Links for Keyword: Chemical Senses (Smell & Taste)

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

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

Tristram Wyatt This Valentine’s Day, like every year, there was a rash of stories in the news about sexy smells and pheromones. You could be forgiven for thinking that human ‘sex pheromones’, in particular the ‘male molecule’ androstadienone, were well established: countless ‘human pheromones’ websites sell it and there are tens of apparently scientific studies on androstadienone published in science journals. These studies are cited hundreds of times and have ended up being treated as fact in books on sexual medicine and even commentary on legislation. The birth place of the pheromone myth was a 1991 conference in Paris sponsored by a US corporation, EROX, which had an interest in patenting androstadienone and another molecule - estratetraenol, from women - as ‘human pheromones’. Unwittingly, leading mammalian olfaction scientists lent the conference credibility. Slotted into the programme and conference proceedings was the short ‘study-zero’ paper on the ‘Effect of putative pheromones on the electrical activity of the human vomeronasal organ and olfactory epithelium’. To my surprise, the authors gave no details at all of how these molecules had been extracted, identified, and tested in bioassays - all routinely required steps in the exhaustive process before any molecule can be shown to be a species-wide chemical signal, a pheromone. Instead there was just a footnote: ‘These putative pheromones were supplied by EROX Corporation’. The missing, essential details were never published. (The claim by EROX-sponsored scientists that adult humans have a functioning vomeronasal organ, against all the evidence, is a story for another day). © 2015 Guardian News and Media Limited

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: 20646 - Posted: 03.04.2015

by Catherine de Lange You won't believe you do it, but you do. After shaking hands with someone, you'll lift your hands to your face and take a deep sniff. This newly discovered behaviour – revealed by covert filming – suggests that much like other mammals, humans use bodily smells to convey information. We know that women's tears transmit chemosensory signals - their scent lowers testosterone levels and dampens arousal in men - and that human sweat can transmit fear. But unlike other mammals, humans don't tend to go around sniffing each other. Wondering how these kinds of signals might be exchanged, Noam Sobel and his colleagues at the Weizmann Institute of Science in Rehovot, Israel turned to one of the most common ways in which people touch each other - shaking hands. "We started looking at people and noticed that afterwards, the hand somehow inadvertently reached the face," says Sobel. To find out if people really were smelling their hands, as opposed to scratching their nose, for example, his team surreptitiously filmed 153 volunteers. Some were wired up to a variety of physiological instruments so that airflow to the nose could be measured without them realising this was the intention. The volunteers were filmed as they greeted a member of the team, either with or without a handshake. The researchers recorded how often the volunteers lifted their hands close to their nose, and how long they kept them there, the minute before and after the greeting. © 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: 20645 - Posted: 03.04.2015

// by Jennifer Viegas It’s long been suspected that males of many species, including humans, can sniff out whether a female is pregnant, and now new research suggests that some — if not all — female primates release a natural “pregnancy perfume” that males can probably detect. What’s more, such scents appear to broadcast whether the mom-to-be is carrying a boy or a girl. The study, published in the journal Biology Letters, focused on lemurs as a model for primates. It presents the first direct evidence in any animal species that a pregnant mother’s scent differs depending on the sex of her baby. The scent signatures “may help guide social interactions, potentially promoting mother–infant recognition, reducing intragroup conflict” or sort out paternity, wrote authors Jeremy Crawford and Christine Drea. The latter presents a loaded scenario, as it could be that males can sense — even before the birth — whether they fathered the baby. The researchers additionally suspect that odors advertising fetal sex may help dads and moms prepare for what’s to come. Crawford, from the University of California, Berkeley, and Drea, from Duke University, used cotton swabs to collect scent secretions from the genital regions of 12 female ringtailed lemurs at the Duke Lemur Center in Durham, N.C., before and during pregnancy. The scientists next used chemical analysis to identify the hundreds of ingredients that make up each female’s scent change during pregnancy. A surprising finding from this is that expectant lemur moms give off simpler scents that contain fewer odor compounds compared with their pre-pregnancy bouquet. The change is more pronounced when the moms are carrying boys, Drea said. © 2015 Discovery Communications, LLC.

