Links for Keyword: Chemical Senses (Smell & Taste)

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Nicola Nosengo If you are a small animal, it is useful to know whether there is anything around that might want to eat you. Stephen Liberles from Harvard Medical School in Cambridge, Massachusetts, and his colleagues have analysed urine samples from a variety of zoo inhabitants, including lions and bears, and discovered how rodents can use smell to do just that. In a research published today in the Proceedings of the National Academy of Science, the team identifies a chemical found in high concentrations in the urine of carnivores that makes mice and rats run for cover1. Chemicals have already been identified that allow prey to recognize a known predator. But this is the first example of a generic clue that allows an animal to detect any potential predator, irrespective of whether the two species have ever come into contact. The researchers started by analysing an engimatic group of olfactory receptors discovered in 2001 called trace amine-associated receptors (TAARs)2. They are found in most vertebrates, in varying numbers. Mice, for example, have 15, rats 17 and humans have just 6. Very little is known about what chemicals bind to them. Liberles and his colleagues found that one member of the receptor family, TAAR4, is strongly activated by bobcat urine, which is sold online and used by gardeners to keep rodents and rabbits away. They managed to extract the molecule responsible for activating the receptor, called 2-phenylethylamine. © 2011 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: 15468 - Posted: 06.21.2011

By Jennifer Welsh WASHINGTON — Suit pressed, mind ready and resume in hand. When preparing for a job interview, most people take every precaution to convey the best impression possible. But aside from body odor, not many people pay attention to the odors that surround them. That onion-laden lunch could give your potential boss-to-be the wrong impression, according to new research presented in May at the Association for Psychological Science annual meeting. "There's a lot of research that's begun now, where people are looking at how the environment affects our well-being," said Jeannette Haviland-Jones, of Rutgers University in New Jersey. "We tend to think of ourselves as separate from the environment, but we're not. We create our environment." Hers and others' research is showing that smell can influence our thoughts and behaviors more expected. Many things in the environment, including verbal and physical cues, can influence how we perceive others. New research presented by Nicole Hovis and Theresa White of Le Moyne College in Syracuse, N.Y., shows that certain smells can influence a first impression. They asked 65 volunteer undergraduates (who were mostly female) to sniff a vial holding either a lemon or onion scent, or no scent, while standing near a gender-neutral silhouette. They were asked to form an impression of the personality of the silhouette and later filled out a form rating several personality traits. © 2011 LiveScience.com

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: 15461 - Posted: 06.20.2011

By NICHOLAS BAKALAR Ants called Pseudomyrmex triplarinus live inside the leaves and trunk of Triplaris americana trees, where they take shelter and eat sugars, fats and proteins supplied by the tree. In return, they bite animals that try to eat the trees’ leaves, and they prune away plants that grow near them. Now researchers have figured out one way in which they can distinguish a foreign plant from their own. A study showed that Pseudomyrmex triplarinus ants were able to recognize extract from different types of trees independent of the shape or texture of the material that carried it. The scientists, working in Peru, found that the ants consistently pruned foreign seedlings that sprouted near their tree. They also removed 80 to 100 percent of foreign leaves experimentally pinned to the trunk, compared with only 10 to 30 percent of T. americana leaves. Then the investigators treated identical strips of filter paper with leaf wax extracts from T. americana; with extracts from T. poeppigiana, a closely related species; or with plain solvents as a control. The ants attacked the control strips more often than the T. poeppigiana, and the T. poeppigiana more often than the T. americana strips. This suggests the ants could, to a significant degree, recognize the extract independent of the shape or texture of the material that carried it. © 2011 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 15327 - Posted: 05.14.2011

