Links for Keyword: Chemical Senses (Smell & Taste)

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Shawna Williams The sensation of perceiving a smell can be induced in people by using electrodes to stimulate the brain’s olfactory bulb, researchers report today (November 27) in the International Forum of Allergy & Rhinology. The results, they suggest, are a proof of concept that it would be possible to develop an “olfactory implant system” to aid people with an impaired sense of smell, known as anosmia. “Our work shows that smell restoration technology is an idea worth studying further,” says coauthor Eric Holbrook of Massachusetts Eye and Ear Infirmary in a press release. “The development of cochlear implants, for example, didn’t really accelerate until someone placed an electrode in the cochlea of a patient and found that the patient heard a frequency of some type.” Holbrook and colleagues enrolled five subjects in the study who were able to smell. Three of them reported perceiving odors not actually present when the researchers stimulated different parts of their olfactory bulbs with electrodes inserted through the nose, a procedure the study authors say caused “minimal discomfort.” Subjects described the smells as “onion-like,” “antiseptic-like,” “sour,” “fruity,” or simply “bad.” The finding follows a report earlier this year that electrically stimulating structures high up in the nasal cavity produced smell sensations. The scientists who conducted that study at Malaysia’s Imagineering Institute aim to one day transmit smells electronically, reportes IEEE Spectrum—for example, to give restaurant-goers a whiff of dishes on the menu as they decide what to order. © 1986 - 2018 The Scientist

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 25726 - Posted: 11.29.2018

Tina Hesman Saey Whether people prefer coffee or tea may boil down to a matter of taste genetics. People with a version of a gene that increases sensitivity to the bitter flavor of caffeine tend to be coffee drinkers, researchers report online November 15 in Scientific Reports. Tea drinkers tended to be less sensitive to caffeine’s bitter taste, but have versions of genes that increase sensitivity to the bitterness of other chemicals, the researchers found. It’s long been thought that people avoid eating bitter foods because bitterness is an indicator of poison, says John Hayes, a taste researcher at Penn State who was not involved in the study. The coffee and tea findings help challenge that “overly simplistic ‘bitter is always bad, let’s avoid it’” view, he says. In the new study, researchers examined DNA variants of genes involved in detecting the bitter taste of the chemicals, caffeine, quinine — that bitter taste in tonic water — and propylthiouracil (PROP), a synthetic chemical not naturally found in food or drink. Other bitter components naturally in coffee and tea may trigger the same taste responses as quinine and PROP do, Hayes says. Researchers in Australia, the United States and England examined DNA from more than 400,000 participants in the UK Biobank, a repository of genetic data for medical research. Participants also reported other information about their health and lifestyle, including how much tea or coffee they drink each day. |© Society for Science & the Public 2000 - 2018

Related chapters from BN8e: 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: 25693 - Posted: 11.16.2018

Susan Milius It’s a lovely notion, but tricky to prove. Still, lemurs sniffing around wild fruits in Madagascar are bolstering the idea that animal noses contributed to the evolution of aromas of fruity ripeness. The idea sounds simple, says evolutionary ecologist Omer Nevo of the University of Ulm in Germany. Plants can use mouth-watering scents to lure animals to eat fruits, and thus spread around the seeds. But are those odors really advertising, or are they just the way fruits happen to smell as they ripen? For some wild figs and a range of other fruits in eastern Madagascar, a strong scent of ripeness does seem to have evolved in aid of allure, Nevo and his colleagues argue October 3 in Science Advances. A lot of fruit collecting and odor chemistry suggest that fruits dispersed by lemurs, with their sensitive noses, change more in scent than fruits that rely more on birds with acute color vision. Earlier studies had sniffed around several species, such as figs. But for a broader look, Nevo and his colleagues analyzed scents from 25 other kinds of fruits as well as five kinds of figs. All grew wild in a “really magnificent” mountainous rainforest preserved as a park in eastern Madagascar, Nevo says. The researchers classified 19 of the plants as depending largely on red-bellied and other local lemurs to spread seeds. Most of these lemurs are red-green color-blind, not great for spotting the ripe fruits among foliage. But the researchers following some lemurs foraging in daylight noticed that sniffing at fruits was a big deal for the primates. |© Society for Science & the Public 2000 - 2018

