Links for Keyword: Chemical Senses (Smell & Taste)

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by Helen Thompson Earth’s magnetic field guides shark movement in the open ocean, but scientists had always suspected that sharks might also get their directions from an array of other factors, including smell. To sniff out smell’s role, biologists clogged the noses of leopard sharks (Triakis semifasciata), a Pacific coastal species that makes foraging trips out to deeper waters. Researchers released the sharks out at sea and tracked their path back to the California coast over four hours. Sharks with an impaired sense of smell only made it 37.2 percent of the way back to shore, while unimpaired sharks made it 62.6 percent of the way back to shore. The study provides the first experimental evidence that smell influences a shark’s sense of direction, the team writes January 6 in PLOS ONE. The animals may be picking up on chemical gradients produced by food sources that live on the coast. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior
Link ID: 21753 - Posted: 01.07.2016

By Christopher Intagliata Back in ancient times, philosophers like Aristotle were already speculating about the origins of taste, and how the tongue sensed elemental tastes like sweet, bitter, salty and sour. "What we discovered just a few years ago is that there are regions of the brain—regions of the cortex—where particular fields of neurons represent these different tastes again, so there's a sweet field, a bitter field, a salty field, etcetera." Nick Ryba [pron. Reba], a sensory neuroscientist at the National Institutes of Health. Ryba and his colleagues found that you can actually taste without a tongue at all, simply by stimulating the "taste" part of the brain—the insular cortex. They ran the experiment in mice with a special sort of brain implant—a fiber-optic cable that turns neurons on with a pulse of laser light. And by switching on the "bitter" sensing part of the brain, they were able to make mice pucker up, as if they were tasting something bitter—even though absolutely nothing bitter was touching the tongues of the mice. In another experiment, the researchers fed the mice a bitter flavoring on their tongues—but then made it more palatable by switching on the "sweet" zone of the brain. "What we were doing here was adding the sweetness, but only adding it in the brain, not in what we were giving to the mouse." Think adding sugar to your coffee—but doing it only in your mind. The findings appear in the journal Nature. © 2015 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21648 - Posted: 11.20.2015

Rachel England Brussels sprouts, Marmite, stinky cheese … these are all foods guaranteed to create divisions around the dinner table –and sometimes extreme reactions. A friend once ordered a baked camembert at dinner and I had to physically remove myself from the vicinity, such was its overpowering stench. Yet foods that once turned my stomach – mushrooms and prawns, in particular – now make a regular appearance on my plate. How is it that my opinion of a juicy grilled mushroom has gone from yuk to yum after 30 years of steadfast objection? And why is it that certain foods leave some diners gagging theatrically while others tuck in with vigour? Taste is a complicated business. In evolutionary terms we’re programmed to prefer sweeter flavours to bitter tastes: sweet ripe fruits provide a good source of nutrients and energy, for example, while bitter flavours can be found in dangerous plant toxins, which we’re better off avoiding. We’re also more likely to go for fatty foods with a high calorie count which would provide the energy needed for hunting our next meal. But now we live in a world where bitter vegetables such as kale reign supreme, kids salivate over eye-wateringly sour sweets and hunting dinner is as strenuous as picking up the phone. There are some environmental factors at play. When you eat something, molecules in the food hit your taste cells in such a way as to send a message to your brain causing one of five sensations: sweetness, saltiness, bitterness, sourness or umami (a loanword from Japanese meaning ‘pleasant savoury taste’). Mix up these taste cells and messages with external influences and the results can be dramatic. © 2015 Guardian News and Media Limited

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21628 - Posted: 11.12.2015

Your sense of smell might be more important than you think. It could indicate how well your immune system is functioning, a study in mice suggests. Evidence of a connection between the immune system and the olfactory system – used for sense of smell – has been building for some time. For instance, women seem to prefer the scent of men with different immune system genes to their own. Meanwhile, other studies have hinted that the robustness of your immune system may influence how extraverted you are. To investigate further, Fulvio D’Acquisto at Queen Mary University of London and his colleagues studied mice missing a recombinant activating gene (RAG), which controls the development of immune cells. Without it, mice lack a working immune system and some genes are expressed differently, including those involved in the olfactory system. “That rang bells, because people with immune deficiencies often lose their sense of smell,” says D’Acquisto. Systemic lupus erythematosus, an autoimmune disease in which the immune system mistakenly attacks tissues in the skin, joints, kidneys, brain, and other organs, is one such example. His team measured how long it took mice to find chocolate chip cookies buried in their cages. Those missing RAG took five times as long as normal mice. They also failed to respond to the scent of almond or banana, which mice usually find very appealing – although they did still react to the scent of other mice. Further study uncovered abnormalities in the lining of their noses; physical evidence that their sense of smell might be disrupted. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 21599 - Posted: 11.04.2015

