Chapter 9. Hearing, Balance, Taste, and Smell

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Edmund Chong When you experience something with your senses, it evokes complex patterns of activity in your brain. One important goal in neuroscience is to decipher how these neural patterns drive the sensory experience. For example, can the smell of chocolate be represented by a single brain cell, groups of cells firing all at the same time or cells firing in some precise symphony? The answers to these questions will lead to a broader understanding of how our brains represent the external world. They also have implications for treating disorders where the brain fails in representing the external world: for example, in the loss of sight of smell. To understand how the brain drives sensory experience, my colleagues and I focus on the sense of smell in mice. We directly control a mouse’s neural activity, generating “synthetic smells” in the olfactory part of its brain in order to learn more about how the sense of smell works. Our latest experiments discovered that scents are represented by very specific patterns of activity in the brain. Like the notes of a melody, the cells fire in a unique sequence with particular timing to represent the sensation of smelling a unique odor. Using mice to study smell is appealing to researchers because the relevant brain circuits have been mapped out, and modern tools allow us to directly manipulate these brain connections. © 2010–2020, The Conversation US, Inc.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27352 - Posted: 07.08.2020

By Bret Stetka How do humans and other animals distinguish between the smell of rotting seafood or the enticing allure of a ripe banana? New research at New York University Langone Health and their colleagues uses artificially created odors to help reveal the intricate chain of events that allow one odor to be distinguished from another. The results were published today in Science. In the deep recesses of the nose are millions of sensory neurons that, along with our eyes and ears, help conjure the world around us. When stimulated by a chemical with a smell, or an odorant, they send nerve impulses to thousands of clusters of neurons in the glomeruli, which make up the olfactory bulb, the brain’s smell center. Different patterns of glomerular activation are known to generate the sensation of specific odors. Firing one set of glomeruli elicits the perception of pineapples; firing another evokes pickles. Unlike other sensations, such as sight and hearing, scientists do not know which qualities of a particular smell are used by the brain to perceive it. When you see a person’s face, you may remember the eyes, which helps you recognize that individual in the future. But the ears and nose might be less important in how the brain represents that person. The authors of the new study sought to identify distinguishing features involved in forming the representation of odors in the brain. To do so, they used a technique called optogenetics to activate glomeruli in mice. Optogenetics uses light to stimulate specific neurons in the brain. And it can help determine the function of particular brain regions. © 2020 Scientific American

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27315 - Posted: 06.22.2020

By Laura Sanders Scientists have implanted an artificial odor directly in the brains of mice. It doesn’t mean that mental Smell-O-Vision technology is coming soon. But the results, published June 18 in Science, deliver clues to how the brain processes information. Details about the synthetic smell may help answer “fundamental questions in olfaction,” says computational biologist Saket Navlakha of Cold Spring Harbor Laboratory in New York, who wasn’t involved in the study. Studies on the senses offer a window into how brains shape signals from the outside world into perceptions, and how those perceptions can guide behavior (SN: 7/18/19). To build artificial smells in mice’s brains, researchers used optogenetics, a technique in which light prods genetically engineered nerve cells to fire signals (SN: 1/15/10). Neuroscientist Dima Rinberg of New York University’s Grossman School of Medicine and colleagues targeted nerve cells in mice’s olfactory bulbs. There, clusters of nerve endings called glomeruli organize the smell signals picked up in the nose. Like playing a short ditty on a piano, Rinberg and colleagues activated nerve cells in six spots (each of which might include between one and three glomeruli) in a certain order. This neural melody was designed to be a simplified version of how a real odor might play those nerve cells. (It’s not known what the artificial odor actually smells like to a mouse.) © Society for Science & the Public 2000–2020.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27312 - Posted: 06.19.2020

