Chapter 9. Hearing, Vestibular Perception, Taste, and Smell

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By SINDYA N. BHANOO Mosquito sperm have a sense of smell, researchers are reporting, in a finding that could suggest ways to help control the spread of disease-carrying insects. The sperm carries a set of chemical sensors identical to the olfactory receptors on the mosquitoes’ antennas, according to a study in Proceedings of the National Academy of Sciences. Mosquitoes mate just once in their lifetime, and the female stores the male’s sperm in an organ called a spermatheca. Before the eggs mature, the female seeks out blood using the receptors on her antennas. Soon after, chemical signals cause the sperm tails to beat rapidly and start the fertilization process. “The sperm may need a chemical signal to become ready for fertilization,” said Jason Pitts, a researcher at Vanderbilt University and an author of the study, which was supported by the Gates Foundation as part of its efforts to improve global health. Another author, Laurence Zwiebel, also a Vanderbilt researcher, called the dual use of the olfactory receptors a clear and clever example of convergent evolution: The mosquitoes, he said, “found something that works and use it in multiple ways.” The scientists think olfactory receptors may exist on the sperm of many other insects, and they are developing chemical compounds that can be applied to breeding grounds to block the receptors. “You can effectively confuse the sperm or make them inactive,” Dr. Zwiebel said. © 2014 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 19241 - Posted: 02.12.2014

by Bob Holmes Midnight fridge raids are part and parcel of a late-night marijuana smoking session. A study in mice has provided the most complete explanation yet for why a spliff triggers intense hunger pangs. The findings, which elucidate the role of smell, also suggest that we might eventually be able to treat common disorders such as obesity and loss of appetite with a simple nasal spray. We know that the active ingredient in cannabis, THC, binds to cannabinoid receptors in the brain called CB1s. This binding inhibits chemical signals that tell us not to eat, and so make us feel hungry. But this isn't the end of the story. Since smell plays such a central role in making us feel hungry, it must be part of the explanation - but no one knew exactly how it fit. To find out, Giovanni Marsicano of the French research agency INSERM in Bordeaux and his colleagues genetically modified mice to make it possible to turn on and off the CB1 receptor in particular nerve cells within the smell, or olfactory, system. The key proved to be a group of nerve cells that carry signals from the cerebral cortex down to the olfactory bulb, the primary smell centre of the brain. When the team switched off CB1 on these cells, they found that hungry mice no longer ate more than their well-fed counterparts. Conversely, activating CB1 in the same cells by injecting THC caused hungry mice to eat even more. THC-treated mice also responded to less-concentrated food smells than untreated mice, a sign that the chemical had enhanced their sense of smell. © Copyright Reed Business Information Ltd.

Keyword: Chemical Senses (Smell & Taste); Drug Abuse
Link ID: 19230 - Posted: 02.10.2014

Dinsa Sachan Could being visually impaired have had a role in the musical genius of Stevie Wonder and Ray Charles? A study provides some clues by showing that adult mice kept in the dark quickly develop sharper hearing and become better at distinguishing pitch and frequency. The improvements were correlated with adaptations in the brain — such as strengthening of connections between neurons — that normally happen only early in life. For their study, published today in Neuron1, Hey-Kyoung Lee, a neuroscientist at Johns Hopkins University in Baltimore, Maryland, and her collaborators selected two sets of healthy adult mice. They kept the first group in a darkened environment for a week, while the other was exposed to natural light. The team used electrodes to measure activity in neurons in the animals' primary auditory cortex — the part of the brain that processes what a sound is, how loud it is and where it comes from. The researchers played sounds of different frequencies and intensities to the mice, and watched how their brain cells reacted. The results “showed that neurons in visually deprived animals can 'hear' much softer sounds” than in control animals, says Lee. “They also have much finer discrimination ability as far as identifying pitch goes.” Previous studies have found that changes in the auditory cortex take a long time, and that people who become blind early in life adapt better than those who lose their sight later. The team's findings, however, show that some modifications can occur rapidly in the adult brain, she says. “Moreover,” she adds, “the changes in the auditory cortex were achieved by changes in the strength of synaptic connections. These were believed to be unchangeable in adults.” © 2014 Nature Publishing Group

