By Morgen E. Peck Like a musician tuning a guitar, adults subconsciously listen to their own voice to tune the pitch, volume and pronunciation of their speech. Young children just learning how to talk, however, do not, a new study suggests. The result offers clues about how kids learn language—­and how parents can help. Past studies have shown that adults use aural feedback to tweak their pronunc­iation. Ewen MacDonald, a professor at the Center for Applied Hearing Research at the Technical University of Denmark, decided to see if toddlers could do this as well. He had adults and children play a video game in which they guided the actions of a robot by repeating the word “bed.” Through headphones, the players heard their own voice every time they spoke—but with the frequency spectrum shifted so they heard “bad” instead of “bed.” MacDonald found that adults and four-year-old kids tried to com­pensate for the error by pronouncing the word more like “bid,” but two-year-olds never budged from “bed,” suggesting that they were not using auditory feedback to monitor their speech. Although the toddlers may have been suppressing the feedback mechanism, MacDonald thinks they might not start listening to themselves until they are older. If that is the case, they may rely heavily on feedback from adults to gauge how they sound. In­deed, most parents and caregivers naturally repeat the words toddlers say, as praise and encouragement. “I think the real take-home message is that social interaction is important for the development of speech,” MacDonald says. “The general act of talking and interacting with the child in a normal way is the key.” © 2012 Scientific American,

Keyword: Language; Development of the Brain
Link ID: 16871 - Posted: 06.05.2012

Lauren Gravitz In an advance that could transform our understanding of the complex cellular dynamics underlying development of animals, researchers have developed a method to track individual cells in a developing fly embryo in real time. Two papers published on the Nature Methods website today describe similar versions of the microscopic technique1, 2. Understanding how an embryo develops from two parental germ cells into an organism with an organized, communicating and interactive group of systems is a difficult task. To date, most studies have only been able to track pieces of that development in animals such as the zebrafish Danio rerio or the fruitfly Drosophila melanogaster. A more comprehensive understanding of the whole process and what drives it could inform research on diseases such as cancer, and help in the development of regenerative stem-cell therapies. Current light-sheet microscopy techniques involve illuminating one side of the sample. Either one side of a developing organism is imaged continuously, or two sides are viewed alternately, with the resultant data reconstructed to form a three-dimensional view. However, viewing from one side at a time means that the cells cannot be tracked as they migrate from top to bottom, and rotating the sample to view both sides takes so much time that when the next image is taken the cells have changed, so that they no longer line up. Simultaneous multi-view imaging solves this problem by taking images from opposing directions at the same time and piecing data together in real time. This required massive computing power. © 2012 Nature Publishing Group

Keyword: Development of the Brain; Genes & Behavior
Link ID: 16870 - Posted: 06.05.2012

Analysis by Jennifer Viegas Monkeys smack their lips during friendly face-to-face encounters, and now a new study says that this seemingly simple behavior may be tied to human speech. Previously experts thought the evolutionary origins of human speech came from primate vocalizations, such as chimpanzee hoots or monkey coos. But now scientists suspect that rapid, controlled movements of the tongue, lips and jaw -- all of which are needed for lip smacking -- were more important to the emergence of speech. For the study, published in the latest Current Biology, W. Tecumseh Fitch and colleagues used x-ray movies to investigate lip-smacking gestures in macaque monkeys. Mother monkeys do this a lot with their infants, so it seems to be kind of an endearing thing, perhaps like humans going goo-goo-goo in a baby's face while playing. (Monkeys will also vibrate their lips to make a raspberry sound.) Monkey lip-smacking, however, makes a quiet sound, similar to "p p p p". It's not accompanied by phonation, meaning sound produced by vocal cord vibration in the larynx. Fitch, who is head of the Department of Cognitive Biology at the University of Vienna, and his team determined that lip-smacking is a complex behavior that requires rapid, coordinated movements of the lips, jaw, tongue and the hyoid bone (which provides the supporting skeleton for the larynx and tongue). © 2012 Discovery Communications, LLC.

