Links for Keyword: Chemical Senses (Smell & Taste)

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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

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 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: 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 BN8e: Chapter 9: Hearing, Vestibular Perception, 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 BN8e: Chapter 9: Hearing, Vestibular Perception, 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 BN8e: Chapter 9: Hearing, Vestibular Perception, 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 BN8e: Chapter 9: Hearing, Vestibular Perception, 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 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: 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 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: 23327 - Posted: 03.08.2017

By Steve Mirsky To conserve water, members of my household abide by the old aphorism “If it's yellow, let it mellow.” You're in a state of ignorance about that wizened phrase? If so, it recommends that one not flush the toilet after each relatively innocent act of micturition. But there's one exception to the rule: after asparagus, it's one and done—because those delicious stalks make urine smell like hell. To me and mine, anyway. The digestion of asparagus produces methanethiol and S-methyl thioesters, chemical compounds containing stinky sulfur, also known as brimstone. Hey, when I said that postasparagus urine smells like hell, I meant it literally. Methanethiol is the major culprit in halitosis and flatus, which covers both ends of that discussion. And although thioesters can also grab your nostrils by the throat, they might have played a key role in the origin of life. So be glad they were there stinking up the abiotic Earth. But does a compound reek if nobody is there to sniff it? Less philosophically, does it reek if you personally can't smell it? For only some of us are genetically gifted enough to fully appreciate the distinctive scents of postasparagus urine. The rest wander around unaware of their own olfactory offenses. Recently researchers dove deep into our DNA to determine, although we've all dealt it, exactly who smelt it. Their findings can be found in a paper entitled “Sniffing Out Significant ‘Pee Values’: Genome Wide Association Study of Asparagus Anosmia.” Asparagus anosmia refers to the inability “to smell the metabolites of asparagus in urine,” the authors helpfully explain. They don't bother to note that their bathroom humor plays on the ubiquity in research papers of the p-value, a statistical evaluation of the data that assesses whether said data look robust or are more likely the stuff that should never be allowed to mellow. © 2017 Scientific American,

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: 23288 - Posted: 02.28.2017

By Robert F. Service Predicting color is easy: Shine a light with a wavelength of 510 nanometers, and most people will say it looks green. Yet figuring out exactly how a particular molecule will smell is much tougher. Now, 22 teams of computer scientists have unveiled a set of algorithms able to predict the odor of different molecules based on their chemical structure. It remains to be seen how broadly useful such programs will be, but one hope is that such algorithms may help fragrancemakers and food producers design new odorants with precisely tailored scents. This latest smell prediction effort began with a recent study by olfactory researcher Leslie Vosshall and colleagues at The Rockefeller University in New York City, in which 49 volunteers rated the smell of 476 vials of pure odorants. For each one, the volunteers labeled the smell with one of 19 descriptors, including “fish,” “garlic,” “sweet,” or “burnt.” They also rated each odor’s pleasantness and intensity, creating a massive database of more than 1 million data points for all the odorant molecules in their study. When computational biologist Pablo Meyer learned of the Rockefeller study 2 years ago, he saw an opportunity to test whether computer scientists could use it to predict how people would assess smells. Besides working at IBM’s Thomas J. Watson Research Center in Yorktown Heights, New York, Meyer heads something called the DREAM challenges, contests that ask teams of computer scientists to solve outstanding biomedical problems, such as predicting the outcome of prostate cancer treatment based on clinical variables or detecting breast cancer from mammogram data. “I knew from graduate school that olfaction was still one of the big unknowns,” Meyer says. Even though researchers have discovered some 400 separate odor receptors in humans, he adds, just how they work together to distinguish different smells remains largely a mystery. © 2017 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: 23254 - Posted: 02.20.2017

By Matt Blois Some of the signals animals use to communicate are obvious. Birds sing. Lions roar. But there’s a whole category of signals in the natural world that humans rarely notice. Researchers have found that one species of cichlid uses urine to send chemical signals to rivals during aggressive displays. The team separated large fish from small fish with a transparent divider. Half the dividers contained holes to allow water to flow back and forth. The scientists then injected the fish with a violet dye (pictured), turning their urine bright blue. When the animals saw each other, they raised their fins and rushed toward the divider. They also changed the way they peed. Fish separated by a solid barrier couldn’t detect their opponent’s urine. In an attempt to get their message across, they urinated even more. Without the chemical cues provided by the urine, smaller fish often tried to attack their larger opponents, the team reports this month in Behavioral Ecology and Sociobiology. Humans could be missing other signals as well, the researchers contend. In addition to chemical signals, animals use seismic vibrations, electricity, and ultraviolet light to communicate. Visual signals might be more obvious, but this research stresses the importance of looking for less noticeable forms of communication, the authors say. © 2017 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: 23160 - Posted: 01.28.2017

