Links for Keyword: Chemical Senses (Smell & Taste)

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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

by Elizabeth Norton Do our brains continue to produce neurons throughout our lifetimes? That's been one of the most hotly debated questions in the annals of science. Since the 1950s, studies have hinted at the possibility, but not until the late 1990s did research prove that the birth of new neurons, called neurogenesis, goes on in the brains of adult primates and humans. Now a surprising new study in humans shows that in the olfactory bulb-the interface between the nose and the brain and an area long—known to be a hot spot of neurogenesis—new neurons may be born but not survive. The finding may rule out neurogenesis in this area, or it might show only that some people don't stimulate their brains enough through the sense of smell, some researchers say. Previous studies have found evidence of neurogenesis in the olfactory bulb of adult humans. But those studies measured only proteins produced by immature neurons, leaving open the question of whether these youngsters ever grew up to connect with other cells to form functional networks, says neuroscientist Jonas Frisén of the Karolinska Institute in Stockholm. If new olfactory neurons really reached adulthood throughout a person's life, researchers should find neurons of a variety of ages in this region. That's not what Frisén and his team saw. The discovery is based on a technique he and his colleague Kirsty Spalding hit upon in 2005, in which they found a clever way to deduce the age of neurons. The method relies on atomic testing carried out in the 1950s and 1960s, which released massive amounts of carbon-14 into the atmosphere; the atmospheric 14C has been steadily declining ever since. Thus, the later a cell is born after this testing, the less 14C it contains. © 2010 American Association for the Advancement of Science.

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: 16844 - Posted: 05.26.2012

By Tina Hesman Saey People may be born with all the smell-sensing brain cells they will ever have, a new study concludes. That makes human brains different from those of rodents, nonhuman primates and other mammals, which constantly make new nerve cells, or neurons, in the odor-processing olfactory bulb. Humans don’t rely on the sense of smell as much as other animals do, so maybe it isn’t surprising that people don’t make new odor-sensing cells, says study author Jonas Frisén, a neuroscientist at the Karolinska Institute in Stockholm. Neurons are born in two areas: a memory-and-learning center called the hippocampus and the subventricular zone, which surrounds the two vacant spaces in the middle of the brain. In mice, neurons from the subventricular zone migrate to the olfactory bulb and wire into neural circuits, helping the animals learn new smells. Some evidence exists already that humans also repopulate their hippocampus with new neurons, but data have been less clear for olfactory neurons. Now, Frisén and colleagues have used the steady decline of radiocarbon produced in 20th century nuclear tests to determine the birth dates of brain cells. The results, published in the May 24 Neuron, show that few if any olfactory neurons are created after a person’s birth. A very small number of neurons may still be born and incorporated in the olfactory bulb, but may not be enough to matter. The researchers calculate that olfactory neurons are replaced at a rate of less than 1 percent per century in humans, compared with about 50 percent annually in rodents. © 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: 16838 - Posted: 05.24.2012

by Mairi Macleod IN ELIZABETHAN England, it was common practice for a maiden to peel an apple, place a slice in her armpit to absorb the smell and then present it to a potential suitor as a memento. Traditional Balkan dancing follows a similar principle. In an activity akin to Morris dancing, but with added odour, men put handkerchiefs in their armpits, work up a sweat by dancing hard and then wave their hankies under the noses of young females. Throughout history and across cultures, body odour has played a key role in attraction, just as it does with many other animals. Yet modern societies tend not to appreciate nature's perfume. Many of us go to considerable lengths to expunge our personal smells and replace them with ones we consider to be more appealing. Instead of apples in our armpits, we have deodorants and perfumes that are marketed as smelling of innocence, vivacity, sophistication or whatever attributes we believe will make us more alluring. Is the multibillion-dollar fragrance industry missing a trick? As we discover which elements of body odour are attractive and to whom, the commercial potential of these chemicals is becoming increasingly apparent. Most people don't want to smell of sweat, but it can only be a matter of time before some components of our natural perfumes are bottled. You might think of yourself as a primarily visual animal, relying little on your sense of smell, but in recent years the idea that olfactory communication is not important in humans has been challenged. © Copyright Reed Business Information Ltd

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: 16793 - Posted: 05.15.2012

