 80, have some degree of olfactory impairment. The sense of taste is often affected at the same time, as the neural pathways of smell and taste commingle in the brain. Having an impaired sense of smell may be more than a nuisance. Studies have linked a decreased sense of smell to a heightened risk for Parkinson’s disease, Alzheimer’s disease, multiple sclerosis and premature death. Common causes of a decreased sense of smell include nasal problems, such as deviated septum and nasal polyps; viruses, such as rhinovirus and Epstein-Barr virus; chronic sinusitis; head injury; and certain cancers. Environmental exposure to cigarette smoke, alcohol, air pollution and toxins further increase the risk. Yet, in about 16 percent of people, no cause can be identified. Eating nuts and fish has been associated with protection against smell impairment, as have exercise and use of cholesterol-lowering drugs and oral steroids. It is unknown, however, whether changing one’s dietary or exercise habits will improve the sense of smell. Medical evaluation typically begins with an otolaryngologist, an ear, nose and throat doctor who will use a standardized scratch-and-sniff test to assess any olfactory deficits. Laboratory tests of blood and nasal mucus and imaging studies, such as CT or M.R.I. scans, are often needed. In some cases, endoscopic surgery, a flexible camera inserted into the nose, may aid in diagnosis and provide therapeutic benefits. © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 26062 - Posted: 03.22.2019

Ian Sample Science editor Scientists have developed a test for Parkinson’s disease based on its signature odour after teaming up with a woman who can smell the condition before tremors and other clinical symptoms appear. The test could help doctors diagnose patients sooner and identify those in the earliest stages of the disease, who could benefit from experimental drugs that aim to protect brain cells from being killed off. Perdita Barran, of the University of Manchester, said the test had the potential to decrease the time it took to distinguish people with normal brain ageing from those with the first signs of the disorder. “Being able to say categorically, and early on, that a person has Parkinson’s disease would be very useful,” she said. Get Society Weekly: our newsletter for public service professionals Read more Most people cannot detect the scent of Parkinson’s, but some who have a heightened sense of smell report a distinctive, musky odour on patients. One such “super smeller” is Joy Milne, a former nurse, who first noticed the smell on her husband, Les, 12 years before he was diagnosed. Milne only realised she could sniff out Parkinson’s when she attended a patient support group with her husband and found everyone in the room smelled the same. She thought little more about it until she mentioned the odour to Tilo Kunath, a neurobiologist who studies Parkinson’s at Edinburgh University. © 2019 Guardian News & Media Limited

Keyword: Parkinsons; Chemical Senses (Smell & Taste)
Link ID: 26056 - Posted: 03.20.2019

Maria Temming A new analysis of people’s brain waves when surrounded by different magnetic fields suggests that people have a “sixth sense” for magnetism. Birds, fish and some other creatures can sense Earth’s magnetic field and use it for navigation (SN: 6/14/14, p. 10). Scientists have long wondered whether humans, too, boast this kind of magnetoreception. Now, by exposing people to an Earth-strength magnetic field pointed in different directions in the lab, researchers from the United States and Japan have discovered distinct brain wave patterns that occur in response to rotating the field in a certain way. These findings, reported in a study published online March 18 in eNeuro, offer evidence that people do subconsciously respond to Earth’s magnetic field — although it’s not yet clear exactly why or how our brains use this information. “The first impression when I read the [study] was like, ‘Wow, I cannot believe it!’” says Can Xie, a biophysicist at Peking University in Beijing. Previous tests of human magnetoreception have yielded inconclusive results. This new evidence “is one step forward for the magnetoreception field and probably a big step for the human magnetic sense,” he says. “I do hope we can see replications and further investigations in the near future.” During the experiment, 26 participants each sat with their eyes closed in a dark, quiet chamber lined with electrical coils. These coils manipulated the magnetic field inside the chamber such that it remained the same strength as Earth’s natural field but could be pointed in any direction. Participants wore an EEG cap that recorded the electrical activity of their brains while the surrounding magnetic field rotated in various directions. |© Society for Science & the Public 2000 - 2019