By Bonnie Berkowitz, Black coffee. Hot peppers. Truffles. Oysters. The world is full of polarizing flavors and foods, beloved by many, despised by just as many. Why is that? Scientists have untangled some — but not nearly all — of the mysteries behind our love and hatred of certain foods. While we might say, “That tastes like strawberry,” scientists who study these things would disagree. Our tongues actually perceive only five basic tastes: sweet, sour, bitter, salty and “umami,” the Japanese word for savory. To go from merely sweet to “Mmm, strawberry!” the nose has to get involved. The taste and olfactory senses, along with any chemical irritation a food creates in the throat (think mint, hot pepper or olive oil), all send the brain the information it needs to distinguish flavors. “We as primates are born liking sweet and disliking bitter,” said Marcia Pelchat, who studies food preferences at the Monell Chemical Senses Center in Philadelphia. The theory is that we’re hard-wired to like and dislike certain basic tastes so that the mouth can act as the body’s gatekeeper. Sweet means energy; sour means not ripe yet. Savory means food may contain protein. Bitter means caution, as many poisons are bitter. Salty means sodium, a necessary ingredient for several functions in our bodies. (By the way, those tongue maps that show taste buds clumped into zones that detect sweet, bitter, etc.? Very misleading. Taste receptors of all types blanket our tongues — except for the center line — and some reside elsewhere in our mouths and throats.)

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: 15269 - Posted: 04.28.2011

By Steve Mirsky All seemed well that morning when the rains came. I was warm and dry and didn’t need to leave the comfort of home. But that comfort swiftly departed. First, I heard the glug glug glug. Then I picked up a whiff both faint and foul. Something was entering the bathroom that should only exit the bathroom—raw sewage was reversing its natural course and fighting its way back into my house. The whiffs got stronger. Human waste includes some fascinating and fragrant organic compounds. Take skatole. (Please.) Skatole bears a heavy responsibility for making poo smell phooey. But remember the axiom: it’s the dose that makes the poison. Because in low concentrations, according to Wikipedia, skatole “has a flowery smell and is found in several flowers and essential oils,” such as orange blossoms and jasmine. It is even used—again, in very small amounts—in perfumes. Think about that when dabbing behind the ears. And Wikipedia notes that cigarette manufacturers add skatole as (drum roll) a flavoring ingredient. Just another reason to stop smoking. In addition, waste contains various stinky sulfur compounds, collectively called thiols or mercaptans. They are not your friends. When sewage is backing up into one’s home, the to-do list instantly becomes an un-doo list with only one item: get the plumbers to come immediately. Upon their swift arrival, they unsealed the trap to gain access to the line, which also sent the incoming waste fluid into the subbasement—still bad, but a big improvement. They then sent a camera down the line to examine the problem, performing their version of the closely related diagnostic technique of colonoscopy. © 2011 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: 15257 - Posted: 04.23.2011

(HealthDay News) -- A hormone called ghrelin enhances the nose's ability to sniff out food, researchers report. It was already known that ghrelin promotes hunger and fat storage. The new study suggests that the hormone may increase the ability to use smell to detect food and link that input with the body's natural regulation of metabolism and body weight, said University of Cincinnati scientists. Click here to find out more! The study, which included experiments with humans and rats, appears in the April 13 issue of the Journal of Neuroscience. It was led by Dr. Jenny Tong and Dr. Matthias Tschop, both of the university's endocrinology, diabetes and metabolism division. "Smell is an integral part of feeding, and mammals frequently rely on smell to locate food and discriminate among food sources. Sniffing is the first stage of the smell process and can enhance odor detection and discrimination," Tong said in a university news release. "Other studies have shown that hunger can enhance odor detection and sniffing in animals," Tschop added in the release. "Since ghrelin is a hunger-inducing stomach hormone that is secreted when the stomach is empty, this hormone pathway may also be responsible for the hunger-induced enhancement of sniffing and odor detection." The researchers plan further research to identify the exact molecular pathways through which ghrelin affects sniff behavior. © 2011 HealthDay.

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: 15209 - Posted: 04.14.2011

by Rachel Courtland How does a nose generate the signals that the brain registers as smell? The conventional theory says it's down to the different shapes of smelly molecules. But fruit flies have now distinguished between two molecules with identical shapes, providing the first experimental evidence to support a controversial theory that the sense of smell can operate by detecting molecular vibrations. The noses of mammals, and the antennae of flies, are lined with different folded proteins that form pocket-shaped "receptors". It has been generally assumed that a smell arises when an odour molecule slides into a receptor like a key in a lock, altering the receptor's shape and triggering a cascade of chemical events that eventually reach the brain. But this "shape" theory has limitations. For one, it can't easily explain why different molecules can have very similar smells. In 1996, Luca Turin, a biophysicist now at the Massachusetts Institute of Technology, proposed a solution. He revived a theory that the way a molecule vibrates can dictate it odour, and came up with a mechanism to explain how this might work. His idea was that electrons might only be able to pass across a receptor if it was bound to a molecule that vibrated at just the right frequency. Ordinarily, the energy needed for the electron to make this journey would be too great, but the right vibrational energy could prompt a quantum effect in which the electron "tunnels" through this energy barrier, and this would then be detected and registered as a particular smell (see diagram). © 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: 15001 - Posted: 02.15.2011