By WILLIAM GRIMES The first show at the Museum of Food and Drink’s new space in Brooklyn is “Flavor: Making It and Faking It,” and it wastes no time in getting to the point. “What makes your favorite food so delicious?” the text on a large free-standing panel near the entrance asks. The one-word answer: “Chemicals.” The word is deflating. It’s a little like being told that the human soul has a specific atomic weight. Chemicals? Yuck. But maybe not. Flavors come in two varieties, natural and artificial, but what do the words really mean? This is the looming question in an exhibition about food and culture that opens next Wednesday, in a museum that until now has been a free-floating idea rather than a building with an address. The show follows the history of lab-created flavors from the middle of the 19th century, when German scientists created artificial vanilla, to the present day, when the culinary spin doctors known as flavorists tweak and blend the myriad tastes found in virtually every food product on supermarket shelves. Flavor is a complex, beguiling subject. At one of several “smell machines” throughout the exhibition, where specific aromas are emitted through silver hoses at the push of a button, visitors learn that coffee gets a little lift — the je ne sais quoi that makes it irresistible in the morning — from a sulfur compound also found in skunk spray. Tiny edible pellets distributed from gumball machines send the message in tactile form. This is an exhibition that is not just hands-on, but tongue-on and nostrils-on. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21536 - Posted: 10.21.2015

The invaders put on a disguise and infiltrate the nest with dark plans: to kill the queen and enslave the kingdom. Usually when ants take pupae from other colonies as future slaves all hell breaks loose in ensuing battles. The enslaved individuals sometimes even strike back against their overlords. It’s a relatively dramatic affair, usually resulting in the aggressive slave-makers carrying the pupae back to their own colony, says Terrence McGlynn at California State University. But a species of ant found in the eastern US, Temnothorax pilagens, does things differently. It is the first ant species known to waltz into a colony and enslave others without killing, and one of a few that take not only pupae but adult workers, too. “This was extremely surprising as ants are usually able to detect foreign species or even individuals from a different colony through their chemical profile and react aggressively towards them,” says Isabelle Kleeberg at Johannes Gutenberg-Universität Mainz, Germany, whose team has found how they get away with it. Kleeberg tracked the behaviour of T. pilagens and their preferred slave species, Temnothorax ambiguus, in 43 raiding experiments using colour-marked individuals. In each experiment the colonies of these two ant species, each housed in a plastic box, were placed 12 centimetres apart from each other. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 21526 - Posted: 10.17.2015

A new clinical trial is set to begin in the United Kingdom using the powerful noses of dogs to detect prostate cancer in humans. While research has been done before, these are the first trials approved by Britain's National Health Service. The trials, at the Milton Keynes University Hospital in Buckinghamshire, will use animals from a nonprofit organization called Medical Detection Dogs, co-founded in 2008 by behavioral psychologist Claire Guest. "What we've now discovered is that lots of diseases and conditions — and cancer included — that they actually have different volatile organic compounds, these smelly compounds, that are associated with them," Guest tells NPR's Rachel Martin. "And dogs can smell them." The dogs offer an inexpensive, non-invasive method to accompany the existing blood tests for prostate cancer, which detect prostate-specific antigen, or PSA, Guest says. "It's a low false-negative but a very high false-positive, meaning that three out of four men that have a raised PSA haven't got cancer," she explains. "So the physician has a very difficult decision to make: Which of the four men does he biopsy? What we want to do is provide an additional test — not a test that stands alone but an additional test that runs alongside the current testing, which a physician can use as part of that patient's picture." The samples come to the dogs — the dogs never go to the patient. At the moment, our dogs would be screening about between a .5- to 1-ml drop of urine [or 1/5 to 1/10 teaspoon], so a very small amount. In the early days, of course, we know whether the samples have come from a patient with cancer or if the patient has another disease or condition, or is in fact healthy. © 2015 NPR