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: 20618 - Posted: 02.26.2015

Maanvi Singh Your tongue doubtless knows the difference between a high-fat food and the low-fat alternative. Full-fat ice cream and cream cheese feel silkier and more sumptuous. Burgers made with fatty meat are typically juicer than burgers made with lean meat. OK, so, we've long known fat gives food a desirable texture. But some scientists are now making the case that we should also think of fat as the sixth primary taste, along with sweet, salt, sour, bitter and umami. Early in February, researchers from Deakin University in Australia published a paper in the journal Flavour arguing that "the next 5 to 10 years should reveal, conclusively, whether fat can be classified as the sixth taste." So what would it take for fat to become an official taste? "Strictly speaking, taste is a chemical function," Russell Keast, a sensory scientist at Deakin and lead author of the paper, tells The Salt. He says that when a chemical substance – a salt or sugar crystal, for example — comes into contact with sensory cells in our mouths, it triggers a series of reactions. The cells in our mouths tell other nerve cells that they're perceiving something sweet or salty and those nerve cells eventually pass this information on to the brain. According to the paper, there are five criteria that need to be met to call something a primary taste. It starts with a chemical stimuli (like sugar or salt), which then trigger specific receptors on our taste buds. Then, there has to be a viable a pathway between these receptors and our brains, and we've got to be able to perceive and process the taste in the brain. And finally, this whole process has to trigger downstream effects in the body. © 2015 NPR

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20596 - Posted: 02.21.2015

By Tina Hesman Saey Gustometer guhs-TOH-meh-ter n. A device used to squirt measured amounts of liquids into the mouth of a person in a taste study. Researchers often pair the instrument with brain scanning technology. Recently, a study of wine tasting pitted 10 of the top sommeliers from France and Switzerland against 10 novices. Researchers led by Lionel Pazart of Besançon University Hospital in France custom-built a gustometer to conduct the blind taste test. The scientists compared how brain activity changed when people tasted chardonnay, pinot noir or water. When sipping wine, the experts had greater activity in several parts of their brains, including regions involved in memory, than novices did, the researchers report in October in Frontiers in Behavioral Neuroscience. Sommeliers’ expertise may allow them to process sensory input about a wine — its taste and bouquet — while simultaneously recalling other information, such as the reputation of the winery that produced the beverage. Citations L. Pazart et al. An fMRI study on the influence of sommeliers’ expertise on the integration of flavor. Frontiers in Behavioral Neuroscience Vol. 8, October 16, 2014. doi: 10.3389/fnbeh.2014.00358. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20516 - Posted: 01.26.2015

|By Gareth Cook What is flavor? Beginning with this simple question, the Pulitzer prize-winning journalist John McQuaid weaves a fascinating story with a beginning some half a billion years ago. In his new book, Tasty, McQuaid argues that the sense of taste has played a central role in the evolution of humans. McQuaid’s tale is about science, but also about culture, history and, one senses, our future. What made you decide to write a book about taste? I have two kids, a boy and a girl born two years apart – now teens – and a few years ago, I became fascinated with how their tastes and preferences in food differed. My son liked extremes, especially super-hot chili peppers and whole lemons and limes. My daughter hated that stuff. She preferred bland comfort foods such as mashed potatoes, pasta, cheese and rice. White foods. Both kids were also picky eaters. They liked what they liked, and it didn’t overlap (except for pizza). Speaking as a parent, this was maddening. So I wondered where these differences came from. Were they genetic? The kids had mostly the same genes. Environment? They lived in the same place. And yet clearly both genes and environment were in play somehow. So I began to look into the question, and a whole world opened up. And the basic answer to my original question is: kids are, biologically speaking, weird creatures. Pickiness seems to be programmed by evolution: it would have protected small children from eating strange, possibly poisonous items. Certain preferences, meanwhile, can develop arbitrarily and become very strong, then suddenly fade – every kid goes through phases as the brain matures and the neural networks that shape perception and behavior grow. Each person’s sense of flavor is like a snowflake or a fingerprint, in this way, shaped by partly by genes, but largely by experience. And always changing as more meals are eaten. © 2015 Scientific American

