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

By Scicurious They are Captain Planet! Ok, not quite. But, strangely, antidepressants on top of stress hormones may be stronger than they are alone. Why is this? And what’s going on? Well, we’re not quite sure. The most commonly prescribed antidepressant (and antianxiety) medications out there are the SSRI, selective serotonin reuptake inhibitors. These include drugs like fluoxetine (Prozac), citalopram (Celexa), or sertraline (Zoloft). How these drugs work, however, is still up for debate. At first, everyone thought that, because these drugs increase levels of the neurotransmitter serotonin in the brain, that depression must be caused by low levels of serotonin, and the increase would make you feel better. We have since learned that this is not the case. Headaches don’t result from lack of aspirin, and depression doesn’t result from lack of serotonin. The next theory for how depression, and antidepressants, might work was the neurogenesis theory. We used to believe that you were born with all the neurons you’d ever have, but we now know that neurogenesis, the birth of new neurons, occurs throughout life in areas of the brain like the hippocampus, an area usually associated with learning and memory. Antidepressants can increase neurogenesis, on a time course which matches the clinical efficacy of antidepressants. © 2012 Scientific American

Keyword: Depression; Stress
Link ID: 16851 - Posted: 05.29.2012

By NICHOLAS BAKALAR Babies delivered by Caesarean section may have an increased risk of obesity by age 3, a new study has found. Among 1,255 women recruited in early pregnancy for the study, 284 gave birth by Caesarean section. By age 3, 15.7 percent of those children were obese (with a body mass index in the 95th percentile or greater), compared with 7.5 percent of those delivered vaginally. Mothers who delivered by Caesarean were on average heavier than those who delivered vaginally, and they breast-fed less. But after controlling for these and other maternal health and socioeconomic factors, the scientists found that Caesarean delivery was associated with a doubling of the odds of obesity in these children. Whether the Caesarean was planned or an emergency delivery made no difference. “Those mothers who are considering C-section in the absence of a medical indication should be counseled about this potential risk,” said the lead author, Dr. Susanna Y. Huh, an assistant professor of pediatrics at Harvard. Babies born by Caesarean develop different intestinal flora from those born vaginally, and the authors suggest this could be a factor. Or, the mode of delivery might have long-term effects on immune or endocrine function. The report was published online Wednesday in The Archives of Disease in Childhood. Copyright 2012 The New York Times Company

Keyword: Obesity; Development of the Brain
Link ID: 16850 - Posted: 05.29.2012

By Meehan Crist For decades researchers have known that our ability to remember everyday experiences depends on a slender belt of brain tissue called the hippocampus. Basic memory functions, such as forming new memories and recalling old ones, were thought to be performed along this belt by different sets of neurons. Now findings suggest that the same neurons in fact perform both these very different functions, changing from one role to another as they age. The vast majority of these hippocampal neurons, called granule cells, develop when we are very young and remain in place throughout our lives. But about 5 percent develop in adulthood through the birth of new neurons, a process known as neurogenesis. Young granule cells help form new memories, but as they get older they switch roles to helping recall the past. Newer granule cells pick up the slack, taking on the role of helping to form new memories. Susumu Tonegawa of the Massachusetts Institute of Technology and his colleagues published the findings on March 30 in the journal Cell. Tonegawa’s team tested the role of these adult-born cells by genetically engineering mice in which the old cells could be selectively turned off. They then put the mice through a series of mazes and fear-conditioning tests, which demonstrated that young granule cells are essential to forming separate memories of similar events, whereas old granule cells are essential to recalling past events based on small cues. This discovery suggests that memory impairments common in aging and in post-traumatic stress disorder may be connected to an imbalance of old and new cells. “If you don’t have a normal amount of young cells, you may have a problem distinguishing between two events that would be seen as different by healthy people,” Tonegawa says. At the same time, the presence of too many old cells would make it easier to recall traumatic past experiences based on current cues. © 2012 Scientific American,