Related chapters from BN8e: 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: 25528 - Posted: 10.04.2018

Imagine the foul smell of an ash tray or burning hair. Now imagine if these kinds of smells were present in your life, but without a source. A new study finds that 1 in 15 Americans (or 6.5 percent) over the age of 40 experiences phantom odors. The study, published in JAMA Otolaryngology-Head and Neck Surgery (link is external), is the first in the U.S. to use nationally representative data to examine the prevalence of and risk factors for phantom odor perception. The study could inform future research aiming to unlock the mysteries of phantom odors. The study was led by Kathleen Bainbridge, Ph.D., of the Epidemiology and Biostatistics Program at the National Institute on Deafness and Other Communication Disorders (NIDCD), part of the National Institutes of Health. Bainbridge and her team used data from 7,417 participants over 40 years of age from the 2011-2014 National Health and Nutrition Examination Survey (NHANES) (link is external). The NHANES data were collected by the National Center for Health Statistics, which is part of the Centers for Disease Control and Prevention; data collection was partly funded by the NIDCD. Donald Leopold, M.D., one of the study’s authors and clinical professor in the Department of Surgery at University of Vermont Medical Center, Burlington, adds that patients who perceive strong phantom odors often have a miserable quality of life, and sometimes cannot maintain a healthy weight. The ability to identify odors tends to decrease with age. Phantom odor perception, on the other hand, seems to improve with age. One previous study, using data from a community in Sweden, showed that 4.9 percent of people over the age of 60 experience phantom odors, with a higher prevalence in women than men. The present study found a similar prevalence in the over-60 age group, but in examining a broader age range, found an even higher prevalence in ages 40-60. The study also found that about twice as many women as men reported phantom odors, and that the female predominance was particularly striking for those under age 60.

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 25347 - Posted: 08.18.2018

By Victoria Davis An elephant’s trunk is the Swiss army knife of appendages: It’s used to breathe, communicate, and even lift objects. Now, a new study finds another use—sniffing out food across long distances. Researchers have long known that elephants and other plant-eating mammals seek their supper with their eyes. But scientists at the Adventures with Elephants facility near Bela Bela, South Africa, wanted to know whether they could do the same thing with their trunks. So they collected 11 plants eaten by wild African elephants (Loxodonta africana), six of which the animals loved and five of which were not nearly as appealing. In one experiment, the elephants had to use their sense of smell to choose between two small samples of plants concealed in black plastic bins. The elephants tended to pick “preferred” plants when the other option was a nonpreferred species, but they had a harder time choosing if both plants were either “preferred” or “nonpreferred.” In a second experiment, the elephants were put into a Y-shaped maze, with a different plant at each end of two 7-meter-long arms. In this formulation, they always chose the preferred plant over the less desired species, the researchers report in Animal Behavior. They were even able to differentiate between plants that fell closely together on the love-hate scale. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 25300 - Posted: 08.07.2018

By James Gorman In the world of noses, the elephant’s trunk clearly stands out for its size, flexibility, strength and slightly creepy gripping ability. Go ahead, try to pluck a leaf with your nostrils and see how you fare.So perhaps it should come as no surprise that the elephant’s sense of smell is also outstanding. Past studies have shown that elephants have more scent receptors than any other mammal. And in other experiments, researchers following up reports that elephants in Angola were avoiding minefields found that they could detect TNT. Another report concluded that elephants could use scent clues to tell the difference between two Kenyan tribes, the Maasai, who traditionally speared them, and the Kamba, who did not. The elephants apparently used these clues to help them avoid the Maasai. The latest bit of research adds to the evidence by showing how they use their great sense of smell in choosing food. Elephants often must find vegetation and water at a distance, and they also distinguish between fairly similar plants once they reach a clump of likely vegetation. It seemed that they probably used their sense of smell, but Melissa Schmitt, a researcher at the University of KwaZulu-Natal in South Africa, and her colleagues wanted to see how good they were. So she tested them at close range, using two buckets with two different hidden foods. They easily picked out the bucket with leaves from plants they enjoyed, say wild pear, and avoided ones they didn’t like, wild olive, for instance. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 25105 - Posted: 06.19.2018