By Laura Sanders The virus responsible for COVID-19 can steal a person’s sense of smell, leaving them noseblind to fresh-cut grass, a pungent meal or even their own stale clothes. But so far, details remain elusive about how SARS-CoV-2, the coronavirus that causes COVID-19, can infiltrate and shut down the body’s smelling machinery. One recent hint comes from a young radiographer who lost her sense of smell. She had signs of viral infection in her brain. Other studies, though, have not turned up signs of the virus in the brain. Contradictory evidence means that no one knows whether SARS-CoV-2 can infect nerve cells in the brain directly, and if so, whether the virus’s route to the brain can sometimes start in the nose. Understanding how people’s sense of smell is harmed (SN: 5/11/20), a symptom estimated to afflict anywhere between 20 and 80 percent of people with COVID-19, could reveal more about how the virus operates. One thing is certain so far, though: The virus can steal the sense of smell in a way that’s not normal. “There’s something unusual about the relationship between COVID-19 and smell,” says neuroscientist Sandeep Robert Datta of Harvard Medical School in Boston. Colds can prevent smelling by stuffing the nose up with mucus. But SARS-CoV-2 generally leaves the nose clear. “Lots of people are complaining about losing their sense of smell when they don’t feel stuffed up at all,” Datta says. © Society for Science & the Public 2000–2020.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27302 - Posted: 06.13.2020

­­Researchers at the National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health, have identified a specific, front-line defense that limits the infection to the olfactory bulb and protects the neurons of the olfactory bulb from damage due to the infection. Neurons in the nose respond to inhaled odors and send this information to a region of the brain referred to as the olfactory bulb. Although the location of nasal neurons and their exposure to the outside environment make them an easy target for infection by airborne viruses, viral respiratory infections rarely make their way from the olfactory bulb to the rest of the brain, where they could cause potentially fatal encephalitis. The study was published in Science Immunology. Taking advantage of special viruses that can be tracked with fluorescent microscopy, the researchers led by Dorian McGavern, Ph.D., senior investigator at NINDS, found that a viral infection that started in the nose was halted right before it could spread from the olfactory bulb to the rest of the central nervous system. “Airborne viruses challenge our immune system all the time, but rarely do we see viral infections leading to neurological conditions,” said Dr. McGavern. “This means that the immune system within this area has to be remarkably good at protecting the brain.” Additional experiments showed that microglia, immune cells within the central nervous system, took on an underappreciated role of helping the immune system recognize the virus and did so in a way that limited the damage to neurons themselves. This sparing of neurons is critical, because unlike cells in most other tissues, most neuronal populations do not come back.

Keyword: Chemical Senses (Smell & Taste); Glia
Link ID: 27287 - Posted: 06.06.2020

By Robert Martone When a concert opens with a refrain from your favorite song, you are swept up in the music, happily tapping to the beat and swaying with the melody. All around you, people revel in the same familiar music. You can see that many of them are singing, the lights flashing to the rhythm, while other fans are clapping in time. Some wave their arms over their head, and others dance in place. The performers and audience seem to be moving as one, as synchronized to one another as the light show is to the beat. A new paper in the journal NeuroImage has shown that this synchrony can be seen in the brain activities of the audience and performer. And the greater the degree of synchrony, the study found, the more the audience enjoys the performance. This result offers insight into the nature of musical exchanges and demonstrates that the musical experience runs deep: we dance and feel the same emotions together, and our neurons fire together as well. In the study, a violinist performed brief excerpts from a dozen different compositions, which were videotaped and later played back to a listener. Researchers tracked changes in local brain activity by measuring levels of oxygenated blood. (More oxygen suggests greater activity, because the body works to keep active neurons supplied with it.) Musical performances caused increases in oxygenated blood flow to areas of the brain related to understanding patterns, interpersonal intentions and expression. Data for the musician, collected during a performance, was compared to those for the listener during playback. In all, there were 12 selections of familiar musical works, including “Edelweiss,” Franz Schubert’s “Ave Maria,” “Auld Lang Syne” and Ludwig van Beethoven’s “Ode to Joy.” The brain activities of 16 listeners were compared to that of a single violinist. © 2020 Scientific American,

