Links for Keyword: Chemical Senses (Smell & Taste)

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

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 11: Emotions, Aggression, and Stress
Link ID: 20443 - Posted: 12.27.2014

Insect hunger games: Male mantises deceived by starving females

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

Related chapters from 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: 20425 - Posted: 12.18.2014

The nose knows a trillion odors

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

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20417 - Posted: 12.16.2014

Brain's taste secrets uncovered

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

Food bland? Electric spoon zaps taste into every bite

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

Lemur Latrine Trees Serve as Community Bulletin Boards

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

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 19: Language and Lateralization
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 15: Brain Asymmetry, Spatial Cognition, and Language
Link ID: 20211 - Posted: 10.18.2014

Smell Turns Up in Unexpected Places

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

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 13: Homeostasis: Active Regulation of the Internal Environment
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell; Chapter 9: Homeostasis: Active Regulation of the Internal Environment
Link ID: 20206 - Posted: 10.14.2014

Better smelling beer, thanks to fruit flies

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

Scientists sniff out unexpected role for stem cells in the brain

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

Related chapters from BN8e: Chapter 7: Life-Span Development of the Brain and Behavior; Chapter 9: Hearing, Vestibular Perception, Taste, and Smell
Related chapters from MM:Chapter 13: Memory, Learning, and Development; Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 20191 - Posted: 10.11.2014

Sense of smell 'may predict lifespan'

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

Related chapters from 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: 20149 - Posted: 10.02.2014

Training Dogs to Sniff Out Cancer

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

Taste Receptors in the Nose Help Fight Infections

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

'Pig Perfume' Stops Dogs From Behaving Badly

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

Hummingbirds turned savoury into sweet to taste nectar

by Philippa Skett It's the strangest sweet tooth in the world. Birds lost the ability to taste sugars, but nectar-feeding hummingbirds re-evolved the capacity by repurposing receptors used to taste savoury food. To differentiate between tastes, receptors on the surface of taste buds on the tongue, known as T1Rs, bind to molecules in certain foods, triggering a neurological response. In vertebrates such as humans, a pair of these receptors – T1R2 and T1R3 – work together to deliver the sweet kick we experience from sugar. But Maude Baldwin at Harvard University and her colleagues found that birds don't have the genes that code for T1R2. They are found in lizards, though, suggesting that they were lost at some point during the evolution of birds or the dinosaurs they evolved from. But hummingbirds clearly can detect sugar: not only do they regularly sup on nectar, taste tests show they prefer sweet tasting foods over blander options. Now Baldwin and her team have worked out why: another pair of receptors – T1R1 and T1R3 – work together to detect sugar. Other vertebrates use T1R1 to taste savoury foods. It seems that in hummingbirds the proteins on the surface of the two receptors have been modified so that they respond to sugars instead. © Copyright Reed Business Information Ltd.

Related chapters from BN8e: Chapter 9: Hearing, Vestibular Perception, Taste, and Smell; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 6: Hearing, Balance, Taste, and Smell
Link ID: 19983 - Posted: 08.22.2014

Nose Knows What the Mind Tells It

|By Karen Hopkin They say that the nose knows. But it still gets its marching orders from the brain—at least when it comes to the lungs. Got that? Nose to brain to lungs. Because a new study shows that when people with asthma think they’re smelling something noxious, their airways become inflamed—even when the odor is harmless. The finding is in the Journal of Psychosomatic Research. [Cristina Jaén and Pamela Dalton, Asthma and odors: The role of risk perception in asthma exacerbation] Asthma attacks can be triggered by pollen, dust, harsh chemicals or scents. These environmental annoyances constrict the airways in the lung, making breathing difficult. In this study, researchers wanted to see whether an individual’s assumptions have any influence over this breathtaking series of events. So they exposed 17 asthma sufferers to a benign chemical that smells like roses for 15 minutes. Nine subjects were told the fragrance was a potential irritant, the other eight that it would be therapeutic. The results were as plain as the nose on your face: subjects who expected an irritant experienced inflammation. And those who were primed to be soothed had no adverse reactions—even if they were normally bothered by perfumes. The results suggest that a rose by any other name would smell as sweet. Or be as irritating as you expect it will. © 2014 Scientific American

Alcohol improves your sense of smell – in moderation

by Helen Thomson How do you smell after a drink? Quite well, it turns out. A modest amount of alcohol boosts your sense of smell. It is well known that we can improve our sense of smell through practice. But a few people have also experienced a boost after drug use or brain damage. This suggests our sensitivity to smell may be damped by some sort of inhibition in the brain, which can be lifted under some circumstances, says Yaara Endevelt of the Weizmann Institute of Science in Rehovot, Israel. To explore this notion, Endevelt and her colleagues investigated whether drinking alcohol – known to lower inhibitory signals in the brain – affected the sense of smell. In one odour-discrimination test, 20 volunteers were asked to smell three different liquids. Two were a mixture of the same six odours, the third contained a similar mixture with one odour replaced. Each volunteer was given 2 seconds to smell each of the liquids and say which was the odd one out. The test was repeated six times with each of three trios of liquids. They were then given a drink that consisted of 35 millilitres of vodka and sweetened grape juice, or the juice alone, before repeating the experiment with the same set of liquids. In a second experiment with a similar drinking structure, the same volunteers were asked which of three liquids had a rose-like odour. The researchers increased the concentration of the odour until the volunteers got the right answer three times in a row. © Copyright Reed Business Information Ltd.