Nicola Davis From whispering sweet nothings to hoping for sweet dreams, sugariness and pleasure have long been bound together. Now scientists studying the brains of mice have revealed why, unpicking the pathways in the brain which result in sweet foods being perceived as nice and bitter foods as nasty. What’s more, they have managed to tinker with these routes so that mice get a kick out of a tasteless substance such as water, and have even managed to switch off such judgments completely. Researchers say the finding may help with the search for treatments for eating disorders. “The very concept of sweet, the very word sweet, implies this goodness, this reward, this craving that we link to it, and similarly bitter on the other side has an immediate meaning to it. So we wanted to know, how does the brain encode meaning on sensory experience?” said Charles Zuker, lead author of the research from Columbia University’s Zuckerman Institute. Advertisement While the work was carried out in mice, Zuker said there could be parallels for the human brain and that understanding the brain circuits involved in taste and our responses to it might eventually open up the possibility of tinkering with our own responses to certain foods – including sugar cravings. © 2018 Guardian News and Media Limited

Related chapters from BN8e: 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: 25041 - Posted: 05.31.2018

By Kenneth Chang Jerrold Meinwald, who conducted pathbreaking studies of how creatures use chemicals to attract mates, repel predators and send other messages back and forth, died on April 23 at his home in Ithaca, N.Y. He was 91. His death was reported by Cornell University, where Dr. Meinwald had worked for more than 50 years. One project that Dr. Meinwald, an organic chemist, tackled soon after he arrived at Cornell in 1952 was determining what exactly in catnip drives some cats into a playful frenzy. Dr. Meinwald isolated from the plant the active ingredient — a chemical called nepetalactone — and then deduced its structure. He soon discovered an aspect of nepetalactone he had not known about. He was a giving a talk about his chemical findings, and someone had brought in a cat so he could demonstrate the effects. “It turns out not all cats respond,” Dr. Meinwald said in an interview in 2011. “I had a nonresponsive cat. The chemistry was good, but I had not realized you have to pick your subjects carefully.” Dr. Meinwald had a fruitful partnership with Thomas Eisner, an entomologist who joined the Cornell faculty in 1957. That collaboration continued for more than a half-century and established a new field of science, chemical ecology. Dr. Eisner died in 2011 at 81. Biologists had noted decades earlier that organisms produced substances that were not directly needed for the biological processes that maintain life. They suspected that these substances might be used for communications or defense. But it was only in the middle of the 20th century that chemists had the tools to study the substances in detail. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 24973 - Posted: 05.15.2018

Joan McFadden When Les Milne was diagnosed with Parkinson’s disease aged just 45, his wife Joy was, understandably, devastated. But her sadness wasn’t just down to the fact her husband was in the grip of such a terrible illness but that, when she’d noticed a change in his smell 12 years earlier, she hadn’t realised the two things might be connected. Upon first noticing a “sort of woody, musky odour” Joy “started suggesting tactfully to him that he wasn’t showering enough or cleaning his teeth,” she recalls. “He clearly didn’t smell it and was quite adamant that he was washing properly.” Joy, a former nurse, let the issue lie, occupied with the far more pressing issue of her husband’s rapidly changing character. “He wasn’t the man I’d known since I was 16. About eight years before he was diagnosed he started suffering from mood swings, with bursts of anger which left me dreading what might come next.” When Les was eventually referred for a brain scan, he was told that his symptoms indicated a diagnosis of either a brain tumour or Parkinson’s, which affects one in 500 people in the UK. As medical professionals - Les worked as an anaesthetist - both knew just how serious the diagnosis was, though Joy admits that it was a relief to have one at all. Forced to retire five years later, the pair moved back to Perth from Cheshire, with his growing inability to sleep and diminishing motor skills seeing Les, a former water polo player for Scotland, give up the swimming he loved to do every day. “He was just a completely different person. It was devastating to watch" Joy, now 67, says. © Telegraph Media Group Limited 2018