By Michael Price We’ve all heard the stories about humans losing their jobs to robots. But what about man’s best friend? A new study suggests that drug-sniffing dogs may soon have a competitor in the workplace: an insect-piloted robotic vehicle that could help scientists build better odor-tracking robots to find disaster victims, detect illicit drugs or explosives, and sense leaks of hazardous materials. The robotic car’s driver is a silkworm moth (Bombyx mori) tethered in a tiny cockpit so that its legs can move freely over an air-supported ball, a bit like an upside-down computer mouse trackball. Using optical sensors, the car follows the ball’s movement and moves in the same direction. With its odor-sensitive antennae, the moth senses a target smell—in this case, female silkworm sex pheromones—and walks toward it along the trackball, driving the robotic car. Across seven trials with seven different drivers, the insects piloted the vehicle consistently toward the pheromones, nearly as well as 10 other silkworm moths who could walk freely on the ground toward the smells, the researchers reported last month in the Journal of Visualized Experiments. On average, the driving moths reached their target about 2 seconds behind the walking moths, although their paths were more circuitous. The researchers say their findings could help roboticists better integrate biologically inspired odor detection systems into their robots. Engineers might even be able to develop more powerful and maneuverable versions of the study’s robot car that could be driven by silkworms genetically modified to detect a wide variety of smells to help with sniffing tasks traditionally done by trained animals. Time to start polishing up those résumés, pooches. © 2016 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: 23051 - Posted: 01.04.2017

By Torah Kachur, A dog's nose is an incredible scent detector. This ability has been used to train bomb-sniffing dogs, narcotics and contraband sniffers as well as tracking hounds. But even the best electronic scent-detection devices — which use the dog's nose as their gold standard — have never been able to quite live up to their canine competition. But new research — which took a plastic dog nose and strapped it to a bomb sniffing device — might change that. The shape and function of a dog's nose is being used to improve electronic scent detectors. (Flickr / montillon.a) Dogs have almost 300 million smell receptors in their noses, compared to the meagre six million us humans have: their sense of smell is more than 40 times better than ours. But those smell receptors are just part of the puzzle. Matthew Staymates, lead author on a new paper published Thursday, figured that the canine sniffing skill also has something to do with the anatomy of a dog's nose. A former roommate of his had done his PhD in dog nose anatomy and actually had a computer model of a dog's nose and entire head. So Staymates used a 3D printer, printed out a dog's nose, and attached it to an electronic detector. "Sure enough, a week or two later, I had a fully functioning, anatomically correct dog's nose that sniffs like a real dog." From that, he worked with something called a schlieren imager to watch air go in and out of a nose when the dog is snuffling around the ground. ©2016 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: 22941 - Posted: 12.03.2016

By Virginia Morell If you’ve ever watched ants, you’ve probably noticed their tendency to “kiss,” quickly pressing their mouths together in face-to-face encounters. That’s how they feed each other and their larvae. Now, scientists report that the insects are sharing much more than food. They are also communicating—talking via chemical cocktails designed to shape each other and the colonies they live in. The finding suggests that saliva exchange could play yet-undiscovered roles in many other animals, from birds to humans, says Adria LeBoeuf, an evolutionary biologist at the University of Lausanne in Switzerland, and the study’s lead author. “We’ve paid little attention to what besides direct nutrition is being transmitted” in ants or other species, adds Diana Wheeler, an evolutionary biologist at the University of Arizona in Tucson, who was not involved with the work. Social insects—like ants, bees, and wasps—have long been known to pass food to one another through mouth-to-mouth exchange, a behavior known as trophallaxis. They store liquid food in “social stomachs,” or crops, from which they can regurgitate it later. It’s how nutrients are passed from foraging ants to nurse ants, and from nurses to the larvae in a colony. Other research has suggested that ants also use trophallaxis to spread the colony’s odor, helping them identify their own nest mates. © 2016 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: 22928 - Posted: 11.29.2016

By Ben Andrew Henry As a graduate student in the field of olfactory neuroscience, conducting what his former mentor describes as ambitiously clever research, Jason Castro felt something was missing. “I wanted to use science to make a connection with people,” he says, not just to churn out results. In 2012, the 34-year-old Castro accepted a faculty position at Bates College, a small liberal arts school in Maine, in order to “do the science equivalent of running a mom-and-pop—a small operation, working closely with students, and staying close to the data and the experiments myself,” he says. Students who passed through his lab or his seminars recall Castro as a dedicated mentor. “He spent hours with me just teaching me how to code,” recalled Torben Noto, a former student who went on to earn a PhD in neuroscience. After he arrived at Bates, Castro, along with two computational scientists, enlisted big-data methodologies to search for the olfactory equivalent of primary colors: essential building blocks of the odors we perceive. Their results, based on a classic set of data in which thousands of participants described various odors, identify 10 basic odor categories.1 Castro launched another project a few months later, when a paper published in Science reported that humans could discriminate between at least a trillion different odors. A friend from grad school, Rick Gerkin, smelled something fishy about the findings and gave Castro a call. “We became obsessed with the topic,” says Gerkin, now at Arizona State University. The researchers spent almost two years pulling apart the statistical methods of the study, finding that little tweaks to parameters such as the number of test subjects created large swings in the final estimate—a sign that the results were not robust.2 This August, the original study’s authors published a correction in Science. © 1986-2016 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: 22922 - Posted: 11.29.2016