Elephants may have best noses on Earth

By Virginia Morell Dogs, most of us think, have the best noses on the planet. But a new study reveals that this honor actually goes to elephants. The power of a mammal’s sniffer hinges on the number and type of its olfactory receptor genes. These genes are expressed in sensory cells that line the nasal cavity and are specialized for detecting odor molecules. When triggered, they set off a cascade of signals from the nose to the brain, enabling an animal to identify a particular smell. In the new study, scientists identified and examined olfactory receptor genes from 13 mammalian species. The researchers found that every species has a highly unique variety of such genes: Of the 10,000 functioning olfactory receptor genes the team studied, only three are shared among the 13 species. Perhaps not surprisingly, given the length of its trunk, the African elephant has the largest number of such genes—nearly 2000, the scientists report online today in the Genome Research. In contrast, dogs have only 1000, and humans and chimpanzees, less than 400—possibly because higher primates rely more on their vision and less on their sense of smell. The discovery fits with another recent study showing that Asian elephants are as good as mice (which have nearly 1300 olfactory receptor genes) at discriminating between odors; dogs and elephants have yet to be put to a nose-to-trunk sniffer test. Other research has also shown just how important a superior sense of smell is to the behemoths. A slight whiff is all that’s necessary, for instance, for elephants, such as those in the photo above, to distinguish between two Kenyan ethnic groups—the Maasai, who sometimes spear them, and the Kamba, who rarely pose a threat. They can also recognize as many as 30 different family members from cues in their urine. © 2014 American Association for the Advancement of Science.

Beyond Salty and Sweet: A Budding Club of Tastes

By PETER ANDREY SMITH Sweet, salty, sour and bitter — every schoolchild knows these are the building blocks of taste. Our delight in every scrumptious bonbon, every sizzling hot dog, derives in part from the tongue’s ability to recognize and signal just four types of taste. But are there really just four? Over the last decade, research challenging the notion has been piling up. Today, savory, also called umami, is widely recognized as a basic taste, the fifth. And now other candidates, perhaps as many as 10 or 20, are jockeying for entry into this exclusive club. “What started off as a challenge to the pantheon of basic tastes has now opened up, so that the whole question is whether taste is even limited to a very small number of primaries,” said Richard D. Mattes, a professor of nutrition science at Purdue University. Taste plays an intrinsic role as a chemical-sensing system for helping us find what is nutritious (stimulatory) and as a defense against what is poison (aversive). When we put food in our mouths, chemicals slip over taste buds planted into the tongue and palate. As they respond, we are thrilled or repulsed by what we’re eating. But the body’s reaction may not always be a conscious one. In the late 1980s, in a windowless laboratory at Brooklyn College, the psychologist Anthony Sclafani was investigating the attractive power of sweets. His lab rats loved Polycose, a maltodextrin powder, even preferring it to sugar. That was puzzling for two reasons: Maltodextrin is rarely found in plants that rats might feed on naturally, and when human subjects tried it, the stuff had no obvious taste. More than a decade later, a team of exercise scientists discovered that maltodextrin improved athletic performance — even when the tasteless additive was swished around in the mouth and spit back out. Our tongues report nothing; our brains, it seems, sense the incoming energy. © 2014 The New York Times Company

What Happens When an Amoeba “Eats” Your Brain?

|By Roni Jacobson Last week, nine-year-old Hally Yust died after contracting a rare brain-eating amoeba infection while swimming near her family’s home in Kansas. The organism responsible, Naegleria fowleri, dwells in warm freshwater lakes and rivers and usually targets children and young adults. Once in the brain it causes a swelling called primary meningoencephalitis. The infection is almost universally fatal: it kills more than 97 percent of its victims within days. Although deadly, infections are exceedingly uncommon—there were only 34 reported in the U.S. during the past 10 years—but evidence suggests they may be increasing. Prior to 2010 more than half of cases came from Florida, Texas and other southern states. Since then, however, infections have popped up as far north as Minnesota. “We’re seeing it in states where we hadn’t seen cases before,” says Jennifer Cope, an epidemiologist and expert in amoeba infections at the U.S. Centers for Disease Control and Prevention. The expanding range of Naegleria infections could potentially be related to climate change, she adds, as the organism thrives in warmer temperatures. “It’s something we’re definitely keeping an eye on.” Still, “when it comes to Naegleria there’s a lot we don’t know,” Cope says—including why it chooses its victims. The amoeba has strategies to evade the immune system, and treatment options are meager partly because of how fast the infection progresses. But research suggests that the infectioncan be stopped if it is caught soon enough. So what happens during an N. fowleri infection? © 2014 Scientific American

Food presented artistically really does taste better

Nicola Davis The old adage that we eat with our eyes appears to be correct, according to research that suggests diners rate an artistically arranged meal as more tasty – and are prepared to pay more for it. The team at Oxford University tested the idea by gauging the reactions of diners to food presented in different ways. Inspired by Wassily Kandinsky's "Painting Number 201" Franco-Columbian chef and one of the authors of the study, Charles Michel, designed a salad resembling the abstract artwork to explore how the presentation of food affects the dining experience. "A number of chefs now are realising that they are being judged by how their foods photograph – be it in the fancy cookbooks [or], more often than not, when diners instagram their friends," explains Professor Charles Spence, experimental psychologist at the University of Oxford and a co-author of the study. Thirty men and 30 women were each presented with one of three salads containing identical ingredients, arranged either to resemble the Kandinsky painting, a regular tossed salad, or a "neat" formation where each component was spaced away from the others. Seated alone at a table mimicking a restaurant setting, and unaware that other versions of the salad were on offer, each participant was given two questionnaires asking them to rate various aspects of the dish on a 10-point scale, before and after tucking into the salad. Before participants sampled their plateful, the Kandinsky-inspired dish was rated higher for complexity, artistic presentation and general liking. Participants were prepared to pay twice as much for the meal as for either the regular or "neat arrangements". © 2014 Guardian News and Media Limited

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: 19759 - Posted: 06.23.2014

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Links for Keyword: Chemical Senses (Smell & Taste)