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 5: The Sensorimotor System
Link ID: 24828 - Posted: 04.06.2018

By Virginia Morell A dog searching for a lost child is typically given an item of clothing to smell. But what does that scent “look” like? To find out, scientists tested 48 dogs, half of which had special police or rescue training. In a laboratory room, the scientists slid each dog’s favorite toy across the floor to a hiding place, while the dog waited in another room. One researcher then brought the dog to the testing room and pointed at the starting point of the odor trail and told the dog, “Look for it! Bring it!” In one trial, the dog found either its favored toy or—surprise!—a different item. Many of the surprised dogs continued searching for the toy used to lay the scent trail—an indication that they had a mental representation of what they expected to find, the scientists report today in the Journal of Comparative Psychology. Both family dogs and working dogs scored about the same on the tests, confirming previous studies showing that education doesn’t necessarily improve a dog’s performance. Previous studies have shown that horses have mental images of their owners and other horses—based on the sounds of their voices and whinnies. But scientists know little about how smell and cognition are linked in animals that rely heavily on smell—such as dogs, elephants, and rats. Now, we have a better idea at least for our pooches: They picture what they’re searching for. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 24722 - Posted: 03.06.2018

By Kimberly Hickok If you ever wanted to know what a moth was thinking, this might be as close as you’re going to get. In a new study published today in Cell Reports, researchers placed female hawkmoths (Manduca sexta) in a wind tunnel containing two pieces of filter paper—one covered in a test odor, and one with no odor. Perhaps not surprisingly, the insects were most attracted to odors containing aromatic chemicals, which are present in plants that are common nectar sources. Some odors consistently caused the moths to touch their feet to the paper while curving their abdomen, which is how they lay eggs, indicating that moths associate those odors with egg laying. With six different odors, the moths alternated touching their feet and their mouths to the same odor, suggesting that plants containing one or all of those chemicals, such as jimson weed, are important for both feeding and egg laying. By combining these data with imaging of nerve cells at the base of the moths’ antennae, the researchers identified four clusters of nerves specifically associated with feeding behavior and six specifically associated with egg laying, but none associated with both behaviors. This means moths use specific odors to direct their behavior. The scientists say more research is needed to see whether nerve clusters respond to odor the same way in other species of moths and pollinating insects, which can help identify important odors and the plants that make them. © 2018 American Association for the Advancement of Science.

Related chapters from BN8e: 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: 24706 - Posted: 02.28.2018

By VERONIQUE GREENWOOD Of the five tastes — sweet, salty, sour, bitter and umami — sour is one of the most mysterious. Bite into a piece of lemon and — bing! — your brain gets a message that something sour has arrived. But unlike sweet and bitter, for example, for which biologists have identified proteins on the tongue’s taste cells that detect the molecules involved, the sourness of acids like lemon juice and vinegar has remained enigmatic, with the exact details of how we pick up on it little understood. Now, however, in a paper published last month in Science, researchers report that they have found a protein in mouse taste cells that is likely a key player in the detection of sour flavors. There’s just one strange thing, though: Biologists have known about this protein for years. It was previously identified in the inner ear, or vestibular system, of mice, humans and many other creatures, where it is required for developing a sense of balance. The results suggest a fascinating truth about evolution: The first place something is discovered may not be the last place it turns up. If it has proved advantageous over the eons, a protein whose purpose we thought we understood may have a rich private life of its own elsewhere in the body, just waiting to be found. Similar discoveries have cropped up more and more in the last decade as researchers look more closely at which genes cells are using. This approach has led to the revelations that smell receptors are alive and well in the kidneys, bitter taste receptors dot the sinuses and testes, and sweet taste receptors are found in the bladder. © 2018 The New York Times Company

