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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 BN: Chapter 9: Hearing, Balance, 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 4: Development of the Brain
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 BN: Chapter 9: Hearing, Balance, Taste, and Smell; Chapter 18: Attention and Higher Cognition
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 14: Attention and Higher Cognition
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 BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Balance, 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

Allison Aubrey What we eat can influence more than our waistlines. It turns out, our diets also help determine what we smell like. A recent study found that women preferred the body odor of men who ate a lot of fruits and vegetables, whereas men who ate a lot of refined carbohydrates (think bread, pasta) gave off a smell that was less appealing. Skeptical? At first, I was, too. I thought this line of inquiry must have been dreamed up by the produce industry. (Makes a good marketing campaign, right?) But it's legit. "We've known for a while that odor is an important component of attractiveness, especially for women," says Ian Stephen of Macquarie University in Australia. He studies evolution, genetics and psychology and is an author of the study. From an evolutionary perspective, scientists say our sweat can help signal our health status and could possibly play a role in helping to attract a mate. How did scientists evaluate the link between diet and the attractiveness of body odor? They began by recruiting a bunch of healthy, young men. They assessed the men's skin using an instrument called a spectrophotometer. When people eat a lot of colorful veggies, their skin takes on the hue of carotenoids, the plant pigments that are responsible for bright red, yellow and orange foods. "The carotenoids get deposited in our skin," explains Stephen. © 2017 npr

Related chapters from BN: Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases; Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 8: Hormones and Sex; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 23961 - Posted: 08.15.2017

By Emily Underwood Viewed under a microscope, your tongue is an alien landscape, studded by fringed and bumpy buds that sense five basic tastes: salty, sour, sweet, bitter, and umami. But mammalian taste buds may have an additional sixth sense—for water, a new study suggests. The finding could help explain how animals can tell water from other fluids, and it adds new fodder to a centuries-old debate: Does water have a taste of its own, or is it a mere vehicle for other flavors? Ever since antiquity, philosophers have claimed that water has no flavor. Even Aristotle referred to it as “tasteless” around 330 B.C.E. But insects and amphibians have water-sensing nerve cells, and there is growing evidence of similar cells in mammals, says Patricia Di Lorenzo, a behavioral neuroscientist at the State University of New York in Binghamton. A few recent brain scan studies also suggest that a region of human cortex responds specifically to water, she says. Still, critics argue that any perceived flavor is just the after-effect of whatever we tasted earlier, such as the sweetness of water after we eat salty food. “Almost nothing is known” about the molecular and cellular mechanism by which water is detected in the mouth and throat, and the neural pathway by which that signal is transmitted to the brain, says Zachary Knight, a neuroscientist at the University of California, San Francisco. In previous studies, Knight and other researchers have found distinct populations of neurons within a region of the brain called the hypothalamus that can trigger thirst and signal when an animal should start and stop drinking. But the brain must receive information about water from the mouth and tongue, because animals stop drinking long before signals from the gut or blood could tell the brain that the body has been replenished, he says. © 2017 American Association for the Advancement of Science. A

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 23680 - Posted: 05.31.2017

By Bob Holmes As soon as I decided to write a book on the science of flavor, I knew I wanted to have myself genotyped. Every one of us, I learned through my preliminary research for Flavor: The Science of Our Most Neglected Sense, probably has a unique set of genes for taste and odor receptors. So each person lives in their own flavor world. I wanted to know what my genes said about my own world. Sure enough, there was a lesson there—but not the one I expected. Our senses of smell and taste detect chemicals in the environment as they bind to receptors on the olfactory epithelium in the nose or on taste buds studding the mouth. From these two inputs, plus a few others, the brain assembles the compound perception we call flavor. Taste is pretty simple: basically, one receptor type each for sweet, sour, salty, and the savory taste called umami, and a family of maybe 20 or more bitter receptors, each of which is sensitive to different chemicals. Smell, on the other hand, relies on more than 400 different odor receptor types, the largest gene family in the human genome. Variation in any of these genes—and, probably, many other genes that affect the pathways involved in taste or smell—should affect how we perceive the flavors of what we eat and drink. Hence the genotyping. One April morning a few years ago, I drooled into a vial and sent that DNA sample off to the Monell Chemical Senses Center in Philadelphia, home to what is likely the world’s biggest research group dedicated to the basic science of flavor. A few months later, I visited Monell to take a panel of perceptual tests and compare the results to my genetic profile. © 1986-2017 The Scientist

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 23652 - Posted: 05.24.2017

By Lindzi Wessel You’ve probably heard that your sense of smell isn’t that great. After all, compared with a dog or even a mouse, the human olfactory system doesn’t take up that much space. And when was the last time you went sniffing the ground alongside your canine companion? But now, in a new review published today in Science, neuroscientist John McGann of Rutgers University in New Brunswick, New Jersey, argues that the myth of the nonessential nose is a huge mistake—one that has led scientists to neglect research in a critical and mysterious part of our minds. Science checked in with McGann to learn more about why he thinks our noses know more than we realize. Q: Many of us assume our sense of smell is terrible, especially compared with other animals. Where did this idea come from? A: I traced part of this history back to 19th century [anatomist and] anthropologist Paul Broca, who was interested in comparing brains across lots of different animals. Compared to the olfactory bulbs [the first stop for smell signals in the brain], the rest of the human brain is very large. So if you look at whole brains, the bulbs look like these tiny afterthoughts; if you look at a mouse or a rat, the olfactory bulb seems quite big. You can almost forgive Broca for thinking that they didn't matter because they look so small comparatively. Broca believed that a key part of having free will was not being forced to do things by odors. And he thought of smell as this almost dirty, animalistic thing that compelled behaviors—it compelled animals to have sex with each other and things like that. So he put humans in the nonsmeller category—not because they couldn't smell, but because we had free will and could decide how to respond to smells. The idea also got picked up by Sigmund Freud, who then thought of smell as an animalistic thing that had to be left behind as a person grew into a rational adult. So you had in psychology, philosophy, and anthropology all these different pathways leading to presumption that humans didn't have a good sense of smell. © 2017 American Association for the Advancement of Scienc