Keyword: Hearing
Link ID: 27277 - Posted: 06.03.2020

A team of researchers has generated a developmental map of a key sound-sensing structure in the mouse inner ear. Scientists at the National Institute on Deafness and Other Communication Disorders (NIDCD), part of the National Institutes of Health, and their collaborators analyzed data from 30,000 cells from mouse cochlea, the snail-shaped structure of the inner ear. The results provide insights into the genetic programs that drive the formation of cells important for detecting sounds. The study also sheds light specifically on the underlying cause of hearing loss linked to Ehlers-Danlos syndrome and Loeys-Dietz syndrome. The study data is shared on a unique platform open to any researcher, creating an unprecedented resource that could catalyze future research on hearing loss. Led by Matthew W. Kelley, Ph.D., chief of the Section on Developmental Neuroscience at the NIDCD, the study appeared online in Nature Communications(link is external). The research team includes investigators at the University of Maryland School of Medicine, Baltimore; Decibel Therapeutics, Boston; and King’s College London. “Unlike many other types of cells in the body, the sensory cells that enable us to hear do not have the capacity to regenerate when they become damaged or diseased,” said NIDCD Director Debara L. Tucci, M.D., who is also an otolaryngology-head and neck surgeon. “By clarifying our understanding of how these cells are formed in the developing inner ear, this work is an important asset for scientists working on stem cell-based therapeutics that may treat or reverse some forms of inner ear hearing loss.”

Keyword: Hearing; Development of the Brain
Link ID: 27268 - Posted: 05.29.2020

By Tina Hesman Saey A loss of smell and taste may be one of the clearest indicators of whether someone has COVID-19, a new study suggests. Researchers gleaned the information from nearly 2.5 million people in the United Kingdom and about 170,000 people in the United States who entered whether they were feeling well or experiencing symptoms into a smartphone app from March 24 to April 21. Some of the app users also reported results of PCR diagnostic tests for the SARS-CoV-2 virus, which causes COVID-19 (SN: 3/6/20). Nearly 65 percent of roughly 6,400 U.K. residents who tested positive for the virus described a loss of taste and smell as a symptom, researchers report May 11 in Nature Medicine. And just over 67 percent of the 726 U.S. participants with a positive test also reported losing those senses. Only about 20 percent of all people who tested negative had diminished smell and taste. Using data from the app, a team of scientists led by clinical researchers Claire Steves and Tim Spector, both of King’s College London, devised a formula for determining which symptoms best predict COVID-19. A combination of loss of taste and smell, extreme fatigue, cough and loss of appetite was the best predictor of having a positive result from the PCR test, the team found. Based on those symptoms, the researchers estimate that more than 140,000 of the more than 800,000 app users who reported symptoms probably have COVID-19. © Society for Science & the Public 2000–2020.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27241 - Posted: 05.12.2020

Sandra G. Boodman First she toppled off a ladder. Then Carol Hardy-Fanta tripped on a step outside her western Massachusetts home while gazing at her cellphone. Next she fell three times during a five-mile hike after catching her left foot on a rock or tree root. At first, Hardy-Fanta thought her repeated stumbles had a simple cause: She was distracted. But when she racked up more than 30 falls in a three-year period — some for no apparent reason — she repeatedly asked her doctors whether an undiagnosed medical problem might be causing her to “drop like a log.” The 10 doctors she consulted between 2016 and 2019 — four orthopedists, three neurologists, a rheumatologist, a podiatrist and her internist — reached disparate conclusions. One suggested she was clumsy. Others suspected her problem was primarily orthopedic or could find no clear explanation. It wasn't until September 2019 that a scan revealed what Hardy-Fanta had come to suspect — a diagnosis she said several of her doctors had brushed off. “These are the smartest people,” said Hardy-Fanta, now 71, whose husband is a Boston physician. “They really wanted to help” but appeared to be misled by her symptoms. “If someone’s falling that much, they should really pay attention.” The falls started in 2016, shortly after Hardy-Fanta and her husband sold their house in a Boston suburb and began splitting their time between a condo in the city and what she described as their “dream home” in the Berkshires. Hardy-Fanta had retired as director of a university think tank. Her fourth book on women and politics had just been published. She was in excellent health, which she regarded as a legacy from her mother, who remained mentally sharp and physically able until shortly before her death at age 100. Hardy-Fanta said she was looking forward to traveling with her husband and taking long bike rides along the scenic rural roads that snake through the Berkshires.