Keyword: Hearing; Vision
Link ID: 19217 - Posted: 02.06.2014

About two-thirds of people are left with ringing in their ears after a night out at a club, gig or pub, a poll suggests. Campaign group Action on Hearing Loss said the poll of 1,000 adults also showed a third would ignore the "safe level" on their music players. The group warns that people doing either increase the risk of tinnitus. DJ Paul Oakenfold urged people to wear ear defenders to gigs and to "turn down the volume". Half of those surveyed said they listened to music for between one and six hours a day - up to a third of their waking day - perhaps in the background at work or on their MP3 player on their way to and from work or studies. But one in five would not do anything differently to take any care of their hearing. Action on Hearing Loss warned that one in 10 people across the UK is affected by tinnitus every day, ranging from a "light buzzing" to a "constant roar" in the ears and head. It can affect everything from the ability to concentrate at work to getting to sleep at night. The poll also found that one in 10 people does not know what tinnitus is, with 3% thinking it was "big ears" and 4% a "repetitive strain injury". It has created an audio version of what tinnitus sounds like in order to raise awareness. Paul Breckell, chief executive of Action on Hearing Loss, said: "Listening to loud music for a long time can trigger tinnitus and is an indication of damaged hearing. BBC © 2014

Keyword: Hearing
Link ID: 19201 - Posted: 02.04.2014

|By Stephanie Pappas and LiveScience Even water tastes sweeter when you're in love, new research finds. But not every emotion heightens the senses. Jealousy fails to bring out bitter or sour tastes, despite metaphors that suggest it might, researchers report in the December 2013 issue of the journal Emotion. That love alters one's sensory perceptions and jealousy does not is important to psychologists who study what are called "embodied" metaphors, or linguistic flourishes people quite literally feel in their bones. For example, studies have shown that people induced to feel lonely rate the temperature of the room as colder than do their unprimed counterparts. And the idea that important things have heft plays out physically, too: When someone believes a book is important, it feels heavier. But "just because there is a metaphor does not necessarily imply that we will get these kind of sensations and perception effects," said study researcher Kai Qin Chan, a doctoral candidate at Radboud University Nijmegen in the Netherlands. After seeing previous research on emotional metaphors, like the studies linking loneliness to coldness and heaviness to importance, Chan and his colleagues wanted to expand the question. "We always say, 'love is sweet,' 'honey baby,' this kind of thing," Chan told LiveScience. "We thought, let's see whether this applies to love." © 2014 Scientific American

Keyword: Sexual Behavior; Chemical Senses (Smell & Taste)
Link ID: 19163 - Posted: 01.25.2014

By TRICIA ROMANO Like many men of his generation, Larry Faust, 61, of Seattle, went to a lot of rock concerts in his youth. And like many men of his generation, his hearing isn’t what it used to be. “My wife has been bugging me for several years to do something about my hearing,” said Mr. Faust. “I spent part of the summer of 1969 at Woodstock. So that probably didn’t help.” Instead of going the traditional route — buying hearing aids through an audiologist or licensed hearing aid dispenser — Mr. Faust purchased a device that is classified as a personal sound amplifier product, or P.S.A.P., which is designed to amplify sounds in a recreational environment. Unlike hearing aids, P.S.A.P.’s are exempt from Food and Drug Administration oversight and can be sold as electronic devices directly to consumers, with no need to see a physician before buying one. They come with a range of features and vary widely in price. And while some hearing professionals have long cautioned against the devices, citing their unreliability and poor quality, many also say that a new generation of P.S.A.P.s that utilize the latest wireless technology are offering promising alternatives for some people with hearing loss. The device Mr. Faust bought, the CS10 from a Chicago-based company called Sound World Solutions, cost $299.99, thousands of dollars cheaper than most digital hearing aids. While it has many of the same features that high-end hearing aids have, including 16 channels to process sound, directional microphones, feedback insulation and noise reduction, it has one capability that hearing aids and other devices on the market currently don’t have. It comes with software that enables consumers to program it themselves, a feature made possible in part by the adoption of the widely available Bluetooth wireless technology, rather than the proprietary platforms used by most wireless hearing aids. © 2014 The New York Times Company