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 23604 - Posted: 05.12.2017

By Kerry Grens In June of 2014, Pablo Meyer went to Rockefeller University in New York City to give a talk about open data. He leads the Translational Systems Biology and Nanobiotechnology group at IBM Research and also guides so-called DREAM challenges, or Dialogue for Reverse Engineering Assessments and Methods. These projects crowdsource the development of algorithms from open data to make predictions for all manner of medical and biological problems—for example, prostate cancer survival or how quickly ALS patients’ symptoms will progress. Andreas Keller, a neuroscientist at Rockefeller, was in the audience that day, and afterward he emailed Meyer with an offer and a request. “He said, ‘We have this data set, and we don’t model,’” recalls Meyer. “‘Do you think you could organize a competition?’” The data set Keller had been building was far from ordinary. It was the largest collection of odor perceptions of its kind—dozens of volunteers, each having made 10 visits to the lab, described 476 different smells using 19 descriptive words (including sweet, urinous, sweaty, and warm), along with the pleasantness and intensity of the scent. Before Keller’s database, the go-to catalog at researchers’ disposal was a list of 10 odor compounds, described by 150 participants using 146 words, which had been developed by pioneering olfaction scientist Andrew Dravnieks more than three decades earlier. Meyer was intrigued, so he asked Keller for the data. Before launching a DREAM challenge, Meyer has to ensure that the raw data provided to competitors do indeed reflect some biological phenomenon. In this case, he needed to be sure that algorithms could determine what a molecule might smell like when only its chemical characteristics were fed in. There were more than 4,800 molecular features for each compound, including structural properties, functional groups, chemical compositions, and the like. “We developed a simple linear model just to see if there’s a signal there,” Meyer says. “We were very, very surprised we got a result. We thought there was a bug.” © 1986-2017 The Scientist

Related chapters from BN: Chapter 9: Hearing, Balance, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 23592 - Posted: 05.09.2017

Natalie Jacewicz Sometimes people develop strange eating habits as they age. For example, Amy Hunt, a stay-at-home mom in Austin, Texas, says her grandfather cultivated some unusual taste preferences in his 80s. "I remember teasing him because he literally put ketchup or Tabasco sauce on everything," says Hunt. "When we would tease him, he would shrug his shoulders and just say he liked it." But Hunt's father, a retired registered nurse, had a theory: Her grandfather liked strong flavors because of his old age and its effects on taste. When people think about growing older, they may worry about worsening vision and hearing. But they probably don't think to add taste and smell to the list. "You lose all your senses as you get older, except hopefully not your sense of humor," says Steven Parnes, an ENT-otolaryngologist (ear, nose and throat doctor) working in Albany, N.Y. To understand how aging changes taste, a paean to the young tongue might be appropriate. The average person is born with roughly 9,000 taste buds, according to Parnes. Each taste bud is a bundle of sensory cells, grouped together like the tightly clumped petals of a flower bud. These taste buds cover the tongue and send taste signals to the brain through nerves. Taste buds vary in their sensitivity to different kinds of tastes. Some will be especially good at sensing sweetness, while others will be especially attune to bitter flavors, and so on. © 2017 npr

Related chapters from BN: Chapter 9: Hearing, Balance, 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 4: Development of the Brain
Link ID: 23577 - Posted: 05.05.2017

By Lindzi Wessel You may have seen the ads: Just spray a bit of human pheromone on your skin, and you’re guaranteed to land a date. Scientists have long debated whether humans secrete chemicals that alter the behavior of other people. A new study throws more cold water on the idea, finding that two pheromones that proponents have long contended affect human attraction to each other have no such impact on the opposite sex—and indeed experts are divided about whether human pheromones even exist. The study, published today in Royal Society Open Science, asked heterosexual participants to rate opposite-sex faces on attractiveness while being exposed to two steroids that are putative human pheromones. One is androstadienone (AND), found in male sweat and semen, whereas the second, estratetraenol (EST), is in women’s urine. Researchers also asked participants to judge gender-ambiguous, or “neutral,” faces, created by merging images of men and women together. The authors reasoned that if the steroids were pheromones, female volunteers given AND would see gender-neutral faces as male, and male volunteers given EST would see gender-neutral faces as female. They also theorized that the steroids corresponding to the opposite sex would lead the volunteers to rate opposite sex faces as more attractive. That didn’t happen. The researchers found no effects of the steroids on any behaviors and concluded that the label of “putative human pheromone” for AND and EST should be dropped. “I’ve convinced myself that AND and EST are not worth pursuing,” says the study’s lead author, Leigh Simmons, an evolutionary biologist at the University of Western Australia in Crawley. © 2017 American Association for the Advancement of Science.

Related chapters from BN: Chapter 9: Hearing, Balance, 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: 23327 - Posted: 03.08.2017