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21302 - Posted: 08.17.2015

Teresa Shipley Feldhausen Move over, umami. Fat is the newest member of the pantheon of basic tastes, joining salty, sweet, sour, bitter and savory, or umami. Researchers at Purdue University in West Lafayette, Ind., conducted taste tests pitting a variety of fats against flavors in the other taste categories, such as monosodium glutamate for umami. The result: People recognize some fats as separate from the other five taste categories, even with plugged noses. The researchers dub this sixth sense oleogustus. For instance, nearly two-thirds of tasters identified one type of fat — linoleic acid, found in vegetable and nut oils — as a distinct flavor. Texture wasn’t a factor; the researchers whipped up tasting samples that gave the same mouthfeel. Pure oleogustus doesn’t invoke notes of olive oil or fresh butter. It’s unpleasant, the researchers report online July 3 in Chemical Senses. Mix oleogustus with some of the other five flavors, however, and you could end up with doughnuts or potato chips. Citations C.A. Running, B.A. Craig and R.D. Mattes. Oleogustus: The unique taste of fat. Chemical Senses. Published online July 3, 2015. doi: 10.1093/chemse/bjv036. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21252 - Posted: 08.02.2015

Michael Sullivan It's 5:45 in the morning, and in a training field outside Siem Reap, home of Angkor Wat, Cambodia's demining rats are already hard at work. Their noses are close to the wet grass, darting from side to side, as they try to detect explosives buried just beneath the ground. Each rat is responsible for clearing a 200-square-meter (239-square-yard) patch of land. Their Cambodian supervisor, Hulsok Heng, says they're good at it. "They are very good," he says. "You see this 200 square meters? They clear in only 30 minutes or 35 minutes. If you compare that to a deminer, maybe two days or three days. The deminer will pick up all the fragmentation, the metal in the ground, but the rat picks up only the smell of TNT. Not fragmentation or metal or a nail or a piece of crap in the ground." That's right: Someone using a metal-detecting machine will take a lot longer to detect a land mine than a rat using its nose. There's plenty of work for the rats here in Cambodia. The government estimates there are 4 million to 6 million land mines or other pieces of unexploded ordnance — including bombs, shells and grenades — littering the countryside, remnants of decades of conflict. Neighboring Vietnam and Laos also have unexploded ordnance left over from the Vietnam War. Dozens of people are killed or maimed in the region every year — and there's a financial toll as well, since the presence of these potentially deadly devices decreases the amount of land available to farmers. © 2015 NPR

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 21246 - Posted: 08.01.2015

By THE ASSOCIATED PRESS WASHINGTON — Move over sweet and salty: Researchers say we have a distinct and basic taste for fat, too. But it's nowhere near as delicious as it sounds. They propose expanding our taste palate to include fat along with sweet, salty, bitter, sour and relative newcomer umami. A research team at Purdue University tested look-alike mixtures with different tastes. More than half of the 28 special tasters could distinguish fatty acids from the other tastes, according to a study published in the journal Chemical Senses. Past research showed fat had a distinct feel in the mouth, but scientists removed texture and smell clues and people could still tell the difference. "The fatty acid part of taste is very unpleasant," study author Richard Mattes, a Purdue nutrition science professor, said Thursday. "I haven't met anybody who likes it alone. You usually get a gag reflex." Stinky cheese has high levels of the fat taste and so does food that goes rancid, Mattes said. Yet we like it because it mixes well and brings out the best of other flavors, just like the bitter in coffee or chocolate, he added. To qualify as a basic taste, a flavor has to have unique chemical signature, have specific receptors in our bodies for the taste, and people have to distinguish it from other tastes. Scientists had found the chemical signature and two specific receptors for fat, but showing that people could distinguish it was the sticky point. Initially Mattes found that people couldn't quite tell fat tastes when given a broad array of flavors. But when just given yucky tastes — bitter, umami, sour — they could find the fat. © 2015 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 21217 - Posted: 07.25.2015

