Links for Keyword: Chemical Senses (Smell & Taste)

Follow us on Facebook and Twitter, or subscribe to our mailing list, to receive news updates. Learn more.


Links 61 - 80 of 441

by Kai Kupferschmidt Human beings tend to avoid places that smell of urine. But to mice, there is something positively addictive about the scent; they like to go back to a spot where they found the excretions again and again. Now, researchers have discovered that this behavior is triggered by a single protein in the urine of male mice. Mice use scent to mark their territory, advertise their social dominance, and convey information about their health and reproductive status. But these are usually volatile pheromones that disperse quickly, and it has remained unclear what exactly stimulates a female to be attracted to a specific male. Previous research had shown that female laboratory mice often return to a place where they have come across cage bedding soiled by males. Now, researchers at the University of Liverpool in the United Kingdom have confirmed this. Female mice spent five times as much time in a place where they had encountered a dish with male urine than at a place where they encountered water. Just 10 minutes of exposure to the urine was enough for the mice to show this place preference even after 14 days. However, if the mice were prevented from by a mesh screen touching the urine with their nose, the place seemed to lose its attractiveness. "That suggested that the story was not as simple as everybody assumed and volatile pheromones were not responsible," says behavioral ecologist Jane Hurst, one of the authors of the study. By separating the urine into different fractions, the scientists showed that a protein called darcin that they had identified in 2005—and which mice can only detect if their noses touch the urine—is responsible for the frequent visits. Pure darcin, produced in cell culture in the lab, elicited the same reaction, the authors report online today in Science. © 2010 American Association for the Advancement of Science.

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: 17606 - Posted: 12.14.2012

By David Brown, We all know that when it comes to enjoying food, taste and smell go hand in hand. But how and where they hold hands in the neural circuits of the brain has been something of a mystery. Neuroscientists have known for a while that odor receptors in the nose send signals to the the brain’s taste center, also known as the gustatory cortex. But does the converse happen? Do taste receptors in the tongue talk to the smell center, the olfactory cortex? New research suggests the answer is yes. The smell center gets and uses information from the tongue even if an animal is not consciously sniffing — or even inhaling. “We know there is a sense of smell in the taste system. What’s new is that we now know that smell, like taste, can’t really work on its own, either,” said Donald B. Katz, a neuroscientist at Brandeis University who co-authored the study. “What this means is that the different senses are really interacting with each other at a much earlier level than previously thought,” said Joost X. Maier, the postdoctoral researcher at Brandeis who did the experiments reported in the current issue of the Journal of Neuroscience. One can construct reasons why this might be the best way to design the brain. But the brain arose by chance, interacting with the world and sculpted by natural selection. For virtually all forms of life, taste and smell were experienced together in the act of finding and consuming food. © 1996-2012 The Washington Post

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: 17573 - Posted: 12.04.2012

A fondness for the burn of spicy food has less to do with tolerance and far more to do with personality, according to a new study. Researchers from Pennsylvania State University have found a love of chili is associated with sensation seeking and reward, but found no evidence that chili lovers get desensitized to chili burn over time. "Rather than merely showing reduced response to the irritating qualities of capsaicin (the compound that gives chili its burn) as might be expected—these findings support the hypothesis that personality differences may drive differences in spicy food liking and intake," the authors wrote in the journal Food Quality and Preference. "We always assumed that liking drives intake—we eat what we like and we like what we eat. But no one had actually directly bothered to connect these personality traits of sensation seeking with intake of chilli peppers," says lead author and self-confessed chili lover Professor John Hayes. The discovery of a relationship between fondness for chilli and sensitivity to reward was also new, says Hayes who is an assistant professor of food science at Pennsylvania State University. Nearly one hundred volunteers were given liquid samples of capsaicin and asked to swill it in their mouth for three seconds before spitting out. They were then asked to rate the burning sensation and, in a separate questionnaire, rate their liking of various foods. © CBC 2012

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: 17572 - Posted: 12.04.2012

