Biological Psychology Links

by Paul Marks How do you give a robot a sharper sense of smell? By using genetically modified frog cells, according to Shoji Takeuchi, a bioengineer at the University of Tokyo in Japan. Today's electronic noses are not up to the job, he says. Although e-noses have been around for a while – and are used to sniff out rotten food in production lines – they lack accuracy. That's because e-noses use quartz rods designed to vibrate at a different frequency when they bind to a target substance. But this is not a foolproof system, as subtly different substances with similar molecular weights may bind to the rod, producing a false positive. Instead, Takeuchi believes there is nothing quite as good as biology for distinguishing between different biomolecules, such as disease markers in our breath. So he and his team have developed a living smell sensor. First, immature eggs, or oocytes, from the African clawed frog Xenopus laevis were genetically modified to express the proteins known to act as smell receptors. He chose X. laevis cells as they are widely studied and their protein expression mechanism is well understood. © Copyright Reed Business Information Ltd.

By Jason Palmer Research has shown that bacteria - among the simplest life forms on Earth - have a sense of smell. Scientists from Newcastle University in the UK have demonstrated that a bacterium commonly found in soil can sniff and react to ammonia in the air. It was previously thought that this "olfaction" was limited to more complex forms of life known as eukaryotes. The finding, published in Biotechnology Journal, means that bacteria have four of the five senses that humans enjoy. The discovery also has implications in the understanding and control of biofilms - the chemical coatings that bacteria can form on, for example, medical implants. Bacteria have already demonstrated the ability to react to light, in analogy to sight, and to change the genes that they express when confronted with certain materials, in analogy to touch. However, there is a distinction between an organism reacting to a chemical that it encounters directly (in analogy to the sense of taste) and a reaction to a chemical that is floating around in the air, says Reindert Nijland, lead author of the study. "The difference is both in the mechanism that does the sensing, as well as in the compounds that are sensed," Dr Nijland, now at University Medical Centre Utrecht in the Netherlands, told BBC News. "The compounds detected by olfactory organs are generally much more volatile than things you can taste like 'sweet' or 'salt', and therefore can provide information about things that can be much further away; you can smell a barbecue from a few blocks away whereas you have to physically touch and eat the steak to be able to actually taste it." (C)BBC

By Susan Milius WILLIAMSBURG, Va. — Putting a female lemur on birth control turns her normally informative scents to nonsense, researchers report. Doses of Depo-Provera, a common contraceptive for people, shift the odor secretions of female lemurs so dramatically that their scents no longer give clear cues to kinship, identity and genetic quality, says study coauthor Christine Drea of Duke University in Durham, N.C. A female lemur whose hormones are disrupted by contraceptives may have real trouble attracting a compatible mate, Drea said July 26 at the annual meeting of the Animal Behavior Society. As for people, men and women might not think they’re influenced by each others’ scents, but “Oh, we are!” said behavioral biologist Susan Jenks of the Sage Colleges in Troy, N.Y., after Drea’s presentation. If women react to the hormones the way lemurs do, “maybe you don’t want to be on contraceptives when you’re picking your mate.” Also, said behavioral ecologist Jill Mateo of the University of Chicago, “For any zoo that is chemically contracepting animals, this could have big implications.” Drea and her colleagues have identified more than 300 compounds in the scent secretions of female lemurs. “There is a rich communication system,” she said. Glands on the forelimbs, tail and other parts of the body secrete chemical cues that the lemurs rub onto branches or other community bulletin boards, where neighbors sniff out the news. © Society for Science & the Public 2000 - 2010