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: 20481 - Posted: 01.14.2015

by Bethany Brookshire Rats stink. First there’s the poop smell and the urine. And then there’s just that smell of rat — a kind of dusty, hairy little smell. But it turns out that rats don’t smell quite the same all the time. When they are stressed, they produce a different odor, one that makes other rats anxious. Now, Hideaki Inagaki and colleagues at the University of Tokyo in Japan have isolated the particular stress-related odor and identified the two specific chemicals behind it. The results reveal the first evidence of an isolated anxiety pheromone in rats, and give reason for scientists to look at — or maybe sniff — their behavioral experiments cautiously. And the findings could also offer glimmerings of a new flavor of rat-be-gone. Pheromones are chemicals that give off distinct odors that allow an animal to communicate within its own ranks. In rats, as in many other animals, many pheromones activate the vomeronasal organ, a small patch of cells at the base of the nasal cavity. Other researchers have found evidence of pheromones in maternal behavior and in the response of rat pups to their mothers. In the new study, the pheromones in question are about alarm and anxiety. Study coauthor Yasushi Kiyokawa of The University of Tokyo says he first came across the alarm odor when he was a graduate student. “I noticed the rats released a specific odor when I handled them for the first time, as they were stressed by the novel handling procedure,” he recalls. He went sniffing to find the source. “I found that the intensity of the odor was strongest around the anal region,” he says. Many mammals have glands around the anus that produce oils and odors. Since that first whiff of a clue, Kiyokawa and colleagues at the University of Tokyo have been working with what they called the “alarm pheromone.” While rats may be smelly to some, Kiyokawa says this particular smell isn’t unpleasant. “Like a hay or dried grass,” he says. “At least for me.” © Society for Science & the Public 2000 - 2014

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: 20443 - Posted: 12.27.2014

By Sandhya Sekar A well-fed female mantis is irresistible to a male. She’s chock-full of eggs and draws him in by producing high levels of pheromones. Now, a new study reveals that starving females can deceive males by enticing them to their doom. Researchers have found that female false garden mantises (Pseudomantis albofimbriata, pictured) that were fed just a quarter of what others got actually produced more pheromones than well-fed females—and attracted almost twice the number of males. This is despite the fact that the number of eggs in the starved females was less than 10, compared with more than 60 eggs in well-fed females. The finding, reported online today in the Proceedings of the Royal Society B, is the first experimental demonstration of sexual deception using false chemical signals in any animal. The starving females seem to be treating the males as easy prey to gain nutritional benefits and potentially produce more eggs. © 2014 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20425 - Posted: 12.18.2014

By Bruce Bower In the movie Roxanne, Steve Martin plays a lovesick guy who mocks his own huge schnoz by declaring: “It’s not the size of a nose that’s important. It’s what’s in it that matters.” Scientists demonstrated the surprising truth behind that joke this year: People can whiff an average of more than 1 trillion different odors, regardless of nose size (SN: 4/19/14, p. 6). No one had systematically probed how many scents people can actually tell apart. So a team led by Leslie Vosshall of Rockefeller University in New York City asked 26 men and women to discriminate between pairs of scents created from mixes of 128 odor molecules. Volunteers easily discriminated between smells that shared as much as 51 percent of their odor molecules. Errors gradually rose as pairs of scents became chemically more alike. Vosshall’s group calculated that an average participant could tell apart a minimum of more than 1 trillion smells made up of different combinations of 30 odor molecules. Really good smellers could have detected way more than 1 trillion odor mixtures, the scientists said. Smell lags behind sight and hearing as a sense that people need to find food, avoid dangers and otherwise succeed at surviving. Still, detecting the faint odor of spoiled food and other olfactory feats must have contributed to the success of Homo sapiens over the last 200,000 years. Perhaps many animals can whiff the difference between a trillion or more smells. For now, odor-detection studies modeled on Vosshall’s approach have been conducted only with humans. © Society for Science & the Public 2000 - 2014.

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: 20417 - Posted: 12.16.2014

By James Gallagher Health editor, BBC News website The brain has specialist neurons for each of the five taste categories - salty, bitter, sour, sweet and umami - US scientists have discovered. The study, published in the journal Nature, should settle years of debate on how the brain perceives taste. The Columbia University team showed the separate taste sensors on the tongue had a matching partner in the brain. The scientists hope the findings could be used to help reverse the loss of taste sensation in the elderly. It is a myth that you taste sweet only on the tip of the tongue. Each of the roughly 8,000 taste buds scattered over the tongue is capable of sensing the full suite of tastes. But specialised cells within the taste bud are tuned to either salty, bitter, sour, sweet or umami tastes. When they detect the signal, a message is sent to the brain. Although how the brain deals with the information has been up for discussion. A team at Columbia University engineered mice so that their taste neurons would fluoresce when they were activated. They then trained their endoscopes on the neurons deep at their base of the brain. The animals were fed chemicals to trigger either a salty, bitter, sour, sweet or umami response on the tongue and the researchers monitored the change in the brain. They found a "hard wired" connection between tongue and brain. Prof Charles Zuker told the BBC News website: "The cells were beautifully tuned to discrete individual taste qualities, so you have a very nice match between the nature of the cells in your tongue and the quality they represent [in the brain]." It scotches the alternative idea that brain cells respond to multiple tastes. BBC © 2014

