Links for Keyword: Chemical Senses (Smell & Taste)

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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 BP7e: 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 BP7e: 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 BP7e: 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 BP7e: 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 BP7e: 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

Annette Heist Nisha Pradhan is worried. The recent college graduate just turned 21 and plans to live on her own. But she's afraid she won't be able to stay safe. That's because Pradhan is anosmic — she isn't able to smell. She can't tell if milk is sour, or if she's burning something on the stove, or if there's a gas leak, and that worries her. "It actually didn't even strike me as being a big deal until I got to college," Pradhan says. Back home in Pennington, N.J., her family did her smelling for her, she says. She's moved in with them for now, but she's looking for a place of her own. "Now that I'm searching for ways or places to live as an independent person, I find more and more that the sense of smell is crucial to how we live our lives," Pradhan says. There's no good estimate for how many people live with smell loss. Congenital anosmia, being born without a sense of smell, is a rare condition. Acquired smell loss is more common. That loss can be total, or what's known as hyposmia, a diminished sense of smell. Pradhan doesn't know how she lost her sense of smell. She thinks she was born with it because as a child, she says she liked to eat and ate a lot. But there came a point where she lost interest in food. "That's actually one of the first things that people notice whenever they have a smell problem, is food doesn't taste right anymore," says Beverly Cowart, a researcher at the Monell Chemical Senses Center in Philadelphia. That's because eating and smell go hand in hand. How food tastes often relies on what we smell. © 2016 npr

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 22735 - Posted: 10.10.2016

Alva Noë Eaters and cooks know that flavor, in the jargon of neuroscientists, is multi-modal. Taste is all important, to be sure. But so is the look of food and its feel in the mouth — not to mention its odor and the noisy crunch, or juicy squelch, that it may or may not make as we bite into it. The perception of flavor demands that we exercise a suite of not only gustatory, but also visual, olfactory, tactile and auditory sensitivities. Neuroscientists are now beginning to grasp some of the ways the brain enables our impressive perceptual power when it comes to food. Traditionally, scientists represent the brain's sensory function in a map where distinct cortical areas are thought of as serving the different senses. But it is increasingly appreciated that brain activity can't quite be segregated in this way. Cells in visual cortex may be activated by tactile stimuli. This is the case, for example, when Braille readers use their fingers to read. These blind readers aren't seeing with their fingers, rather, they are deploying their visual brains to perceive with their hands. And, in a famous series of studies that had a great influence on my thinking on these matters, Miriganka Sur at MIT showed that animals whose retinas were re-wired surgically to feed directly into auditory cortex do not hear lights and other visible objects presented to the eyes, rather, they see with their auditory brains. The brain is plastic, and different sensory modalities compete continuously for control over populations of cells. An exciting new paper on the gustatory cortex from the laboratory of Alfredo Fontanini at Stony Brook University shows that there are visual-, auditory-, olfactory- and touch-sensitive cells in the gustatory cortex of rats. There are even some cells that respond to stimuli in more than one modality. But what is more remarkable is that when rats learn to associate non-taste qualities — tones, flashes of lights, etc. — with food (sucrose in their study), there is a marked transformation in the gustatory cortex. © 2016 npr

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 10: Vision: From Eye to Brain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 7: Vision: From Eye to Brain
Link ID: 22675 - Posted: 09.21.2016

By Jessica Hamzelou As any weight-watcher knows, carb cravings can be hard to resist. Now there’s evidence that carbohydrate-rich foods may elicit a unique taste too, suggesting that “starchy” could be a flavour in its own right. It has long been thought that our tongues register a small number of primary tastes: salty, sweet, sour and bitter. Umami – the savoury taste often associated with monosodium glutamate – was added to this list seven years ago, but there’s been no change since then. However, this list misses a major component of our diets, says Juyun Lim at Oregon State University in Corvallis. “Every culture has a major source of complex carbohydrate. The idea that we can’t taste what we’re eating doesn’t make sense,” she says. Complex carbohydrates such as starch are made of chains of sugar molecules and are an important source of energy in our diets. However, food scientists have tended to ignore the idea that we might be able to specifically taste them, says Lim. Because enzymes in our saliva break starch down into shorter chains and simple sugars, many have assumed we detect starch by tasting these sweet molecules. Her team tested this by giving a range of different carbohydrate solutions to volunteers – who it turned out were able to detect a starch-like taste in solutions that contained long or shorter carbohydrate chains. “They called the taste ‘starchy’,” says Lim. “Asians would say it was rice-like, while Caucasians described it as bread-like or pasta-like. It’s like eating flour.” © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 22639 - Posted: 09.10.2016