by Kirsten Weir 1 Remember the tongue map you learned about in junior high—the one showing taste receptors for sweet flavors on the tip of the tongue, bitter in the back, and sour on the sides? It’s totally wrong. 2 That bogus map came from an English mistranslation of a German research paper. 3 In truth, any area can pick up any taste (although sensitivity does vary across the tongue). 4 We all know about sweet, salty, sour, and bitter. Less widely known is the fifth taste: umami, that savory flavor of soy sauce, tomatoes, and many other foods high in glutamate. 5 Go with your gut: Japanese scientists recently identified umami receptors not only on the tongue but throughout the digestive tract. Their role in digestion and nutrition remains a mystery. 6 Those bumps on your tongue aren’t actually your taste buds. They are fungiform papillae—“mushroom-shaped nipples,” to any Latin speakers out there—and each houses 50 to 100 buds. 7 Scientists believe there are only a few receptor types each for sweet, sour, salty, and umami. But there are a lot more for bitter (at least 25), as anyone paying alimony is probably aware. © 2011, Kalmbach Publishing Co.

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: 14989 - Posted: 02.12.2011

In 2004, American neuroscientists Linda Buck and Richard Axel shared a Nobel Prize for their identification of the genes that control smell, findings which they first published in the early 1990s. Their work revived interest in the mysterious workings of our noses, interest which is now generating some surprising insights – not least that each of us inhabits our own, personal olfactory world. "When I give talks, I always say that everybody in this room smells the world with a different set of receptors, and therefore it smells different to everybody," says Andreas Keller, a geneticist working at the Rockefeller University in New York City. He also suspects that every individual has at least one odorant he or she cannot detect at all – one specific anosmia, or olfactory "blind spot", which is inherited along with his or her olfactory apparatus. The human nose contains roughly 400 olfactory receptors, each of which responds to several odorants, and each of which is encoded by a different gene. But, says Boris Schilling, a biochemist working for Givaudan, the world's largest flavour and fragrance company, based in Geneva, Switzerland, "unless you are dealing with identical twins, no two persons will have the same genetic make-up for those receptors." The reason, according to Doron Lancet, a geneticist at the Weizmann Institute of Science in Israel, is that those genes have been accumulating mutations over evolution. This has happened in all the great apes, and one possible explanation is that smell has gradually become less important to survival, having been replaced to some extent by colour vision – as an indicator of rotten fruit, for example, or of a potentially venomous predator. ©independent.co.uk

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: 14906 - Posted: 01.24.2011

By Laura Spinney Scientists have long known that people perceive scents differently. But emerging evidence from several large-scale studies shows that the variation is larger than previously known. It turns out that people differ in how they perceive many if not all odors, and most of us have at least one scent we cannot detect at all. “Everybody’s olfactory world is a unique, private world,” says Andreas Keller, a geneticist at the Rockefeller University. Over the course of evolution, partly because humans grew more reliant on vision and smell became relatively less important, the genes encoding our 400 or so olfactory receptors began to accumulate mutations. Once a gene has accumulated enough mutations, it becomes a “pseudogene,” notes geneticist Doron Lancet of Israel’s Weizmann Institute of Science, meaning it no longer encodes a functioning receptor. Different people have different combinations of pseudogenes, however. “You end up with a bar code situation, whereby each individual has a slightly different bar code,” he says. That genetic variability seems to translate into behavioral variability. When Keller and his colleagues asked 500 people to rate a panel of 66 odors for intensity and pleasantness, they gave the full range of responses—from weak to intense and from pleasant to unpleasant. In an ongoing study at the University of Dresden, Thomas Hummel and his associates have tested 1,500 young adults on a panel of 20 odors and found specific insensitivities to all but one—citralva, which has a citrus smell. Based on these findings, Keller suspects that each person has an olfactory blind spot. © 2011 Scientific American, a Division of Nature America, Inc.