Roger Dobson Love, according to romantics, can have a dramatic effect on the senses: striking lovers blind, deaf or rendering them tongue-tied. But the simple answer to the question of whether any relationship is "the one" seems to be that your ideal man or woman gets up your nose. New research suggests a sense of smell is vital for a good long-term relationship. In the new study, reported in the journal Biological Psychology, researchers looked for the first time at the effect of being born without a sense on smell on men and women's relationships. The research involved analysing data on men and women aged 18 to 46 with no sense of smell and comparing it with information gleaned from a healthy control group. The results showed that men and women who were unable to smell had higher levels of social insecurity, although this manifested itself in different ways. In men, but not in women, it led to fewer relationships. The men with a faulty sense of smell averaged two partners compared with 10 for healthy men. One theory is that the lack of a sense of smell may make men less adventurous. They may have more problems assessing and communicating with other people. They may also be concerned about how they are perceived by others, and worry about their own body odour. © independent.co.uk

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: 17566 - Posted: 12.03.2012

By Christina Agapakis White is a mixture, made by a combination of signals at equal intensity across a perceptual space. White light can be split up into all the colors of the visible spectrum, and white noise covers a range of frequencies within the audible range. Our other senses don’t have as clearly defined ranges of perception. We can’t give a smell, a taste, or a texture a number the same way that a color or a tone can be defined by a wavelength, but a fascinating recent paper shows that by mixing many different smelly molecules at equal intensities, our perception of the odor will converge on “olfactory white.” The researchers created this strangely neutral smell from different mixtures of up to thirty odors, chosen from a set of 86 molecules that represent a wide range of the kinds of things that we can smell. Human “olfactory stimulus space” contains thousands of molecules, from the fragrant and floral to the putrid. We can distinguish and name many smells, but odors don’t map neatly onto a one dimensional spectrum. Sampling the multidimensional stimulus space of odors requires a much more complicated mapping of the smell universe. The figure on the left shows the position of the 86 molecules within two maps of olfactory stimulus space. The first is based on the way that we perceive odors (perceptual space, A) and the second based on the chemical structures of the molecules (physicochemical space, B). The perceptual map is built with data from Dravnieks’ Atlas of Odor Character Profiles of 144 different molecules. Each smell was compared by 150 professional noses against a list of 146 different odor descriptions like “fruity” “etherish” “decayed” or “seasoning for meat.” © 2012 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: 17547 - Posted: 11.28.2012

by Sid Perkins If you play sounds of many different frequencies at the same time, they combine to produce neutral "white noise." Neuroscientists say they have created an analogous generic scent by blending odors. Such "olfactory white" might rarely, if ever, be found in nature, but it could prove useful in research, other scientists say. Using just a few hundred types of biochemical receptors, each of which respond to just a few odorants, the human nose can distinguish thousands of different odors. Yet humans can't easily identify the individual components of a mixture, even when they can identify the odors alone, says Noam Sobel, a neuroscientist at the Weizmann Institute of Science in Rehovot, Israel. Now, he and his colleagues suggest, various blends made up of a large number of odors all begin to smell the same—even when the blends share no common components. For their study, the researchers used 86 nontoxic odorants that had a wide variety of chemical and physical properties such as molecular structure, molecular weight, and volatility. Those chemicals also spanned a perceptual scale from "pleasant" to "unpleasant" and another such scale on which scents were judged to range from "edible" to "poisonous." The researchers then diluted the chemicals so that their odors were equally intense. Finally, they created mixtures by dripping individual odorants onto separate regions of an absorptive pad in a jar, a technique that prevented the substances from reacting in liquid form to create new substances or odors. The odor blends contained anywhere from one to 43 of the chemicals, Sobel says. © 2010 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: 17510 - Posted: 11.20.2012

By Tia Ghose, LiveScience Humans can smell fear and disgust, and the emotions are contagious, according to a new study. The findings, published Nov. 5 in the journal Psychological Science, suggest that humans communicate via smell just like other animals. "These findings are contrary to the commonly accepted assumption that human communication runs exclusively via language or visual channels," write Gün Semin and colleagues from Utrecht University in the Netherlands. Most animals communicate using smell, but because humans lack the same odor-sensing organs, scientists thought we had long ago lost our ability to smell fear or other emotions. To find out, the team collected sweat from under the armpits of 10 men while they watched either frightening scenes from the horror movie "The Shining" or repulsive clips of MTV's "Jackass." Next, the researchers asked 36 women to take a visual test while they unknowingly inhaled the scent of men's sweat. When women sniffed "fear sweat," they opened their eyes wide in a scared expression, while those smelling sweat from disgusted men scrunched their faces into a repulsed grimace. (The team chose men as the sweat donors and women as the receivers because past research suggests women are more sensitive to men's scent than vice versa.) © 2012 NBCNews.com

