By CARL ZIMMER In the middle of a phone call four years ago, Paula Niedenthal began to wonder what it really means to smile. The call came from a Russian reporter, who was interviewing Dr. Niedenthal about her research on facial expressions. “At the end he said, ‘So you are American?’ ” Dr. Niedenthal recalled. Indeed, she is, although she was then living in France, where she had taken a post at Blaise Pascal University. “So you know,” the Russian reporter informed her, “that American smiles are all false, and French smiles are all true.” “Wow, it’s so interesting that you say that,” Dr. Niedenthal said diplomatically. Meanwhile, she was imagining what it would have been like to spend most of her life surrounded by fake smiles. “I suddenly became interested in how people make these kinds of errors,” Dr. Niedenthal said. But finding the source of the error would require knowing what smiles really are — where they come from and how people process them. And despite the fact that smiling is one of the most common things that we humans do, Dr. Niedenthal found science’s explanation for it to be weak. “I think it’s pretty messed up,” she said. “I think we don’t know very much, actually, and it’s something I want to take on.” © 2011 The New York Times Company

Keyword: Emotions
Link ID: 14915 - Posted: 01.25.2011

By NICHOLAS BAKALAR A new study suggests that a widely prescribed antidepressant may provide at least some relief for women with hot flashes. Hormone replacement therapy is now the only treatment approved by the Food and Drug Administration for menopausal symptoms, but many believe its risks outweigh its benefits. This study, published Thursday in The Journal of the American Medical Association, was a randomized, double-blinded, placebo-controlled trial of escitalopram (brand name Lexapro) in which 97 menopausal women took the drug for eight weeks while a matched group took a placebo. Just over half of the women in the treatment group reported a decrease of at least 50 percent in the frequency of hot flashes; 36 percent did in the placebo group. Women taking escitalopram averaged 1.41 fewer hot flashes per day than in those on the placebo, and there were no serious side effects. And almost two-thirds of the treatment group wanted to continue the medication, compared with 42 percent of the others. The lead author, Ellen W. Freeman, a professor of obstetrics and gynecology at the University of Pennsylvania, stressed that this is an off-label use of the drug not approved by the F.D.A. Still, she said, “it provides an option, and there’s not much out there that has been shown to be effective.” © 2011 The New York Times Company

Keyword: Hormones & Behavior; Depression
Link ID: 14914 - Posted: 01.25.2011

By Christof Koch Perceptual psychology and the brain sciences emphasize the communality in the way that people experience reality. Leaving aside cases of brain damage or mental disease, we all see the sun rise in the east, enjoy the scent of a rose and experience a jolt of fear when we are woken up in the middle of the night by the sound of breaking glass. This is a reflection of the great similarities of our brains compared with the brains of our close cousins on the evolutionary tree, the great apes. Laboratory science reinforces this bias by lumping together the performance of its subjects on any one experiment and reporting only the average and the variation around this mean. This conflation is also true for the telltale hot spots that show up in functional magnetic resonance brain images that we are used to seeing in newspapers, in magazines such as this one, on television and in the movies. Yet as we know from our own life, each one of us has his or her own preferences, likes and dislikes. Some people are acutely sensitive to flashing lights, some have perfect pitch, some cannot see in depth, some can introspect and analyze their own failures and triumphs, whereas others—remarkably frequently, public figures such as politicians—lack this knack. Take me. I am hopelessly attracted to brilliant colors. As a magpie is drawn to anything glittering, I am drawn to school-bus yellow, tangerine orange, burgundy red, rich magenta, electric violet, imperial purple and navy blue. My love of the garish is reflected in my flowery shirts and pants and, I’m sure, in an enhanced cortical representation of these hues. It is obvious that if the apparatus that senses the world differs between two individuals, then the conscious experience of the brains wired to these sensors cannot be the same either. In a previous Consciousness Redux column, I discussed color blindness—the fact that about 7 percent of men lack one of the genes for the retinal photopigments needed to see hue. But what about differences in the brain proper? Do they influence consciousness in measurable ways? To answer this question, scientists must plumb the minds of many individuals and relate them to measures of their brains. The widespread availability of fMRI scanners makes such a project feasible today. © 2011 Scientific American, a Division of Nature America, Inc.