By Alison F. Takemura A stationary Carolina sphinx moth (Manduca sexta) is the Cinderella of the animal kingdom. The hummingbird-size insect has dull, dark wings that are mottled like charred wood, and a plump body reminiscent of a small breakfast sausage. Casual observers of M. sexta often see little else. “They say, ‘Oh, it doesn’t look so nice. It’s just grey.’ But as soon as [the moths] start flying, they’re completely impressed,” says Danny Kessler, a pollination ecologist at the Max Planck Institute of Chemical Ecology in Germany. “They change their minds completely.” Hawkmoths, the group to which M. sexta belongs, whir their wings like hummingbirds as they flit between flowers, hovering to drink nectar. M. sexta’s proboscis, longer than its 2-inch body, stays unfurled, a straw ready to sip. Kessler studies the interaction between the Carolina sphinx moth, whose larvae are known as tobacco hornworms, and its preferred food source, the coyote tobacco plant (Nicotiana attenuata), to better understand how insect behavior affects a plant’s reproductive success. M. sexta adults drink nectar from tobacco’s skinny, white, trumpet-shape flowers, foraging from them at night and pollinating them in the process. Scientists have known for decades that the moth uses its antennae to detect the flowers’ scent—even from several miles away, Kessler says. © 1986-2016 The Scientist

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 22626 - Posted: 09.05.2016

By Simon Oxenham It can seem like barely a week goes by without a new study linking the stage in a woman’s monthly cycle to her preferences in a sexual partner. Reportedly, when women are ovulating they are attracted to men who are healthier, more dominant, more masculine, have higher testosterone levels– the list goes on. But do women really exhibit such behavioural changes – and why are we so fascinated by the idea that they do? A popular theory in evolutionary psychology is that women seek out men with better genes while they are ovulating to have short term affairs with, so as to produce healthier babies. These men may not necessarily stick around for the long haul, but appear particularly attractive when a woman is in the fertile stage of her cycle. During the non-fertile phase, the theory goes that women seek out men who are more likely to make reliable long-term partners and good fathers. But something smells a bit fishy here. Are women really evolutionarily hard-wired to cuckold their partners? Or might the attraction of a salacious hypothesis – with slightly sexist overtones – be shaping some of this research? Masculine all month A review of these kinds of studies is now challenging this often-told story. Wendy Wood at the University of Southern California and her team have analysed 58 studies – some of which were never published – and found that this theory is largely unsupported by evidence. © Copyright Reed Business Information Ltd.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 22611 - Posted: 08.30.2016

By Michael Price Doctors and soldiers could soon place their trust in an unusual ally: the mouse. Scientists have genetically engineered mice to be ultrasensitive to specific smells, paving the way for animals that are “tuned” to sniff out land mines or chemical signatures of diseases like Parkinson’s and Alzheimer’s. Trained rats and dogs have long been used to detect the telltale smell of TNT in land mines, and research suggests that dogs can smell the trace chemical signals of low blood sugar or certain types of cancer. Mice also have powerful sniffers: They sport about 1200 genes dedicated to odorant receptors, cellular sensors that react to a scent’s chemical signature. That’s a few hundred less than rats and about the same as dogs. (Humans have a paltry 350.) Paul Feinstein wants to upgrade the mouse’s already sensitive nose. For the last decade, the neurobiologist at Hunter College in New York City has been studying how odorant receptors form on the surface of neurons within the olfactory system. During development, each olfactory neuron specializes to express a single odorant receptor, which binds to chemicals in the air to detect a specific odor. In other words, each olfactory neuron has a singular receptor that senses a particular smell. Normally, there is an even distribution of receptors throughout the system, so each receptor can be found in about 0.1% of mouse neurons. Feinstein wondered if he could make the mouse’s nose pay more attention to particular scents by making certain odorant receptors more numerous. He and colleagues developed a string of DNA that, when injected into the nucleus of a fertilized mouse egg, appears to make olfactory neurons more likely to develop one particular odorant receptor than the others. This receptor, called M71, detects acetophenone, a chemical that smells like jasmine. When the team added four or more copies of the DNA sequence to a mouse egg, a full 1% of neurons carried it—10 times more than normal. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 22412 - Posted: 07.08.2016

