By Catherine Offord Researchers have tested a proof-of-concept device that enabled people who had lost their normal sense of smell to detect the presence of certain odors. Rather than exploiting the smell pathway, in which nasal cells send signals along olfactory nerves to the brain, the technology makes use of a less known nerve highway in the nose that transmits other sensations, including the kick of wasabi and the coolness of mint. “It’s an interesting study,” says Zara Patel, a rhinologist at Stanford Medicine who was not involved in the work, published today in Science Advances. “This is not recovering a sense of smell, this is activating a different system.” But she and others caution it remains to be seen how beneficial this kind of technology could be for people with smell loss, or anosmia. Humans have about 400 different olfactory receptors that are thought to enable the nose to detect billions of odors. But people can lose some or all of their sense of smell for a variety of reasons, including head trauma and viral infections such as COVID-19. People with long-term anosmia describe a significantly reduced quality of life and are at higher risk of mental health disorders, notes Halina Stanley, a research scientist at CNRS, the French national research agency, and co-author on the new paper. “The idea that if you lose your sense of smell, this isn’t as bad as losing another sense, I think is actually quite wrong.” Research by another team in 2018 found that electrodes placed in the sinuses near the olfactory bulb, the brain region that processes odor signals, could stimulate perception of smell, with people reporting onion or fruity scents, for example. Scientists are now working to develop implants that could more directly and specifically stimulate the olfactory bulb—akin to cochlear implants, which replace lost hearing by detecting sounds and stimulating the auditory nerve. However, such technology would be complex and invasive, and, at present, is a long way from becoming a therapy. © 2025 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Robotics
Link ID: 30032 - Posted: 11.29.2025

Davide Castelvecchi Pigeons can sense Earth’s magnetic field by detecting tiny electrical currents in their inner ears, researchers suggest. Such an inner compass could help to explain how certain animals can achieve astonishing feats of long-distance navigation. The team performed advanced brain mapping as well single-cell RNA sequencing of pigeon inner-ear cells. Both lines of evidence point to the inner ear as the birds’ ‘magnetoreception’ organ. The results appeared in the Science on 20 November 1. “This is probably the clearest demonstration of the neural pathways responsible for magnetic processing in any animal,” says Eric Warrant, a sensory biology researcher at the University of Lund in Sweden. Studies have suggested that various animals, including turtles, trout and robins, can sense the direction and strength of magnetic fields, although the evidence has sometimes been contested — and the mechanisms have remained controversial. Bird-brained navigation Two leading hypotheses have led the research into how birds sense magnetic fields. One is a quantum-physics effect in retina cells where birds ‘see’ magnetic fields. Another is that microscopic iron oxide particles in the beak could act as tiny compass needles. However, it’s largely unknown where magnetic information is sensed in animals’ brains and how sensory neurons confer sensitivity to electromagnetic changes. In 2011, researchers found hints that magnetic fields triggered pigeons’ vestibular system, the organ that enables vertebrates to sense accelerations (including gravity) and helps them to stay balanced2. The structure is made of three fluid-filled loops which are mutually perpendicular, so they can communicate to the brain the direction of an acceleration by breaking it down into three ‘x, y, z’ components. © 2025 Springer Nature Limited

Keyword: Animal Migration; Hearing
Link ID: 30024 - Posted: 11.22.2025

By Siddhant Pusdekar Taste and smell are so intimately connected that a whiff of well-loved foods evokes their taste without any conscious effort. Now, brain scans and machine learning have for the first time pinpointed the region responsible for this sensory overlap in humans, a region called the insula, researchers report September 12 in Nature Communications. The findings could explain why people crave certain foods or are turned away from them, says Ivan de Araujo, a neuroscientist at Max Planck Institute for Biological Cybernetics in Tübingen, Germany. Smell and taste become associated from the moment we bite into something, says Putu Agus Khorisantono, a neuroscientist at Karolinska Institutet in Stockholm. Some food chemicals activate sweet, salty, sour, bitter or umami taste receptors on the tongue. Others travel through the roof of the mouth, activating odor receptors in the back of the nose. These “retronasal odors” are what distinguish mangoes from peaches, for example. Both taste mostly sour, Khorisantono says, “but it’s really the aroma that differentiates them.” The brain combines these signals to create our sense of flavor, but scientists have struggled to identify where this happens in the brain. In the new study, Khorisantono and colleagues gave 25 people drops of beverages designed to activate only their taste or retronasal receptors, while scanning brain activity over multiple sessions. Previously, the participants had learned to associate the combination of smells and tastes with particular flavors. © Society for Science & the Public 2000–2025.