Keyword: Parkinsons
Link ID: 27216 - Posted: 04.27.2020

By Elizabeth Pennisi Ring-tailed lemurs have a peculiar habit of shaking their tails at potential rivals. New research shows that during the breeding season, a male’s trembling tail may instead be whisking sexy odors toward potential mates. The work is still preliminary, but chemical analyses have revealed the odor is a mixture of three chemicals that seem to pique a female’s interest. The new work “calls attention to the often underappreciated fact” that odors play an important role in primate societies, says Peter Kappeler, a primatologist at the University of Göttingen. Insects often use behavior-altering odors called pheromones to attract mates. So do mice. But biochemist Kazushige Touhara at the University of Tokyo wanted to know whether primates—including humans—use them as well. Some researchers say yes, but the existence of such “sex attractants” remains controversial. Ring-tailed lemurs (Lemur catta), named for their fluffy gray and black tails, are unusual among their fellow primates. Males have glands on their wrists that produce chemicals that quickly vaporize when exposed to air—similar to pheromones. They rub their wrists on their tails to transfer the odors before they vaporize, then shake their tails to broadcast the scent. For most of the year, these lemurs make bitter, leathery smelling chemicals used to keep other males at bay. But during the breeding season, they instead emit a sweet scent, Touhara says. He and his colleagues collected these secretions from the wrist glands with a tiny pipette and analyzed the chemical components. © 2020 American Association for the Advancement of Science.

Keyword: Sexual Behavior; Chemical Senses (Smell & Taste)
Link ID: 27203 - Posted: 04.17.2020

Our ability to study networks within the nervous system has been limited by the tools available to observe large volumes of cells at once. An ultra-fast, 3D imaging technique called SCAPE microscopy, developed through the National Institutes of Health (NIH)’s Brain Research through Advancing Innovative Technologies (BRAIN) Initiative, allows a greater volume of tissue to be viewed in a way that is much less damaging to delicate networks of living cells. In a study published in Science, researchers used SCAPE to watch for the first time how the mouse olfactory epithelium — the part of the nervous system that directly perceives smells — reacted in real time to complex odors. They found that those nerve cells may play a larger and more complex role in interpreting smells than was previously understood. “This is an elegant demonstration of the power of BRAIN Initiative technologies to provide new insights into how the brain decodes information to produce sensations, thoughts, and actions,” said Edmund Talley, Ph.D., program director, National Institute of Neurological Disorders and Stroke (NINDS), a part of NIH. The SCAPE microscope was developed in the laboratory of Elizabeth M.C. Hillman, Ph.D., professor of biomedical engineering and radiology and principal investigator at Columbia’s Zuckerman Institute in New York City. “SCAPE microscopy has been incredibly enabling for studies where large volumes need to be observed at once and in real time,” said Dr. Hillman. “Because the cells and tissues can be left intact and visualized at high speeds in three dimensions, we are able to explore many new questions that could not be studied previously.”

Keyword: Brain imaging; Chemical Senses (Smell & Taste)
Link ID: 27189 - Posted: 04.14.2020

Oliver Wainwright Some whisper gently into the microphone, while tapping their nails along the spine of a book. Others take a bar of soap and slice it methodically into tiny cubes, letting the pieces clatter into a plastic tray. There are those who dress up as doctors and pretend to perform a cranial nerve exam, and the ones who eat food as noisily as they can, recording every crunch and slurp in 3D stereo sound. To an outsider, the world of ASMR videos can be a baffling, kooky place. In a fast-growing corner of the internet, millions of people are watching each other tap, rattle, stroke and whisper their way through hours of homemade videos, with the aim of being lulled to sleep, or in the hope of experiencing “the tingles” – AKA, the autonomous sensory meridian response. “It feels like a rush of champagne bubbles at the top of your head,” says curator James Taylor-Foster. “There’s a mild sense of euphoria and a feeling of deep calm.” Taylor-Foster has spent many hours trawling the weirdest depths of YouTube in preparation for a new exhibition, Weird Sensation Feels Good, at ArkDes, Sweden’s national centre for architecture and design, on what he sees as one of the most important creative movements to emerge from the internet. (Though the museum has been closed due to the coronavirus pandemic, the show will be available to view online.) It will be the first major exhibition about ASMR, a term that was coined a decade ago when cybersecurity expert Jennifer Allen was looking for a word to describe the warm effervescence she felt in response to certain triggers. She had tried searching the internet for things like “tingling head and spine” or “brain orgasm”. In 2009, she hit upon a post on a health message board titled WEIRD SENSATION FEELS GOOD. © 2020 Guardian News & Media Limited