By Victoria Gill Science reporter, BBC News Cat v mouse: it is probably the most famous predator-prey pairing, enshrined in idioms and a well-known cartoon. And cats, it turns out, even have chemical warfare in their anti-mouse arsenal - contained in their urine. Researchers found that when very young mice were exposed to a chemical in cat urine, they were less likely to avoid the scent of cats later in life. The findings were presented at the Society for Experimental Biology's annual meeting in Prague. The researchers, from the AN Severtov Institute of Ecology and Evolution in Moscow, had previously found that the compound - aptly named felinine - causes pregnant mice to abort. Dr Vera Voznessenskaya explained that mice have a physiological response to this cat-specific compound. Chemical-sensing mouse neurons in the mouse's brain pick up the scent, triggering a reaction which includes an increase in the levels of stress hormones. "It's something that has existed in cats and mice for thousands of years," said Dr Voznessenskaya. This new study revealed that baby mice exposed to the compound during a "critical period" in their development would, as adults, react quite differently to their arch enemy's smell. The team exposed one-month-old mice to the chemical over two weeks. When they were tested later for their reaction, they were much less likely to flee the same scent. The interaction between cats and mice has a long history "Their physical sensitivity [to the chemical] was actually actually much higher," Dr Voznessenskaya explained. "More of their receptors detect the compound and they produce higher levels of stress hormone." Despite this though, mice raised around the unmistakable scent of cat pee are less inclined to show signs of fear, or to flee when they sniff it out. © 2015 BBC.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 21128 - Posted: 07.04.2015

by Sarah Zielinski Seabirds called shearwaters manage to navigate across long stretches of open water to islands where the birds breed. It’s not been clear how the birds do this, but there have been some clues. When scientists magnetically disturbed Cory’s shearwaters, the birds still managed to find their way. But when deprived of their sense of smell, the shearwaters had trouble homing in on their final destination. Smell wouldn’t seem to be all that useful out over the ocean, especially with winds and other atmospheric disturbances playing havoc on any scents wafting through the air. But now researchers say they have more evidence that shearwaters are using olfactory cues to navigate. Andrew Reynolds of Rothamsted Research in Harpenden, England, and colleagues make their case June 30 in the Proceedings of the Royal Society B. Messing with Cory’s shearwaters or other seabirds, like researchers did in earlier studies, wasn’t a good option, the researchers say, because there are conservation concerns when it comes to these species. Instead, they attached tiny GPS loggers to 210 shearwaters belonging to three species: Cory’s shearwaters, Scopoli’s shearwaters and Cape Verde shearwaters. But how would the birds’ path reveal how they were navigating? If they were using olfactory cues, the team reasoned, the birds wouldn’t take a straight path to their target. Instead, they would fly straight for a time, guided in that direction by a particular smell. When they lost that scent, their direction would change, until they picked up another scent that could guide them. And only when a bird got close would it use landmarks, other birds and the odor of the breeding colony as guides. If the birds were using some other method of navigation — or randomly searching for where to go — their paths would look much different. © Society for Science & the Public 2000 - 2015

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21127 - Posted: 07.04.2015

By Christopher Intagliata Two decades ago, Swiss researchers had women smell the tee shirts that various men had slept in for two nights. Turned out that if women liked the aroma of a particular shirt, the guy who’d worn it was likely to have genetically coded immunity that was unlike the woman’s. Well the effect isn't just limited to sweaty shirts. Turns out we all smell things a little differently—you pick up a note of cloves, say, where I smell something more soapy—and that too gives clues to our degree of genetic similarity. Researchers tried that test with 89 people—having them sniff a couple dozen samples, and label each one using terms like lemony, coconut, fishy and floral. And each volunteer classified the scents differently enough that the researchers could single them out in subsequent tests, based on what they called each subject’s "olfactory fingerprint." Researchers then repeated that sniff test on another 130 subjects. But this time they did a blood test, too, to figure out each person's HLA type—an immune factor that determines whether you'll reject someone's organ, for example. They found that people who perceived smells similarly also had similar HLA types. Study author Lavi Secundo, a neuroscientist at the Weizmann Institute of Science in Israel, says the smell test could have real-world applications. "For organ donation you can think of this method as a quick, maybe a quick and dirty, method to sift between the best and the rest." He and his colleagues say it might even eliminate the need for 30 percent of the HLA tests done today. The work appears in the Proceedings of the National Academy of Sciences. [Lavi Secundo et al, Individual olfactory perception reveals meaningful nonolfactory genetic information] © 2015 Scientific American