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: 20295 - Posted: 11.10.2014

by Aviva Rutkin IF DINNER is missing some zing, a spoon studded with electrodes could help. It creates tastes on your tongue with a pulse of electricity. The utensil may add some extra flavour for people who shouldn't eat certain foods. Different frequencies and magnitudes of current through the electrodes can create the impression of saltiness, sourness or bitterness. The spoon was developed by Nimesha Ranasinghe at the New York University Abu Dhabi in the United Arab Emirates and his team, who have also developed a water bottle with similar hardware on the mouthpiece. Both devices use various coloured lights, like blue for salty, in an attempt to augment the perceived intensity of the flavour. "Taste is not only taste. It's a multisensory sensation, so we need smell, colour, previous experiences, texture," says Ranasinghe. "I am trying to integrate different aspects of these sensations." By boosting the flavour of plain foods, he says a tool like this could be useful for people with diabetes or heart issues who have been ordered to cut down on salt and sugar. To see how well the electric utensils could fool diners, 30 people tried them out in a taste test with plain water and porridge. The spoon and bottle were judged 40 to 83 per cent successful at recreating the tastes, depending on which one they were aiming for. Bitter was the hardest sensation to get right. Some testers also said they were distracted by the metallic taste of the electrodes – a pitfall the researchers will work on next. © 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: 20268 - Posted: 11.03.2014

|By Steve Mirsky People have been leaving messages on bathroom walls for thousands of years. Just google “ancient Roman bathroom graffiti.” But we’re not the only ones to use latrines for information exchange—as two German researchers have confirmed after hundreds of hours watching lemurs pee and poop. For science. Primatologists Iris Dröscher and Peter Kappeler concentrated on seven sets of pair-bonded members of a species called white-footed sportive lemurs, at a nature reserve in southern Madagascar. Their report is in the journal Behavioral Ecology and Sociobiology. [Iris Dröscher & Peter M. Kappeler Maintenance of familiarity and social bonding via communal latrine use in a solitary primate (Lepilemur leucopus)] Many animals use the same spots repeatedly to do their business, primates in particular. For these lemurs, a specific tree becomes the urine and feces focal point. And because chemical compounds in their waste transmit information, the so-called latrine tree becomes like a bulletin board to post messages for the rest of the community. Based on their 1,097 hours of observations, the researchers conclude that urine and glandular secretions left on the tree trunk are the primary message vehicles. Feces mostly just collects on the ground. Some urine telegrams are probably signals from a particular lemur to the neighbors that he or she is around. But male lemurs upped their latrine visits when potential competitors for females came into their home area. So the frequent chemical messages left on the tree probably say in that case, “Buzz off, buddy, she’s with me.” In lemur. © 2014 Scientific American,

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 15: Language and Our Divided Brain
Link ID: 20211 - Posted: 10.18.2014

By ALEX STONE Smell is one of the oldest human faculties, yet it was one of the last to be understood by scientists. It was not until the early 1990s that biologists first described the inner workings of olfactory receptors — the chemical sensors in our noses — in a discovery that won a Nobel Prize. Since then, the plot has thickened. Over the last decade or so, scientists have discovered that odor receptors are not solely confined to the nose, but found throughout body — in the liver, the heart, the kidneys and even sperm — where they play a pivotal role in a host of physiological functions. Now, a team of biologists at Ruhr University Bochum in Germany has found that our skin is bristling with olfactory receptors. “More than 15 of the olfactory receptors that exist in the nose are also found in human skin cells,” said the lead researcher, Dr. Hanns Hatt. Not only that, but exposing one of these receptors (colorfully named OR2AT4) to a synthetic sandalwood odor known as Sandalore sets off a cascade of molecular signals that appears to induce healing in injured tissue. In a series of human tests, skin abrasions healed 30 percent faster in the presence of Sandalore, a finding the scientists think could lead to cosmetic products for aging skin and to new treatments to promote recovery after physical trauma. The presence of scent receptors outside the nose may seem odd at first, but as Dr. Hatt and others have observed, odor receptors are among the most evolutionarily ancient chemical sensors in the body, capable of detecting a multitude of compounds, not solely those drifting through the air. “If you think of olfactory receptors as specialized chemical detectors, instead of as receptors in your nose that detect smell, then it makes a lot of sense for them to be in other places,” said Jennifer Pluznick, an assistant professor of physiology at Johns Hopkins University who in 2009 found that olfactory receptors help control metabolic function and regulate blood pressure in the kidneys of mice. © 2014 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 20206 - Posted: 10.14.2014