Keyword: Hearing; Attention
Link ID: 27169 - Posted: 04.04.2020

By Mitch Leslie Like many animals, you couldn’t see without proteins called opsins, which dwell in the light-sensitive cells of your eyes. A new study reveals for the first time that fruit flies can also use some of these proteins, nestled at the tip of their nose, to taste noxious molecules in their food. Opsins in our bodies could also serve the same function, researchers speculate. The results are “paradigm shifting,” says sensory biologist Phyllis Robinson of the University of Maryland, Baltimore County, who wasn’t connected to the research. The most famous opsin forms the backbone of rhodopsin, the pigment in eye cells known as rods that allow you to see in low light. Your cone cells, which permit vision in bright light, harbor different opsins. Altogether, researchers have uncovered about 1000 other varieties of the proteins in various animals and microbes since rhodopsin was discovered more than 150 years ago. But the opsin molecular family still offers some surprises, notes neuroscientist Craig Montell of the University of California, Santa Barbara. A handful of studies, including one in 2011 by Montell and his team, have implicated opsins in hearing, touch, and temperature detection. Montell and colleagues wanted to determine whether any opsins play a role in taste—specifically, whether flies use them to detect a bitter molecule they are known to dislike. The researchers set up a taste test for unmodified Drosophila melanogaster fruit flies and for seven strains that had been genetically altered to each lack a different opsin. All of the flies had the choice between two sugar solutions, one of which was spiked with the bitter compound. © 2020 American Association for the Advancement of Science

Keyword: Vision; Chemical Senses (Smell & Taste)
Link ID: 27166 - Posted: 04.03.2020

By Michelle Roberts Health editor, BBC News online A loss of smell or taste may be a sign that you have coronavirus, according to UK researchers. A team at King's College London looked at responses from more than 400,000 people reporting suspected Covid-19 symptoms to an app. But loss of smell and taste are also signs of other respiratory infections, such as the common cold. And experts say fever and cough remain the most important symptoms of the virus to look out for and act upon. If you or someone you live with has a new continuous cough or high temperature, the advice is stay at home to stop the risk of spreading coronavirus to others. Coronavirus: What should I do? What did the study find? The King's College researchers wanted to gather information on possible coronavirus symptoms to help experts better understand and fight the disease. Of those reporting one or more symptoms of coronavirus to the Covid Symptom Tracker app: 53% said they had fatigue or tiredness 29% persistent cough 28% shortness of breath 18% loss of sense of smell or taste 10.5% suffered from fever Of these 400,000 people, 1,702 said they had been tested for Covid-19, with 579 receiving a positive result and 1,123 a negative one. Among the ones who had coronavirus infection confirmed by a positive test, three-fifths (59%) reported loss of smell or taste. © 2020 BBC

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27157 - Posted: 04.01.2020

By Erin Garcia de Jesus Myriad microbes dwell on human tongues — and scientists have now gotten a glimpse at the neighborhoods that bacteria build for themselves. Bacteria grow in thick films, with different types of microbes clustered in patches around individual cells on the tongue’s surface, researchers report online March 24 in Cell Reports. This pattern suggests individual bacterial cells first attach to the tongue cell’s surface and then grow in layers as they form larger clusters — creating miniature environments the different species need to thrive. “It’s amazing, the complexity of the community that they build right there on your tongue,” says Jessica Mark Welch, a microbiologist at the Marine Biological Laboratory in Woods Hole, Mass. Methods to identify microbial communities typically hunt for genetic fingerprints from various types of bacteria (SN: 11/05/09). The techniques can reveal what lives on the tongue, but not how the bacterial community is organized in space, Mark Welch says. So she and her colleagues had people scrape the top of their tongues with plastic scrapers. Then the team tagged various types of bacteria in the tongue gunk with differently colored fluorescent markers to see how the microbial community was structured. Bacterial cells, largely grouped by type in a thick, densely packed biofilm, covered each tongue surface cell. While the overall patchwork appearance of the microbial community was consistent among cells from different samples and people, the specific composition of bacteria varied, Mark Welch says. © Society for Science & the Public 2000–2020.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27141 - Posted: 03.25.2020