Keyword: Attention; Vision
Link ID: 14913 - Posted: 01.25.2011

By Tina Hesman Saey “You must remember this,” Sam the piano player crooned to Humphrey Bogart and Ingrid Bergman in Casablanca. The couple might have recalled even more about their days in Paris if they’d been napping when Sam played the tune again. Replaying memories while people are awake leaves their memories subject to tinkering. But reactivating memories during sleep protects them from interference, researchers in Germany and Switzerland report online January 23 in Nature Neuroscience. The finding shows that the brain handles memories differently during sleep than while awake, says Sara Mednick, a cognitive neuroscientist at the University of California, San Diego who was not involved in the research. Armed with this new knowledge, she says, therapists may be able to destabilize traumatic memories and overwrite the bad memories with good ones, then solidify the new memory with a nap. In the new study, volunteers played a Concentration-type game in which they had to remember the locations of pairs of cards. Meanwhile, a mask wafted a slightly unpleasant odor into the volunteers’ nostrils. Once the volunteers had mastered the game, some stayed awake while others took about a 40-minute nap. Researchers reactivated the memory in some volunteers by releasing the odor again. After the nappers woke up, the volunteers played a slightly different version of the card game and were tested to see how well they recalled the locations of the original cards. © Society for Science & the Public 2000 - 2011

Keyword: Sleep; Learning & Memory
Link ID: 14912 - Posted: 01.25.2011

By Bruce Bower Young kids lacking self-management skills are way more than annoying. They’re more likely to be big-time losers in the game of life, a new study finds. Low levels of conscientiousness, perseverance and other elements of self-control in youngsters as young as age 3 herald high rates of physical health problems, substance abuse, financial woes, criminal arrests and single parenthood by age 32, says an international team led by psychologists Terrie Moffitt and Avshalom Caspi of Duke University in Durham, N.C. Increasing self-control difficulties among children herald progressively greater numbers and seriousness of these adult troubles, the scientists report online January 24 in the Proceedings of the National Academy of Sciences. Intelligence, as measured by IQ tests, has long held sway as the prime mental influence on health and achievement. But self-control’s close link to adult health and accomplishment remained after researchers accounted for children’s IQ scores and family income. “Self-control and intelligence are both valuable for life success, but after years of effort, IQ has proven difficult to change through interventions,” Moffitt says. For as-yet-unknown reasons, 7 percent of youngsters in the long-term study developed notably better self-control as they got older. Members of this group displayed better health, made more money and had fewer criminal run-ins as adults than would have been predicted by their self-control levels as young children. © Society for Science & the Public 2000 - 2011

Keyword: ADHD
Link ID: 14911 - Posted: 01.25.2011

Cooling the brain of patients who have suffered a stroke could dramatically improve their recovery, a group of Scottish doctors has said. They are joining others from across Europe who believe that inducing hypothermia in some patients can boost survival rates and reduce brain damage. Similar techniques have already been tried successfully on heart attack patients and those with birth injuries. Scientists are in Brussels to discuss a Europe-wide trial of the technique. To date, studies have involved the body of patients being cooled using ice cold intravenous drips and cooling pads applied to the skin. This lowers the body temperature to about 35C, just a couple of degrees below its normal level. The technique puts the body into a state of artificial hibernation, where the brain can survive with less blood supply, giving doctors vital time to treat blocked or burst blood vessels. Dr Malcolm Macleod, head of experimental neuroscience at the Centre for Clinical Brain Sciences at the University of Edinburgh, said: "Every day 1,000 Europeans die from stroke - that's one every 90 seconds - and about twice that number survive but are disabled. BBC © MMXI

Keyword: Stroke
Link ID: 14910 - Posted: 01.24.2011

HOUSTON — The Houston hospital treating Rep. Gabrielle Giffords said Sunday that her condition is improving daily, but gave no update on the buildup of brain fluid that has kept the Arizona congresswoman in intensive care. A hospital statement said Giffords would continue to receive therapy in the intensive care unit "until her physicians determine she is ready for transfer" to a nearby center where she would begin a full rehabilitation program. They said the next medical updates would be provided when that happens. Giffords was flown to Memorial Hermann Texas Medical Center Hospital on Friday from Tucson, where she was shot in the forehead on Jan. 8 while meeting with constituents. Story: Case in Giffords shooting likely to take years At a news conference shortly after her arrival in Houston, doctors said she had been given a tube to drain excess cerebrospinal fluid. Everyone makes such fluid, but an injury can cause the fluid to not be cleared away as rapidly as normal. A backup can cause pressure and swelling within the brain. "It's a common problem," occurring in 15 to 20 percent of people with a brain injury or brain surgery, said Dr. Reid C. Thompson, chairman of neurological surgery at Vanderbilt University Medical Center in Nashville, who is not involved in Giffords' care. Another possible reason for a drainage tube: "After a gunshot wound to the head and brain where there is a lot of soft tissue injury, it is common to develop a leak of spinal fluid. This raises the risk of a meningitis and slows down wound healing," he said. Copyright 2011 The Associated Press.