By Jennifer Verdolin Typically we think of eavesdropping as a human endeavor. Individually we all do it to a certain degree. Call it social listening, if you will. Sometimes we can’t help but overhear a conversation. Other times we might deliberately try to listen in on what someone else is saying. I remember as a kid putting a cup up against the door to try and hear what was going on behind closed doors. Collectively as nations we eavesdrop on a massive scale, in times of peace and war. Currently, the military spends a considerable amount of money on ‘electronic intelligence’, so much so that there is an entire center devoted to eavesdropping: Menwith Hill in North Yorkshire. We certainly did not invent this strategy of watching or listening in on others. Like most things, we’ve copied it from nature. Eavesdropping is ubiquitous across the animal kingdom. Whenever substantial time or resources are devoted to an activity there is usually a payoff to be found. This got me wondering, what is the payoff for eavesdropping? Several advantages immediately come to mind. For example, perhaps you can increase your access to resources. One way to do this would be to avoid wasting time going after resources that someone else has already used up. This is frequently observed among competitors searching for similar resources. When one thinks of fierce competitors, two stingless bee species may not be the first thing that comes to mind. © 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: 16788 - Posted: 05.14.2012

By Erin Johnson As a woman scientist in the beginning of my career I’m always interested in the journey of more established female scientists: how their interest in science developed, how they’ve overcome challenges to be successful, and how they’ve balanced their goals of establishing a successful career with the desire to have a family. So when I had the opportunity to speak with and interview the Nobel Laureate Dr. Linda Buck during the Frontiers in the Life Sciences symposium, I was immediately intimidated but ultimately excited about speaking to someone who has obtained what many consider to be the most prestigious award in science. What I learned, however, is that Dr. Buck is extremely approachable and an ardent proponent for increasing the representation of women in the life sciences. Additionally, she is a passionate spokeswoman for basic research and gets her motivation and drive, which led to her notable successes, from a true passion for discovery. Dr. Linda Buck was born in Seattle, Washington where at an early age her parents instilled in her a “can-do” attitude, which she credits as a major factor in her road to success. “They taught me to think independently and to be critical of my own ideas, and they urged me to do something worthwhile with my life, to not settle for something mediocre,” says Dr. Buck. She never felt that as a woman she couldn’t achieve the things she set out to do. © 2012 Scientific American,

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: 16698 - Posted: 04.24.2012

By C. CLAIBORNE RAY Q. Are taste buds really divided into sections on the tongue that sense four different flavors? A. Trying to navigate the sense of taste with a map of the tongue labeled with regions sensitive to four kinds of flavor would be like trying to drive cross-country with a map that did not show the Interstate System. “Although there are subtle regional differences in sensitivity to different compounds over the lingual surface, the oft-quoted concept of a ‘tongue map’ defining distinct zones for sweet, bitter, salty and sour has largely been discredited,” according to a review article in The Journal of Cell Biology in August 2010. That map of relative sensitivities, frequently reproduced in textbooks after the researcher Edwin G. Boring sketched it in 1942, neglected the “fifth taste,” called umami, from the Japanese for rich, meaty protein flavors. The outdated map also did not reflect later findings that taste buds, clusters of sensitive cells, have different degrees of sensitivity to molecules carrying more than one basic taste and that these clusters are distributed across the entire surface of the tongue. Recognizing bitterness is thought to protect against bitter poisons; sweet tastes signal sugars and carbohydrates; salty tastes signal sodium compounds and other salts; and sour tastes indicate organic acids. The tongue may also have specialized receptors for fatty flavors, researchers say. © 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: 16544 - Posted: 03.20.2012

Ewen Callaway Many meat-eating animals have lost their ability to taste sugars over the course of evolution. Sea mammals, spotted hyenas and other carnivores have all shed a working copy of a gene that encodes a ‘taste receptor’ that senses sugars, finds a study published this week in the Proceedings of the National Academy of Sciences1. An animal with a diet devoid of vegetables may have little need to detect sugars, says Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia, Pennsylvania, and the lead author of the study. He sees parallels with cave-dwelling fish that have lost their sense of sight. Most mammals, including humans, are equipped with taste receptors that detect salty, sour, sweet, bitter and savoury foods. But past studies suggest that some animals lack certain taste receptors. Felines such as house cats, tigers and cheetahs do not favour sugar water over plain water, for example, and they all possess an identical mutation in a gene called Tas1r2 that renders the sweet-taste receptor inactive2. To see whether other carnivores also lack sweet receptors, Beauchamp and his team collected DNA from 12 members of the order Carnivora, including spotted hyenas, a cat-like creature from Madagascar called a fossa, a civet called a banded linsang and several species of sea mammal. © 2012 Nature Publishing Group

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: 16506 - Posted: 03.13.2012

by Vivien Marx Call it the fish version of instant messaging. When a fish is injured, it secretes a compound that makes other fish dart away (as seen in the latter half of the sped up video above, when the red light flashes). The substance, named Schreckstoff (German for "scary stuff"), protects the entire community of fish, but no one knew how it worked. Now they do, thanks to an analysis of fish mucus reported today in Current Biology. The key ingredient in Schreckstoff is a sugar called chondroitin sulfate, which is found in abundance in fish skin. When the skin is torn, enzymes break the compound down into sugar fragments that activate an unusual class of sensory neurons known as crypt cells in other fish. And the fish take off. © 2010 American Association for the Advancement of Science