by Dolly J. Krishnaswamy Seven months ago, a 51-year-old woman known only to the public as patient LI1 suffered a severe stroke and lost her ability to communicate with the outside world. She couldn't even blink her eyes. But now, thanks to a new technology, the woman can write long, emotional e-mails to her loved ones just by sniffing. Like many quadriplegics, patient LI1's stroke damaged a region high up on her spinal column, paralyzing her from the neck down. But LI1's injury was so extensive that she also lost the ability to speak. Such patients are referred to as "locked-in" because they can't communicate with the outside world, even though their brain functions normally. Some can blink to answer simple yes or no questions or even string words together by picking out letters as someone recites them (as in the case of Jean-Dominique Bauby, author of The Diving Bell and the Butterfly). But this isn't an option for Patient LI1. So neurobiologist Noam Sobel of the Weizmann Institute of Science in Rehovot, Israel, turned to sniffing. He and colleagues had been studying the human sense of smell and had developed a device, which looks like the oxygen tubes patients wear in the hospital, that releases an odor when a subject sniffs forcefully. Sobel's team soon realized that the device could be configured to respond to various types of sniffing, such as sniffing harder or softer. And that meant it could have applications for locked-in patients. "We thought you could use this sniff to control anything, " Sobel says. "You could even fly a plane." © 2010 American Association for the Advancement of Science.

By Matt Walker Bowhead whales have a previously undiscovered ability to smell the air. The finding could change our understanding of how baleen whales locate prey, as scientists suspect the bowhead whales sniff out krill swarms. The whales' sense of smell was revealed when scientists dissected their bodies and found olfactory hardware linking the brain and nose, and functional protein receptors required to smell. Previously, whales and dolphins were thought to lack the ability. Details are published in the journal Marine Mammal Science. Cetacean expert Professor Hans Thewissen of the Northeastern Ohio Universities College of Medicine and colleagues based in Japan and Alaska made the discovery while evaluating the brain size of bowhead whales. The whales had been landed as part of the biannual Inupiat subsistence hunt along the north coast of Alaska, and Prof Thewissen's team was allowed to dissect the brain cavities, to evaluate how much of the brain casing a bowhead whale's brain actually fills. "Upon taking a brain out, I noticed that there were olfactory tracts, which, in other mammals, connect the brain to the nose," Prof Thewissen told the BBC. "I followed those to the nose, and noted that all the olfactory hardware is there." BBC © MMX

When a person loses his sense of smell, does he also lose any memory associated with a smell? —Ana Artega, via e-mail David Smith, a professor of psychology and a researcher at the Center for Smell and Taste at the University of Florida, replies: Normally people can detect a cacophony of odors using the 40 million olfactory receptor neurons that reside in the nasal cavity. When we encounter a new odor, these neurons send information about the whiff to a brain area called the olfactory cortex, leaving an imprint of the smell there. These memories accumulate over time to create a library of odors. Although we do not fully understand how the olfactory cortex encodes these memories, we do know that olfactory memories seem to be particularly rich—perhaps because the olfactory cortex is closely connected to the brain regions important for recollection. These areas include the amygdala, which processes emotions, and the hippocampus, which encodes and stores memories. Damage to the olfactory receptor neurons because of a respiratory infection, a head injury or a neurodegenerative disease can disrupt the brain’s ability to process different smells. When olfactory neurons stop working altogether, a person develops anosmia, or the inability to discern odors. According to a 2008 report from the National Institutes of Health, 1 to 2 percent of the U.S. population younger than 65 years old, and more than half older than 65, have almost completely lost their sense of smell. © 2010 Scientific American,

Researchers conclude men are more attracted to women wearing pheromones, resulting in more formal dates, kissing, affection, sexual intercourse SAN FRANCISCO, — Women’s perfume laced with synthetic pheromones acts as a sexual magnet and increases the sexual attractiveness of women to men, San Francisco State University researchers conclude in a study appearing in the current issue of the quarterly journal Physiology and Behavior. The study, the first of its kind to independently test a sex attractant pheromone for women, showed that of the 36 women tested, 74 percent of those wearing their regular perfume with the pheromone saw an overall increase in three or more of the following sociosexual behaviors: frequency of kissing, heavy petting and affection, sexual intercourse, sleeping next to their partner, and formal dates with men. In contrast, only 23 percent of the women who had a placebo added to their perfume saw an increase in these sociosexual behaviors. Researchers conclude from these data that the pheromone users were more sexually attractive to men.