Keyword: Pain & Touch
Link ID: 26052 - Posted: 03.19.2019

Tina Hesman Saey BALTIMORE — Some police dogs may smell fear, and that could be bad news for finding missing people whose genetic makeup leaves them more prone to stress. Trained police dogs couldn’t recognize stressed-out people with a particular version of a gene that’s involved in stress management, geneticist Francesco Sessa reported February 22 at the annual meeting of the American Academy of Forensic Sciences. The dogs had no trouble identifying the men and women volunteers when the people weren’t under stress. The study may help explain why dogs can perform flawlessly in training, but have difficulty tracking people in real-world situations. Sessa, of the University of Foggia in Italy, and colleagues wondered whether fear could change a person’s normal scent and throw off dogs’ ability to find missing people. The researchers also investigated whether people’s genes might make some individuals easier or harder for dogs to pick out of a lineup. Previous studies already had linked different versions of the serotonin transporter gene SLC6A4 to stress management. People with the long version of the gene tend to handle stress better than people with the short version, Sessa said. He and colleagues recruited four volunteers — a man and a woman who each have the long version of the gene and a man and a woman with the short version. Each of the participants wore a scarf for a couple of hours a day to imprint their scent on the garment. Then the researchers brought the volunteers into the lab. In the first session, the volunteers wore a T-shirt and weren’t subjected to any stressors. The team then created two lineups of T-shirts, one with those of the men and another for the women. After sniffing the scarves, two trained police dogs had no trouble identifying any of the volunteers in a lineup of 10 T-shirts. The canine units identified each of the volunteers in three out of three attempts. |© Society for Science & the Public 2000 - 2019

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 25993 - Posted: 02.28.2019

Laura Sanders Sometimes a really good meal can make an evening unforgettable. A new study of rats, published online February 18 in the Journal of Neuroscience, may help explain why. A select group of nerve cells in rats’ brains holds information about both flavors and places, becoming active when the right taste hits the tongue when the rat is in a certain location. These double-duty cells could help animals overlay food locations onto their mental maps. Researchers implanted electrodes into the hippocampus, an area of the brain that is heavily involved in both memory formation and mapping. The rats then wandered around an enclosure, allowing researchers to identify “place cells” that become active only when the rat wandered into a certain spot. At the same time, researchers occasionally delivered one of four flavors (sweet, salty, bitter and plain water) via an implanted tube directly onto the wandering rats’ tongues. Some of the active place cells also responded to one or more flavors, but only when the rat was in the right spot within its enclosure. When the rat moved away from a place cell’s preferred spot, that cell no longer responded to the flavor, the researchers found. A mental map of the best spots for tasting something good would come in handy for an animal that needs to find its next meal. Citations L.E. Herzog et al. Interaction of taste and place coding in the hippocampus. Journal of Neuroscience. Published online February 18, 2019. doi: 10.1523/JNEUROSCI.2478-18.2019. |© Society for Science & the Public 2000 - 2019

Keyword: Chemical Senses (Smell & Taste)
Link ID: 25973 - Posted: 02.19.2019

Shawna Williams Watch a bacterium chase down the source of an enticing molecular trail using chemo-taxis, and it’s clear that its sensory and navigation abilities are tightly linked. But could the same be true for humans? In 2014, Louisa Dahmani, then a graduate student at McGill University in Montreal, set out to answer that question. After having reviewed the literature on studies of spatial memory and olfaction in people, “I realized that the two functions seemed to rely on similar brain regions,” she explains. “But no one had actually looked at it directly and tested the same sample of participants on an olfaction and on a spatial memory task.” Dahmani, her advisor Véronique Bohbot, and their colleagues set out to rectify that. The group recruited 60 volunteers and tested their ability to identify 40 odors, from menthol to cucumber to lavender. The researchers also had the subjects do a computer-based task in which they moved through a virtual town. After their exploration, the subjects navigated through the virtual town from one of its eight landmarks to a different destination via the shortest route possible. “People who are better at finding their way are also better at identifying smells,” Dahmani says, summing up the study’s biggest takeaway. The scientists also imaged participants’ brains using MRI and found that a larger medial orbitofrontal cortex—a brain region known to be associated, along with the hippocampus, with spatial navigation—correlated with both better smell identification and fewer errors on the navigation task (Nat Comm, 9:4162, 2018). © 1986 - 2019 The Scientist.