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29967 - Posted: 10.11.2025

By Jeré Longman Dr. A. James Hudspeth, a neuroscientist at the Rockefeller University in Manhattan who was pivotal in discovering how sound waves are converted in the inner ear to electrical signals that the brain can perceive as a whisper, a symphony or a thunderclap, died on Aug. 16 at his home in Manhattan. He was 79. His wife, Dr. Ann Maurine Packard, said the cause was glioblastoma, a brain cancer. Scientists have long understood how sound waves enter the ear canal and cause the eardrum to vibrate. They have also understood how the vibrations travel through the three small bones of the middle ear, then to the cochlea in the inner ear, a tiny organ about the size of a chickpea that is filled with fluid and is shaped like a snail’s shell. And they have long known that microscopic receptor cells in the cochlea play a role in the process of hearing. But by the time Dr. Hudspeth began his research in the 1970s, it was still unclear how these cells — known as hair cells (the name derives from tufts of cylindrical, hairlike rods known as stereocilia) — transformed the mechanical vibrations of sound waves into nerve impulses that the brain could interpret as, say, a child crying or a dog barking. Dr. Hudspeth “provided the major framework” for this understanding, the committee that awarded him and two other scientists (Robert Fettiplace and Christine Petit) the Kavli Prize in Neuroscience for their pioneering work on the processes of hearing wrote in its citation in 2018. Each cochlea contains about 16,000 hair cells. Atop each cell, 20 to 300 of these rods are gathered in a bundle — the shortest to the tallest — in rows that resemble a staircase or a pipe organ. Hair cells line the cochlea, with each tuned to a narrow frequency range that collectively decodes the broad spectrum of tones in every sound. © 2025 The New York Times Compan

Keyword: Hearing
Link ID: 29915 - Posted: 09.06.2025

By K. R. Callaway Ever bite into something so bitter that you had to spit it out? An ages-old genetic mutation helps you and other animals perceive bitterness and thus avoid toxins associated with it. But while most creatures instinctively spit first and ask questions later, molecular biologists have been trying to get a taste of what bitterness can tell us about sensory evolution and human physiology. A new study, published in the Journal of Agricultural and Food Chemistry, is the first analysis of how taste receptors respond to a mushroom’s bitter compounds—which include some of the most potently bitter flavors currently known to science. The bitter bracket mushroom is nontoxic but considered inedible because of its taste. Researchers extracted its bitter compounds, finding two familiar ones—and three that were previously unknown. Instead of tasting these substances themselves, the scientists introduced them to an “artificial tongue” that they made by inserting human taste receptors into fast-growing embryonic kidney cells. One of the newfound bitter substances activated the taste receptors even at the lowest concentration measured, 63.3 micrograms per liter. That’s like sensing three quarters of a cup of sugar in an Olympic-sized swimming pool. Humans have about 25 kinds of bitter taste receptors lining our mouths and throats, but these same receptors also grow throughout the body—in the lungs, digestive tract and even brain. Despite their ubiquity, they have been only partially explored. Four of our bitter receptors have no known natural activator. Finding activating compounds could illuminate the interactions that might have shaped those taste receptors’ evolution, says study lead author Maik Behrens, a molecular biologist at the Leibniz Institute for Food Systems Biology. © 2025 SCIENTIFIC AMERICAN,