Related chapters from BP7e: Chapter 15: Emotions, Aggression, and Stress; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 11: Emotions, Aggression, and Stress; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 17470 - Posted: 11.08.2012

by Joel Winston Never mind the bitter end – it is the bitter beginning of an infection that triggers an immune response. We know that taste receptors on the tongue can detect bitter foods, but it turns out that there are also identical taste receptors in the upper airway. Noam Cohen at the University of Pennsylvania in Philadelphia and his team think they know why. They grew cell cultures from sinus tissue samples collected from surgical patients, and found that bitter taste receptors in the tissue picked up the presence of Pseudomonas aeruginosa, a bacterium that can cause pneumonia. The sinus tissue responded by producing nitric oxide to kill the invading microbes. "Certain people have strong innate defences against these bacteria, which is based on their ability to detect bitterness," says Cohen. "Others who don't really 'taste' these bitter compounds have a weakened defence." The research could lead to nasal sprays designed to activate the taste receptors and boost people's natural defences against sinus infections. "This is probably the most exciting clinical link found for bitter receptors," says Liquan Huang of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, who was not involved in the study. "However, further work is needed to see if this can be translated into treatments." Journal reference: Journal of Clinical Investigation, doi.org/jj4 © Copyright Reed Business Information Ltd.

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: 17415 - Posted: 10.24.2012

By Christina Agapakis Smell is notoriously subjective and hard to define. Odors can be perceived differently by different people depending on genetics, culture, past experience, the environment, and whether they’ve had a really bad sinus infection or not. Even worse, the same person can perceive the same smell differently at different times, depending on how the smell is described and other sensory fluctuations. Leslie Vosshall’s Laboratory of Neurogenetics and Behavior at Rockefeller University studies how complex behaviors are influenced by the chemical senses in organisms ranging from mosquitoes to humans. In order to better understand how human odor perception varies, both within individuals at different times and between different people, the lab asked nearly 400 New Yorkers to describe and rate the intensity and pleasantness of 66 different smells, at the same time collecting demographic data (significantly more diverse than the typical study of undergraduate psychology students) as well as data about their eating habits and perfume usage, finding many instances of variability in how people perceive smells. The lab recently published their extensive survey titled “An olfactory demography of a diverse metropolitan population” in the open-access journal BMC Neuroscience. They’ve also made their data freely available (you can download the huge excel file here) for further analysis or data-mining. This study has been ongoing for several years, and two years ago inspired Nicola Twilley’s wonderful Scratch-and-Sniff Map of New York’s olfactory psychogeography. Rather than mapping what people smell, the odors that they would encounter in different neighborhoods, she mapped how they smell, mapping odor preferences by neighborhood using homemade scratch-and-sniff stickers, sampling some of the variation in our smell universe. © 2012 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: 17404 - Posted: 10.22.2012

By HENRY FOUNTAIN SAINT-LOUIS, France — Denis Spitzer wants to beat dogs at their own game. At a binational armaments and security research center here in eastern France, Dr. Spitzer and his colleagues are working on a sensor to detect vapors of TNT and other explosives in very faint amounts, as might emanate from a bomb being smuggled through airport security. Using microscopic slivers of silicon covered with forests of even smaller tubes of titanium oxide, they aim to create a device that could supplement, perhaps even supplant, the best mobile bomb detector in the business: the sniffer dog. But emulating the nose and brain of a trained dog is a formidable task. A bomb-sniffing device must be extremely sensitive, able to develop a signal from a relative handful of molecules. And it must be highly selective, able to distinguish an explosive from the “noise” of other compounds. While researchers like Dr. Spitzer are making progress — and there are some vapor detectors on the market — when it comes to sensitivity and selectivity, dogs still reign supreme. “Dogs are awesome,” said Aimee Rose, a product sales director at the sensor manufacturer Flir Systems, which markets a line of explosives detectors called Fido. “They have by far the most developed ability to detect concealed threats,” she said. But dogs get distracted, cannot work around the clock and require expensive training and handling, Dr. Rose said, so there is a need for instruments. © 2012 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: 17372 - Posted: 10.16.2012