By Eva Frederick They’re the undertakers of the bee world: a class of workers that scours hives for dead comrades, finding them in the dark in as little as 30 minutes, despite the fact that the deceased haven’t begun to give off the typical odors of decay. A new study may reveal how they do it. “The task of undertaking is fascinating” and the new work is “pretty cool,” says Jenny Jandt, a behavioral ecologist at the University of Otago, Dunedin, who was not involved with the study. Wen Ping, an ecologist at the Chinese Academy of Sciences’s Xishuangbanna Tropical Botanical Garden, wondered whether a specific type of scent molecule might help undertaker bees find their fallen hive mates. Ants, bees, and other insects are covered in compounds called cuticular hydrocarbons (CHCs), which compose part of the waxy coating on their cuticles (the shiny parts of their exoskeletons) and help prevent them from drying out. While the insects are alive, these molecules are continually released into the air and are used to recognize fellow hive members. Wen speculated that less of the pheromones were being released into the air after a bee died and its body temperature decreased. When he used chemical methods of detecting gases to test this hypothesis, he confirmed that cooled dead bees were indeed emitting fewer volatile CHCs than living bees. © 2020 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Animal Communication
Link ID: 27138 - Posted: 03.24.2020

By Roni Caryn Rabin A mother who was infected with the coronavirus couldn’t smell her baby’s full diaper. Cooks who can usually name every spice in a restaurant dish can’t smell curry or garlic, and food tastes bland. Others say they can’t pick up the sweet scent of shampoo or the foul odor of kitty litter. Anosmia, the loss of sense of smell, and ageusia, an accompanying diminished sense of taste, have emerged as peculiar telltale signs of Covid-19, the disease caused by the coronavirus, and possible markers of infection. On Friday, British ear, nose and throat doctors, citing reports from colleagues around the world, called on adults who lose their senses of smell to isolate themselves for seven days, even if they have no other symptoms, to slow the disease’s spread. The published data is limited, but doctors are concerned enough to raise warnings. “We really want to raise awareness that this is a sign of infection and that anyone who develops loss of sense of smell should self-isolate,” Prof. Claire Hopkins, president of the British Rhinological Society, wrote in an email. “It could contribute to slowing transmission and save lives.” She and Nirmal Kumar, president of ENT UK, a group representing ear, nose and throat doctors in Britain, issued a joint statement urging health care workers to use personal protective equipment when treating any patients who have lost their senses of smell, and advised against performing nonessential sinus endoscopy procedures on anyone, because the virus replicates in the nose and the throat and an exam can prompt coughs or sneezes that expose the doctor to a high level of virus. Two ear, nose and throat specialists in Britain who have been infected with the coronavirus are in critical condition, Dr. Hopkins said. Earlier reports from Wuhan, China, where the coronavirus first emerged, had warned that ear, nose and throat specialists as well as eye doctors were infected and dying in large numbers, Dr. Hopkins said. © 2020 The New York Times Company