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 24616 - Posted: 02.05.2018

By Diana Kwon Search for “pheromones products” on the internet, and dozens of sprays and perfume additives will appear—many claiming to be able to increase your attractiveness to the opposite sex. Some companies, such as the Athena Institute, which, according to its founder, Winnifred Cutler, published its 108th consecutive ad in The Atlantic this month, assert that scientific studies back up their claims. While there have been several experiments examining the effects of compounds extracted from people’s armpits, much of the data on sex-related behaviors, The Scientist has found, go back more than a decade and were met then—and still now—with skepticism from pheromone researchers. “I am not compelled by any studies that are out there that say there is an active steroid component from the underarm that causes [sexual attraction],” says George Preti, an organic chemist at the Monell Chemical Senses Center in Philadelphia who conducted some of the early human pheromone trials. Within the scientific community, pheromones are broadly defined as chemical signals released by an animal that induce specific effects on other members of the same species. Although these substances are typically associated with sexual attraction, researchers have found they can have a broader range of influence, such as prompting aggression or modifying parental behaviors. © 1986-2018 The Scientist

Related chapters from BN8e: 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: 24565 - Posted: 01.25.2018

Bruce Bower Smell has a reputation as a second-rate human sense. But that assumption stinks once hunter-gatherers enter the picture. Semaq Beri hunter-gatherers, who live in tropical forests on the eastern side of the Malay Peninsula in Southeast Asia, name various odors as easily as they name colors, say psycholinguist Asifa Majid and linguist Nicole Kruspe. Yet Semelai rice farmers, who live in forest outposts near the Semaq Beri and speak a closely related language, find odors much more difficult to name than colors, the researchers report online January 18 in Current Biology. By including members of a farming community that inhabit a common forest environment and speak a similar language, the new study indicates for the first time that the cultural practices of hunter-gatherers help enhance their odor-naming ability — and possibly their smell-detection skills — relative to settled peoples. Neuroscientist and odor researcher John McGann of Rutgers University in Piscataway, N.J., calls these results “unexpected and deeply interesting.” Genetics apparently interact with personal experiences of different smells and one’s cultural background to produce odor-naming abilities, McGann says. Previous research has found that like Semelai farmers, Westerners describe colors far more easily than smells. People in Western societies often talk about odors by resorting to analogies, such as “It smells like banana.” Semaq Beri hunter-gatherers usually used specific terms for a range of odors as well as colors, say Majid of Radboud University in Nijmegen, the Netherlands, and Kruspe of Lund University in Sweden. These forest dwellers are attuned to odors by virtue of their lifestyle and culture, the investigators propose. |© Society for Science & the Public 2000 - 2017.

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 24541 - Posted: 01.19.2018

By Kelly Crowe, "Scientists identify a sixth taste sense." It's a claim that has made headlines several times over the last few years — first for fat, then for starch and even for water. Now the new candidate for the sixth taste is calcium, after scientists identified the first calcium taste receptors in fruit flies. Researchers at the University of California studied fruit fly behaviour and discovered the flies could taste toxic levels of calcium and didn't like it. Then they used genetics to show that the calcium taste sense is hardwired into the fruit fly brain. University of California professor Craig Montell believes humans might share the fruit fly's taste sensor for calcium. (UC Santa Barbara) And because fruit flies and humans share the other main taste senses — sweet, sour, bitter, salty and savoury (called "umami") — the study's lead author, Craig Montell, thinks there's a good chance that humans also have specific calcium taste receptors. "I would say there is very good reason that, given that all the other tastes have been well conserved between flies and humans, that there probably is," said Montell. But the science of taste is surprisingly complicated. Even the idea that there might be additional taste receptors is controversial. As far back as Aristotle's time, scientists have been puzzling over the question. ©2018 CBC/Radio-Canada.