Keyword: Brain Injury/Concussion; Neuroimmunology
Link ID: 14909 - Posted: 01.24.2011

(PARIS-AFP) - Good news for chronic migraine sufferers: even the most severe forms of these blindingly painful headaches do not cause damage to the brain. "It is almost always the first question that migraine patients ask," said Christophe Tzourio, a doctor and researcher at the Universite Pierre et Marie Curie in Paris, and the main architect of a study published online this week in the British Medical Journal. "Today we can provide an answer: there's nothing to worry about," he told AFP. Migraines are acutely debilitating headaches -- sometimes with an "aura", in which patients have the impression of seeing through frosted glass -- that strike around one out of nine adults. The causes remain uncertain, but are known to involve a link with blood vessels in the brain. Earlier research using magnetic resonance imaging technology showed that people with a history of full-on migraines are more likely to incur tiny lesions to microvessels inside the brain. Such ruptures result from a deterioration of the small cerebral arteries that supply blood to so-called white matter, which facilitates the flow on information across different parts of the brain. © 2011 NY Times Co.

Keyword: Pain & Touch
Link ID: 14908 - Posted: 01.24.2011

* By Jonah Lehrer Why does music make us feel? On the one hand, music is a purely abstract art form, devoid of language or explicit ideas. The stories it tells are all subtlety and subtext. And yet, even though music says little, it still manages to touch us deep, to tickle some universal nerves. When listening to our favorite songs, our body betrays all the symptoms of emotional arousal. The pupils in our eyes dilate, our pulse and blood pressure rise, the electrical conductance of our skin is lowered, and the cerebellum, a brain region associated with bodily movement, becomes strangely active. Blood is even re-directed to the muscles in our legs. (Some speculate that this is why we begin tapping our feet.) In other words, sound stirs us at our biological roots. As Schopenhauer wrote, “It is we ourselves who are tortured by the strings.” We can now begin to understand where these feelings come from, why a mass of vibrating air hurtling through space can trigger such intense states of excitement. A brand new paper in Nature Neuroscience by a team of Montreal researchers marks an important step in revealing the precise underpinnings of “the potent pleasurable stimulus” that is music. Although the study involves plenty of fancy technology, including fMRI and ligand-based positron emission tomography (PET) scanning, the experiment itself was rather straightforward. After screening 217 individuals who responded to advertisements requesting people that experience “chills to instrumental music,” the scientists narrowed down the subject pool to ten. (These were the lucky few who most reliably got chills.) The scientists then asked the subjects to bring in their playlist of favorite songs – virtually every genre was represented, from techno to tango – and played them the music while their brain activity was monitored. © 2010 Condé Nast Digital.

Keyword: Hearing; Emotions
Link ID: 14907 - Posted: 01.24.2011

In 2004, American neuroscientists Linda Buck and Richard Axel shared a Nobel Prize for their identification of the genes that control smell, findings which they first published in the early 1990s. Their work revived interest in the mysterious workings of our noses, interest which is now generating some surprising insights – not least that each of us inhabits our own, personal olfactory world. "When I give talks, I always say that everybody in this room smells the world with a different set of receptors, and therefore it smells different to everybody," says Andreas Keller, a geneticist working at the Rockefeller University in New York City. He also suspects that every individual has at least one odorant he or she cannot detect at all – one specific anosmia, or olfactory "blind spot", which is inherited along with his or her olfactory apparatus. The human nose contains roughly 400 olfactory receptors, each of which responds to several odorants, and each of which is encoded by a different gene. But, says Boris Schilling, a biochemist working for Givaudan, the world's largest flavour and fragrance company, based in Geneva, Switzerland, "unless you are dealing with identical twins, no two persons will have the same genetic make-up for those receptors." The reason, according to Doron Lancet, a geneticist at the Weizmann Institute of Science in Israel, is that those genes have been accumulating mutations over evolution. This has happened in all the great apes, and one possible explanation is that smell has gradually become less important to survival, having been replaced to some extent by colour vision – as an indicator of rotten fruit, for example, or of a potentially venomous predator. ©independent.co.uk