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: 16429 - Posted: 02.25.2012

By Ferris Jabr There's a scene in Pixar's Finding Nemo when Dory, a yellow-finned regal tang, injures herself in a tug-of-war over a snorkel mask. A tiny plume of blood curls away from Dory's face into the water around her, where it is sucked into the nostrils of Bruce, a "vegetarian" shark who immediately recants his no-sushi policy. (Fortunately, Dory escapes.) Scientists have known for some time that many ocean predators relish the scent of an injured fish, whereas fish that are more likely to end up as a meal flee from the same scent. Now, researchers think they have pinpointed the key chemical in fish skin that warns nearby fish of danger—a chemical related to a supplement some people take for joint pain. In the 1930s Austrian animal behavior scientist Karl von Frisch accidentally injured a minnow in a tank. He noticed that the other fish in the tank began alternately darting back and forth and freezing in place—classic predator-evading behavior. Subsequent experiments established that the frightened fish were responding to chemicals released from the skin of their injured peer—a cocktail dubbed schreckstoff, which is German for "scary stuff." For decades, the chemistry of schreckstoff remained unknown. In the 1970s and '80s some scientists discovered that exposing fish to a chemical known as hypoxanthine-3-N-oxide (H3NO) frightened them in the same way as schreckstoff, albeit to a lesser degree. H3NO, they concluded, was probably the active compound in schreckstoff. But there was a problem with that idea: scientists had never reliably detected H3NO in fish skin. Instead, some researchers proposed, H3NO may mimic the genuine active compound. © 2012 Scientific American,

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: 16428 - Posted: 02.25.2012

By Victoria Gill Science reporter, BBC Nature Ant colonies - one of nature's most ancient and efficient societies - are able to form a "collective memory" of their enemies, say scientists. When one ant fights with an intruder from another colony it retains that enemy's odour: passing it on to the rest of the colony. This enables any of its nest-mates to identify an ant from the offending colony. The findings are reported in the journal Naturwissenschaften. For many ant species, chemicals are key to functioning as a society. Insects identify their nest-mates by the specific "chemical signature" that coats the body of every member of that nest. The insects are also able to sniff out any intruder that might be attempting to invade. This study, carried out by a team from the University of Melbourne in Australia, set out to discover if ants were able to retain memories of the odours they encounter. The researchers studied the tropical weaver ant (Oecophylla smaragdina), which builds is home in trees; one nest can contain up to 500,000 workers. The team set up a "familiarisation test" to allow ants from one nest to encounter intruders from another. BBC © 2012

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: 16413 - Posted: 02.23.2012

By Adam Hadhazy Love might be in the air on Valentine's Day, metaphorically speaking. But scientists have long debated whether love—or, at least, sexual attraction—is literally in the air, in the form of chemicals called pheromones. Creatures from mice to moths send out these chemical signals to entice mates. And if advertisements about pheromone-laden fragrances are to be believed, one might conclude that humans also exchange molecular come-hithers. Still, after decades of research, the story in humans is not quite so clear. Rather than positing that single, pheromone-esque compounds strike us like Cupid's arrow, investigators now suggest that a suite of chemicals emitted from our bodies subliminally sways potential partnerings. Smell, it seems, plays an underappreciated role in romance and other human affairs. "We've just started to understand that there is communication below the level of consciousness," says Bettina Pause, a psychologist at Heinrich Heine University of Düsseldorf (H.H.U.), who has been studying pheromones and human social olfaction for 15 years. "My guess is that a lot of our communication is influenced by chemosignals." Animals, plants and even bacteria produce pheromones. These precise cocktails of compounds trigger various reactions in fellow members of a species—not all of which are sexual. Pheromonal messages can range from the competitive, such as the "stink fights" of male lemurs, to the collaborative, such as ants laying down chemical trails to food sources. © 2012 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: 16374 - Posted: 02.14.2012

Allie Bidwell, Chronicle Staff Writer For most of his adult life, Michael Berg has suffered from sinus problems that led to strange reactions to the way he smelled and tasted things. Drinking a glass of wine or smoking a cigar, for example, would drastically reduce his sense of smell. He knew that alcohol and smoking could dull the senses, so he thought nothing of it. Then one day in 2005, his sense of smell completely vanished. "Literally one day we were having dinner, and I remember I couldn't smell or taste anything," Berg, 55, said. Experts estimate that about 2 percent of the U.S. population suffers from Berg's condition, a lack of smell known as anosmia. And research by neuroscientists at UC Berkeley provides hope of new therapies for those who have lost their sense of smell, whether due to aging, trauma or a viral infection. In the study published this month in the journal Neuron, the researchers - led by campus neurobiology Professor John Ngai - found a genetic trigger responsible for renewing smell sensors in the nose. That gene, known as p63, tells olfactory stem cells whether to replace themselves or to change into different types of cells. Under normal circumstances, Ngai said, there is a balance between the two outcomes. © 2011 Hearst Communications Inc.