By Meghan Rosen David Ferrero wasn’t expecting the jaguar to pounce. When he approached the holding pens at Massachusetts’ Stone Zoo, the big cat watched but looked relaxed, lounging on her cage’s concrete floor. Two other jaguars rested in separate cages nearby. The jaguars usually prowled outside, in the grassy grounds of the zoo’s enclosure. But this afternoon, zookeepers kept the animals inside so that Ferrero and a colleague could grab a behind-the-scenes peek. Here, the jaguars slept at night — and fed. Here, only metal bars stood between the humans and the cats. As Ferrero stepped closer to the cages, the watchful female sprang up, twisting her body toward him, front paws thumping the bars. Fully extended, she was as tall as Ferrero. “I think she wanted to eat me,” he says. The zookeepers weren’t afraid, but Ferrero flinched. He wasn’t familiar with the lean, black-spotted feline. He was just there to pick up some pee. Ferrero, a neurobiologist from Harvard, was visiting the zoo to gather urine specimens for a study linking odors to instinctual behavior in rodents. Early lab results had hinted that a whiff of a chemical in carnivore pee flashed a sort of billboard message, blinking “DANGER” in neon lights — enough to make animals automatically shrink away in fear. © Society for Science & the Public 2000 - 2012

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: 17334 - Posted: 10.06.2012

By Sandra G. Boodman, The 80th birthday party for Josephine van Es marked two milestones, only one of which was apparent at the time. Held in November 2004 at her daughter’s house in Rehoboth Beach, Del., the event was a celebration of her longevity, good health and loving family. It also marked one of the last times van Es can remember feeling well and not beset by the pain that developed soon afterward and has left the inside of her mouth feeling perpetually scalded and with a constant metallic taste. “It’s awful,” said van Es, 87, who says the burning is worse than the taste, which she likens to “sucking on a penny.” Her daughter Karen van Es says that her mother’s problem has taken a toll on both their lives. For nearly eight years, she has taken time from her job at a Northern Virginia veterinary clinic to ferry her mother, who lives independently in a condominium in Lewes, Del., to doctors in Delaware, Philadelphia and Washington. She also has contacted specialists in Florida and Canada hoping one would propose an effective remedy for an ailment that took more than a year to diagnose and has so far eluded treatment. “She tells me, ‘I just feel rotten all the time,’ ” said Karen van Es, 63, an only child who speaks to her mother every day and sees her often. “My mother has lost confidence as a result of this,” Karen van Es said, adding that she often feels helpless and frustrated about not being able to do more. © 1996-2012 The Washington Post

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 5: The Sensorimotor System
Link ID: 17305 - Posted: 09.26.2012

By Susan Milius Caterpillars way too immature for actual sex turn out to detect and take an interest in adult sex pheromones. Caterpillars of the cotton leafworm moth (Spodoptera littoralis) don’t have working sex organs. They’re just long, black-green larvae eating as much as they can before transforming into the completely different body shape and lifestyle of an adult moth. Yet these caterpillars can sense, and appear to like, the adult sex pheromone of their species, an international team reports September 4 in Nature Communications. “This is a funny fact because sex pheromones are supposed to be for sex,” says coauthor Emmanuelle Jacquin-Joly of the French agricultural research agency INRA in Versailles. Adult female moths release puffs of these chemicals, and males catching a whiff — sometimes from considerable distances — sniff their way through the night to the female. Evolution may have repurposed some chemistry in this species, Jacquin-Joly and her colleagues propose. What means “come hither” to adult moths may indicate something quite different, perhaps “here’s food,” to a youngster, she says. She began looking for a cotton leafworm caterpillar pheromone response after another lab found that larval silkworm antennae make the adult-style proteins required to bind molecules of adult sex pheromones from the air and shuttle them to nerve cells. Young silkworms didn’t seem to use the information, but Jacquin-Joly wondered if young cotton leafworms, with a much broader diet, might respond differently. © Society for Science & the Public 2000 - 2012

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: 17227 - Posted: 09.07.2012