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 14906 - Posted: 01.24.2011

By Bruce Bower In chimpanzees, as in humans, faces are personality billboards, a new study suggests. People can usually tell whether or not a chimp acts dominantly and is physically active simply by looking at a picture of the ape’s expressionless mug, says a research team led by psychologist Robert Ward of Bangor University, Wales. Consistent with earlier evidence from other researchers, Ward and his colleagues reported last year that volunteers can also accurately detect whether people are extroverted, emotionally stable, agreeable and imaginative by looking at pictures of their neutral-looking faces. Extroversion in people and dominance in chimps both relate to assertiveness and sociability, and both partly derive from an individual’s genetic makeup. An ability to discern key personality traits via facial structure evolved more than 7 million years ago in a shared ancestor of people and chimps, the researchers propose in a paper published online January 14 in Evolution and Human Behavior. “The fact that chimpanzee facial signals can be read by humans suggests that our ability to read others’ faces accurately is not solely acquired through culture, but is part of an evolved system,” Ward says. That’s an intriguing hypothesis in need of testing with composite images that digitally combine many pictures of the same chimps into single mug shots, remarks psychologist and chimp researcher Lisa Parr of Emory University in Atlanta. Composites minimize slight variations from one photograph to another in lighting, skin hue, head angles and other factors that can create different personality impressions of the same individual, Parr says. © Society for Science & the Public 2000 - 2011

Keyword: Emotions; Evolution
Link ID: 14905 - Posted: 01.24.2011

Sandrine Ceurstemont, Dolphins keep amazing people with their clever tricks. Now it seems they can even copy the moves of others without needing to see them (see video above). A team at the Dolphin Research Center in Grassy Key, Florida, conducted the first experiment with blindfolded dolphins to investigate how they imitate others. Although they are known to mimic sounds and actions, it's unclear exactly what senses they use to do this. A dolphin called Tanner that had previously been trained to imitate other dolphins visually was chosen for the task. When his trainer gives a hand signal, Tanner knows to copy the moves of the dolphin next to him. To see how he performed without sight, his eyes were covered with plastic eye cups after he was given the cue. Then a second dolphin performed an action, or produced a sound Tanner was familiar with, and the researchers observed his ability to replicate it. Unsurprisingly, the team found that he had no problem reproducing sounds blindfolded. But he also reproduced a lot of actions with his eyes covered up, and even when he made mistakes the move wasn't too far off. "Since we know he wasn't using sight, he had to be using sound," says Kelly Jaakkola, a member of the team. "Either by recognising the characteristic sound that the behaviour makes, like you or I may recognise the sound of hands clapping, or by using echolocation." © Copyright Reed Business Information Ltd.

Keyword: Animal Communication; Language
Link ID: 14904 - Posted: 01.24.2011

by Linda Geddes Chemical messengers from the immune system can wreak emotional havoc if they cross into the brain – even in people who otherwise seem healthy When we get sick, we often feel lethargic and lose our appetites. Our concentration suffers and we might feel anxious, depressed or anti-social. These changes are caused by signalling molecules called cytokines, which are released by immune cells in response to stress and infection. Although cytokines are too large to pass freely through the blood-brain barrier, recent studies have shown that they can enter through naturally occurring leaky regions and via specialised channels. They can also affect nerves that transmit signals into the brain. There is growing evidence that cytokines associated with inflammation can cause depression. For instance, if you inject a healthy person with interferon-alpha, an antiviral drug that prompts the release of inflammatory cytokines, they will begin to show symptoms of depression (Brain Behavior and Immunity, vol 23, p 149). "Cytokines can interact with virtually every pathway relevant to depression," says Andrew Miller of Emory University School of Medicine in Atlanta, Georgia. And the idea that inflammation induces behavioural changes makes evolutionary sense too, he says. "Cytokines are trying to shut your body down so that you can devote your resources to healing. But at the same time, a wounded animal is a target so it needs to be hyper-alert in case a predator comes onto the scene." © Copyright Reed Business Information Ltd.