Keyword: Language; Evolution
Link ID: 16869 - Posted: 06.02.2012

By Tina Hesman Saey Bruce Spiegelman isn’t always happy with the way his research gets portrayed. He and colleagues discovered a hormone that muscles make during exercise. When given to mice, the hormone causes the animals to burn more energy and lose weight, and improves their response to insulin — all without changing how much the mice eat or exercise. The press touted the discovery as “exercise in a pill.” “I really hate that,” says Spiegelman, a cell biologist at the Dana-Farber Cancer Institute and Harvard Medical School in Boston. “The goal is not to put exercise in a pill.” His goal, instead, is to harness a special type of fat, called brown fat for its color, to replicate the metabolic benefits that exercise delivers. While some researchers have dismissed this fat as a mostly obsolete relic that makes little if any contribution to people’s energy expenditure, new research shows that it can make humans feel the energy burn. Some scientists have found chemical secrets for activating brown fat already in the body, while others are learning how to turn energy-storing white fat brown. Together, such efforts may help fight the battle of the bulge, reducing obesity and the diseases that go along with it. Turning brown fat on may also benefit people who cannot exercise because of disabilities. For many years scientists have recognized brown fat as an energy-burning powerhouse that helps animals and human babies stay warm. © Society for Science & the Public 2000 - 2012

Keyword: Obesity
Link ID: 16868 - Posted: 06.02.2012

by Zoë Corbyn If you want to enhance your memory, consider moving up a mountain. The spatial recall of mountain chickadees – tiny songbirds that inhabit high regions of the western US – is better the higher up they live. Vladimir Pravosudov of the University of Nevada, in Reno, and his colleagues collected 48 juvenile birds (Poecile gambeli) from three different elevations in the Sierra Nevada mountains. Chickadees that lived just 600 metres higher than others had larger hippocampi – a part of the brain strongly linked to memory. Not only that, they were also better at remembering where food was hidden in lab tests. It makes sense that birds living higher up would have a better memory, says Pravosudov. Mountain chickadees are "scatter hoarders", storing their favourite winter food of pine seeds in thousands of different spots among the trees. At higher altitudes, where it stays cold for longer, birds must store more seeds, and remember where they cached them. The effect could apply to other scatter-hoarding species, says Pravosudov, though he rules out most squirrels and rodents, which are either not active during the winter or put everything in one place and so do not need a better memory. Could global warming change things? Very possibly. "The selection pressure that the winter provides will be less, so the birds are going to get dumber," says Pravosudov. Time to consider a simpler pantry? Journal reference: Animal Behaviour, DOI: 10.1016/j.anbehav.2012.04.018 © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory; Evolution
Link ID: 16867 - Posted: 06.02.2012

By Tina Hesman Saey WASHINGTON — A protein famous for slowing aging and increasing life span also acts as a metronome, helping coordinate metabolism and the body’s daily rhythms. SIRT1, one of a group of proteins called sirtuins, plays roles in many cellular processes, including aging. Researchers hope that activating the protein with drugs such as resveratrol can extend life span and improve health for people, as it does in animal studies. Now, researchers at MIT have evidence that SIRT1 may not only help determine long-term health and longevity, but it also has a hand in setting the body’s daily or “circadian” clock. The finding, reported May 31 at the Metabolism, Diet and Disease meeting, could be important for understanding how metabolism and life span are linked. Studies of cells in laboratory dishes had suggested that SIRT1 might work with certain gears of the circadian clock in liver cells. But until now no one has shown that the protein could influence the body’s master clock in the brain, says Raul Mostoslavsky, a molecular biologist at Harvard Medical School. In the new study, scientists led by Leonard Guarente of MIT monitored the natural activity patterns of mice. Normally, mice’s circadian clocks run just shy of a 24-hour day, at about 23.5 hours. Mice that lack SIRT1 in their brains have a longer internal day, closer to 24 hours, Guarente said. And mice that made twice as much SIRT1 as normal in their brains had a shorter-than-usual day. Mice making five times as much SIRT1 as normal had even shorter natural days. © Society for Science & the Public 2000 - 2012