Keyword: Learning & Memory; Neurogenesis
Link ID: 16849 - Posted: 05.29.2012

By Morgen E. Peck Tracking eye movements lets scientists figure out what we pay attention to in a scene. When people blink during such experiments, those few milliseconds are usually discarded as junk data. A new study finds that blinking might reveal important information, too. It turns out that the more we blink, the less focused is our attention. In kids with autism, blink patterns appear to offer clues about how they engage with the world around them. During eye-tracking experiments with toddlers, Warren Jones, a pedia­trician at the Emory University School of Medicine, found that the children were strategic about when they blinked. While watching a recorded scene, the toddlers seemed to inhibit their blink­ing during the moments that sucked them in. “The timing of when we don’t blink seems to relate to how engaged we are with what we’re looking at,” Jones says. He now uses this discovery as a tool to study attention in autistic children. In a paper published last December in the Proceedings of the National Academy of Sciences USA, Jones observed differences in the blinking patterns of autistic and develop­mentally normal children. Both groups watched a video that included moments of human emotion and sudden action. Developmentally normal children inhibited their blinking before emo­tional climaxes, as though they were following the narrative and predicting an outcome. Autistic children blinked right through those moments, sug­gesting they were not following the emotional arc of the story, but they responded sharply when an object suddenly moved. © 2012 Scientific American,

Keyword: Autism; Attention
Link ID: 16848 - Posted: 05.29.2012

By Keith Seinfeld If you came face to face with a great whale, you might find a few surprises in its chin: Like whiskers, if you look closely at the surface. And, hidden inside the chin, lies a mysterious sensory organ, unknown to centuries of whalers and biologists. You just need the right tools to find it: a high-tech, oversized x-ray machine, and the right saws to slice it into thin pieces that fit in a microscope. A group of scientists based at the University of British Columbia, in Vancouver, BC, have done all that looking—and they discovered an organ that serves a crucial purpose and answers a longstanding mystery. Here is a graphic from the science study, published in Nature (expand the graphic to full screen to for best browsing of the information and images): How do great whales, such as humpbacks and blues, drive their jaws so wide open and then snap them shut, while swimming at full speed? “These heads are five meters long and weigh close to ten tons,” says Nick Pyenson, first author of the new study, published in the journal Nature. He’s now the curator of fossil marine mammals at the Smithsonian Institution. “What we found in the course of our investigation into the jaw and skull anatomy was this surprising structure in the chin. We had no idea what it was.” KPLU is a service of Pacific Lutheran University | ©2012

Keyword: Pain & Touch; Evolution
Link ID: 16847 - Posted: 05.29.2012

by Jeff Hecht After overindulging in berries, flocks of cedar waxwings flew drunkenly to their doom. That's the conclusion of a new report in the Journal of Ornithology. Cedar waxwings have evolved to live on a diet that averages 84 per cent fruit. But those evolutionary innovations backfired on several occasions between 2005 and 2007 when flocks of them died after crashing into windows and fences in broad daylight in the Los Angeles area. Residents puzzled by the deaths sent the bodies to the California Animal Health and Food Safety Laboratory in San Bernardino. Necropsies performed by Hailu Kinde and colleagues at the lab showed the birds had been healthy when they gorged on berries from the Brazilian pepper tree, then died from ruptured livers or other traumas caused by the collisions. Flocking hell Cedar waxwings have the most fruit-rich diet of all North American birds, and dining on overripe berries can leave them visibly tipsy. Their short intestines can process large volumes of fruit, and their large livers – about 5 per cent of body mass – can break down toxic ethanol before it causes serious damage. Yet although earlier studies had found isolated birds that had died from collisions when flying drunk, no one had seen whole flocks careen to their doom. © Copyright Reed Business Information Ltd.