Memory slipping, Thelma Walton strains to read, something she had no trouble with five years ago. Her husband, Jim, prompts her every morning with simple math equations and writing tasks, constantly repeating patterns laid in her brain long ago. Now hard at this work, the promise of retirement and a leisurely everyman's every day is no longer theirs to enjoy. For Thelma and Jim, her Alzheimer's disease is fresh at every waking. "It's a frustrating disease," says Jim, a seventy-something retiree living in Raleigh, North Carolina. "You see a whole body and you expect that whole body to perform like it always did and it's not going to do that. The mind's not going to function that way." Slowly, as Alzheimer's creeps through the brain, it's likely to first affect something we take for granted: our library of smells. "Identifying smells involves not only perceiving the smell but comparing against your bank of smells in the brain," explains D.P. Devanand, a memory disorder researcher and co-director of the Memory Disorders Center at the New York State Psychiatric Institute. "People lose their memories for the smells that they had all their lives." Now, Devanand and a team of researchers have developed a simple scratch and sniff smell test aimed at detecting Alzheimer's early on, when olfactory memory wanes as a small brain area beneath the medial temporal lobe—it directs smell—starts accumulating tangles of stringy protein strands. © ScienCentral, 2000- 2004

The best place to sell magazines could be in the gym locker room, according to a study which found that pheromones in male sweat makes men opt for a manly read. Men under the influence of androstenol – a pheromone found in men’s underarm sweat – find men’s lifestyle magazines to be more attractive and are more likely to purchase them than those not exposed to the pheromone, suggests the research. Michael Kirk-Smith, from the University of Ulster, UK, and Claus Ebster, from the University of Vienna, Austria showed 120 student volunteers three magazines: the female lifestyle magazine Allure, the neutrally pitched National Geographic, and the male lifestyle magazine Men’s Health. The students were split into two groups with equal numbers of men and women. The first group wore a mask sprayed with androstenol and the second wore a mask permeated with a control solvent. The concentrations of the solvents in the masks were low enough as to have imperceptible odour to the wearers. The two groups were asked to rate the magazines according to how masculine they found each, how appealing and how likely they were to purchase them. The male participants exposed to androstenol rated Men’s Health as significantly more masculine and more appealing compared with the control group. They also had a higher tendency to report that they might buy the magazine. Women appeared to be completely unaffected by the pheromone. © Copyright Reed Business Information Ltd.

DAVIS—It’s all about “the birds and the bees.” And now, “the silkworm moths and the fruit flies.” A chemical ecologist and a genetics researcher at the University of California, Davis, have joined forces to trick fruit flies into thinking that silkworm moths are potential mates. Groundbreaking research in the labs of chemical ecologist Walter Leal and genetics researcher Deborah Kimbrell shows that genetically engineered fruit flies responded to the silkworm moth scent of a female. The practical implications of the findings could be widespread. Methods that can attract or repel insects have important applications for agricultural pests and medical entomology. The research could lead to designing better chemicals to attract insects and designing better chemicals to suppress insect communication. That is because insects communicate or smell through their antennae. Many insect species, including silkworm moths, release sex pheromones or chemical signals to attract a mate. “Silkworm moths utilize smell more strongly than any other senses,” said Leal, professor and chair of the Department of Entomology. “Moths keep on the trail of a scent until they find a female.” “We got a very clear response,” he said. “Our electrophysiological recordings and direct stimulation testing showed that the transgenic fruit flies definitely responded to the moth pheromone.” © 2006, The Regents of the University of California.