Keyword: Hearing
Link ID: 19144 - Posted: 01.16.2014

Ask a group of people to describe the color of a sheet of paper, a cloud, or a glass of milk, and chances are they’ll all say “white.” But ask the same group to describe the smell of cinnamon, and you’ll likely get a potpourri of answers, ranging from “spicy” to “smoky” to “sweet,” and sometimes all three. When it comes to naming smells, humans struggle to find concise, universal terms. Indeed, scientists have long thought the ability was out of our reach. But a new study indicates that the inhabitants of a remote peninsula in Southeast Asia can depict smells as easily as the rest of us pick colors. The study concerns the Jahai, nomadic hunter-gatherers who live in the mountain rainforests along the border between Malaysia and Thailand. Smell is very important to this society. Odors are often evoked in illness, or medicine, for example, and it is one of the few cultures to have words devoted exclusively to smells. “For example, the term pʔus (pronounced ‘pa-oos’) describes the smell of old huts, day-old food, and cabbage,” says Asifa Majid, a psychologist at the Centre for Language Studies at Radboud University Nijmegen in the Netherlands. This suggests, she says, that the Jahai can isolate basic smell properties, much like we can isolate the color white from milk. To find out if the Jahai are better at naming smells than the rest of us, Majid and colleagues asked native Jahai speakers and native English speakers to describe 12 different odors: cinnamon, turpentine, lemon, smoke, chocolate, rose, paint thinner, banana, pineapple, gasoline, soap, and onion. The Jahai easily and consistently named the odors, whereas English speakers struggled, the team reports in the February issue of Cognition. © 2014 American Association for the Advancement of Science

Keyword: Chemical Senses (Smell & Taste)
Link ID: 19129 - Posted: 01.14.2014

by Helen Thomson A drug for perfect pitch is just the start: mastering new skills could become easy if we can restore the brain's youthful ability to create new circuits WANNABE maestros, listen up. A mood-stabilising drug can help you achieve perfect pitch – the ability to identify any note you hear without inferring it from a reference note. Since this is a skill that is usually acquired only early in life, the discovery is the first evidence that it may be possible to revert the human brain to a childlike state, enabling us to treat disorders and unlock skills that are difficult, if not impossible, to acquire beyond a certain age. From bilingualism to sporting prowess, many abilities rely on neural circuits that are laid down by our early experiences. Until the age of 7 or so, the brain goes through several "critical periods" during which it can be radically changed by the environment. During these times, the brain is said to have increased plasticity. In order to take advantage of these critical periods, the brain needs to be stimulated appropriately so it lays down the neuronal circuitry needed for a particular ability. For example, young children with poor sight in one eye may develop lazy eye, or amblyopia. It can be treated by covering the better eye, forcing the child to use the lazy eye – but this strategy only works during the critical period. These windows of opportunity are fleeting, but now researchers are beginning to understand what closes them and how they might be reopened. © Copyright Reed Business Information Ltd.

Keyword: Development of the Brain; Hearing
Link ID: 19115 - Posted: 01.09.2014

Fifty million Americans experience chronic ringing in the ears, a condition known as tinnitus. But new research from the University of Michigan Medical School may soon provide solace to those suffering. The discovery helps to explain what is going on inside the brains of those with tinnitus and may provide a new approach to treat the nagging noise. The research team already has a patent pending and device in development. The findings, published in the Journal of Neuroscience, explain that a process called stimulus-timing dependent multisensory plasticity is altered in animals with tinnitus and the results have revealed the relationship between tinnitus, hearing loss and sensory input. Dr. Susan Shore, senior author of the paper notes that any treatment likely will have to be customized to each patient and delivered on a regular basis. Some patients may be more likely to benefit than others. © 1996-2013 MacNeil/Lehrer Productions