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 24526 - Posted: 01.15.2018

By Mary Bates Whip spiders, also known as tailless whip scorpions, are actually neither spiders nor scorpions. These strange creatures belong to a separate arachnid order called Amblypygi, meaning “blunt rump,” a reference to their lack of tails. Little was known about whip spiders before the turn of this century, but a recent flurry of behavioral and neurophysiological studies has opened a window into their unique sensory world. Researchers have discovered that some of the more than 150 species engage in curious behaviors, including homing, territorial defense, cannibalism, and tender social interactions—all mediated by a pair of unusual sensory organs. Like all arachnids, whip spiders have eight legs. However, they walk on only six. The front two legs are elongated, antennae-like sensory structures called antenniform legs. These legs, three to four times longer than the walking legs, are covered with different types of sensory hairs. They constantly sweep the environment in a whiplike motion, earning whip spiders their common name. Whip spiders use their antenniform legs the way a blind person uses a cane—except that in addition to feeling their environment, whip spiders can smell, taste, and hear with their antenniform legs. All aspects of a whip spider’s life center on the use of these legs, including hunting—whip spiders are dangerous predators, if you’re a small invertebrate that shares the arachnids’ tropical and subtropical ecosystems. When Eileen Hebets, a biologist at the University of Nebraska–Lincoln, recorded the prey capture behavior of the whip spider Phrynus marginemaculatus, she observed a well-choreographed pattern. © 1986-2017 The Scientist

Related chapters from BN8e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 24437 - Posted: 12.19.2017

By VERONIQUE GREENWOOD When people tell you, “wake up and smell the roses,” they might be giving you bad advice. Your sense of smell may fluctuate in sensitivity over the course of 24 hours, in tune with our circadian clocks, with your nose best able to do its job during the hours before you go to sleep, according to a study published last month. The work, reported in the journal Chemical Senses, is part of a larger push to explore whether adolescents’ senses of taste and smell influence obesity. Rachel Herz, a sensory researcher at Brown University, and her colleagues designed this study to see if there might be times of day when the sense of smell was more powerful — perhaps making food smell particularly inviting. For the experiment, 37 adolescents ranging in age from 12 to 15 came into a lab for a very long sleepover party. For nine days, they followed a strict schedule to allow researchers to focus on the circadian clock, which helps control wake and sleep, but also influences other processes in the body, including metabolism. While more research is needed to test whether the results fully apply to adults, Dr. Herz says that as you grow up, the makeup of the smell receptors inside your nose doesn’t seem to change, although there is evidence your body clock may. The team kept track of where the teenagers were in their circadian cycle by measuring their saliva’s levels of melatonin, a hormone that rises and falls regularly over the course of the day. Every few hours, the children took a scent test, sniffing different concentrations of a chemical that smells like roses. The researchers recorded the lowest concentration they could detect at each time point. When the results were tallied up, the researchers saw a range of responses. “Nobody has the same nose,” Dr. Herz said. Some adolescents had only very mild changes in sensitivity, while sensitivity altered dramatically in others. Averaged together, however, the results showed that overall the circadian clock does affect smell, and that the times when the children’s noses were most sensitive tended to correspond to the evening, with an average peak of 9 p.m. © 2017 The New York Times Company

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 14: Biological Rhythms, Sleep, and Dreaming
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 10: Biological Rhythms and Sleep
Link ID: 24311 - Posted: 11.09.2017