By Jonathan Ball BBC News Young male fruit flies learn the smell of a receptive female to avoid wasting their sexual efforts, research shows. Promiscuous male flies initially court all females, but are rejected by those who have already mated. It is clear that the flies eventually learn to spot mated females, but just how they do has remained a mystery. Research published in Nature suggests that they smell a chemical signal called a pheromone left by other males during mating. The studies were performed using the common fruit fly - Drosophila melanogaster. This insect is used widely in genetic studies because they are easy to grow and they reproduce quickly - but principally because it is possible to generate and study flies that possess changes - or mutations - in their genetic material. In the study, Prof Barry Dickson and colleagues from the Research Institute of Molecular Pathology in Vienna, Austria, performed a series of studies to identify the mechanism that led to this change in behaviour in older flies. Using complementary approaches, the team showed that a pheromone called cVA was responsible. Pheromones are substances produced by one individual which modify the behaviour of another. They are widely known to work in the animal kingdom to warn of danger, define territories or attract mates. Mosquito The finding could be used for the control of other insects such as mosquitoes, which spread malaria BBC © 2012

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 17: Learning and Memory
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 13: Memory, Learning, and Development
Link ID: 17184 - Posted: 08.20.2012

By Tina Hesman Saey When a cold takes away a person’s sense of smell, part of the brain that helps link odors with memory, emotion and reward works overtime in preparation for the return of air flow. The way smell rebounds from a period of diminished sensory input distinguishes it from the other senses, researchers at the Northwestern University School of Medicine in Chicago report online August 12 in Nature Neuroscience. Other senses tend to back off when their functions are restricted. When a person wears a patch over one eye, for example, the part of the brain devoted to processing information from that eye weakens while the part linked to the other eye grows stronger. The same is true for hearing and touch, such as when a person goes deaf in one ear or loses a finger. To find out what happens to the olfactory system — the part of the brain that processes scents — when it’s completely odor deprived, Northwestern neuroscientist Joanna Keng Nei Wu and her colleagues set up a scent-free zone in a hospital’s research wing. Volunteers had to give up scented toiletries and spend a week with cotton stuffed up their nostrils to seal their noses off from the outside world. The researchers even took away the volunteers’ toothpaste, forcing them to brush with baking soda instead. Despite the hardships, it wasn’t difficult to find willing volunteers, Wu says. “We had a lot of medical students who wanted us to lock them up in the hospital for a week so they could study.” © Society for Science & the Public 2000 - 2012

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: 17158 - Posted: 08.14.2012

by Gisela Telis During mating season, a moss needs a little help from its friends—and it uses smell to recruit them. A new study has found that mosses, which were long thought to require only water or wind to reproduce, release an aroma that entices tiny animals such as mites and little bugs called springtails to help fertilize the plants. The discovery challenges current ideas about plant evolution, but experts say it raises more questions than it answers. For mosses, sex can be tricky. They can reproduce asexually, or they can develop male and female sex organs and wait for their fragile sperm to travel from one to the other. If the latter occurs, they rely on the elements—wind or splashing rain—to help with transport. In 2006, researchers discovered a third means of delivery. They found that tiny arthropods, a group of creepy-crawlies that includes mites and springtails, seemed to help disperse moss sperm. But the study didn't pinpoint how they did it or whether this kind of fertilization was critical to the moss life cycle. In hopes of answering those lingering questions, biologist Sarah Eppley of Portland State University in Oregon and colleagues gathered and grew moss samples from local forests and tested reproductive outcomes with and without rain and springtails. They found that water alone and springtails alone were equally effective at fertilizing mosses, but putting the two together made the mosses more than twice as successful at reproducing. © 2010 American Association for the Advancement of Science

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: 17068 - Posted: 07.19.2012

By Victoria Gill BBC Nature Seabirds are able to pick out their relatives from smell alone, according to scientists. In a "recognition test", European storm petrels chose to avoid the scent of a relative in favour of approaching the smell of an unrelated bird. The researchers think this behaviour prevents the birds from "accidentally inbreeding". The study is the first evidence that birds are able to sniff out a suitable mate. It is published in the journal Animal Behaviour. Lead researcher Francesco Bonadonna, from the Centre of Functional and Evolutionary Ecology in Montpellier, France, told BBC Nature that the birds used smell to recognise and communicate their "genetic compatibility". Sniffing out a genetically suitable mate is a well-known phenomenon in mammals. But until recently, scientists thought that birds relied on vision and sound when choosing a partner. According to Dr Bonadonna, the fact that they use odours explains how these birds manage to return to their family colony to breed and avoid mating with a relative. European storm petrels remain in the colony they are born in throughout their life, so this site is also home to several of their family members. BBC © 2012