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: 14896 - Posted: 01.21.2011

By Rachel Ehrenberg A nip of Pernod or Ouzo before dinner to stimulate the appetite may be a sound strategy. When mouse gut cells are stimulated with bitter compounds they trigger secretion of a hunger hormone, researchers report online January 18 in the Proceedings of the National Academy of Sciences. Whetting the appetite with a before-dinner drink, or aperitif — from the Latin aprire, to open — has long been associated with improved digestion. The often bitter drinks typically contain a secret mixture of herbs and spices, sometimes to deliberately quell the taste of another common aperitif ingredient — quinine. Quinine is one of a number of compounds that stimulate the bitter taste receptors — cells that, in the mouth, are seen as a first line of defense against ingesting toxins. So scientists thought that eating such compounds would inhibit appetite, not rev it up. But when mice were fed a bitter mixture, their levels of the hunger hormone ghrelin spiked, a research team from the Catholic University of Leuven in Belgium reports. These mice then went on a half-hour eating binge, unlike counterparts that had impaired machinery for sensing bitter compounds. Oddly, this binge was followed by several hours of fasting, and experiments revealed a delay in digestion of the large meal. © Society for Science & the Public 2000 - 2011

Related chapters from BP7e: Chapter 13: Homeostasis: Active Regulation of the Internal Environment; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 9: Homeostasis: Active Regulation of the Internal Environment; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 14894 - Posted: 01.21.2011

By Bruce Bower Crying women may literally turn men off. Odorless chemical signals in a woman’s waterworks lessen any stirrings of sexual interest in a guy who whiffs her tear-stained cheeks, a new study suggests. In a paper published online January 6 in Science, a team led by neuroscientists Shani Gelstein and Noam Sobel of the Weizmann Institute of Science in Rehovot, Israel, presents the first evidence that human tears contain pheromones, substances that influence behavior via smell. “Our experiments suggest that women’s emotional tears contain a chemosignal that reduces sexual arousal in men,” Sobel says. Chemical compounds in tears that douse men’s desire have yet to be identified. “This new report makes a strong case for pheromones in women’s tears, but the results clearly warrant replication,” comments neuroscientist Robert Provine of the University of Maryland Baltimore County. The reasons why people, but not any other animal, cry at sad thoughts or events remain poorly understood. Tears provide key visual cues to a person’s inner emotional distress, Provine says. In a 2009 study that he directed, men and women rated the faces of crying people with visible tears as much sadder than the same faces digitally altered to remove tears. Tear removal made faces appear emotionally ambiguous, with participants saying that awe, concern or puzzlement often outweighed sadness. © Society for Science & the Public 2000 - 2011

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: 14842 - Posted: 01.07.2011

By Laura Sanders A rose sniffed through a snotty nose may not smell so sweet. Enzymes in mice’s nasal mucus transform certain scents before the nose can detect them, a new study finds. The results, published December 1 in the Journal of Neuroscience, show that lowly mucus may feature prominently in the sense of smell. “It is completely unexpected that snot would play a potential role in changing how we perceive odors,” says neuroscientist Leslie Vosshall at Rockefeller University in New York City. “Most people and most scientists pay no attention at all to mucus.” But there’s more to mucus than what meets the nose: The thick goo that serves to lubricate the nose is teeming with proteins and protein-chopping enzymes. Some of these molecules are thought to catch smells and shuttle them to odor receptors in the nose. Other components may protect the body from toxic chemicals by chopping them up into less harmful pieces. But no one knew whether this chopping action had any effect on smell perception. In the new study, Ayumi Nagashima and Kazushige Touhara of the University of Tokyo added particular odorants to tiny amounts of mucus sucked out of a mouse’s nose and tested the resulting chemical composition of the mix. After five minutes of sitting in mucus, about 80 percent of almond-smelling benzaldehyde was converted into benzyl alcohol (a scent found in some teas and plants) and the odorless benzoic acid. Inactive enzymes in boiled mucus couldn’t do this odor conversion, the team found. © Society for Science & the Public 2000 - 2010

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: 14725 - Posted: 12.02.2010