By Patrick Monahan Birds are perhaps best known for their bright colors, aerial prowess, and melodic songs. But research presented in Austin last week at the Evolution Conference shows that bacteria have granted some birds another important attribute: stink. Having long taken a back seat to sight and sound, scent is becoming more and more recognized as an important sense for songbirds, and dark-eyed juncos (Junco hyemalis, pictured) are no stranger to it. When these common birds clean their feathers—or preen—they spread pungent oil from their “preen glands” all over their bodies. The act is important for enticing mates: Three of the gland’s smelly chemicals are found in very different quantities in the two sexes, and males with a more masculine musk end up with more offspring. Females with a more feminine scent profile are more successful, too. But juncos likely aren’t making their perfume alone: Lots of those preen gland chemicals are naturally made by bacteria. And new work is making the bird-bacteria link even more firm. When researchers inject antibiotics into the juncos’ preen glands, the concentrations of three smelly molecules tend to decrease—the same three molecules that juncos find sexy in the right proportions, Danielle Whittaker of Michigan State University in East Lansing told attendees. So it seems like juncos may actually be picking mates based on their bacterial—rather than self-produced—body odor, a first for birds. © 2016 American Association for the Advancement of Science.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 22377 - Posted: 06.30.2016

By REUTERS SINGAPORE — Phones or watches may be smart enough to detect sound, light, motion, touch, direction, acceleration and even the weather, but they can't smell. That's created a technology bottleneck that companies have spent more than a decade trying to fill. Most have failed. A powerful portable electronic nose, says Redg Snodgrass, a venture capitalist funding hardware start-ups, would open up new horizons for health, food, personal hygiene and even security. Imagine, he says, being able to analyze what someone has eaten or drunk based on the chemicals they emit; detect disease early via an app; or smell the fear in a potential terrorist. "Smell," he says, "is an important piece" of the puzzle. It's not through lack of trying. Aborted projects and failed companies litter the aroma-sensing landscape. But that's not stopping newcomers from trying. Like Tristan Rousselle's Grenoble-based Aryballe Technologies, which recently showed off a prototype of NeOse, a hand-held device he says will initially detect up to 50 common odors. "It's a risky project. There are simpler things to do in life," he says candidly. The problem, says David Edwards, a chemical engineer at Harvard University, is that unlike light and sound, scent is not energy, but mass. "It's a very different kind of signal," he says. That means each smell requires a different kind of sensor, making devices bulky and limited in what they can do. The aroma of coffee, for example, consists of more than 600 components. France's Alpha MOS was first to build electronic noses for limited industrial use, but its foray into developing a smaller model that would do more has run aground. Within a year of unveiling a prototype for a device that would allow smartphones to detect and analyze smells, the website of its U.S.-based arm Boyd Sense has gone dark. Neither company responded to emails requesting comment. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 22354 - Posted: 06.24.2016

By C. CLAIBORNE RAY Insects have an odor-sensing system that is roughly analogous to that of vertebrates, according to “The Neurobiology of Olfaction,” a survey published in 2010. Different species have varying numbers of odor receptors, special molecules that are attuned to specific odor molecules. Genes govern the production of each kind of receptor; the more genes, the more kinds of receptor. A big difference with insects is that their olfactory receptors are basically external, often within hairlike groups of cells, called sensilla, on the antennas, not inside a collection organ like a nose. Sign Up for the Science Times Newsletter Every week, we'll bring you stories that capture the wonders of the human body, nature and the cosmos. The odorant molecules encounter odorant-binding proteins, assumed to guide them to the long receptor nerve cells, called axons. Electrical signals are sent along the axons. The axons are usually connected to specific processing centers in the brain called glomeruli, held in a region called the antennal lobe. There the signals are analyzed. Depending on the nature, quantity and timing of the odor signals received, still other cells appear to excite or inhibit reactions. Exactly how the reaction system works is not yet fully understood. The Florida carpenter ant and the Indian jumping ant both have wide-ranging abilities to sense odors, with more than 400 genes to make different odor receptors, a 2012 study found. The fruit fly has only 61. The research also found marked differences in the smelling ability of the sexes, with the female ants well ahead. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 22316 - Posted: 06.14.2016