Keyword: Hearing
Link ID: 19050 - Posted: 12.18.2013

Bats can understand the emotional state of other bats from the intonations of their calls, a new study suggests. In the lab, researchers observed greater false vampire bats (Megaderma lyra, pictured) that had been trained to wait for food on a perch. In some tests, they played “aggression calls” over a speaker, typically made by a bat defending its place on a perch from an approaching bat. In other trials, the researchers played “appeasement calls” often made by a bat approaching one already ensconced on a perch and thus seeking to share its space. (Bats were tested individually, and the use of recorded calls ensured that the bats were responding to the content of the call and not visual cues from another bat.) In all tests, the scientists played a call once every 20 seconds until the bats began to ignore the call (by not turning toward the speaker), and then they played a slightly different version of the same call—one that was either more urgent (with shorter, more closely spaced syllables) or less urgent. The novel aggression calls always caused a bat to turn toward the speaker, but the novel appeasement calls only drew a response when they became more urgent, the researchers report online today in Frontiers of Zoology. The failure of a bat to react to weakening appeasement calls suggests that the bats can interpret the emotional content of the calls—a sign that such perception might exist more widely in mammals than previously thought. © 2013 American Association for the Advancement of Science.

Keyword: Hearing; Emotions
Link ID: 19037 - Posted: 12.16.2013

Associated Press The U.S. Navy plans to increase sonar testing over the next five years, even as research it funded reveals worrying signs that the loud underwater noise could disturb whales and dolphins. Reported mass strandings of whale species have increased worldwide since the military started using sonar half a century ago. Scientists think the sounds scare animals into shallow waters where they can become disoriented and wash ashore, but technology capable of close monitoring has emerged only in the past decade. Aside from strandings, biologists are concerned marine mammals could suffer prolonged stress from changes in diving, feeding and communication. Two studies off the Southern California coast found certain endangered blue whales and beaked whales stopped feeding and fled from recordings of sounds similar to military sonar. Beaked whales are highly sensitive to sound and account for the majority of beachings near military exercises. Scientists, however, were surprised by the reaction of blue whales - the world's largest animal - long thought to be immune to the high-pitched sounds. It's unclear how the change in behavior would affect the overall population, estimated at between 5,000 and 12,000 animals. The studies involved only a small group of tagged whales, and noise levels were less intense than what's used by the Navy. Shy species - such as the Cuvier's beaked whale, which can dive 3,000 feet below the surface - have taken years to find and monitor. "This is a warning flag and deserves more research," said Stanford University biologist Jeremy Goldbogen, who led the blue whale study published this summer in the journal Proceedings of the Royal Society B. © 2013 Hearst Communications, Inc.

Keyword: Hearing; Animal Migration
Link ID: 19036 - Posted: 12.16.2013

Brian Owens Fruitflies know exactly how much alcohol will be good for their young. Larvae living on a food source with the right concentration of ethanol will grow into heavy, healthy adults and will be protected against parasites — which explains why the insects are attracted to rotting fruit or the crate of empty beer bottles in your kitchen but not to the vodka or gin. Now researchers have uncovered the neural mechanism that allows the fruitfly Drosophila melanogaster to choose the best place to lay its eggs. The work is published today in Proceedings of the National Academy of Sciences1. A team led by Ulrike Heberlein, a molecular biologist at the Howard Hughes Medical Institute’s Janelia Farm Research Campus in Ashburn, Virginia, found that clusters of neurons, working in opposition to each other, help the flies to choose the place with the most beneficial concentration of ethanol in which to lay their eggs. The neurons all release the neurotransmitter dopamine, a key player in the brain's reward circuitry. Neurons of the PAM and PPM3 clusters encourage the flies to seek out ethanol, whereas PPL1 neurons apply the brakes, preventing the flies from laying their eggs on food containing high levels of ethanol that could harm the larvae. “They can discriminate among ethanol concentrations that are very similar — 3% versus 5% — so the system evolved to have great sensitivity,” says Heberlein. Their favourite booze strength is 5%, similar to that of a typical beer. Heberlein's team also traced the neurons involved in ethanol preference to specific brain regions. Both the pro-ethanol PAM and anti-ethanol PPL1 neurons were active in the mushroom body, whereas the pro-ethanol PPM3 ones were active in the ellipsoid body. Both of these brain structures are involved in decision-making and memory, and mushroom body neurons also play a part in ethanol-reward memory. © 2013 Nature Publishing Group,