Keyword: Chemical Senses (Smell & Taste); Learning & Memory
Link ID: 25963 - Posted: 02.14.2019

Emily Conover Lasers can send sounds straight to a listener’s ear, like whispering a secret from afar. Using a laser tuned to interact with water vapor in the air, scientists created sounds in a localized spot that were loud enough to be picked up by human hearing if aimed near a listener’s ear. It’s the first time such a technique can be used safely around humans, scientists from MIT Lincoln Laboratory in Lexington, Mass., report in the Feb. 1 Optics Letters. At the wavelengths and intensities used, the laser won’t cause burns if it grazes eyes or skin. The scientists tested out the setup on themselves in the laboratory, putting their ears near the beam to pick up the sound. “You move your head around, and there’s a couple-inch zone where you go ‘Oh, there it is!’… It’s pretty cool,” says physicist Charles Wynn. The researchers also used microphones to capture and analyze the sounds. The work relies on a phenomenon called the photoacoustic effect, in which pulses of light are converted into sound when absorbed by a material, in this case, water vapor. Based on this effect, the researchers used two different techniques to make the sounds. The first technique, which involves rapidly ramping the intensity of the laser beam up and down, can transmit voices and songs. “You can hear the music really well; you can understand what people are saying,” says physicist Ryan Sullenberger, who coauthored the study along with Wynn and physicist Sumanth Kaushik. |© Society for Science & the Public 2000 - 2019.

Keyword: Hearing
Link ID: 25925 - Posted: 02.02.2019

By James Gorman Carpenter ants follow trails. Just watch them wandering about on your wooden porch until they strike a trail of pheromones (chemicals ants use for communication) that another ant has laid down. Ants don’t have noses, so they wave their antennas around to pick up the trail, then off they go on the road to ruin. (Carpenter ants destroy houses.) Scientists know plenty about ants, including their ability to follow scent trails, but researchers at Harvard wanted to get a more detailed understanding of how exactly ants sniff, or taste, the pheromone-marked path. First, some basics: Ants use their antennas to pick up chemical cues left by other ants. And the chemical sense of ants, call it smell or taste or chemo-reception, enables them to follow straight trails, curved trails, even zigzags. To see how ants do it, the scientists mixed ink and ant pheromones and used the result to paint trails on paper. They set ants out on trails and recorded dozens of hours of ant movement. They analyzed the video and tried out different computer models of the ants’ behavior. What Ryan W. Dash and his adviser, Venkatesh N. Murthy, and other researchers found was that the ants had several strategies for path-following. The scientists published their results in the Journal of Experimental Biology. All the ants used their antennas to sweep the trail side to side. One strategy they used was probing. A probing ant moved slowly, keeping its antennas close together. The researchers termed another strategy exploratory: Ants still moved slowly, but they took winding paths moving away from and back to a trail. When they were locked into a pheromone trail, they moved along more quickly, keeping their antennas on either side of the path. They kept one antenna closer to the path, but which antenna varied from ant to ant. In other words, some were lefties and others were righties. © 2019 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 25891 - Posted: 01.22.2019

By Elizabeth Pennisi TAMPA, FLORIDA—The pinnacle of beauty to most people is a symmetrical face, one without any major left-right differences. But for blind Mexican cavefish (Astyanax mexicanus), asymmetry may be a lifesaver. That’s because their lopsided skulls may help them feel their way along dark cave walls—similar to a person navigating by touch in the dark. That behavior, presented here this week at the annual meeting of the Society for Integrative and Comparative Biology, suggests being a little “off” can have evolutionary benefits. Lots of cave dwellers are a bit unbalanced. Cave fish tend to have one eye that is larger than the other, for example, and cave crickets have different size antennae. Some researchers wondered whether left-right differences might help these creatures get around. They scanned the skulls of A. mexicanus fish from three caves in Mexico. Their computerized tomography scans revealed most fish skulls bent slightly to the left, giving the right side of their faces slightly more exposure. Other tests showed these fish tended to drift along the right-hand side of cave walls, presumably using the larger side of their faces to feel their way in the dark. Amanda Powers and Josh Gross Next, the researchers counted mechanical sensors known as neuromasts in the heads of embryonic fish. These sensors, or “nerve buttons,” detect water flow and sometimes vibrations. Blind fish had more—and larger—neuromasts than fish of the same species that lived on the surface, they reported. © 2018 American Association for the Advancement of Science.