Robert Wilson, of Rush University Medical Center, gave smell tests to 600 incoming study volunteers aged 54 to 100. (The volunteers were all from the ongoing Rush Memory and Aging Project.) For the next five years, he gave the volunteers a battery of thinking and memory tests. The smell test he used, which can be completed in about five minutes, assesses whether the participants can identify 12 familiar smells such as chocolate, rose and smoke. Each odor is released from the paper in the test booklet by scratching with a pencil, and then placed under the volunteer's nose. Wilson compared volunteers who scored below average (four or more errors) on the smell test with above average scorers (one or no errors). The smell test takes about five minutes. His study, published in the July 2007 issue of Archives of General Psychiatry, found that people with the low scores were 50 percent more likely to develop certain memory and thinking problems, called Mild Cognitive Impairment or MCI. These symptoms are often an early stage of Alzheimer's. Wilson says, "This suggests that problems with smelling even in healthy aging could be a very, very early sign of Alzheimer's disease." This study builds on the work in two previous studies. In the first study, conducted in 2004, researcher Dev Devanand, of Columbia University Medical Center, found a link between low smell test scores and the likelihood of progression from MCI to Alzheimer's disease. © ScienCentral, 2000-2007.

NEW YORK - Cigarette smoking and a family history of alcoholism both alter how women perceive sweet foods and what foods they crave, according to studies conducted by two researchers from the Monell Chemical Senses Center in Philadelphia. Marta Yanina Pepino and Julie A. Mennella found that women who smoked were less sensitive to sweet taste than women who never smoked. Women who smoked needed higher concentrations of sugar to detect a sweet taste, and the more years a woman smoked, the less she was able to perceive a sweet taste. “Smoking dulls sweet taste sensitivity,” Pepino and Mennella noted in a joint email to Reuters Health. “Whether this reduced sensitivity for sweets helps smokers control their weight is an important question that is not addressed in the current study.” The researchers also found that cigarette smoking leads to increased food cravings, particularly for starchy carbohydrates and high-fat foods. “We found that food cravings were associated with nicotine dependence ... the more intense the cravings for cigarettes, the more frequent the cravings for foods high in fat and carbohydrates,” Pepino explained. Copyright 2007 Reuters.

By Rachel Ehrenberg People deceive their taste buds every day — a dash of Sweet'N Low in the coffee, perhaps, a diet soda or a stick of sugarless gum. These little white lies seem to cover up harmless, even healthy choices. After all, fooling the mouth with artificial sweeteners provides a fix without the calories or the cavities. But these sweeteners aren’t just tricking the taste buds on the tongue. Taste, scientists are discovering, is a whole-body sensation. There are taste cells in the stomach, intestine and, evidence suggests, the pancreas, colon and esophagus. These sensory cells are part of an ancient battalion tasked with guiding food choices since long before nutrition labels, Rachael Ray or even agriculture existed. While taste cells in the mouth make snap judgments about what should be let inside, new work suggests that gut taste cells serve as specialized ground forces, charged with preparing the digestive system for the aftermath of the tongue’s decisions. Stimulating these gut cells triggers a complex series of events that can dial down, or amp up, the digestion and absorption of the body’s fuel. When hit by bitter — potentially toxic — substances, gut taste cells sound an alarm that may lead to slower absorption or spur vomiting. And when the gut’s taste sensors encounter something sweet, they send a “prepare for fuel” missive that results in cranked-up insulin levels in the blood. Though scientists don’t fully understand what follows, studies hint at a tantalizing, if convoluted, connection between gut taste cell activity and metabolism. © Society for Science & the Public 2000 - 2010

Linda Geddes Humans can follow scent trails across a field in the same way that dogs can – and they improve with practice – a intriguing new field study has revealed. Jess Porter and Noam Sobel at the University of California in Berkeley, US, and colleagues tested whether 32 people were able to follow a 10-metre-long scent trail of chocolate essence through open grass using only their noses. Two-thirds of them could. They then trained four of the subjects three times a day for three days over a two week period to see whether they improved with practice. After training the subjects followed the trail more accurately and at more than double the speed. Watch a human sniffer dog in action (2.1MB, requires QuickTime player). “Once people realised that they could do this, they seemed to develop a good sense of how to zig-zag their noses back and forth across the odour plume in order to pick up the scent most effectively,” says Porter. The findings also shed new insight into how mammals smell. Sensory biologists have long-argued about whether mammals compare the scent inputs coming into each nostril in order to localise where a smell is coming from, in the same way they use their left and right ears. © Copyright Reed Business Information Ltd.