By Wynne Parry, A group of scientists has genetically altered mice so they could "smell" light. That is their neurons responded to light in the same way they would to an odor. This allowed them to study the brain's response without having to deal with the complications associated with smelling. The approach the scientists used to help the mice "smell" the light is called optogenetics. The method uses light to control actions within other specific cells and is broadly applicable. The noses of mice (and humans) are chock-full of sensory neurons that respond to scent molecules that waft by. That odor information gets sent to the olfactory bulb, a part of the brain above the nasal cavities, where the sensory neurons meet up with relay neurons. These two types of neurons then meet within structures called glomeruli. "If you look at two cells receiving input from the same glomerulus, are they just passing it on [in] the same way, or is there something more to it?" said study researcher Venkatesh Murthy from Harvard University, who collaborated with others at Harvard, Cold Spring Harbor Laboratory and in India. A mouse has about 200,000 relay cells, with between 60 and 100 connected to each glomerulus, or hub. Identifying pairs of relay cells that connect to the same glomerulus is difficult, because when a rodent catches a whiff of something, multiple glomeruli go into action, according to Graeme Lowe, a neuroscientist at the independent Monell Chemical Senses Center who was not involved in the research. © The Christian Science Monitor

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 7: Vision: From Eye to Brain
Link ID: 14609 - Posted: 11.01.2010

By Rachel Ehrenberg Inhaling a blast of bitter fumes sends a breathe-easy message to the lungs, a new study shows. Stimulating bitterness receptors in the lungs relaxes and opens the airways, a counterintuitive finding that could lead to new asthma medications, scientists report online October 24 in Nature Medicine. Bitter-taste receptors just like the ones on the tongue abound on the smooth muscle tissue that wraps around the airway tubes leading to the lungs, reports a team from the University of Maryland and Johns Hopkins in Baltimore. In mice bred to have asthma, inhaled bitter compounds such as quinine did a better job of relaxing airways than did the standard asthma drug albuterol. These bitter-taste receptors in lung muscles should be good targets for new asthma medications that are based on the multitude of molecules known to stimulate bitter receptors, says Mathur Kannan, a pharmacologist in the College of Veterinary Medicine at the University of Minnesota in St. Paul. The relaxation response to bitter-flavored air remains somewhat puzzling. In the mouth, bitter receptors are part of the body’s first line of defense against possibly poisonous compounds. Cells lining the upper part of the respiratory tract also have bitter-taste receptors, scientists reported earlier this year. But there, they can trigger an “out, out” reaction, stimulating the featherlike cilia of the airways to push whatever’s nearby up and away. So it seemed more logical that muscles controlling air flow to lungs would constrict when stimulated by potential toxins, says Stephen Liggett of the University of the Maryland School of Medicine in Baltimore, who led the new work. © Society for Science & the Public 2000 - 2010

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: 14586 - Posted: 10.26.2010

by Paul Marks How do you give a robot a sharper sense of smell? By using genetically modified frog cells, according to Shoji Takeuchi, a bioengineer at the University of Tokyo in Japan. Today's electronic noses are not up to the job, he says. Although e-noses have been around for a while – and are used to sniff out rotten food in production lines – they lack accuracy. That's because e-noses use quartz rods designed to vibrate at a different frequency when they bind to a target substance. But this is not a foolproof system, as subtly different substances with similar molecular weights may bind to the rod, producing a false positive. Instead, Takeuchi believes there is nothing quite as good as biology for distinguishing between different biomolecules, such as disease markers in our breath. So he and his team have developed a living smell sensor. First, immature eggs, or oocytes, from the African clawed frog Xenopus laevis were genetically modified to express the proteins known to act as smell receptors. He chose X. laevis cells as they are widely studied and their protein expression mechanism is well understood. © 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: 14390 - Posted: 08.24.2010

By Jason Palmer Research has shown that bacteria - among the simplest life forms on Earth - have a sense of smell. Scientists from Newcastle University in the UK have demonstrated that a bacterium commonly found in soil can sniff and react to ammonia in the air. It was previously thought that this "olfaction" was limited to more complex forms of life known as eukaryotes. The finding, published in Biotechnology Journal, means that bacteria have four of the five senses that humans enjoy. The discovery also has implications in the understanding and control of biofilms - the chemical coatings that bacteria can form on, for example, medical implants. Bacteria have already demonstrated the ability to react to light, in analogy to sight, and to change the genes that they express when confronted with certain materials, in analogy to touch. However, there is a distinction between an organism reacting to a chemical that it encounters directly (in analogy to the sense of taste) and a reaction to a chemical that is floating around in the air, says Reindert Nijland, lead author of the study. "The difference is both in the mechanism that does the sensing, as well as in the compounds that are sensed," Dr Nijland, now at University Medical Centre Utrecht in the Netherlands, told BBC News. "The compounds detected by olfactory organs are generally much more volatile than things you can taste like 'sweet' or 'salt', and therefore can provide information about things that can be much further away; you can smell a barbecue from a few blocks away whereas you have to physically touch and eat the steak to be able to actually taste it." (C)BBC