By Bob Holmes It’s not something to be sniffed at. Computers have cracked a problem that has stumped chemists for centuries: predicting a molecule’s odour from its structure. The feat may allow perfumers and flavour specialists to create new products with much less trial and error. Unlike vision and hearing, the result of which can be predicted by analysing wavelengths of light or sound, our sense of smell has long remained inscrutable. Olfactory chemists have never been able to predict how a given molecule will smell, except in a few special cases, because so many aspects of a molecule’s structure could be important in determining its odour. Andreas Keller and Leslie Vosshall at Rockefeller University in New York City decided to crowdsource the power of machine learning to address the problem. First, they had 49 volunteers rate the odour of 476 chemicals according to how intense and how pleasant the smell was, and how well it matched 19 other descriptors, such as garlic, spice or fruit. Then they released the data for 407 of the chemicals, along with 4884 different variables measuring chemical structure, and invited anyone to develop machine-learning algorithms that would make sense of the patterns. They used the remaining 69 chemicals to evaluate the accuracy of the algorithms of the 22 teams that took up the challenge. © Copyright Reed Business Information Ltd.

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: 22806 - Posted: 10.29.2016

Laura Sanders Pain is contagious, at least for mice. After encountering bedding where mice in pain had slept, other mice became more sensitive to pain themselves. The experiment, described online October 19 in Science Advances, shows that pain can move from one animal to another — no injury or illness required. The results “add to a growing body of research showing that animals communicate distress and are affected by the distress of others,” says neuroscientist Inbal Ben-Ami Bartal of the University of California, Berkeley. Neuroscientist Andrey Ryabinin and colleagues didn’t set out to study pain transfer. But the researchers noticed something curious during their experiments on mice who were undergoing alcohol withdrawal. Mice in the throes of withdrawal have a higher sensitivity to pokes on the foot. And surprisingly, so did these mice’s perfectly healthy cagemates. “We realized that there was some transfer of information about pain” from injured mouse to bystander, says Ryabinin, of Oregon Health & Sciences University in Portland. When mice suffered from alcohol withdrawal, morphine withdrawal or an inflaming injection, they become more sensitive to a poke in the paw with a thin fiber — a touchy reaction that signals a decreased pain tolerance. Mice that had been housed in the same cage with the mice in pain also grew more sensitive to the poke, Ryabinin and colleagues found. These bystander mice showed other signs of heightened pain sensitivity, such as quickly pulling their tails out of hot water and licking a paw after an irritating shot. |© Society for Science & the Public 2000 - 20

Related chapters from BN8e: Chapter 8: General Principles of Sensory Processing, Touch, and Pain; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 11: Emotions, Aggression, and Stress
Link ID: 22773 - Posted: 10.20.2016

By JAN HOFFMAN Our daily tug of leash war goes like this. I tell Chico we’re taking a left. He yanks right, wet black nostrils burrowing in loamy leaf piles. Me versus a 15-pound Havanese, incensed by scent. Today, I let him win. That’s because I have fresh appreciation for his sniffing behavior, after reading a new book, “Being a Dog: Following the Dog into a World of Smell,” by Alexandra Horowitz, a professor of cognitive science who runs the Dog Cognition Lab at Barnard College. In it, she explains the elegant engineering of the dog’s olfactory system and how familiar canine behaviors — licking, sneezing, tail-wagging — have associations with smell. Dr. Horowitz also describes how she trained herself to enhance her inferior human sniffing ability. On a recent afternoon at Riverside Park in Manhattan, I met Dr. Horowitz and Finn (short for Finnegan), her affable, glossy black 9-year-old mixed breed. There she — and he — shared some sniffing insights that have since made my walks with Chico more intriguing and fun. “There are many ways to sniff, and the human method is not the best,” Dr. Horowitz said. Sniff researchers (yes, you read that correctly) have found we have about six million olfactory receptors; dogs have 300 million. Humans sniff once per second-and-a-half; dogs, five to 10 times a second. “They even exhale better than we do,” Dr. Horowitz continued, describing a sort of doggy yoga breath. Dogs exhale through the side slits of their nostrils, so they keep a continuous flow of inhaled air in their snout for smelling. “This gives them a continuous olfactory view of the world.” © 2016 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: 22742 - Posted: 10.11.2016