Keyword: Chemical Senses (Smell & Taste)
Link ID: 19013 - Posted: 12.10.2013

By Julia Calderone As we sat in my car outside a silent movie theater in Los Angeles, my friend anxiously opened a plastic bag containing a white T-shirt she’d slept in for the past three nights. “Does it smell like me?” she asked nervously, gesturing the open end toward my face. I stuck my nose into the bag and inhaled. We were about to attend a pheromone-based speed dating party with the following rules: 1. Find a clean white T-shirt. 2. Sleep in only that shirt for three consecutive nights. 3. Bring the shirt to the party sealed in a bag. As we walked into the theater, coordinators assigned each of our bags a unique color-coded sticker (pink for female, blue for male), and tossed them into a pile. A pack of hipsters nursing PBRs sat in the wooden theater seats, slightly amused by the bizarre 70s Egyptian-themed silent porn projected onto the screen. In the courtyard, 20-somethings mingled by the outdoor bar. Did they think alcohol would make us okay with sniffing strangers’ dirty laundry? Mounds of bags sat on two long tables – beckoning our nostrils. We were instructed to sniff as many T-shirts of the sex we were attracted to, and select shirts that innately smelled the sexiest. I came across bag number 166, which shockingly smelled exactly like my grandmother’s house – a delightful mix of Christmas and chicken parmesan. The point was to trust our instincts, right? I went with it. © 2013 Scientific American

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 19005 - Posted: 12.06.2013

By NICHOLAS BAKALAR A high body mass and a large waist are both associated with self-reported hearing loss, a new study has found. Researchers used data from a 20-year prospective study of 68,421 women who were25 to 42 years old at the start. After controlling for age, smoking, diabetes, hypertension and other factors, they found that the higher the body mass index, the greater the risk for hearing loss. Compared with women with a B.M.I. under 25, those with an index of 25 to 29 had an 8 percent increased risk. The numbers kept going up in tandem: 11 percent for 30 to 34, 16 percent for 35 to 39 and 19 percent for those above 40. The increasing risk associated with larger waist circumference followed a similar pattern. The study, published in the December issue of The American Journal of Medicine, found that moderate physical activity — as little as four hours of walking a week — also reduced the risk for hearing loss. Researchers found no further advantage in more vigorous exercise. The lead author, Dr. Sharon G. Curhan, a clinical researcher at Brigham and Women’s Hospital in Boston, suggested that obesity might compromise blood flow to the inner ear, and that exercise might improve it, which could explain the associations. “Hearing loss may not be an inevitable part of growing older,” she said. “There may be things we can do to prevent it.” Copyright 2013 The New York Times Company

Keyword: Hearing; Obesity
Link ID: 19004 - Posted: 12.06.2013

By JOYCE COHEN Earlier this fall, Seattle Seahawks fans at CenturyLink Field broke the world record for loudest stadium crowd with a skull-splitting 136.6 decibels. That volume, as the Seahawks’ website boasts, hits the scale somewhere between “serious hearing damage” and “eardrum rupture.” Just weeks later, Kansas City Chiefs fans at Arrowhead Stadium topped that number with 137.5 screaming decibels of their own. The measuring method used for the Guinness World Record has an edge of gimmickry. That A-weighted peak measurement, reached for a split second near the measuring device, displays the highest possible readout. For a vulnerable ear, however, game-day noise isn’t just harmless fun. With peaks and troughs, the decibel level of noise reaching a typical spectator averages in the mid-90s, but for a longer time. Such noise is enough to cause permanent damage and to increase the likelihood of future damage. “The extent to which hearing-related issues get so little attention is amazing and troubling,” said M. Charles Liberman, a professor of otology at Harvard Medical School and director of a hearing research lab at the Massachusetts Eye and Ear Infirmary. “Many people are damaging their ears with repeated noise exposure such that their hearing abilities will significantly diminish as they age, much more so than if they were more careful,” he said. Ears are deceptive. Even if they seem to recover from the muffling, ringing and fullness after a rousing game, they don’t really recover. It’s not just the tiny sensory cells in the cochlea that are damaged by noise, Dr. Liberman said, but also the nerve fibers between the ears and the brain that degrade over time. Copyright 2013 The New York Times Company