Keyword: Laterality; Pain & Touch
Link ID: 25838 - Posted: 01.05.2019

By Jane E. Brody The earsplitting sound of ambulance sirens in New York City is surely hastening the day when I and many others repeatedly subjected to such noise will be forced to get hearing aids. I just hope this doesn’t happen before 2021 or so when these devices become available over-the-counter and are far less expensive and perhaps more effective than they are now. Currently, hearing aids and accompanying services are not covered by medical insurance, Medicare included. Such coverage was specifically excluded when the Medicare law was passed in 1965, a time when hearing loss was not generally recognized as a medical issue and hearing aids were not very effective, said Dr. Frank R. Lin, who heads the Cochlear Center for Hearing and Public Health at the Johns Hopkins Bloomberg School of Public Health. Now a growing body of research by his colleagues and others is linking untreated hearing loss to several costly ills, and the time has come for hearing protection and treatment of hearing loss to be taken much more seriously. Not only is poor hearing annoying and inconvenient for millions of people, especially the elderly. It is also an unmistakable health hazard, threatening mind, life and limb, that could cost Medicare much more than it would to provide hearing aids and services for every older American with hearing loss. Currently, 38.2 million Americans aged 12 or older have hearing loss, a problem that becomes increasingly common and more severe with age. More than half of people in their 70s and more than 80 percent in their 80s have mild to moderate hearing loss or worse, according to tests done by the National Health and Nutrition Examination Survey between 2001 and 2010. Two huge new studies have demonstrated a clear association between untreated hearing loss and an increased risk of dementia, depression, falls and even cardiovascular diseases. In a significant number of people, the studies indicate, uncorrected hearing loss itself appears to be the cause of the associated health problem. © 2018 The New York Times Company

Keyword: Hearing; Alzheimers
Link ID: 25834 - Posted: 01.01.2019

By: Robert Zatorre, Ph.D. Human beings seem to have innate musicality. That is, the capacity to understand and derive pleasure from complex musical patterns appears to be culturally universal.1 Musicality is expressed very early in development.2 In this sense, music may be compared to speech—the other cognitively interesting way that we use sound. But whereas speech is most obviously important for communicating propositions or concepts, obtaining such knowledge, this is not the primary function of music. Rather, it is music’s power to communicate emotions, moods, or affective mental states that seems beneficial to our quality of life. Which brings us to the question that forms the title of this article: why do we love music? On its face, there is no apparent reason why a sequence or pattern of sounds that has no specific propositional meaning should elicit any kind of pleasurable response. Yet music is widely considered amongst our greatest joys.3 Where does this phenomenon come from? There are several approaches to this question. A musicologist might have a very different answer than a social scientist. Since I’m a neuroscientist, I would like to address it from that perspective—recognizing that other perspectives may also offer valuable insights. An advantage of neuroscience is that we can relate our answer to established empirical findings and draw from two especially relevant domains: the neuroscience of auditory perception and of the reward system. To give away the punch line of my article, I believe that music derives its power from an interaction between these two systems, the first of which allows us to analyze sound patterns and make predictions about them, and the second of which evaluates the outcomes of these predictions and generates positive (or negative) emotions depending on whether the expectation was met, not met, or exceeded. © 2018 The Dana Foundation

Keyword: Hearing; Emotions
Link ID: 25832 - Posted: 01.01.2019

By Penelope Green On winter nights, the white-noise app on my phone is tuned to Air Conditioner: a raspy, metallic whir that sounds like the mechanical noise that might echo deep inside the ductwork of a huge commercial building. (Among the app’s other offerings are Dishwasher Rinsing, Crowded Room and Vacuum Cleaner.) It lulls me to sleep nonetheless, because it blankets the din in my apartment (the ragged snore of a roommate; the clanking of the steam radiator; the cat’s skidding pursuit of something only he can see). It may also soothe because it replicates an early sound environment, probably that of a Manhattan childhood, though perhaps it suggests something much, much older. Some sleep experts note that babies, their ears accustomed to the whisper of the maternal circulatory system and the slosh of the womb, sleep better accompanied by a device that mimics those familiar whooshings. My app is but one note in the mighty chorus of white-noise generators, an exploding industry of mechanical and digital devices; apps and websites, and Sonos and Spotify playlists that grows ever more refined, as if to block out the increased rate of speeding, the wrecks, on the information superhighway. Car Interior? Oil Tanker? Laundromat? These ballads are in the vast soundscape library created by Stephane Pigeon, a Belgian electrical engineer, and ready to play on, a sound generator he put online in 2013 that now has one million page views each month. It’s a nearly philanthropic enterprise, as it runs on donations. “I have enough stress,” Dr. Pigeon said. Reddit, among other message boards, offers D.I.Y. white-noise hacks for light sleepers, shift workers and tinnitus sufferers. Rough up the blades of a box fan with a box cutter, suggested Christopher Suarez, a field service technician from Riverside, Calif., whose wife is an insomniac, on one captivating thread there. © 2018 The New York Times Company