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: 16189 - Posted: 12.27.2011

By Katherine Harmon Weakening eyesight can be sharpened with lenses, and impaired hearing can be improved with aids. What about a failing sense of smell? Detecting and distinguishing the floral bouquet of fresh honey or the miasma of bad lunchmeat might not seem quite as critical for day-to-day existence as sight or hearing. But what the nose knows is clearly important for quality of life. Research has linked this diminution, which is common in people over the age of 60 and can be exacerbated by smoking and some diseases, to loss of appetite and even to depression. Now sufferers might not have to give in to an odorless future, according to a new study, published online Sunday in Nature Neuroscience. Researchers at the New York University Langone Medical Center have found that, with some simple training, over time lab rats could actually improve their brain’s ability to distinguish smells. Without any practice rats could tell when one scent—in a mélange of 10—had been switched for another. (Researchers figured this out by waiting until the rodents were thirsty, then training them to look for water in one of a selection of holes based on what odor combination they had detected.) But their powers of discrimination were not perfect. If a scent was missing from the mix, the rats did not seem to be able to discern it from a full 10-scent combination. Other rats, however, were trained to become extra-familiar with the different combinations through repeated exposures and rewards. “We made them connoisseurs,” co-author Donald Wilson, a professor of psychiatry at NYU Langone, said in a prepared statement. © 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: 16072 - Posted: 11.22.2011

By Rachel Ehrenberg Scientists have finally explained how a little red berry makes just about anything, from the sourest lemon to the bitterest beer, taste as sweet as honey. A protein found in the fruit tickles the tongue’s sweet-sensing machinery, its effects intensifying in the presence of acidic flavors like citrus and carbonated drinks. Researchers and foodies alike have long known the effects of the miracle fruit (a.k.a. Richadella dulcifica). At flavor-tripping parties, guests will pop a berry then chew, chew and chew some more, letting the masticated fruit linger on the tongue. Then the sampling begins: Guinness tastes like a chocolate shake, Tabasco loses its sting and pickles their mouth-pinching tang. Lemons and limes gush with sweetness. While the active ingredient in miracle fruit — miraculin — has been known for decades, it hasn’t been clear exactly how the protein confers its sweetness. Now scientists in Japan and France report that miraculin’s interaction with the tongue’s sweet sensors depends on the acidity of the local environment. At a pH of 4.8 (water is neutral with a pH close to 7), the sweet-tasting cells respond twice as vigorously to miraculin than they do at a less acidic pH of 5.7. At closer-to-neutral pH levels of 6.7 and higher, the protein seems to slightly shift shape, blocking the sweet sensors but not activating them. This explains why under certain conditions sweet foods may taste less flavorful after eating the berry, researchers led by Keiko Abe of the University of Tokyo report online September 26 in the Proceedings of the National Academy of Sciences. © Society for Science & the Public 2000 - 2011

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: 15853 - Posted: 09.29.2011

By Nick Bascom Even the inside of the nose can be a little cliquish. Like birds of a feather, nasal molecules that respond to pleasant smells flock together, keeping their distance from sensor molecules that pick up unpleasant smells. Sensor molecules, or receptors, appear to be organized according to the pleasantness (or unpleasantness) of the odors they sense, a new study finds. For example, locations in the nose that respond strongly to one fragrant aroma will respond strongly to other delectable smells. Patches of nasal surfaces that process putrid stenches also handle specific sorts of smells and leave the rest of the work to someone else, Noam Sobel of the Weizmann Institute of Science in Rehovot, Israel and colleagues reported online September 25 in Nature Neuroscience. The researchers inserted an electrode into 16 subjects’ noses and then showered the volunteers with six different scents. Because certain odors provoked stronger responses at different locations in the nose, the research team was able to confirm previous evidence suggesting a variegated nasal receptor surface. “We’re not the first to find that,” says Sobel. But he and his colleagues have added an important new wrinkle. “Not only are the receptors organized in patches, but the axis that best describes their organization is pleasantness.” This discovery sheds new light on a relatively poorly studied sensory organ. Compared with eyes or ears, scientists don’t know much about how the nose works. © Society for Science & the Public 2000 - 2011

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: 15837 - Posted: 09.26.2011