Keyword: Hearing
Link ID: 18950 - Posted: 11.21.2013

Female mice that compete in promiscuous environments have sexier smelling sons, research has found. Scientists in Utah, US, studied the pheromones produced in the urine of male mice. They found that those whose mothers competed for mates were more sexually attractive to females. But this success was short-lived: their life spans were shorter than mice with monogamous parents. Adam Nelson from the University of Utah completed the study alongside senior author Prof Wayne Potts. It is published in the journal Proceedings of the National Academy of Sciences. "Only recently have we started to understand that environmental conditions experienced by parents can influence the characteristics of their offspring. This study is one of the first to show this kind of 'epigenetic' process working in a way that increases the mating success of sons," said Prof Potts. Epigenetics is the study of how differences in a parent's environment can influence how its offspring's genes are expressed. The researchers studied domestic mice which are usually paired in a cage and therefore breed with only one partner. To reintroduce the social competition wild mice experience, lab mice were kept in "mouse barns" which were large enclosures divided by mesh to create territories. The mice were able to climb over the mesh to access nest boxes, feeding stations and drinking water. BBC © 2013

Keyword: Sexual Behavior; Aggression
Link ID: 18941 - Posted: 11.19.2013

by Erika Engelhaupt When I was in graduate school, I once gassed out my lab with the smell of death. I was studying the products of plant decomposition, and I had placed copious quantities of duckweed into large tubs and let the mix decompose for a few weeks. Duckweed is a small floating aquatic plant; it looks harmless enough. But when I dragged my tubs into the lab and set up a pump and filtration system, all hell broke loose. The filter clogged, the back pressure threw the hose off the pump, and a spray of decomposed mess flew all over a poor professor who had come in to help. For the rest of the day, he smelled like a pile of dead raccoons. That day, I learned about cadaverine and putrescine. These two molecules are produced during the decomposition of proteins, when the amino acids lysine and ornithine break down, and they are largely responsible for the smell of rotting flesh. My mistake in the lab was to think that rotting plants are more innocuous than rotting animals. Duckweed, it turns out, has such high protein levels that it’s used as animal feed, and those proteins, like any proteins, can create a deathly stench. The smells of cadaverine and putrescine tend to provoke a strong reaction (as I learned once the duckweed stench subsided and my labmates were able to return to the lab). But not every animal finds the odors disgusting. Carrion flies, rats and other animals that eat or lay eggs in dead things are attracted to the molecules. So researchers have started to look for exactly how animals tune in to these smells. Pinning down animals' odor detectors gives researchers a way to study aversion or attraction to certain objects. And understanding how these behavioral responses work will, I believe, help researchers clarify why humans feel the distinct emotion known as disgust. © Society for Science & the Public 2000 - 2013.

Keyword: Chemical Senses (Smell & Taste); Emotions
Link ID: 18939 - Posted: 11.16.2013