By Charles Q. Choi Here's the new taste sensation — your tongue might be able to taste calcium. The capability to taste calcium has now been discovered in mice. With these rodents and humans sharing many of the same genes, the new finding suggests that people might also have such a taste. The four tastes we are most familiar with are sweet, sour, salty and bitter. Recently scientists have discovered tongue molecules called receptors that detect a fifth distinct taste — "umami," or savory. Story continues below ↓advertisement "But why stop there?" asked researcher Michael Tordoff, a behavioral geneticist at the Monell Chemical Senses Center in Philadelphia. "My group has been investigating what we believe is another taste quality — calcium." So assuming the human palate can detect calcium, what does the mineral taste like? "Calcium tastes calcium-y," Tordoff said. "There isn't a better word for it. It is bitter, perhaps even a little sour. But it's much more because there are actual receptors for calcium, not just bitter or sour compounds." One way we might regularly perceive calcium is when it comes to minute levels found in drinking water. "In tap water, it's fairly pleasant," Tordoff said. "But at levels much above that, the taste becomes increasingly bad." © 2008 Microsoft

By Josie Glausiusz A tangle of tubes and polyurethane pouches binds a naked man and woman—he, paunchy and unperturbed, she, slim and similarly unself-conscious. This setup is not some esoteric sex game; it’s “Smell Blind Date,” an installation created by artist James Auger on display this past spring in New York City as part of the Museum of Modern Art’s exhibition Design and the Elastic Mind. The PVC tubes—which run between the subjects’ chests, with outlets extending to pouches attached to their noses, armpits and genitals—allow the man and woman to inhale each other’s body odor through a wall that divides them. In theory, they are on a truly blind date, each undistracted by the other’s looks, assessing the other’s potential as a mating partner by his or her smell alone. The human sense of smell is often seen as insignificant, dismissed as a distant also-ran to our keen eyesight or sensitive hearing. But this sense is keener and more influential on our species than many people realize. In particular, as Auger’s fanciful art project illustrates, smell facilitates a variety of human social interactions, both casual and intimate. Indeed, people who lose their sense of smell often gain a new appreciation for its importance [see “When the Nose Doesn’t Know,” by Eleonore von Bothmer; Scientific American Mind, October/November 2006]. Much of this influence goes unnoticed because it falls under the radar of consciousness. For instance, research demonstrates that we subconsciously use smell to assess a person’s likability, sexual attractiveness and emotional state. Through scent, people can distinguish stranger from friend, male from female and gay from straight. Thus, olfaction may facilitate reproduction and prevent risky encounters. “If you look at nature, you see that every living organism has some form of chemosensory detection mechanism” that enables it to sense threats at a distance, explains neuroscientist Johan Lundström of the Monell Chemical Senses Center in Philadelphia. By the same token, deficiencies in olfaction may contribute to social withdrawal, such as that which accompanies schizophrenia. © 1996-2008 Scientific American Inc

by Peter Aldhous When you're in love, everything seems different - and that includes your sense of smell. Women who are deeply in love struggle to recognise the body odour of male friends, but their ability to distinguish their partner's smell is unaffected. Body odours are known to play a role in human sexual attraction. But how does falling in love affect our perception and processing of these smells? To find out, Johan Lundström and Marilyn Jones-Gotman of McGill University in Montreal, Canada, asked a group of 20 young women with boyfriends to fill in a Passionate Love Scale questionnaire (pdf format) to determine just how much in love they were. Meanwhile, the women's partners and male and female friends slept for a seven nights in a cotton T-shirt with pads sewn into the underarms to soak up their sweat. In a series of trials, each woman was asked to pick out their lover's or a friend's T-shirt from three garments, two of which had been worn by strangers. The women's scores on the Passionate Love Scale made no difference to their ability to recognise a lover's shirt, or that worn by a female friend. But those who were more deeply in love were less good at distinguishing a male friend's odour from those of strangers. © Copyright Reed Business Information Ltd