“I understand how the appearance and texture of food can change the experience,” says food writer and Great British Bake Off finalist Tamal Ray, “but I never really considered how the other senses might have a role to play.” An anaesthetist by day, Ray is best-known for creating spectacular tiered cakes and using a syringe to inject extra, syrupy deliciousness into them. Which is why we introduced him to Oxford psychologist Charles Spence and chef Jozef Youssef – and turned what they taught him about the science of taste into the video above. Part mad professor, part bon vivant, Spence has spent the past 15 years discovering that little of how we experience flavour is to do with our taste buds – smell, vision, touch and even sound dictate how we perceive flavours. Youssef, meanwhile, sharpened his culinary skills at the Fat Duck, the Connaught and the Dorchester, before starting experimental dining outfit Kitchen Theory, where he applies science to meals that play with the multisensory experience of eating. When Spence started studying the sensory science behind flavour perception, it was a deeply unfashionable subject. “There’s some ancient Roman notion that eating and drinking involve lower senses,” he says, “not higher, rational senses like hearing and vision.” Now, the fruits of the research field he calls “gastrophysics” can be seen everywhere from the world’s top restaurants to airline food, via progressive hospital kitchens and multisensory cocktail bars. Spence heads the Crossmodal Research Laboratory at the University of Oxford. “Crossmodal”, in this context, means the investigation of how all the senses interact. Although we’re often unaware of it, when it comes to flavour perception, we all have synaesthesia. That is, our senses intermingle so that our brains combine shapes, textures, colours and even sounds with corresponding tastes.

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 22239 - Posted: 05.23.2016

By C. CLAIBORNE RAY Q. Why do we become desensitized to a perfume we are wearing while others can still smell it? A. Ceasing to smell one’s perfume after continuous exposure while casual passers-by can still smell it is just one example of a phenomenon called olfactory adaptation or odor fatigue. After some time without exposure, sensitivity is usually restored. A similar weakening of odor signals with continued exposure also takes place in animals other than humans, and researchers often rely on animal studies to try to understand the cellular and molecular bases for the condition. It has been suggested that odor fatigue is useful because it enables animals to sort out the signals of a new odor from the background noise of continuous odors. It may also enable them to sense when an odor grows stronger. Studies published in the journal Science in 2002 pinpointed a chemical that seems to act as a gatekeeper for neurons involved in smell, opening and closing their electric signal channels. Genetically engineered mice that did not produce the substance, a protein called CNGA4, had profoundly impaired olfactory adaptation. A separate test-tube study found similar changes on a cellular level, with the signal channels remaining open when CNGA4 was absent. question@nytimes.com © 2016 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 5: The Sensorimotor System
Link ID: 22042 - Posted: 03.29.2016

By RACHEL NUWER For all the havoc that zebra mussels, Asian carp, round gobies and dozens of other alien species have wrought on the Great Lakes, those waters have never known a foe like the sea lamprey. The vampirelike parasites cost many millions each year in depleted fisheries and eradication efforts. Wildlife managers have long used lampricide — the lamprey version of pesticide — with mixed results. Now, an innovative control program seeks to improve on that method by using pheromones to trick the bloodsuckers into voluntarily corralling themselves in designated areas, to then be trapped or poisoned. But achieving this depends on cracking the fish’s olfactory language. “The broad goal is to understand how this animal makes decisions,” said Michael Wagner, a fish ecologist at Michigan State University. “Then, we want to use that understanding to guide lampreys’ movements by manipulating the landscape of fear and opportunity.” Lampreys look like the stuff of horror films: a slithering, tubular body topped with a suction-cup mouth ringed with row upon row of hooked yellow teeth. With this mouth, a sea lamprey anchors to its fish prey and uses its rasping tongue to drill into the victim’s flesh. It remains there for up to a month, feeding on blood and body fluids. Even if a fish survives the attack, the gaping wound left behind often results in death. In their natural ranges, lampreys are important components of food webs. The problems begin only when they shift from native to invader. Sea lampreys slipped into Lake Ontario through the Erie Canal in the mid-19th century, and then made it past Niagara Falls around 1919 with the renovation of the Welland Canal. In the lakes, lampreys found a utopia: no predators, and bountiful prey that had no natural defenses against their voracious appetites. Biological disaster ensued. © 2016 The New York Times Company