Keyword: Sleep; Hearing
Link ID: 25828 - Posted: 12.28.2018

Shawna Williams The sensation of perceiving a smell can be induced in people by using electrodes to stimulate the brain’s olfactory bulb, researchers report today (November 27) in the International Forum of Allergy & Rhinology. The results, they suggest, are a proof of concept that it would be possible to develop an “olfactory implant system” to aid people with an impaired sense of smell, known as anosmia. “Our work shows that smell restoration technology is an idea worth studying further,” says coauthor Eric Holbrook of Massachusetts Eye and Ear Infirmary in a press release. “The development of cochlear implants, for example, didn’t really accelerate until someone placed an electrode in the cochlea of a patient and found that the patient heard a frequency of some type.” Holbrook and colleagues enrolled five subjects in the study who were able to smell. Three of them reported perceiving odors not actually present when the researchers stimulated different parts of their olfactory bulbs with electrodes inserted through the nose, a procedure the study authors say caused “minimal discomfort.” Subjects described the smells as “onion-like,” “antiseptic-like,” “sour,” “fruity,” or simply “bad.” The finding follows a report earlier this year that electrically stimulating structures high up in the nasal cavity produced smell sensations. The scientists who conducted that study at Malaysia’s Imagineering Institute aim to one day transmit smells electronically, reportes IEEE Spectrum—for example, to give restaurant-goers a whiff of dishes on the menu as they decide what to order. © 1986 - 2018 The Scientist

Keyword: Chemical Senses (Smell & Taste)
Link ID: 25726 - Posted: 11.29.2018

Tina Hesman Saey Whether people prefer coffee or tea may boil down to a matter of taste genetics. People with a version of a gene that increases sensitivity to the bitter flavor of caffeine tend to be coffee drinkers, researchers report online November 15 in Scientific Reports. Tea drinkers tended to be less sensitive to caffeine’s bitter taste, but have versions of genes that increase sensitivity to the bitterness of other chemicals, the researchers found. It’s long been thought that people avoid eating bitter foods because bitterness is an indicator of poison, says John Hayes, a taste researcher at Penn State who was not involved in the study. The coffee and tea findings help challenge that “overly simplistic ‘bitter is always bad, let’s avoid it’” view, he says. In the new study, researchers examined DNA variants of genes involved in detecting the bitter taste of the chemicals, caffeine, quinine — that bitter taste in tonic water — and propylthiouracil (PROP), a synthetic chemical not naturally found in food or drink. Other bitter components naturally in coffee and tea may trigger the same taste responses as quinine and PROP do, Hayes says. Researchers in Australia, the United States and England examined DNA from more than 400,000 participants in the UK Biobank, a repository of genetic data for medical research. Participants also reported other information about their health and lifestyle, including how much tea or coffee they drink each day. |© Society for Science & the Public 2000 - 2018

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 25693 - Posted: 11.16.2018

Jennifer Leman Some moths aren’t so easy for bats to detect. The cabbage tree emperor moth has wings with tiny scales that absorb sound waves sent out by bats searching for food. That absorption reduces the echoes that bounce back to bats, allowing Bunaea alcinoe to avoid being so noticeable to the nocturnal predators, researchers report online November 12 in the Proceedings of the National Academy of Sciences. “They have this stealth coating on their body surfaces which absorbs the sound,” says study coauthor Marc Holderied, a bioacoustician at the University of Bristol in England. “We now understand the mechanism behind it.” Bats sense their surroundings using echolocation, sending out sound waves that bounce off objects and return as echoes picked up by the bats’ supersensitive ears (SN: 9/30/17, p. 22). These moths, without ears that might alert them to an approaching predator, have instead developed scales of a size, shape and thickness suited to absorbing ultrasonic sound frequencies used by bats, the researchers found. The team shot ultrasonic sound waves at a single, microscopic scale and observed it transferring sound wave energy into movement. The scientists then simulated the process with a 3-D computer model that showed the scale absorbing up to 50 percent of the energy from sound waves. What’s more, it isn’t just wings that help such earless moths evade bats. Other moths in the same family as B. alcinoe also have sound-absorbing fur, the same researchers report online October 18 in the Journal of the Acoustical Society of America. |© Society for Science & the Public 2000 - 2018

Keyword: Hearing; Evolution
Link ID: 25679 - Posted: 11.14.2018