Keyword: Biological Rhythms; Development of the Brain
Link ID: 16866 - Posted: 06.02.2012

Sandrine Ceurstemont, editor, New Scientist TV Watching a moving car can sometimes be mind-bending. At certain speeds, the wheels of a forward-moving vehicle can appear to turn backwards due to a common brain trick called the wagon wheel effect. But to confuse your brain even more, a new variation by Arthur Shapiro and his team from the American University in Washington DC shows how adding colour to a wheel can further alter the motion perceived. In the first example in the video, some of the dots in the wheel are coloured, allowing us to perceive the actual clockwise motion as well as the reverse at the same time. The effect is maintained when all of the dots are coloured using hues of the same brightness. However, by changing the brightness of the background, only one type of motion is perceived once again. When the animation is made up of both bright and dark colours, two types of motion are perceived simultaneously once again. But by applying a bright background, the animation appears to flash as both types of motion seem to cancel each other out. The classic monochrome wagon wheel effect occurs since our brain doesn't perceive motion continuously, but instead breaks it down into a series of snapshots, just like a video camera. When a wheel rotates clockwise, anti-clockwise information is sometimes generated after each step, causing our brain to misinterpret the direction of motion. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 16865 - Posted: 06.02.2012

By Ferris Jabr The rat stood on its hind limbs at one end of a narrow runway. It wore a tiny black vest attached to a robotic arm that hovered above its head. Without such mechanical support, the rat would have fallen over—its spinal cord had two deep cuts, rendering its back legs useless. Rubia van den Brand, then a doctoral candidate at the University of Zurich, stood at the other end of the runway, urging the animal to walk. Although the robotic arm kept the rat upright, it could not help the creature move; if the rodent were ever to walk again, it would have to will its feet forward. For the first time since van den Brand began her experiments, the rat moved one of its back legs on its own—a small, effortful step. She ran to her boss's office with the news and a crowd immediately gathered in the lab to watch what many had deemed impossible. Van den Brand and Grégoire Courtine, now at the École Polytechnique Fédérale de Lausanne (E.P.F.L.), along with their colleagues, have trained rats with nearly severed spinal cords to walk again. One week after being injured, the rats could not move their hind limbs at all. Six weeks later they could walk, run, climb stairs and even sprint—but only with the support of the robotic arm accompanied by electrical and chemical stimulation of the spinal cord. Rats that trained on a moving treadmill instead of on a stationary runway moved their feet reflexively but never learned to walk voluntarily. Only conscious participation in walking encouraged new connections between the rodents' brains, spinal cords and limbs, which they needed to take those first deliberate steps. "It's kind of like how a toddler learns to walk," Courtine says. "Their spinal cord is full of activity and the brain needs to learn to take control of the spinal cord. As long as the brain has something to control it can learn progressively to communicate again with these cells." © 2012 Scientific American,

Keyword: Regeneration
Link ID: 16864 - Posted: 06.02.2012

By James Gallagher Health and science reporter, BBC News Being born prematurely is linked to an increased risk of a range of mental health problems much later in life, according to researchers. Bipolar disorder, depression and psychosis were all more likely, the study in The Archives of General Psychiatry suggested. The overall risk remained very low, but was higher in premature babies. Experts cautioned there have since been significant advances in caring for premature babies. Full-term pregnancies last for around 40 weeks, but one in 13 babies are born prematurely, before 36 weeks. Researchers at the Institute of Psychiatry at King's College London and the Karolinska Institute in Sweden analysed data from 1.3m people born in Sweden between 1973 and 1985. They found 10,523 people were admitted to hospital with a psychiatric disorders, 580 of those had been born prematurely. The academics showed full-term children had a two in 1,000 chance of being admitted. The risk was four in 1,000 for premature babies born before 36 weeks and six in 1,000 for those born before 32 weeks. Very premature babies were more than seven times more like to have bipolar disorder and nearly three times as likely to have depression. One of the researchers, Dr Chiara Nosarti, said the real figures may be higher as milder conditions would not have needed a hospital visit. BBC © 2012