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29882 - Posted: 08.09.2025

By Nazeefa Ahmed Humans prefer fruit at its sweetest, whereas many birds happily snack on the sourest of the bunch, from zesty lemons to unripe honey mangoes. Researchers may now know why. A study published today in Science suggests birds have evolved a specialized taste receptor that’s suppressed by high acidity, which effectively dulls the sharp, sour taste of fruits they eat. The finding reveals the evolutionary history of the pucker-inducing diets of many fruit-eating birds around the world—and may also help explain birds’ knack for survival, by broadening their potential food sources. The study is a “robust” addition to our understanding of how birds taste sour foods, which is still a research area in its infancy, says Leanne Grieves, an ornithologist at Cornell University’s Lab of Ornithology. Scientists identified a sour taste receptor in vertebrates—known as OTOP1—only 7 years ago, and few studies focus on why birds eat what they eat, rather than simply what they eat. Grieves, who studies birds’ sense of smell but who was not involved with the current work, adds that the new study “provides a really nice starting point.” To examine how birds approach sour-tasting foods, scientists exposed OTOP1 receptors from mice, domestic pigeons, and canaries to various acidic solutions. The activity of the mouse version of the receptor increased with greater acidity—meaning more acidic foods register to mice, and other mammals like us, as increasingly sour. However, the pigeon and canary versions of OTOP1 became less active in solutions about as acidic as a lemon. As a result, the birds wouldn’t perceive as much of a sour taste, allowing them to take advantage of the fruits mammals can’t stomach. Determining why bird OTOP1 reacted differently was a challenge, according to study author Hao Zhang, an evolutionary biologist at the Chinese Academy of Sciences (CAS). So, the researchers mutated sections of the gene that encodes the OTOP1 receptor, which let them identify four candidate amino acids within the protein that are responsible for sour tolerance. One of them, known as G378, is found almost exclusively in songbirds such as the canary—a species that showed greater sour tolerance than the pigeon, which lacks this variance. “A single amino acid in the bird OTOP1 can increase sour tolerance,” says study author Lei Luo, a biologist at CAS. © 2025 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 29840 - Posted: 06.21.2025

By Sofia Quaglia When octopuses extend their eight arms into hidden nooks and crannies in search of a meal, they are not just feeling around in the dark for their food. They are tasting their prey, and with even more sensory sophistication than scientists had already imagined. Researchers reported on Tuesday in the journal Cell that octopus arms are fine-tuned to “eavesdrop into the microbial world,” detecting microbiomes on the surfaces around them and deriving information from them, said Rebecka Sepela, a molecular biologist at Harvard and an author of the new study. Where octopus eyes cannot see, their arms can go to identify prey and make sense of their surroundings. Scientists knew that those eight arms (not tentacles) sense whether their eggs are healthy or need to be pruned. And the hundreds of suckers on each arm have over 10,000 chemotactile sensory receptors each, working with 500 million neurons to pick up that information and relay it throughout the nervous system. Yet, what exactly the octopus is tasting by probing and prodding — and how its arms can distinguish, say, a rock from an egg, a healthy egg in its clutch from a sick one or a crab that’s safe to eat from a rotting, toxic one — has long baffled scientists. What about the surfaces are they perceiving? For Dr. Sepela, this question was heightened when her team discovered 26 receptors along the octopuses’ arms that didn’t have a known function. She supposed those receptors were tuned only to molecules found on surfaces, rather than those diffused in water. So she and her colleagues collected swaths of molecules coating healthy and unhealthy crabs and octopus eggs. They grew and cultured the microbes from those surfaces in the lab, then tested 300 microbial strains, one by one, on two of those 26 receptors. During the screening, only particular microbes could switch open the receptors, and these microbes were more abundant on the decaying crabs and dying eggs than on their healthy counterparts. © 2025 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Neuroimmunology
Link ID: 29831 - Posted: 06.18.2025