By David Shultz The next time you see a fruit fly hovering around your pint of beer, don’t swat it—appreciate it. You’re witnessing a unique relationship between yeast and insect. A new study reveals that the single-celled organisms have evolved to secrete a fruity scent that attracts fruit flies, which they hitch a ride on for greener pastures. The findings may also explain the sweet aroma of some craft beers. Like many scientific discoveries, the new work was the product of a happy accident. Kevin Verstrepen, a geneticist at KU Leuven in Belgium, was working with two types of yeast: a normal strain and another with a mutation in a gene called ATF1 that causes the cells to produce fewer odors during fermentation. “Nobody really knew what was happening until I was lazy enough to leave the lab on a Friday with these yeast left out on the bench,” he says. By coincidence, a group of fruit flies (Drosophila melanogaster) chose that weekend to escape from a neighboring genetics lab. When Verstrepen returned to work on Monday, he discovered that the insects had found their way into the smelly yeast culture but had ignored the mutant colony. To probe further, Verstrepen and colleagues set up an enclosed “arena” and pumped ATF1 aromas, which are either fruity, flowery, or solventlike, into one corner. Another corner received a dose of odors from the ATF1-deficient yeast. The remaining two corners emitted odorless streams of air to serve as controls. As expected, the flies congregated almost exclusively in the corner emitting the fragrant odors of yeast with intact ATF1 genes. Analyses of the insects’ brains revealed that the neurons in flies exposed to smelly yeast responded in an entirely different way from those exposed to odorless air or the scent of ATF1-deficient yeast strain, the researchers report online today in Cell Reports. © 2014 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: 20192 - Posted: 10.11.2014

For decades, scientists thought that neurons in the brain were born only during the early development period and could not be replenished. More recently, however, they discovered cells with the ability to divide and turn into new neurons in specific brain regions. The function of these neuroprogenitor cells remains an intense area of research. Scientists at the National Institutes of Health (NIH) report that newly formed brain cells in the mouse olfactory system — the area that processes smells — play a critical role in maintaining proper connections. The results were published in the October 8 issue of the Journal of Neuroscience. “This is a surprising new role for brain stem cells and changes the way we view them,” said Leonardo Belluscio, Ph.D., a scientist at NIH’s National Institute of Neurological Disorders and Stroke (NINDS) and lead author of the study. The olfactory bulb is located in the front of the brain and receives information directly from the nose about odors in the environment. Neurons in the olfactory bulb sort that information and relay the signals to the rest of the brain, at which point we become aware of the smells we are experiencing. Olfactory loss is often an early symptom in a variety of neurological disorders, including Alzheimer’s and Parkinson’s diseases. In a process known as neurogenesis, adult-born neuroprogenitor cells are generated in the subventricular zone deep in the brain and migrate to the olfactory bulb where they assume their final positions. Once in place, they form connections with existing cells and are incorporated into the circuitry.

Related chapters from BP7e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20191 - Posted: 10.11.2014

By Smitha Mundasad Health reporter, BBC News Measuring people's sense of smell in later life could help doctors predict how likely they are to be alive in five years' time, a PLOS One study suggests. A survey of 3,000 adults found 39% with the poorest sense of smell were dead within five years - compared to just 10% who identified odours correctly. Scientists say the loss of smell sense does not cause death directly, but may be an early warning sign. They say anyone with long-lasting changes should seek medical advice. Researchers from the University of Chicago asked a representative sample of adults between the ages of 57-85 to take part in a quick smell test. The assessment involved identifying distinct odours encased on the tips of felt-tip pens. The smells included peppermint, fish, orange, rose and leather. Five years later some 39% of adults who had the lowest scores (4-5 errors) had passed away, compared with 19% with moderate smell loss and just 10% with a healthy sense of smell (0-1 errors). And despite taking issues such as age, nutrition, smoking habits, poverty and overall health into account, researchers found those with the poorest sense of smell were still at greatest risk. Lead scientist, Prof Jayant Pinto, said: "We think loss of the sense of smell is like the canary in the coal mine. BBC © 2014