Keyword: Development of the Brain; Schizophrenia
Link ID: 16863 - Posted: 06.02.2012

A treatment to reduce the body temperatures of infants who experience oxygen deficiency at birth has benefits into early childhood, according to a follow-up study by a National Institutes of Health research network. Children who received the hypothermia treatment as infants were more likely to have survived to ages 6 and 7, when they were evaluated again, than were children who received routine care, the study found. They were no more likely than the routine care group to experience a physical or cognitive impairment, it said. The report appears in the New England Journal of Medicine. “The findings show that the use of this cooling technique after birth increases the chances of survival, without increasing the risk of long-term disability,” said senior author Rosemary D. Higgins, M.D. The study was conducted by Seetha Shankaran, M.D., of Wayne State University in Detroit, Dr. Higgins, and 25 other researchers in the NICHD Neonatal Research Network. Infants born at term may fail to get enough oxygen, from blood loss or other birth complications. Oxygen deprivation during the birth process is called hypoxic-ischemic encephalopathy, or HIE. In severe cases of HIE, death rates can reach 50 percent. Survivors often sustain brain damage, which can result in cerebral palsy, cognitive impairment, or hearing and vision loss. Even if they do not experience detectable brain damage, children who experience HIE at birth are at higher risk for learning disabilities, language delays, and memory deficits. Severe oxygen deficiency at birth is also known as birth asphyxia.

Keyword: Development of the Brain
Link ID: 16862 - Posted: 06.02.2012

by Pamela Weintraub; Jaak Panksepp has taken on many unusual roles in his storied career, but none so memorable as rat tickler: He learned how to stimulate the animals to elicit high-frequency chirps that he identified as laughter. Panksepp’s interspecies game-playing garnered amused media coverage, but the news also stirred up old controversies about human and animal emotions. Since the 1960s, first at Bowling Green State University and later at Washington State University, Panksepp has charted seven networks of emotion in the brain: SEEKING, RAGE, FEAR, LUST, CARE, PANIC/GRIEF, and PLAY. He spells them in all caps because they are so fundamental, he says, that they have similar functions across species, from people to cats to, yes, rats. Panksepp’s work has led him to conclude that basic emotion emerges not from the cerebral cortex, associated with complex thought in humans, but from deep, ancient brain structures, including the amygdala and the hypothalamus. Those findings may show how talk therapy can filter down from the cortex to alter the recesses of the mind. But Panksepp says his real goal is pushing cures up from below. His first therapeutic effort will use deep brain stimulation in the ancient neural networks he has charted to counteract depression. Panksepp recently sat down with DISCOVER executive editor 
Pamela Weintraub at the magazine’s offices in New York City to explain his iconoclastic take on emotion. His new book, The Archaeology of Mind: 
Neuroevolutionary Origins of Human Emotion, will be published in July. Your interest in emotion was sparked by an odd job you had in college. What
 happened there?
 © 2012, Kalmbach Publishing Co.