By Katharine Gammon Picture this: You’re sitting down, engrossed in a meal, when an unfamiliar person walks by. There’s something about them—Hair? Smile? Vibes?—that instantly draws you in and makes you want to strike up a friendship. A new study suggests that it could be the scent they exude that attracts you to them. Not just the way their skin or hair smells, but the deodorant and shampoo they use, the foods they consume, even their laundry detergent. Our sense of smell tends to operate below the level of conscious awareness, says Jessica Gaby, a psychology researcher at Middle Tennessee State University and an author of the study, so our responses to it are often hidden from us. “But at the same time, it’s inescapable,” she says. “You can’t fake it.” Gaby and her colleagues, who were at Cornell University when the study was conducted, brought 40 women aged 18-30 together in a Cornell dining hall, a large, refurbished barn with café tables that doubles as a beer hall at night. The scent of popcorn, beer, and leftover dinner wafted over the room: The idea was to have a complex olfactory environment. The women all identified as heterosexual, so the researchers could focus on the type of attraction that might lead to friendship. In the first phase of the study, the participants received cotton T-shirts and were instructed to wear them for 12 hours straight without altering their daily routines, and to keep notes about their activities. One participant used spray paint in an art project, another had sex, another said she spilled a small amount of black beans on her shirt. In the second phase of the study, the participants were instructed to view photographs of different individual women, some of whom they would later meet. They then each sniffed the worn T-shirts, then had four-minute meetings, speed-dating style, with the other individual women, then sniffed their T-shirts again. After each step, they judged their friendship potential with the other women on a scale of 1 to 7. © 2025 NautilusNext Inc.,

Keyword: Chemical Senses (Smell & Taste); Emotions
Link ID: 29783 - Posted: 05.11.2025

By Susan Milius Here’s a great case of real life turning out to be stranger than fiction. From baby’s first storybook to sly adult graphic novels, the story we’re told is the same: Male frogs croak with the bottom of their mouths ballooning out in one fat, rounded bubble. Yet “that’s actually only half the species of frogs,” says herpetologist Agustín Elías-Costa of the Bernardino Rivadavia Natural Science Museum in Buenos Aires. The diversity of body parts for ribbitting is astounding. Some males serenade with a pair of separate puff-out disks like padded headphones that slipped down the frog’s neck, throbbing in brilliant blue. Some have sacs that look like balloon Mickey Mouse ears in khaki. Others ribbit with a single upright like a fat horn stub on some inflatable swimming pool toy rhino. All together, 20 basic forms for vocal sacs have evolved among frogs and toads, Elías-Costa and herpetologist Julián Faivovich report in March in the Bulletin of the American Museum of Natural History. Still, about 18 percent of the 4,358 species examined didn’t have vocal sacs at all. The team studied 777 specimens over 10 years of visiting museums around the world, including the Smithsonian’s National Museum of Natural History in Washington, D.C. “Libraries of nature,” Faivovich calls them. Just drawing a picture of something doesn’t authenticate details the way a preserved specimen does. These collections for biodiversity studies are “what makes them a science,” he says. The survey showed that vocal sacs disappeared between 146 and 196 times across the very twiggy evolutionary branchings of the frog and toad family tree. That’s “an astounding number considering their biological importance,” Elías-Costa says. Even without sacs, the animals still emit sounds because, like human speech, frog and toad ribbits originate from the larynx. Vocal sacs amplify the sound and could convey nuances of male quality and sexiness, but can also tip off eavesdropping predators. Females in a few species vocalize too, but it’s mostly a male endeavor. © Society for Science & the Public 2000–2025.

Keyword: Sexual Behavior; Hearing
Link ID: 29774 - Posted: 05.07.2025

Logan S. James It is late at night, and we are silently watching a bat in a roost through a night-vision camera. From a nearby speaker comes a long, rattling trill. The bat briefly perks up and wiggles its ears as it listens to the sound before dropping its head back down, uninterested. Next from the speaker comes a higher-pitched “whine” followed by a “chuck.” The bat vigorously shakes its ears and then spreads its wings as it launches from the roost and dives down to attack the speaker. Bats show tremendous variation in the foods they eat to survive. Some species specialize on fruits, others on insects, others on flower nectar. There are even species that catch fish with their feet. At the Smithsonian Tropical Research Institute in Panama, we’ve been studying one species, the fringe-lipped bat (Trachops cirrhosus), for decades. This bat is a carnivore that specializes in feeding on frogs. Male frogs from many species call to attract female frogs. Frog-eating bats eavesdrop on those calls to find their next meal. But how do the bats come to associate sounds and prey? We were interested in understanding how predators that eavesdrop on their prey acquire the ability to discriminate between tasty and dangerous meals. We combined our expertise on animal behavior, bat cognition and frog communication to investigate. © 2010–2025, The Conversation US, Inc.