Keyword: Depression; Neuroimmunology
Link ID: 14903 - Posted: 01.24.2011

by Greg Miller There's a stark contrast in the media coverage of yesterday's FDA advisory committee meeting on a test for a signature feature of Alzheimer's disease. At The New York Times, Gina Kolata's cup of enthusiasm is at least half full: F.D.A. Sees Promise in Alzheimer's Imaging Drug An advisory committee to the Food and Drug Administration recommended unanimously Thursday that the agency approve the first test--a brain scan that can show the characteristic plaques of Alzheimer's disease in the brain of a living person. The approval was contingent on radiologists agreeing on what the scans say and doctors being trained in how to read the scans. The article quotes Alzheimer's experts enthusing about "a monumental step forward," and "a landmark day for our field." Several other outlets, including CNN Health, took more of a glass-half-empty approach: FDA on new Alzheimer's test: No, or at least not yet A new test to detect or rule out Alzheimer's is not quite ready for prime time, an FDA advisory panel said Thursday afternoon. The test, a type of PET scan developed by Avid Radiopharmaceuticals, is designed to detect the telltale buildups of amyloid plaque in the brain that signify Alzheimer's disease. © 2010 American Association for the Advancement of Science.

Keyword: Alzheimers
Link ID: 14902 - Posted: 01.24.2011

By SUZETTE LABOY GRASSY KEY, Fla. -- In a lagoon in the Florida Keys, trainer Emily Guarino blindfolds a male dolphin named Tanner with special latex goggles. "You ready, Tanner?" Guarino asks the young dolphin, waiting beside his companion Kibby. At a command, another trainer gets Kibby to say 'hello' by flapping his fins on the water, splashing noisily in the enclosed lagoon at the Dolphin Research Center here, which houses 22 dolphins and is one of the leaders in dolphin cognitive studies. "Can you imitate what Kibby is doing?" Guarino asks Tanner. Within seconds, Tanner is splashing "hello" - a seemingly extraordinary feat given the blindfolded dolphin appears to only be using sound to perceive and imitate the actions of his fellow dolphin. It turns out dolphins are master imitators that somehow can "see" their environment despite blindfolds. But exactly how such a dolphin can mimic another's action is a matter of ongoing scientific study. Dr. Kelly Jaakkola, director of the nonprofit marine mammal research center, said the research to better understand dolphin intelligence will surely help further their conservation. She said such study may also be helpful in better grasping the complexities of human intelligence. "It's human nature to care more about animals we perceive as intelligent. So the more we can showcase that intelligence we give people a way to connect, to care and therefore conserve," she said. Copyright 2011 Miami Herald Media Co.

Keyword: Hearing; Vision
Link ID: 14901 - Posted: 01.24.2011

By Neil Bowdler Science reporter, BBC News Researchers in the United States say they have uncovered tentative evidence of a genetic component to friendship. Using data from two independent studies, they found carriers of one gene associated with alcoholism tended to stick together. However, people with another gene linked with metabolism and openness, stayed apart. Details are published in the journal Proceedings of the National Academy of Sciences. The researchers looked at six genetic markers in two long-running US studies, the National Longitudinal Study of Adolescent Health and the Framingham Heart Study, which contain both genetic data and information on friends. With one gene, called DRD2, which has been associated with alcoholism, they found clusters of friends with the very same marker. Another gene called CYP2A6, which has a suspected role in the metabolism of foreign bodies including nicotine, appeared more divisive. People with this gene seemed to steer clear of those who also carry the gene. Why, the researchers don't know, but they speculate it could form part of a defensive ploy. They say similar patterns have been observed among couples, with individuals avoiding prospective partners who are susceptible to the same diseases. BBC © MMXI

Keyword: Genes & Behavior
Link ID: 14900 - Posted: 01.21.2011

Alan Boyle If you have a knack for knowing just the right move to make — in a board game or in other walks of life — it might be because your brain has built up a special kind of connection. Researchers at Japan's RIKEN Brain Science Institute report evidence that the professional players of a chesslike board game from Japan, known as shogi, have brains that crackle with activity in two areas that are less active in amateurs. Their findings are published in this week's issue of the journal Science. The activity was monitored using functional magnetic resonance imaging, or fMRI, while professionals and amateurs were shown pictures of shogi board patterns. Shogi is regarded as a game as cerebral and as tricky to master as chess — perhaps even more tricky, because players can add pieces captured from an opponent to their own side. The professionals were more adept at intuitively recognizing the "next best move" for a given pattern, but the really interesting part of this game had to do with what went on in their brains. The pros' brains showed more activity in the precuneus region of the parietal lobe, which has been linked to pattern recognition, as well as in the head of the caudate nucleus, deep within the brain. The caudate nucleus has been previously linked with cognitive functions, and game-playing in particular In fact, a different team of researchers reported last year that people who showed an aptitude for arcade games tended to have a bigger caudate nucleus (along with other structures) than less skilled players. © 2011 msnbc.com