by Colin Barras IT'S musical mind-reading. Your patterns of brain activity can show what song you are listening to. In the area of the brain that processes sound – the auditory cortex – different neurons become active in response to different sound frequencies. So it should be possible to work out which musical note someone is listening to just by looking at this activity, says Geoff Boynton at the University of Washington in Seattle. To find out, Boynton and his colleague Jessica Thomas had four volunteers listen to various notes, while they used fMRI to record the resulting neural activity. "Then the game is to play a song and use the neural activity to guess what was played," he says. They were able to identify melodies like Twinkle, Twinkle, Little Star from neural activity alone, Boynton told the Society for Neuroscience annual meeting in San Diego, California, this week. The results could help probe the neural roots of people who are tone deaf. This can be a problem for people with cochlear implants, says Rebecca Schaefer, who researches neuroscience and music at the University of California in Santa Barbara. Another study into the music of the mind, also presented this week in San Diego, suggests that the brain is highly attuned to rhythm and this might explain why we talk at certain speeds. David Poeppel at New York University and his colleagues monitored brain activity in 12 volunteers while they listened to three piano sonatas. One sonata had a quick tempo, with around eight notes per second, one had five per second, and the slowest had one note every 2 seconds. © Copyright Reed Business Information Ltd.

Keyword: Hearing; Brain imaging
Link ID: 18924 - Posted: 11.14.2013

by Jennifer Viegas Music skills evolved at least 30 million years ago in the common ancestor of humans and monkeys, according to a new study that could help explain why chimpanzees drum on tree roots and monkey calls sound like singing. The study, published in the latest issue of Biology Letters, also suggests an answer to this chicken-and-egg question: Which came first, language or music? The answer appears to be music. "Musical behaviors would constitute a first step towards phonological patterning, and therefore language," lead author Andrea Ravignani told Discovery News. For the study, Ravignani, a doctoral candidate at the University of Vienna's Department of Cognitive Biology, and his colleagues focused on an ability known as "dependency detection." This has to do with recognizing relationships between syllables, words and musical notes. For example, once we hear a certain pattern like Do-Re-Mi, we listen for it again. Hearing something like Do-Re-Fa sounds wrong because it violates the expected pattern. Normally monkeys don't respond the same way, but this research grabbed their attention since it used sounds within their frequency ranges. In the study, squirrel monkeys sat in a sound booth and listened to a set of three novel patterns. (The researchers fed the monkeys insects between playbacks, so the monkeys quickly got to like this activity.) Whenever a pattern changed, similar to our hearing Do-Re-Fa, the monkeys stared longer, as if to say, "Huh?" © 2013 Discovery Communications, LLC.

Keyword: Hearing; Language
Link ID: 18918 - Posted: 11.13.2013

Brian Owens The hordes of microbes that inhabit every nook and cranny of every animal are not just passive hitchhikers: they actively shape their hosts’ well-being and even behaviour. Now, researchers have found evidence that bacteria living in the scent glands of hyenas help to produce the smells that the animals use to identify group members and tell when females are ready to mate. Kevin Theis, a microbial ecologist at Michigan State University in East Lansing, had been studying hyena scent communication for several years when, after he gave a talk on the subject, someone asked him what part the bacteria might play. “I just said, ‘I don’t know’,” he says. He started investigating. He found that for 40 years, scientists had wondered whether smelly bacteria were involved in animals' chemical communication. But experiments to determine which bacteria were present had been inconclusive, because the microbes had to be grown in culture, which is not possible with all bacteria. However, next-generation genetic sequencing would enable Theis to identify the microbes in a sample without having to grow them in a dish. Using this technique, Theis and his colleagues last year published a study1 that identified more types of bacterium living in the hyenas’ scent glands than the 15 previous studies of mammal scent glands combined. In both spotted hyenas (Crocuta crocuta) and striped hyenas (Hyaena hyaena), most of the bacteria were of a kind that ferments nutrients exuded by the skin and produces odours. “The diversity of the bacteria is enough to potentially explain the origin of these signals,” says Theis. Now, they have found that the structure of the bacterial communities varied depending on the scent profiles of the sour, musky-smelling 'pastes' that the animals left on grass stalks to communicate with members of their clan. In addition, in the spotted hyenas, both the bacterial and scent profiles varied between males and females, and with the reproductive state of females — all attributes that hyenas are known to be able to infer from scent pastes. The work is published this week in Proceedings of the National Academy of Sciences. © 2013 Nature Publishing Group

Keyword: Chemical Senses (Smell & Taste); Sexual Behavior
Link ID: 18915 - Posted: 11.12.2013