Keyword: Hearing; Development of the Brain
Link ID: 29768 - Posted: 05.03.2025

By Gina Kolata Do we really have free will when it comes to eating? It’s a vexing question that is at the heart of why so many people find it so difficult to stick to a diet. To get answers, one neuroscientist, Harvey J. Grill of the University of Pennsylvania, turned to rats and asked what would happen if he removed all of their brains except their brainstems. The brainstem controls basic functions like heart rate and breathing. But the animals could not smell, could not see, could not remember. Would they know when they had consumed enough calories? To find out, Dr. Grill dripped liquid food into their mouths. “When they reached a stopping point, they allowed the food to drain out of their mouths,” he said. Those studies, initiated decades ago, were a starting point for a body of research that has continually surprised scientists and driven home that how full animals feel has nothing to do with consciousness. The work has gained more relevance as scientists puzzle out how exactly the new drugs that cause weight loss, commonly called GLP-1s and including Ozempic, affect the brain’s eating-control systems. The story that is emerging does not explain why some people get obese and others do not. Instead, it offers clues about what makes us start eating, and when we stop. While most of the studies were in rodents, it defies belief to think that humans are somehow different, said Dr. Jeffrey Friedman, an obesity researcher at Rockefeller University in New York. Humans, he said, are subject to billions of years of evolution leading to elaborate neural pathways that control when to eat and when to stop eating. © 2025 The New York Times Company

Keyword: Obesity; Chemical Senses (Smell & Taste)
Link ID: 29762 - Posted: 04.26.2025

Andrew Gregory Health editor Doctors in London have successfully restored a sense of smell and taste in patients who lost it due to long Covid with pioneering surgery that expands their nasal airways to kickstart their recovery. Most patients diagnosed with Covid-19 recover fully. But the infectious disease can lead to serious long-term effects. About six in every 100 people who get Covid develop long Covid, with millions of people affected globally, according to the World Health Organization. Losing a sense of smell and taste are among more than 200 different symptoms reported by people with long Covid. Now surgeons at University College London Hospitals NHS Foundation Trust (UCLH) have cured a dozen patients, each of whom had suffered a profound loss of smell after a Covid infection. All had experienced the problem for more than two years and other treatments, such as smell training and corticosteroids, had failed. In a study aiming to find new ways to resolve the issue, surgeons tried a technique called functional septorhinoplasty (fSRP), which is typically used to correct any deviation of the nasal septum, increasing the size of nasal passageways. This boosts airflow into the olfactory region, at the roof of the nasal cavity, which controls smell. Doctors said the surgery enabled an increased amount of odorants – chemical compounds that have a smell – to reach the roof of the nose, where sense of smell is located. They believe that increasing the delivery of odorants to this area “kickstarts” smell recovery in patients who have lost their sense of smell to long Covid. © 2025 Guardian News & Media Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29697 - Posted: 03.08.2025

By Laura Sanders Ancient ear-wiggling muscles kick on when people strain to hear. That auricular activity, described January 30 in Frontiers in Neuroscience, probably doesn’t do much, if anything. But these small muscles are at least present, and more active than anyone knew. You’ve probably seen a cat or dog swing their ears toward a sound, like satellite dishes orienting to a signal. We can’t move our relatively rigid human ears this dramatically. And yet, humans still possess ear-moving muscles, as those of us who can wiggle our ears on demand know. Neuroscientist Andreas Schröer and colleagues asked 20 people with normal hearing to listen to a recorded voice while distracting podcasts played in the background. All the while, electrodes around the ears recorded muscle activity. An ear muscle called the superior auricular muscle, which sits just above the ear and lifts it up, fired up when the listening conditions were difficult, the researchers found. Millions of years ago, these muscles may have helped human ancestors collect sounds. Today, it’s doubtful that this tiny wisp of muscle activity helps a person hear better, though scientists haven’t tested that. “It does its best, but it probably doesn’t work,” says Schröer, of Saarland University in Saarbrücken, Germany. These vestigial muscles may not help us hear, but their activity could provide a measurement of a person’s hearing efforts. That information may be useful to hearing aid technology, telling the device to change its behavior when a person is struggling, for instance. © Society for Science & the Public 2000–2025.