Keyword: Emotions; Evolution
Link ID: 16861 - Posted: 06.02.2012

By Rachel Ehrenberg “Old people smell” is for real — and it isn’t mothballs, Jean Naté or pipe tobacco. It’s a mild and not unpleasant odor compared with the intense, unpleasant smell emitted by 40- to 50-something guys, a new study finds. Scientists don’t know what makes up this vintage chemical fingerprint, but the research suggests that apologies to your grandparents may be in order. The negative association with the smell of the elderly appears to be more about context than scent, says Johan Lundström of the Monell Chemical Senses Center in Philadelphia. Lundström and his colleagues collected underarm odors from 12 to 16 people in each of three age groups: young (20 to 30 years old), middle-aged (45 to 55 years old) and old (75 to 95 years old). For five nights while they slept, the study participants wore T-shirts with breast-feeding pads sewn in the underarms. The shirts and bed linens had been washed with scent-free soap and the participants did the same to themselves before going to bed each night. They also refrained from smoking, drinking alcohol or eating foods that are known to contribute odors to bodily secretions. Evaluators (aged 20 to 30) then sniffed the armpit pads. Evaluators rated the samples on pleasantness and intensity, guessed which of two odors came from the older donor and then labeled all of the scents by age category. The evaluators had trouble discerning young from middle-aged odors. But the odors from old donors were correctly identified more often than would be expected by chance, the research team reports online May 30 in PLoS ONE. © Society for Science & the Public 2000 - 2012

Keyword: Chemical Senses (Smell & Taste); Development of the Brain
Link ID: 16860 - Posted: 05.31.2012

by Debora MacKenzie Ever blushed in an inappropriate situation, like when the doctor is listening to your heart? It turns out that the same regions of your face that redden during sexual stimulation also heat up, slightly, during innocent social interactions. Amanda Hahn and colleagues at St Andrew's University in Fife, UK, used a heat-sensitive camera to map small changes of temperature in the faces of young heterosexual women while an experimenter touched them with an instrument they were told was measuring skin colour (it wasn't). Touching the palm or elbow had no effect, but contact with the cheek or top of the breastbone raised the temperature around the eyes, mouth and nose by 0.2 °C to 0.5 °C on average, and by a full degree in certain spots. An earlier study found this area heats up in sexually aroused men. The female subjects reported few or no feelings of arousal or embarrassment, but their facial temperature rose more when the experimenter was a young man. "What is surprising is the magnitude," says Hahn. She now hopes to determine whether we are aware of these subtle changes in others, and if they affect how we interact. Journal reference: Biology Letters, DOI: 10.1098/rsbl.2012.0338 © Copyright Reed Business Information Ltd

Keyword: Emotions
Link ID: 16859 - Posted: 05.31.2012

Genetics can help determine whether a person is likely to quit smoking on his or her own or need medication to improve the chances of success, according to research published in today's American Journal of Psychiatry. Researchers say the study moves health care providers a step closer to one day providing more individualized treatment plans to help patients quit smoking. The study was supported by multiple components of the National Institutes of Health, including the National Institute on Drug Abuse (NIDA), the National Human Genome Research Institute, the National Cancer Institute, and the Clinical and Translational Science Awards program, administered by the National Center for Advancing Translational Sciences. “This study builds on our knowledge of genetic vulnerability to nicotine dependence, and will help us tailor smoking cessation strategies accordingly,” said NIDA Director Nora D. Volkow, M.D. “It also highlights the potential value of genetic screening in helping to identify individuals early on and reduce their risk for tobacco addiction and its related negative health consequences.” Researchers focused on specific variations in a cluster of nicotinic receptor genes, CHRNA5-CHRNA3-CHRNB4, which prior studies have shown contribute to nicotine dependence and heavy smoking. Using data obtained from a previous study supported by the National Heart Lung and Blood Institute, researchers showed that individuals carrying the high-risk form of this gene cluster reported a 2-year delay in the median quit age compared to those with the low-risk genes. This delay was attributable to a pattern of heavier smoking among those with the high risk gene cluster.