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 21112 - Posted: 06.30.2015

Sarah Schwartz A person’s sense of smell may reveal a lot about his or her identity. A new test can distinguish individuals based upon their perception of odors, possibly reflecting a person’s genetic makeup, scientists report online June 22 in Proceedings of the National Academy of Sciences. Most humans perceive a given odor similarly. But the genes for the molecular machinery that humans use to detect scents are about 30 percent different in any two people, says neuroscientist Noam Sobel of the Weizmann Institute of Science in Rehovot, Israel. This variation means that nearly every person’s sense of smell is subtly different. Nobody had ever developed a way to test this sensory uniqueness, Sobel says. Sobel and his colleagues designed a sensitive scent test they call the “olfactory fingerprint.” In an experiment, test subjects rated how strongly 28 odors such as clove or compost matched 54 adjectives such as “nutty” or “pleasant.” An olfactory fingerprint describes individuals’ perceptions of odors’ similarities, not potentially subjective scent descriptions. All 89 subjects in the study had distinct olfactory fingerprints. The researchers calculated that just seven odors and 11 descriptors could have identified each individual in the group. With 34 odors, 35 descriptors, and around five hours of testing per person, the scientists estimate they could individually identify about 7 billion different people, roughly the entire human population. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21087 - Posted: 06.23.2015

By Brian Handwerk When it comes to mating, female mice must follow their noses. For the first time, scientists have shown that hormones in mice hijack smell receptors in the nose to drive behavior, while leaving the brain completely out of the loop. According to the study, appearing this week in Cell, female mice can smell attractant male pheromones during their reproductive periods. But during periods of diestrus, when the animals are unable to reproduce, the hormone progesterone prompts nasal sensory cells to block male pheromone signals so that they don't reach a female's brain. During this time, female mice display indifference or even hostility toward males. The same sensors functioned normally with regard to other smells, like cat urine, showing they are selective for male pheromones. When ovulation begins, progesterone levels drop, enabling the females to once more smell male pheromones. In short, the system "blinds" female mice to potential mates when the animals are not in estrus. The finding that the olfactory system usurped the brain's role shocked the research team, says lead author Lisa Stowers of the Scripps Research Institute. “The sensory systems are just supposed to sort of suck up everything they can in the environment and pass it all on to the brain. The result just seems wacky to us,” Stowers says. “Imagine this occurring in your visual system," she adds. "If you just ate a big hamburger and then saw a buffet, you might see things like the table and some people and maybe some fruit—but you simply wouldn't see the hamburgers anymore. That's kind of what happens here. Based on this female's internal-state change, she's missing an entire subset of the cues being passed on to her brain.”

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 21024 - Posted: 06.06.2015

By Emily DeMarco For owners of picky cats, that disdainful sniff—signaling the refusal of yet another Friskies flavor—can be soul-crushing. Some cats are notoriously finicky eaters, but the reasons behind such fussy behavior remain fuzzy. Previous research has shown that cats can’t taste sweet flavors, but little is known about how they perceive bitter tastes. Now, researchers in the pet food industry have identified two bitter taste receptors in domestic cats, which could help explain why some felines are so choosy when it comes to their chow. In the study, published today in BMC Neuroscience, the scientists used cell-based experiments to see how the two cat taste receptors, known as Tas2r38 and Tas2r43, responded to bitter compounds such as phenylthiocarbamide (PTC) and 6-n-propylthiouracil (PROP)—which have molecular structures similar to ones in Brussels sprouts and broccoli—as well as aloin (from the aloe plant) and denatonium (used to prevent inadvertent ingestion of some chemicals). When compared with the human versions of these receptors, the researchers found that the cat bitter receptor Tas2r38 was less sensitive to PTC and did not respond to PROP, whereas Tas2r43 was less sensitive to aloin but more sensitive to denatonium, leading the researchers to conclude that cats taste different, and perhaps more narrow, ranges of bitter flavors than humans. The research could help pharmaceutical and pet food manufacturers create compounds that block or inhibit these bitter taste receptors, the team says, potentially leading to more appetizing medicines (if such a thing exists) and foods for our feline companions. © 2015 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21012 - Posted: 06.03.2015