Keyword: Hearing; Evolution
Link ID: 29665 - Posted: 02.12.2025

By Jackson Ryan Fruit fly larvae can sense the texture of rotting fruit.Credit: Scott Bauer/USDA/SPL For maggots, the experience of eating a succulent meal isn’t just about how their food tastes, but also how it feels. Researchers used genetic tools to reveal that certain neurons in the brain control food choice and can sense both taste and texture1 . The conventional view of taste sensing holds that specific neurons carry single signals to the brain, says study co-author Simon Sprecher, a neurobiologist at the University of Fribourg in Switzerland. For instance, sweet taste neurons carry sweet signals and bitter taste neurons carry bitter signals. But those assumptions have been challenged over the past two decades by studies in fruit flies and mice that suggest neurons might have the capacity to respond to both chemical signals, such as bitter or sweet, as well as mechanical signals, such as texture. In the current study, published in PLoS Biology on 30 January, Sprecher and his colleagues set out to see whether individual neurons in taste organs have this ‘multimodal’ capacity. They fed fruit-fly larvae — maggots — different preparations of agarose, a sugary gel. The maggots showed a propensity for a ‘Goldilocks’ preparation, one that was neither too hard nor too soft. The preferred hardness for larvae is “similar to [that] of decaying fruit”, says Sprecher. The researchers then used genetic engineering tools to disable a subset of taste-sensing neurons in the larval taste-sensing organs. Disabling the neurons prevented the maggots from tasting the sweetness of the agarose, as expected, but it also changed which preparations they ate — the maggots no longer preferred Goldilocks preparations, suggesting that they had also lost their ability to feel their food. By studying individual neurons, the researchers determined that C6 neurons can both taste sugar and sense mechanical simulation. © 2025 Springer Nature Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29650 - Posted: 02.01.2025

Nicola Davis Science correspondent Wiggling your ears might be more of a pub party piece than a survival skill, but humans still try to prick up their ears when listening hard, researchers have found. Ear movement is crucial in many animals, not least in helping them focus their attention on particular noises and work out which direction they are coming from. But while the human ear is far more static, traces of our ancestors’ ear-orienting system remain in what has been called a “neural fossil”. “It is believed that our ancestors lost their ability to move their ears about 25m years ago. Why, exactly, is difficult to say,” said Andreas Schröer, the lead author of the research from Saarland University in Germany. “However, we have been able to demonstrate that the neural circuits still seem to be present in some state, [that is] our brain retained some of the structures to move the ears, even though they apparently are not useful any more.” The team previously found the movement of these muscles in humans is related to the direction of the sounds they are paying attention to. Now, they have found that some of these muscles become activated when humans listen hard to a sound. Writing in the journal Frontiers in Neuroscience, the team reported how they asked 20 adults without hearing problems to listen to an audiobook played through a speaker at the same time as a podcast was played from the same location. The team created three different scenarios: in the “easiest” scenario the podcast was quieter than the audiobook, with a large difference in pitch between the voices. In the “hardest” scenario, two podcasts were played which, taken together, were louder than the audiobook, with one of the podcasts spoken at a similar pitch to the audiobook. © 2025 Guardian News & Media Limited