Keyword: Drug Abuse; Genes & Behavior
Link ID: 16858 - Posted: 05.31.2012

By Bora Zivkovic The biannual meeting of the Society for Research on Biological Rhythms happened last week. Unfortunately, I could not attend, so will have to wait another two years for the next opportunity. I am not sure how this stuff happens, but there was a flurry of new papers in the circadian field just preceding the event. Several of them have already received quite a lot of attention in both old and new media, and rightfully so, but I decided not to cover them one at a time just as the embargo lifted for each one of them. Instead, I will just very briefly describe and explain the main take-home messages of each one of them, link to the best coverage for those who want more detail (“Cover what you do best. Link to the rest.“), and then try to come up with more of a ‘big picture’ summary of the current state of the field. I apologize in advance for covering and linking to some of the papers that are not published in Open Access journals. I am not as strict about this policy as some other bloggers are (“if my readers cannot access it, they cannot fact-check me”), and will occasionally cover non-OA papers. Even if most of my readers cannot access them, I gather that a miniscule proportion can access and, if I got something wrong, can alert the other readers in the comments. And speaking of Open Access, I am not one to sign many online petitions, but this one is worth it so please sign if you have not done it already. So, let’s see what new and exciting in chronobiology these days… © 2012 Scientific American,

Keyword: Biological Rhythms; Obesity
Link ID: 16857 - Posted: 05.31.2012

by Kayt Sukel The sexes may be more alike than we thought. A startling new theory says that some of the disparities between our brains may be there to make us act the same SEVERAL years ago, the car I was driving was rear-ended by another at a stop sign. No one was hurt, but my passenger and I had to wait around to give a statement to the local police. Later on I asked my companion if he had noticed that the officer addressed most of the questions to him, even though I was the one who had been driving. "I think he was just afraid you were going to do the typical female thing and fall apart," he replied. The notion that men can face adversity with stoicism while women are more likely to respond with histrionics is just one example of the gender stereotypes that permeate our culture. If my friend was right, they even persist among those who should be taking particular care to treat people equally. Perhaps such prejudice is justified, though. After all, in recent years evidence has turned up of numerous differences between men and women's brains, whether at the level of synapses, signalling chemicals, or gross anatomy. Brains come in hues of either pink or blue, as one researcher puts it. But could we be overlooking an important caveat? A new theory that has sprung from research on prairie voles says that at least some of those disparities evolved not to create differences in behaviour or ability, but to prevent them. They are there to compensate for the genetic or hormonal differences that are necessary to create two sexes with different sets of genitals and reproductive behaviours. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior
Link ID: 16856 - Posted: 05.31.2012

By Kay Lazar, Globe Staff Federal regulators announced a multi-year initiative Wednesday to slash the inappropriate use of antipsychotic drugs in nursing home residents, saying that nearly 40 percent of residents with dementia were receiving the powerful sedatives though they didn’t have a condition that would warrant it. The US Centers for Medicare & Medicaid Services said it was aiming to reduce the use of antipsychotic drugs in nursing home residents by 15 percent by the end of this year, through training of nursing home staff and state inspectors to use alternative methods instead of relying on antipsychotics to quell agressive and agitated behavior among people with dementia. Alice Bonner, director of the agency’s nursing home division, said in an interview that the 15 percent reduction is just the first step. “In 2013 we will set another goal,” Bonner said. “At that point, we will be looking at even more significant reductions.” Another agency official said during a conference call with reporters that between July and September of 2010, almost 40 percent of nursing home residents with signs of dementia were receiving antipsychotic drugs even though they had not been diagnosed with a psychosis. The drugs have sometimes-lethal side effects, prompting the US Food and Drug Administration to issue two warnings since 2005 against using them in elderly patients with dementia. © 2012 NY Times Co