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: 17064 - Posted: 07.19.2012

By Julie Wan, For many years, scientists agreed that human tongues perceived four basic tastes: sweet, sour, salty and bitter. Then in 2002, receptors were confirmed for a taste called umami — first proposed by a Japanese chemist in 1908 and commonly described as meatiness or savoriness — and it became widely accepted as the fifth basic taste. Since then, molecular biologists have theorized that humans may have as many as 20 distinct receptors for such tastes as calcium, carbonation, starch and even water. The data supporting each vary widely, but one contender for a sixth taste has begun to stand out from the rest: fat. The growing evidence is intriguing to scientists and food developers, who hope that a better understanding of our perception of fat will have applications in health and obesity management. But that’s far down the road. Currently, the debate is still over whether fat is a taste, and studies are increasingly likely to say that it is. In 2010, for example, researchers at Deakin University in Australia found that people were able to detect the taste of fatty acids. This year, researchers at the Center for Human Nutrition at Washington University School of Medicine in St. Louis said they had discovered that some people may be more sensitive to the presence of fat in foods than others. For the latter study, published in March in the Journal of Lipid Research, 21 people with a body mass index of 30 or more — considered clinically obese — tasted three solutions with a similarly viscous texture and were asked to identify the one that was different. © 1996-2012 The Washington Post

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: 16875 - Posted: 06.05.2012

By Rachel Ehrenberg “Old people smell” is for real — and it isn’t mothballs, Jean Naté or pipe tobacco. It’s a mild and not unpleasant odor compared with the intense, unpleasant smell emitted by 40- to 50-something guys, a new study finds. Scientists don’t know what makes up this vintage chemical fingerprint, but the research suggests that apologies to your grandparents may be in order. The negative association with the smell of the elderly appears to be more about context than scent, says Johan Lundström of the Monell Chemical Senses Center in Philadelphia. Lundström and his colleagues collected underarm odors from 12 to 16 people in each of three age groups: young (20 to 30 years old), middle-aged (45 to 55 years old) and old (75 to 95 years old). For five nights while they slept, the study participants wore T-shirts with breast-feeding pads sewn in the underarms. The shirts and bed linens had been washed with scent-free soap and the participants did the same to themselves before going to bed each night. They also refrained from smoking, drinking alcohol or eating foods that are known to contribute odors to bodily secretions. Evaluators (aged 20 to 30) then sniffed the armpit pads. Evaluators rated the samples on pleasantness and intensity, guessed which of two odors came from the older donor and then labeled all of the scents by age category. The evaluators had trouble discerning young from middle-aged odors. But the odors from old donors were correctly identified more often than would be expected by chance, the research team reports online May 30 in PLoS ONE. © Society for Science & the Public 2000 - 2012

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 13: Memory, Learning, and Development
Link ID: 16860 - Posted: 05.31.2012

By AMANDA SCHAFFER When one fish is injured, others nearby may dart, freeze, huddle, swim to the bottom or leap from the water. The other fish know that their school mate has been harmed. But how? In the 1930s, Karl von Frisch, the famous ethologist, noted this behavior in minnows. He theorized that injured fish release a substance that is transmitted by smell and causes alarm. But Dr. von Frisch never identified the chemical composition of the signal. He just called it schreckstoff, or “scary stuff.” Schreckstoff is a long-standing biological mystery, but now researchers may have solved a piece of it. In a study published in February in Current Biology, Suresh Jesuthasan, a neuroscientist at the Biomedical Sciences Institutes in Singapore, and his colleagues isolated sugar molecules called chondroitins from the outer mucus of zebra fish. They found that when these molecules are broken into fragments, as they might be when the fish’s skin is injured, and added to water, they prompt alarm behavior in other fish. At low concentrations, the fish were “mildly perturbed,” Dr. Jesuthasan said. At high concentrations, they stopped darting altogether and froze in place for an hour or longer. He and his colleagues also showed that neurons in the olfactory bulb of these fish were activated when exposed to the sugar fragments. In a sense, the fish seemed to “smell” the injury. © 2012 The New York Times Company

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: 16852 - Posted: 05.29.2012