Keyword: Hearing; Evolution
Link ID: 29649 - Posted: 02.01.2025

Nicola Davis Science correspondent The human sense of smell is nothing to turn one’s nose up at, research suggests, with scientists revealing we are far more sensitive to the order of odours captured by a sniff than previously thought. Charles Darwin is among those who have cast aspersions on our sense of smell, suggesting it to be “of extremely slight service” to humans, while scientists have long thought our olfactory abilities rather sluggish. “Intuitively, each sniff feels like taking a long-exposure shot of the chemical environment,” said Dr Wen Zhou, co-author of the research from the Chinese Academy of Sciences, adding that when a smell is detected it can seem like one scent, rather than a discernible mixture of odours that arrived at different times. “Sniffs are also separated in time, occurring seconds apart from one another,” she said. But now researchers have revealed our sense of smell operates much faster than previously thought, suggesting we are as sensitive to rapid changes in odours as we are to rapid changes in colour. A key challenge to probing our sense of smell, said Zhou, is that it has been difficult to create a setup that enables different smelly substances to be presented in a precise sequence in time within a single sniff. However, writing in the journal Nature Human Behaviour, Zhou and colleagues report how they did just that by creating an apparatus in which two bottles containing different scents were hooked up to a nosepiece using tubes of different lengths. These tubes were fitted with miniature check valves that were opened by the act of taking a sniff. © 2024 Guardian News & Media Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29518 - Posted: 10.16.2024

By Angie Voyles Askham Unlike the primary sensory brain areas that process sights and sounds, the one that decodes scents also responds to other stimuli, such as images and words associated with an odor, according to a study published today in Nature. The extent to which neurons in the primary olfactory cortex, which includes the piriform cortex, respond to non-odor stimuli was surprising, says Marc Spehr, head of the Chemosensation Laboratory at RWTH Aachen University, who co-led the study. One neuron, for example, which activated in response to the scent of black licorice, also responded to the word “licorice,” images of the candy and the odor of anise seed, which is unrelated but has a similar scent. Cells in the amygdala also showed multimodal responses; one neuron, for example, responded to a banana scent as well as the word “banana.” “These aren’t odor signals that these cells are encoding; these cells are encoding concepts,” says Kevin Franks, associate professor of neurobiology at Duke University, who was not involved in the work but wrote a News and Views article on it. “So in this part of the brain, traditionally being considered this primary sensory area, you have sensory invariant conceptual representations of specific types of objects. And that’s really, really cool.” Smell-detecting neurons in the nose project into the brain’s olfactory bulb, which then passes information directly to the piriform cortex and other parts of the primary olfactory cortex. That means the piriform cortex lies only two synapses away from the stimuli it decodes, Franks says. In the visual system, on the other hand, a cell two synapses away from a photon is still in the retina, he says. Despite the limited odor processing that happens before the signal reaches the piriform cortex, there have been earlier hints that the area acts more like an association cortex than like other primary sensory areas, says Thorsten Kahnt, investigator at the U.S. National Institute on Drug Abuse, who was not involved in the work. © 2024 Simons Foundation

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29514 - Posted: 10.12.2024

By Shaena Montanari Sea robins skitter across the sea floor with six tiny fins-turned-legs. And at least one species of these bottom feeders is exceptionally skilled at digging up food—so good that other fishes follow these sea robins to snatch up leftover snacks. The sea robins owe this talent to their legs, according to a pair of studies published today in Current Biology. The new work shows that the appendages evolved a specialized sensory system to feel and taste hidden prey. The legs of one common species, for example, are innervated by touch-sensitive neurons and dotted with tiny papillae that express taste receptors. “It’s just really neat to see the molecular components that nature is using to spin out not only new structures, but also new behaviors,” says David Kingsley, professor of developmental biology at Stanford University and an investigator on both studies. The results formalize work from the 1960s and ’70s that first indicated the special chemosensory abilities of sea robins, says Tom Finger, professor of cell and developmental biology at the University of Colorado Anschutz Medical Campus, who was not involved in the new studies. This is “a major, important contribution to show that taste receptors have become expressed in the specialized sensory organ.” This finding “demonstrates, I think, an evolutionary principle, which is that evolution uses the tool kit that’s in place and then just slightly changes it,” says Nicholas Bellono, professor of molecular and cellular biology at Harvard University, who is an investigator on both new studies and also researches unique senses in cephalopods. Last year, he and his colleagues described a similar adaptation in octopuses: “They took this receptor that was for neurotransmission and then just repurposed it with a slight tinkering to now be a sensory receptor. So it’s sort of a theme we keep seeing repeat across the diversity of life.” © 2024 Simons Foundation