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: 20149 - Posted: 10.02.2014

By JOSHUA A. KRISCH PHILADELPHIA — McBaine, a bouncy black and white springer spaniel, perks up and begins his hunt at the Penn Vet Working Dog Center. His nose skims 12 tiny arms that protrude from the edges of a table-size wheel, each holding samples of blood plasma, only one of which is spiked with a drop of cancerous tissue. The dog makes one focused revolution around the wheel before halting, steely-eyed and confident, in front of sample No. 11. A trainer tosses him his reward, a tennis ball, which he giddily chases around the room, sliding across the floor and bumping into walls like a clumsy puppy. McBaine is one of four highly trained cancer detection dogs at the center, which trains purebreds to put their superior sense of smell to work in search of the early signs of ovarian cancer. Now, Penn Vet, part of the University of Pennsylvania’s School of Veterinary Medicine, is teaming with the university’s chemistry and physics departments to isolate cancer chemicals that only dogs can smell. They hope this will lead to the manufacture of nanotechnology sensors that are capable of detecting bits of cancerous tissue 1/100,000th the thickness of a sheet of paper. “We don’t ever anticipate our dogs walking through a clinic,” said the veterinarian Dr. Cindy Otto, the founder and executive director of the Working Dog Center. “But we do hope that they will help refine chemical and nanosensing techniques for cancer detection.” Since 2004, research has begun to accumulate suggesting that dogs may be able to smell the subtle chemical differences between healthy and cancerous tissue, including bladder cancer, melanoma and cancers of the lung, breast and prostate. But scientists debate whether the research will result in useful medical applications. © 2014 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: 20063 - Posted: 09.11.2014

|By Jill U. Adams Our noses are loaded with bitter taste receptors, but they're not helping us taste or smell lunch. Ever since researchers at the University of Iowa came to this conclusion in 2009, scientists have been looking for an explanation for why the receptors are there. One speculation is that they warn us of noxious substances. But they may play another role too: helping to fight infections. In addition to common bitter compounds, the nose's bitter receptors also react to chemicals that bacteria use to communicate. That got Noam Cohen, a University of Pennsylvania otolaryngologist, wondering whether the receptors detect pathogens that cause sinus infections. In a 2012 study, his team found that bacterial chemicals elicited two bacteria-fighting responses in cells from the nose and upper airways: movement of the cells' projections that divert noxious things out of the body and release of nitric oxide, which kills bacteria. The findings may have clinical applications. When Cohen recently analyzed bitter taste receptor genes from his patients with chronic sinus infections, he noticed that practically none were supertasters, even though supertasters make up an estimated 25 percent of the population. Supertasters are extra sensitive to bitter compounds in foods. People are either supertasters or nontasters, or somewhere in between, reflecting the genes they carry for a receptor known as T2R38. Cohen thinks supertasters react vigorously to bacterial bitter compounds in the nose and are thus resistant to sinus infections. In nontasters the reaction is weaker, bacteria thrive and sinus infections ensue. These results suggest that a simple taste test could be used to predict who is at risk for recurrent infections and might need more aggressive medical treatment. © 2014 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: 20022 - Posted: 09.02.2014

by Jennifer Viegas Spritzing dogs with a “pig perfume” helps prevent them from barking incessantly, jumping frantically on house guests and from engaging in other unwanted behaviors, according to new research. The eau de oink, aka “Boar Mate” or “Stop That,” was formulated by Texas Tech scientist John McGlone, who was looking for a way to curb his Cairn terrier Toto’s non-stop barking. One spritz of the pig perfume seemed to do the trick in an instant without harming his dog. “It was completely serendipitous,” McGlone, who works in the university’s Animal and Food Sciences department of the College of Agriculture and Natural Sciences, said in a press release. “One of the most difficult problems is that dogs bark a lot, and it’s one of the top reasons they are given back to shelters or pounds.” The key ingredient is androstenone, a steroid and pheromone produced by male pigs and released in their saliva and fat. When detected by female pigs in heat, they seem to find the male more attractive. (The females assume a mating stance.) One can imagine that dogs spritzed with the scent should not hang around amorous female pigs, but other than that, the product seems to work, according to McGlone. Androstenone smells pungent and is not very appealing to humans, but it can have an effect on mammal behavior, he said. © 2014 Discovery Communications, LLC.

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: 19994 - Posted: 08.26.2014