Keyword: Drug Abuse; Evolution
Link ID: 16846 - Posted: 05.26.2012

by Linda Geddes SECOND by second changes in the brain's pH can be visualised for the first time. This ability may provide fresh insights into learning, memory and disease. Oxygen deprivation can alter the brain's pH, and even normal brain signals from acidic neurotransmitters or metabolic by-products such as lactic acid may lead to local changes in pH. Studies in mice have also uncovered pH-sensitive receptors in brain areas involved in emotion and memory - although their function is something of a mystery. "If these receptors are activated by pH change, it's possible that abnormalities in this system could lead to changes in learning, memory and mood," says Vincent Magnotta at the University of Iowa in Iowa City. A common way of studying the brain is with an MRI scanner, which detects differences in the spin of protons in tissues according to water content. Although brain pH can be measured using a form of MRI called MR spectroscopy, it only detects changes that occur over minutes - not fast enough to keep up with the rapid pace of the brain. T1ρ MRI analyses the interaction between spinning protons and other ions in a solution, which changes under different pHs. By tweaking the technique so that multiple measurements could be taken simultaneously, Magnotta and his colleagues have found that T1ρ MRI can detect changes in brain acidity happening over seconds. © Copyright Reed Business Information Ltd.

Keyword: Brain imaging
Link ID: 16845 - Posted: 05.26.2012

by Elizabeth Norton Do our brains continue to produce neurons throughout our lifetimes? That's been one of the most hotly debated questions in the annals of science. Since the 1950s, studies have hinted at the possibility, but not until the late 1990s did research prove that the birth of new neurons, called neurogenesis, goes on in the brains of adult primates and humans. Now a surprising new study in humans shows that in the olfactory bulb-the interface between the nose and the brain and an area long—known to be a hot spot of neurogenesis—new neurons may be born but not survive. The finding may rule out neurogenesis in this area, or it might show only that some people don't stimulate their brains enough through the sense of smell, some researchers say. Previous studies have found evidence of neurogenesis in the olfactory bulb of adult humans. But those studies measured only proteins produced by immature neurons, leaving open the question of whether these youngsters ever grew up to connect with other cells to form functional networks, says neuroscientist Jonas Frisén of the Karolinska Institute in Stockholm. If new olfactory neurons really reached adulthood throughout a person's life, researchers should find neurons of a variety of ages in this region. That's not what Frisén and his team saw. The discovery is based on a technique he and his colleague Kirsty Spalding hit upon in 2005, in which they found a clever way to deduce the age of neurons. The method relies on atomic testing carried out in the 1950s and 1960s, which released massive amounts of carbon-14 into the atmosphere; the atmospheric 14C has been steadily declining ever since. Thus, the later a cell is born after this testing, the less 14C it contains. © 2010 American Association for the Advancement of Science.

Keyword: Chemical Senses (Smell & Taste); Neurogenesis
Link ID: 16844 - Posted: 05.26.2012

By Jason G. Goldman Getting around is complicated business. Every year, animals traverse miles of sky and sea (and land), chasing warmth or food or mates as the planet rotates and the seasons change. And with such precision! Some animals rely on visual landmarks, others on subtle changes in magnetic fields, and yet others match their internal clocks with the movement of the sun and stars across the sky. One researcher, Jennifer A. Mather, wondered: how do octopuses navigate? Do they rely on chemotactile sensory information, or do they orient towards visual landmarks? Octopuses occupy “homes” for several days or in some instances for several weeks, and when they go out looking for food, they are sometimes gone for several hours at a time. Therefore, they must use some sort of memory to find their way back home. Many molluscs use trail-following, and follow their own mucus trails, or the trails of others. You might expect that octopuses use trail-following as well, since they forage by using chemotactile exploration – at least four different types of receptors on their suckers gather chemical and tactile information as they move along the rocky seafloor. However, many other species use visual scene recognition to aid in navigation: ants, bees, gerbils, hamsters, pigeons, and even humans, use visual landmarks to navigate around their environments. Since octopuses use visual information to distinguish among different objects, they could use visual landmarks to get home as well. © 2012 Scientific American

Keyword: Animal Migration; Chemical Senses (Smell & Taste)
Link ID: 16843 - Posted: 05.26.2012