Keyword: Chemical Senses (Smell & Taste); Evolution
Link ID: 29500 - Posted: 10.02.2024

By Daniela Hirschfeld Peter Mombaerts is a man of strong preferences. He likes Belgian beer — partly, but not entirely, for patriotic reasons. He likes classical music and observing the Earth from above while flying small planes with his amateur pilot’s license. He loves the feel of alpaca clothing during winter. But Mombaerts, who leads the Max Planck Research Unit for Neurogenetics in Frankfurt, Germany, says he has no favorite odor — even though he has been studying smells for more than 30 years. Mombaerts’s research has focused on how the brain processes odors, and on the impressive group of genes encoding odorant receptors in mammals. Humans have about 400 of these genes, which means that 2 percent of our roughly 20,000 genes help us to smell — the largest gene family known to date, as Mombaerts noted back in 2001 in the Annual Review of Genomics and Human Genetics. More than two decades later, it remains the record holder, and Mombaerts continues to delve into the genetics and neuroscience of how we smell the world around us. He spoke with Knowable Magazine about what’s been learned about the genes, receptors and neurons involved in sensing odors — and the mysteries that remain. This interview has been edited for length and clarity. Why did you start working on smell? When studying medicine in my native Belgium in the 1980s, I learned that I don’t really like to work so much with patients. But research interested me. I wanted to do neurobiology. I did my PhD in immunology with mice and genetics, and then moved to neuroscience. It was what I always wanted to do, but I had to find the right topic, the right lab and the right mentor — and all that came together when Linda Buck and Richard Axel published their paper about their discovery of the genes for odorant receptors. This paper came out in the journal Cell on April 5, 1991, and when I read the first few sentences I thought, “That’s what I want to work on.” Axel became my postdoc mentor. When Buck and Axel won the Nobel Prize in Physiology or Medicine in 2004, I wrote a Perspective piece for the New England Journal of Medicine  that I titled “Love at First Smell.” © 2024 Annual Reviews

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29469 - Posted: 09.07.2024

By Kerri Smith The smell in the laboratory was new. It was, in the language of the business, tenacious: for more than a week, the odour clung to the paper on which it had been blotted. To researcher Alex Wiltschko, it was the smell of summertime in Texas: watermelon, but more precisely, the boundary where the red flesh transitions into white rind. “It was a molecule that nobody had ever seen before,” says Wiltschko, who runs a company called Osmo, based in Cambridge, Massachusetts. His team created the compound, called 533, as part of its mission to understand and digitize smell. His goal — to develop a system that can detect, predict or create odours — is a tall order, as molecule 533 shows. “If you looked at the structure, you would never have guessed that it smelled this way.” That’s one of the problems with understanding smell: the chemical structure of a molecule tells you almost nothing about its odour. Two chemicals with very similar structures can smell wildly different; and two wildly different chemical structures can produce an almost identical odour. And most smells — coffee, Camembert, ripe tomatoes — are mixtures of many tens or hundreds of aroma molecules, intensifying the challenge of understanding how chemistry gives rise to olfactory experience. Another problem is working out how smells relate to each other. With vision, the spectrum is a simple colour palette: red, green, blue and all their swirling intermediates. Sounds have a frequency and a volume, but for smell there are no obvious parameters. Where does an odour identifiable as ‘frost’ sit in relation to ‘sauna’? It’s a real challenge to make predictions about smell, says Joel Mainland, a neuroscientist at the Monell Chemical Senses Center, an independent research institute in Philadelphia, Pennsylvania. © 2024 Springer Nature Limited

Keyword: Chemical Senses (Smell & Taste)
Link ID: 29463 - Posted: 09.04.2024