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 21869 - Posted: 02.08.2016

by Bethany Brookshire Unless you’re in the middle of biting into a delicious Reuben sandwich, you might forget that taste is one of the fundamental senses. “It’s required for our enjoyment of food,” explains Emily Liman, a taste researcher at the University of Southern California in Los Angeles. “Without taste … people stop eating. They don’t enjoy their food.” A life without the sweet jolt of sugar or the savory delights of umami seems, well, tasteless. When you put that mouthwatering combination of corned beef, Swiss cheese, Thousand Island dressing, sauerkraut and rye in your mouth, the chemicals in the sandwich stimulate taste buds on your tongue and soft palate. Those taste buds connect to the ends of nerve fibers extending delicately into the mouth. Those nerve fibers are the ends of cells located in the geniculate ganglion, a ball of cells nestled up against the ear canal on the side of your head. From there, taste sensations head toward the brain. Chemical messengers bridge the gap between the taste bud and the end of the nerve fiber. But what chemical is involved depends on the type of cell within the bud. There are three types of taste cells (imaginatively titled I, II and III). Type I is not well-understood, but it may be a kind of support cell for other taste cells. Type II, in contrast, is better known. These taste cells sense the slight bitterness of the rye seeds, the sweet edge of the Thousand Island dressing and the savory umami of the beef. They pass that delightful message on using the chemical ATP. © Society for Science & the Public 2000 - 2016

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 16: Psychopathology: Biological Basis of Behavior Disorders
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 12: Psychopathology: The Biology of Behavioral Disorders
Link ID: 21823 - Posted: 01.26.2016

By Kerry Klein With their suction cup mouths filled with concentric circles of pointy teeth that suck the body fluid of unsuspecting victims, lampreys may seem like the stuff of horror movies. And indeed the 50-centimeter-long, eellike creatures can wreak havoc on freshwater communities when they invade from the sea, with a single sea lamprey able to kill 18 kilograms of fish in its lifetime. Now, the U.S. government has approved of a new way to combat these fearsome fish by using their own sense of smell against them. Sea lampreys are a particular problem in the Great Lakes regions of the United States and Canada. They hitchhiked into the region more than a century ago, likely attaching themselves to ships or fish that traveled along shipping channels from the Atlantic Ocean. Although most lampreys are mere parasites in their native habitats, those in the Great Lakes are far worse, says Nicholas Johnson, a research ecologist at the U.S. Geological Survey’s Hammond Bay Biological Station on Lake Huron in Millersburg, Michigan. “They kill their host, they get too big, they eat too much,” he says. “They’re really more of a predator.” After the toothy invaders proliferated in the mid-20th century, ecosystems all but collapsed, taking prosperous fishing and tourism industries with them. “It’s fair to say that lamprey[s] changed the way of life in the region,” says Marc Gaden of the Great Lakes Fishery Commission, a joint U.S. and Canadian organization based in Ann Arbor, Michigan, that’s tasked with managing the rebounding ecosystems. “Just about every fishery management decision that we make to this day has to take lamprey into consideration.” © 2016 American Association for the Advancement of Science

Related chapters from BP7e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 8: Hormones and Sex
Link ID: 21808 - Posted: 01.21.2016

by Helen Thompson Earth’s magnetic field guides shark movement in the open ocean, but scientists had always suspected that sharks might also get their directions from an array of other factors, including smell. To sniff out smell’s role, biologists clogged the noses of leopard sharks (Triakis semifasciata), a Pacific coastal species that makes foraging trips out to deeper waters. Researchers released the sharks out at sea and tracked their path back to the California coast over four hours. Sharks with an impaired sense of smell only made it 37.2 percent of the way back to shore, while unimpaired sharks made it 62.6 percent of the way back to shore. The study provides the first experimental evidence that smell influences a shark’s sense of direction, the team writes January 6 in PLOS ONE. The animals may be picking up on chemical gradients produced by food sources that live on the coast. © Society for Science & the Public 2000 - 2015.

Related chapters from BP7e: Chapter 1: Biological Psychology: Scope and Outlook
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior
Link ID: 21753 - Posted: 01.07.2016