By Paca Thomas Wasabi and Sriracha each activate different receptors on the tongue, both of which warn your brain of the atomic reaction to come. These key flavor receptors, TRPA1 and TRPV1, have been the subject of recent research—but why all the scientific study of hot and spicy condiments? One word: pain. The video above explains how our tongues react to heat in our food, and how that often triggers the body’s own bespoke painkiller.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20879 - Posted: 05.04.2015

Nala Rogers People who are ill often complain of changes in their sense of taste. Now, researchers report that this sensory shift may be caused by a protein that triggers inflammation. Mice that cannot produce the protein, called tumour necrosis factor-α (TNF-α), are less sensitive to bitter flavours than normal mice, according to a study published on 21 April in Brain, Behavior, and Immunity1. People with infections, autoimmune disease or other inflammatory conditions have higher levels of TNF-α than healthy people, and the protein has been shown to reduce food intake2. To investigate the influence of TNF-α on taste, researchers at the Monell Chemical Senses Center in Philadelphia, Pennsylvania, used engineered mice that could not produce the protein. The researchers offered the engineered mice and normal mice water that contained different types and concentrations of flavours. The mice that could not produce TNF-α had normal reactions to sweet, sour, salty and umami flavours, but were less sensitive to bitter ones. “Normal mice will pick up [that taste] at a much lower concentration. They will know this is bitter; they will not like it,” says Hong Wang, a molecular biologist at Monell and an author of the study. “But if the TNF-α gene is not there, then the mice will only start to avoid the bitter solution at higher concentrations.” © 2015 Nature Publishing Group

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 20868 - Posted: 04.30.2015

By Rachel E. Gross “By being a guy’s best first move … Axe is designed to keep guys a step ahead in the dating game,” boasts Unilever, the company that sells Axe products. Of course, if you don’t happen to be a gullible 13-year-old boy, you probably don’t believe that body spray or deodorant is a magic elixir with the power to turn nice girls naughty. But what if it were possible to change a person’s mood with just a scent? The idea may not be that far-fetched, according to a new study in the journal Psychological Science—reporting work that was funded by Unilever. The study found that it might be possible to subconsciously trigger a state of happiness using the scent of—deep breath now—human sweat. People send all kinds of secret messages through their secretions. When smelling chemicals in male sweat, women become more alert, and they can even tell whether that sweat was made by a guy who was particularly turned on. (Cautions the New York Times: “No man should imagine that based on these conclusions he can improve his sex life by refraining from bathing.”) But until now, most sweat studies have focused on sexual arousal or negative emotions like fear. For obvious reasons, these emotions are crucial to survival and evolutionary success. If your friend spots a puma, it may be helpful for you to be able to sniff out instant cues to be on the alert or flee for cover. Being able to transmit positive emotions may also have a profound social impact, says Gün Semin, a psychologist at Utrecht University in the Netherlands and lead researcher on the study. After all, “the pursuit of happiness is not an individual enterprise,” as he and his fellow researchers write rather eloquently in the new study. So Semin’s team decided to test whether people could communicate happiness via sweat.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 20863 - Posted: 04.30.2015

By James Gallagher Health editor, BBC News website, San Diego A dog has been used to sniff out thyroid cancer in people who had not yet been diagnosed, US researchers say. Tests on 34 patients showed an 88% success rate in finding tumours. The team, presenting their findings at the annual meeting of the Endocrine Society, said the animal had an "unbelievable" sense of smell. Cancer Research UK said using dogs would be impractical, but discovering the chemicals the dogs can smell could lead to new tests. The thyroid is a gland in the neck that produces hormones to regulate metabolism. Thyroid tumours are relatively rare and are normally diagnosed by testing hormone levels in the blood and by using a needle to extract cells for testing. Cancers are defective, out-of-control cells. They have their own unique chemistry and release "volatile organic compounds" into the body. The canine approach relies on dogs having 10 times the number of smell receptors as people and being able to pick out the unique smells being released by cancers. The man's best friend approach has already produced promising results in patients with bowel and lung cancers. A team at the University of Arkansas for Medical Sciences (UAMS) had previously showed that a dog could be trained to smell the difference between urine samples of patients with and without thyroid cancer. Frankie the dog Frankie gave the correct diagnosis in 30 out of 34 cases The next step was to see if it could be used as a diagnostic test. Frankie the German Shepherd was trained to lie down when he could smell thyroid cancer in a sample and turn away if the urine was clean.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20668 - Posted: 03.09.2015