By NICHOLAS BAKALAR A poor sense of smell may indicate an increased risk for dementia, a new study has found. Researchers recruited 2,906 men and women ages 57 to 85, testing their ability to identify five odors — orange, leather, peppermint, rose and fish. Five years later, 4.1 percent of them had dementia. Of all the factors the researchers measured — age, sex, race, ethnicity, education, other diseases the subjects may have had — only cognitive ability at the start of the study and poorer performance on the “smell test” were associated with an increased risk for dementia. The study is in the Journal of the American Geriatrics Society. The risk went up steadily with the number of odors they failed to recognize, and over all, compared with those with no olfactory impairment, those with smelling difficulties had more than twice the likelihood of developing dementia. Even among those who initially tested within the normal range for mental ability, a poor sense of smell more than doubled the risk for dementia five years later. “This is not a simple, single-variable test for the risk of dementia,” said the lead author, Dr. Jayant M. Pinto, a specialist in sinus and nasal diseases at the University of Chicago. “But sensory function is an indicator of brain function. When sensory function declines, it can be a signal to have a more detailed examination to see if everything’s O.K.” © 2017 The New York Times Company

Related chapters from BN8e: 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: 24137 - Posted: 10.03.2017

James Gorman Imagine a species that lived in a world of smells and didn’t pay a lot of attention to what things look like. What would members of that species use for a mirror? Would they even want a mirror? Yes, of course, we are talking about dogs, who usually don’t seem to understand the mirrors humans use. Sometimes they ignore them. Often they bark as if the dog in the mirror were a stranger. Scientists use mirrors to find out if animals recognize themselves, to see if they have some sense of self. Chimpanzees do very well on what is called the mirror test. A chimp will notice a mark on his face and perhaps even use the mirror to aid in removing it. He might use the mirror to examine parts of his body he can’t normally see, like the inside of his mouth. Researchers have reported that dolphins, one elephant and a magpie have also passed this test. Dogs have not, and that has raised questions about whether dogs might recognize themselves if another sense were tested. Alexandra Horowitz, a psychologist at Barnard College who studies the behavior of dogs and has written several books about them, decided to give dogs a chance at showing self-recognition on their own, smelly terms. In a recent study, she concludes that they do recognize the smell of their own urine. While some researchers find the study intriguing, the scientist who first developed that mirror mark test doesn’t think the evidence supports her conclusion. Still, even the idea of a smell mirror is mind (nose?) boggling. “I had always flirted with the idea in my head that there should be an olfactory mirror,” Dr. Horowitz said, acknowledging that “it could be horrifying for humans.” © 2017 The New York Times Company

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 14: Attention and Consciousness
Link ID: 24095 - Posted: 09.22.2017

By Elizabeth Pennisi GRONINGEN, THE NETHERLANDS—For insects such as the tobacco budworm moth, beauty is actually in the “nose” of the beholder, as females use chemical scents called pheromones to lure in potential mates. And—as in people—some moths are attractive. Others … well, not so much. Now, evolutionary biologists have learned that these unattractive female moths better their odds of mating by hanging out with their more attractive counterparts. “We often think of mate choice as a perfect and entirely binary process—you are attractive or you are not—but this is clearly not the case,” says Therésa Jones, a behavioral and evolutionary ecologist at the University of Melbourne in Australia, who was not involved with the work. Wouter Halfwerk, a behavioral ecologist at the University of Amsterdam, adds that the results, reported this week here at the XIV Congress of the European Society of Evolutionary Biology, “provide an answer of how unattractiveness can evolve, which challenges our notion of beauty.” The new work was done by Astrid Groot, an evolutionary biologist at the University of Amsterdam who studies the evolution of sexual signals. She specializes in the tobacco budworm moth (Heliothis virescens) because so much is already known about its caterpillar, a widespread crop pest in the United States often caught by farmers with pheromone-scented traps. In field studies, she and other researchers noticed that some females never seem to attract males. But how could they reproduce enough to pass along their less-than-sexy scent? To find out, she and colleagues raised multiple generations of the budworm in the lab, testing each generation’s females for how quickly males home in on their scents. By separately breeding the most and least attractive females, the researchers gradually created two strains, one of supersexy smellers and one of, for lack of a better word, stinkers. © 2017 American Association for the Advancement of Science

Related chapters from BN8e: 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: 24000 - Posted: 08.26.2017