Keyword: Schizophrenia; Alzheimers
Link ID: 16855 - Posted: 05.31.2012

By Nathan Seppa Spiking a fever in pregnancy may contribute to autism risk in the offspring. Researchers report that women who run a high temperature while pregnant — and don’t treat it — appear twice as likely to have a child with autism as women who don’t report any untreated fevers. Other studies have suggested a link between infectious diseases during gestation and a heightened risk of having a child with an autism spectrum disorder. But the new study didn’t find a specific connection between influenza and the behavioral disorders, the researchers report in an upcoming issue of the Journal of Autism and Developmental Disorders. “I think this is the largest and most careful study that’s been done on the topic of fever and influenza in autism development,” says Paul Patterson, a developmental neurobiologist at Caltech, who wasn’t part of this study. Researchers at the University of California, Davis identified 538 children with an autism spectrum disorder, 163 others with developmental delays and 421 who were developing without any apparent problems. The children’s mothers provided health information on their pregnancies. After accounting for differences in race, child’s age, insurance, smoking, mother’s education and residence at the time of birth, the scientists found that women who had suffered an uncontrolled fever during pregnancy were roughly twice as likely to have an autistic child as mothers with no untreated fevers. Fever in gestation was also associated with a more than doubled risk of developmental delays, report the researchers, who recently also linked autism risk with obesity in pregnancy (SN: 5/19/12, p. 16). © Society for Science & the Public 2000 - 2012

Keyword: Autism; Development of the Brain
Link ID: 16854 - Posted: 05.31.2012

By Julian De Freitas What did you eat for dinner one week ago today? Chances are, you can’t quite recall. But for at least a short while after your meal, you knew exactly what you ate, and could easily remember what was on your plate in great detail. What happened to your memory between then and now? Did it slowly fade away? Or did it vanish, all at once? Memories of visual images (e.g., dinner plates) are stored in what is called visual memory. Our minds use visual memory to perform even the simplest of computations; from remembering the face of someone we’ve just met, to remembering what time it was last we checked. Without visual memory, we wouldn’t be able to store—and later retrieve—anything we see. Just as a computer’s memory capacity constrains its abilities, visual memory capacity has been correlated with a number of higher cognitive abilities, including academic success, fluid intelligence (the ability to solve novel problems), and general comprehension. For many reasons, then, it would be very useful to understand how visual memory facilitates these mental operations, as well as constrains our ability to perform them. Yet although these big questions have long been debated, we are only now beginning to answer them. Memories like what you had for dinner are stored in visual short-term memory—particularly, in a kind of short-term memory often called “visual working memory.” Visual working memory is where visual images are temporarily stored while your mind works away at other tasks—like a whiteboard on which things are briefly written and then wiped away. We rely on visual working memory when remembering things over brief intervals, such as when copying lecture notes to a notebook. © 2012 Scientific American

Keyword: Learning & Memory
Link ID: 16853 - Posted: 05.31.2012

By AMANDA SCHAFFER When one fish is injured, others nearby may dart, freeze, huddle, swim to the bottom or leap from the water. The other fish know that their school mate has been harmed. But how? In the 1930s, Karl von Frisch, the famous ethologist, noted this behavior in minnows. He theorized that injured fish release a substance that is transmitted by smell and causes alarm. But Dr. von Frisch never identified the chemical composition of the signal. He just called it schreckstoff, or “scary stuff.” Schreckstoff is a long-standing biological mystery, but now researchers may have solved a piece of it. In a study published in February in Current Biology, Suresh Jesuthasan, a neuroscientist at the Biomedical Sciences Institutes in Singapore, and his colleagues isolated sugar molecules called chondroitins from the outer mucus of zebra fish. They found that when these molecules are broken into fragments, as they might be when the fish’s skin is injured, and added to water, they prompt alarm behavior in other fish. At low concentrations, the fish were “mildly perturbed,” Dr. Jesuthasan said. At high concentrations, they stopped darting altogether and froze in place for an hour or longer. He and his colleagues also showed that neurons in the olfactory bulb of these fish were activated when exposed to the sugar fragments. In a sense, the fish seemed to “smell” the injury. © 2012 The New York Times Company

Keyword: Chemical Senses (Smell & Taste); Stress
Link ID: 16852 - Posted: 05.29.2012