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: 14363 - Posted: 08.16.2010

By Susan Milius WILLIAMSBURG, Va. — Putting a female lemur on birth control turns her normally informative scents to nonsense, researchers report. Doses of Depo-Provera, a common contraceptive for people, shift the odor secretions of female lemurs so dramatically that their scents no longer give clear cues to kinship, identity and genetic quality, says study coauthor Christine Drea of Duke University in Durham, N.C. A female lemur whose hormones are disrupted by contraceptives may have real trouble attracting a compatible mate, Drea said July 26 at the annual meeting of the Animal Behavior Society. As for people, men and women might not think they’re influenced by each others’ scents, but “Oh, we are!” said behavioral biologist Susan Jenks of the Sage Colleges in Troy, N.Y., after Drea’s presentation. If women react to the hormones the way lemurs do, “maybe you don’t want to be on contraceptives when you’re picking your mate.” Also, said behavioral ecologist Jill Mateo of the University of Chicago, “For any zoo that is chemically contracepting animals, this could have big implications.” Drea and her colleagues have identified more than 300 compounds in the scent secretions of female lemurs. “There is a rich communication system,” she said. Glands on the forelimbs, tail and other parts of the body secrete chemical cues that the lemurs rub onto branches or other community bulletin boards, where neighbors sniff out the news. © Society for Science & the Public 2000 - 2010

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: 14301 - Posted: 07.29.2010

By Matt Walker Bowhead whales have a previously undiscovered ability to smell the air. The finding could change our understanding of how baleen whales locate prey, as scientists suspect the bowhead whales sniff out krill swarms. The whales' sense of smell was revealed when scientists dissected their bodies and found olfactory hardware linking the brain and nose, and functional protein receptors required to smell. Previously, whales and dolphins were thought to lack the ability. Details are published in the journal Marine Mammal Science. Cetacean expert Professor Hans Thewissen of the Northeastern Ohio Universities College of Medicine and colleagues based in Japan and Alaska made the discovery while evaluating the brain size of bowhead whales. The whales had been landed as part of the biannual Inupiat subsistence hunt along the north coast of Alaska, and Prof Thewissen's team was allowed to dissect the brain cavities, to evaluate how much of the brain casing a bowhead whale's brain actually fills. "Upon taking a brain out, I noticed that there were olfactory tracts, which, in other mammals, connect the brain to the nose," Prof Thewissen told the BBC. "I followed those to the nose, and noted that all the olfactory hardware is there." BBC © MMX

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 14293 - Posted: 07.27.2010

When a person loses his sense of smell, does he also lose any memory associated with a smell? —Ana Artega, via e-mail David Smith, a professor of psychology and a researcher at the Center for Smell and Taste at the University of Florida, replies: Normally people can detect a cacophony of odors using the 40 million olfactory receptor neurons that reside in the nasal cavity. When we encounter a new odor, these neurons send information about the whiff to a brain area called the olfactory cortex, leaving an imprint of the smell there. These memories accumulate over time to create a library of odors. Although we do not fully understand how the olfactory cortex encodes these memories, we do know that olfactory memories seem to be particularly rich—perhaps because the olfactory cortex is closely connected to the brain regions im­­portant for recollection. These areas include the amygdala, which processes emotions, and the hippocampus, which encodes and stores memories. Damage to the olfactory receptor neurons because of a respiratory infection, a head injury or a neurodegenerative disease can disrupt the brain’s ability to process different smells. When olfactory neurons stop working altogether, a person develops anosmia, or the inability to discern odors. According to a 2008 report from the National Institutes of Health, 1 to 2 percent of the U.S. population younger than 65 years old, and more than half older than 65, have almost completely lost their sense of smell. © 2010 Scientific American,

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: 14255 - Posted: 07.13.2010