Keyword: Attention; Brain imaging
Link ID: 14899 - Posted: 01.21.2011

By GINA KOLATA An advisory committee to the Food and Drug Administration recommended unanimously Thursday that the agency approve the first test — a brain scan — that can show the characteristic plaques of Alzheimer’s disease in the brain of a living person. The approval was contingent on radiologists agreeing on what the scans say and doctors being trained in how to read the scans. The F.D.A. usually follows advice from its advisory committees, and Alzheimer’s experts anticipated that the scans would be approved. The additional requirement would not be a big hurdle, said Dr. Daniel M. Skovronsky, chief executive of the company, Avid Radiopharmaceuticals, that applied to market the scans. “We don’t know exactly what F.D.A. will want,” Dr. Skovronsky said. “But it should take months to generate this type of data, not years.” The committee vote is “a very positive thing,” said Maria Carrillo, senior director of medical and scientific relations for the Alzheimer’s Association. “This is nothing but a positive for our families.” More than five million Americans have Alzheimer’s disease. Plaques are part of the criteria for having Alzheimer’s — if a person with memory problems does not have plaques, that person does not have Alzheimer’s. But without the scan, the only way to know if plaques were present is to do an autopsy. Alzheimer’s specialists said they expected that if the scan were approved it would come into widespread use. © 2011 The New York Times Company

Keyword: Alzheimers; Brain imaging
Link ID: 14898 - Posted: 01.21.2011

The effectiveness of an experimental treatment for alcoholism depends on the genetic makeup of individuals who receive it, according to a new study supported by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health. A report of the findings appears online in the American Journal of Psychiatry. Researchers led by Bankole Johnson, M.D., Ph.D., professor and chair of the Department of Psychiatry and Neurobehavioral Sciences at the University of Virginia, Charlottesville, conducted a controlled trial to determine if the medication ondansetron could reduce problem drinking, in alcohol-dependent individuals. Ondansetron is currently used to treat nausea and vomiting, often following chemotherapy. It works by blocking receptors for the brain chemical serotonin. The current study extends the researchers’ previous work on the role the brain’s serotonin system plays in alcohol misuse. Serotonin mediates many processes in the brain, including the rewarding effects of alcohol. Dr. Johnson’s group has shown that variations in the gene that encodes the serotonin transporter, a protein that regulates the concentration of serotonin between nerve cells, can significantly influence drinking intensity. Specifically, serotonin transporter variants designated as LL and TT have been associated with more severe drinking problems. The researchers have also reported that ondansetron may be an effective therapy for some people with alcoholism. In this study, Dr. Johnson and his colleagues performed genetic analyses to determine which serotonin transporter gene variants were carried by each subject, then randomly assigned each subject to treatment regimens with ondansetron or placebo.

Keyword: Drug Abuse; Genes & Behavior
Link ID: 14897 - Posted: 01.21.2011

By Laura Spinney Scientists have long known that people perceive scents differently. But emerging evidence from several large-scale studies shows that the variation is larger than previously known. It turns out that people differ in how they perceive many if not all odors, and most of us have at least one scent we cannot detect at all. “Everybody’s olfactory world is a unique, private world,” says Andreas Keller, a geneticist at the Rockefeller University. Over the course of evolution, partly because humans grew more reliant on vision and smell became relatively less important, the genes encoding our 400 or so olfactory receptors began to accumulate mutations. Once a gene has accumulated enough mutations, it becomes a “pseudogene,” notes geneticist Doron Lancet of Israel’s Weizmann Institute of Science, meaning it no longer encodes a functioning receptor. Different people have different combinations of pseudogenes, however. “You end up with a bar code situation, whereby each individual has a slightly different bar code,” he says. That genetic variability seems to translate into behavioral variability. When Keller and his colleagues asked 500 people to rate a panel of 66 odors for intensity and pleasantness, they gave the full range of responses—from weak to intense and from pleasant to unpleasant. In an ongoing study at the University of Dresden, Thomas Hummel and his associates have tested 1,500 young adults on a panel of 20 odors and found specific insensitivities to all but one—citralva, which has a citrus smell. Based on these findings, Keller suspects that each person has an olfactory blind spot. © 2011 Scientific American, a Division of Nature America, Inc.

Keyword: Chemical Senses (Smell & Taste); Genes & Behavior
Link ID: 14896 - Posted: 01.21.2011