The paper referred to is ‘Non-Advertized does not Mean Concealed: Body Odour Changes across the Human Menstrual Cycle’, Jan Havl��ek, Radka Dvo��kov�, Lud�k Barto� and Jaroslav Flegr, Ethology, 112:1, page 81 - January 2006. To view the article in full, visit www.blackwell-synergy.com and Login/Register for free. Click on the My Synergy tab at the top of the screen and then on the blue Access tab. On the next screen type in the access token: ETHJan06 and click Continue. This will activate your free online access to Ethology. The Access Token is valid for 30 days. Next time you want to view the article, Login at Blackwell Synergy, click on the My Synergy tab and a hyperlink to the journal will be listed. For further information about this press release please contact: Jan Havl��ek, Charles university in Prague, email address Jan.Havlicek@fhs.cuni.cz Ethology publishes original contributions from all branches of behavioural research on all species of animals, both in the field and lab. It contains scientific articles of general interest in English language that are based on a theoretical framework. A section on "Current issues - perspectives and reviews" is included as well as theoretical investigations, essays on controversial topics and reviews of notable books. Further details of the journal are available at www.blackwellpublishing.com/eth

By CAMILLE SWEENEY ON a recent evening, an unusual experiment took place at a lounge in downtown Manhattan. Nine blindfolded women were asked to determine, by smell alone, whether any among a group of nine men was worth pursuing. Three men had just showered using a body wash with synthesized pheromones, three had used a body wash without pheromones, and the rest had worked up a sweat and not washed at all. They then rubbed their arms on scent strips, and handed them to the women to sniff. One participant, Michelle Hotaling, 24, chose a man who had used the pheromone body wash. “In appearance and personality he was not someone I would otherwise be convinced to go out with,” she said, once her blindfold came off. “But his scent was a factor that would push my decision to say, ‘Yes.’ ” Which was just what Dial, the event’s sponsor and maker of the new “pheromone-infused” Dial for Men Magnetic Attraction Enhancing Body Wash, wanted to hear. “We don’t claim using our product you’re going to hit a home run,” said Ryan Gaspar, a brand manager. “We say, ‘We’ll get you to first base.’ ” As the science — or, as some believe, pseudo-science — of pheromones advances toward commercial applications, more manufacturers of personal-care products are dropping tinctures of synthesized pheromones into their formulas, with claims that they will boost sex appeal and confidence. The pheromone of choice for men is a family of steroids, related to testosterone, found near the axillary glands in the underarm area. For women, a commonly used compound is estratetraenol, a derivative of the sex hormone estradiol. (The patents of these synthesized hormones are proprietary, and when asked, the makers would not reveal their ingredients.) Copyright 2009 The New York Times Company

By Stephen Smith Just the other day, a man weighing 470 pounds lumbered into Dr. Caroline Apovian’s office at Boston Medical Center. He was young - only 32 years old - but already, his heart had begun to fail him, a legacy of his extreme obesity. Maybe, he asked Apovian, I should have weight-loss surgery. She told him that first, he would need to alter what he eats - and drinks, especially the 2 liters of sugary soft drinks he drains every day. “I gave him a high-protein, low-fat diet,’’ Apovian recalled. “Everything was fine until I said, ‘No soda.’ And he said, ‘You don’t understand. The soda calls to me.’ ’’ Last week, federal disease investigators reported that the cost of treating obesity has doubled in the past decade, and they pointed to sugar-laden beverages - sodas, energy drinks, fruity libations - as a prime culprit. Three months earlier, one of the nation’s premier nutrition specialists, Dr. Walter Willett of the Harvard School of Public Health, embarked on a personal crusade to persuade consumers to forgo sugary drinks. Research conducted by Willett and other Boston scientists has shown that women who quaffed more than two sweetened beverages a day had an almost 40 percent higher risk of heart disease than those who rarely touched the drinks. © 2009 NY Times Co.

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