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27135 - Posted: 03.23.2020

Amy Schleunes Preti was a leading expert on human odors who sought to understand the chemistry of odor in the underarm and the behavior aspects of human scents, and an ambassador to patients suffering from rare metabolic diseases who provided communities worldwide with knowledge about their condition and how to cope with it. Preti was also dedicated to using odor biomarkers to detect cancer in its early stages, contributing both research and money to the cause, according to a Monell Center press release. Born on October 7, 1944 in Brooklyn, New York, Preti received a bachelor’s degree in chemistry from the Polytechnic Institute of Brooklyn in 1966. He then went on to MIT, where he earned a PhD in chemistry in 1971. His thesis was titled, “A Study of the Organic Compounds in the Lunar Crust and in Terrestrial Model Systems,” according to the Monell Center’s statement. Preti coauthored a paper published in Science on the same topic, and reportedly saved a vial of “moon dust” that he sometimes showed off to visitors to his lab. Upon completing his doctorate in 1971, he immediately accepted a postdoc at Monell and later become a member of the Monell Chemical Senses Center and an adjunct professor at the University of Pennsylvania School of Medicine. While Preti and his colleagues investigated a range of odors in different species—anal sac emissions from dogs, scent marks by marmoset monkeys, urine from guinea pigs and mice—Preti’s main focus was on the meaning of human odors. He studied the scents of human underarms and melanoma cells as well as the odors associated with generalized stress. Along with his collaborator, Charles Wysocki, Preti published papers on how human physiology and behavior are affected by body odor. Preti was skeptical of human pheromones and their associated hype, telling The Scientist in 2018, “I am not compelled by any studies that are out there that say there is an active steroid component from the underarm that causes [sexual attraction].” © 1986–2020 The Scientist

Keyword: Chemical Senses (Smell & Taste)
Link ID: 27133 - Posted: 03.23.2020

By Maria Temming When it comes to identifying scents, a “neuromorphic” artificial intelligence beats other AI by more than a nose. The new AI learns to recognize smells more efficiently and reliably than other algorithms. And unlike other AI, this system can keep learning new aromas without forgetting others, researchers report online March 16 in Nature Machine Intelligence. The key to the program’s success is its neuromorphic structure, which resembles the neural circuitry in mammalian brains more than other AI designs. This kind of algorithm, which excels at detecting faint signals amidst background noise and continually learning on the job, could someday be used for air quality monitoring, toxic waste detection or medical diagnoses. The new AI is an artificial neural network, composed of many computing elements that mimic nerve cells to process scent information (SN: 5/2/19). The AI “sniffs” by taking in electrical voltage readouts from chemical sensors in a wind tunnel that were exposed to plumes of different scents, such as methane or ammonia. When the AI whiffs a new smell, that triggers a cascade of electrical activity among its nerve cells, or neurons, which the system remembers and can recognize in the future. Like the olfactory system in the mammal brain, some of the AI’s neurons are designed to react to chemical sensor inputs by emitting differently timed pulses. Other neurons learn to recognize patterns in those blips that make up the odor’s electrical signature. © Society for Science & the Public 2000–2020

Keyword: Chemical Senses (Smell & Taste); Robotics
Link ID: 27126 - Posted: 03.17.2020

Laura Reiley A study published in the journal Cell Metabolism by a group of Yale researchers found that the consumption of the common artificial sweetener sucralose (which is found in Splenda, Zerocal, Sukrana, SucraPlus and other brands) in combination with carbohydrates can swiftly turn a healthy person into one with high blood sugar. From whole grain English muffins to reduced-sugar ketchup, sucralose is found in thousands of baked goods, condiments, syrups and other consumer packaged goods — almost all of them containing carbs. The finding, which researchers noted has yet to be replicated in other studies, raises new questions about the use of artificial sweeteners and their effects on weight gain and overall health. In the Yale study, researchers took 60 healthy-weight individuals and separated them into three groups: A group that consumed a regular-size beverage containing the equivalent of two packets of sucralose sweetener, a second group that consumed a beverage sweetened with table sugar at the equivalent sweetness, and a third control group that had a beverage with the artificial sweetener as well as a carbohydrate called maltodextrin. The molecules of maltodextrin don’t bind to taste receptors in the mouth and are impossible to detect. While the sensation of the third group’s beverage was identical to the Splenda-only group, only this group exhibited significant adverse health effects. The artificial sweetener by itself seemed to be fine, the researchers discovered, but that changed when combined with a carbohydrate. Seven beverages over two weeks and the previously healthy people in this group became glucose intolerant, a metabolic condition that results in elevated blood glucose levels and puts people at an increased risk for diabetes.

Keyword: Obesity; Chemical Senses (Smell & Taste)
Link ID: 27113 - Posted: 03.12.2020