by Gisela Telis A would-be mom worried about Down syndrome faces an unpleasant choice: undergo an invasive test that can kill her fetus, or forgo a definitive answer until after birth. But a new method that involves tracing differences between a mother's DNA and her baby's could provide doctors with a safe and inexpensive way to diagnose the condition, one practical enough to become a part of routine prenatal care. Down syndrome is the world's most common genetic condition, affecting about one in every 700 live births. Babies with the disorder carry an extra copy of chromosome 21, which causes cognitive disabilities, heart defects, and other problems. Although certain markers in a mother's blood can tip off doctors that a fetus is at higher risk of Down syndrome, only invasive and expensive procedures such as amniocentesis—which requires poking a needle into the uterus to obtain a fluid sample—can give a 99% accurate answer. But these invasive tests are risky: They can cause miscarriage in 1% to 2% of cases. In an attempt to find a safer alternative, researchers have turned to the mother's blood. In a recent study, scientists ferreted out the fragments of fetal DNA that leak into a mother's bloodstream and then sequenced both genomes to check for extra copies of chromosome 21. Those attempts were successful, but they were time-consuming and required specialized and expensive DNA-sequencing equipment that would put the process out of reach for most people. Philippos Patsalis wanted something more accessible. A geneticist at the Cyprus Institute of Neurology and Genetics in Nicosia, Patsalis has provided diagnostic prenatal testing for 20 years and has long lamented that women who want accurate testing face greater risk and expense. © 2010 American Association for the Advancement of Science.

Keyword: Development of the Brain; Genes & Behavior
Link ID: 15075 - Posted: 03.07.2011

By Daniel Strain In “Memory,” a song from the musical Cats, an aging feline invites old memories to live again. Now, that power may be in the hands of the cat’s worst enemy — the rat. Increased levels of one natural brain enzyme supercharge rat memories, a study suggests. And it’s not just new, short-term memories. The enzyme — called PKM-zeta — gives rats better recall of old remembrances, too, a U.S.-Israeli team reports in the March 5 Science. So far, existing memory boosters mostly help animals like rats store lessons or events more efficiently. It’s a lot harder to give furry critters better recall of memories already sitting in long-term cold storage, says study coauthor Yadin Dudai. In a number of recent studies, researchers showed that they could make rats forget a range of old learned behaviors by blocking the protein in the brain. Rodents with too little PKM-zeta, for instance, didn’t know to avoid liquids that had made them sick in the past. So Dudai’s team tackled the next big question. “If you, indeed, can block the memory by blocking the enzyme, can you enhance the memory by enhancing the enzyme?” says Dudai, a neurobiologist at the Weizmann Institute of Science in Rehovot, Israel. Spoiler alert: You can. Dudai’s team injected rats with viruses carrying loads of PKM-zeta–producing genes, shooting the infectious agents right into the wrinkly, outer region of the brain called the neocortex. Cells in the cortex then churned out lots of the protein. The rodents didn’t instantly recall where they left that cheese, though. Researchers trained the rats to associate certain tastes — like sugary or salty — with gross feelings akin to mild food poisoning. Rats that received the enzyme boost remembered to steer clear of those tastes much better than control rats did. © Society for Science & the Public 2000 - 2011

Keyword: Learning & Memory
Link ID: 15074 - Posted: 03.05.2011

By Bruce Bower The Go-Go’s had a 1982 hit record with “We Got the Beat,” but a 23-year-old man named Mathieu never got their message. Researchers have identified Mathieu as the first documented case of beat deafness, a condition in which a person can’t feel music’s beat or move in time to it. Mathieu flails in a time zone of his own when bouncing up and down to a melody, unlike people who don’t dance particularly well but generally move in sync with a musical beat, according to a team led by psychologists Jessica Phillips-Silver and Isabelle Peretz, both of the University of Montreal. What’s more, Mathieu usually fails to recognize when someone else dances out of sync to a tune, the researchers report in a paper that will appear in Neuropsychologia. “We suspect that beat deafness is specific to music and is quite rare,” Phillips-Silver says. She and her colleagues plan to investigate whether Mathieu takes an offbeat approach to nonmusical activities, such as conversational turn-taking and adjusting one’s gait to that of someone else. Language lacks the periodic rhythms found in music, so it’s unlikely that Mathieu’s problem affects speech perception, remarks cognitive scientist Josh McDermott of New York University. If periodic sounds of all kinds confuse Mathieu, this problem may loom large when he confronts complex musical beats, McDermott suggests. © Society for Science & the Public 2000 - 2011

Keyword: Hearing; Language
Link ID: 15073 - Posted: 03.05.2011

by Carrie Arnold Why does the rustle of sheets wake us up on some nights, but we sleep through the sound of our alarm clocks going off on others? A new study implicates a type of brain activity known as alpha waves. With better monitoring of these waves, researchers might be able to develop therapies that could help all of us get a better night's sleep. Our brain activity changes throughout the day. When we're awake, our neurons chatter in short, frequent bursts. Measured on an electroencephalogram (EEG), these "alpha waves" look a lot like earthquake squiggles on a seismograph. When we sleep, our neuron chatter slows down, resulting in less squiggly theta and delta waves. Scientists have shown that alpha waves help us respond to the sights and sounds of our environment. Yet they seem to disappear during sleep, even though we are still able to respond to environmental cues, such as smoke or a passing police siren. So do alpha waves really disappear when we slumber? Sleep scientists Scott McKinney and Jeffrey Ellenbogen of Massachusetts General Hospital in Boston and colleagues used a sophisticated computer program to find out. Rather than eyeballing EEGs, as researchers had done in the past, the program teases apart the complicated patterns of brain activity. During sleep, the researchers found, alpha waves are still present—they're just drowned out by the theta and delta waves, like the din of a noisy restaurant drowns out individual conversations. © 2010 American Association for the Advancement of Science.

Keyword: Sleep
Link ID: 15072 - Posted: 03.05.2011

by Ferris Jabr Alzheimer's disease kills brain cells that are vital for memory – but now we can make new ones from human embryonic stem cells in the lab. The breakthrough opens the way for testing new anti-Alzheimer's drugs, and raises the hope that one day people with Alzheimer's could receive transplants of lab-grown neurons into their brains to improve their memory. A type of brain cell called basal forebrain cholinergic neurons is among those that Alzheimer'sMovie Camera hits hardest. They die off early in the progress of the disease, a loss which devastates memory and our ability to fully understand our environment. Christopher Bissonnette and colleagues at Northwestern University in Evanston, Illinois, took the first step in growing new ones by studying the genetics of these neurons. Once the team had deciphered the genetic signals that guide the development of these cells, they were able to coerce human embryonic stem cells into developing in the same way. To initiate the metamorphosis, they created pores in the walls of the stem cell nuclei and slipped in segments of DNA and gene-regulating proteins called transcription factors that are associated with the neurons. When the researchers transplanted the neurons they had engineered into slices of mouse brain, the cells wove themselves into the tissue of the hippocampus, a brain region involved in the formation of memories. They then began producing the neurotransmitter acetylcholine, which is necessary for memory retrieval. © Copyright Reed Business Information Ltd.

Keyword: Alzheimers; Stem Cells
Link ID: 15071 - Posted: 03.05.2011

Catherine de Lange, reporter Want to see an illusion that will get your cogs turning? In the video above, you can see three versions of a new illusion by Sung Ho-Kim at Rutgers University, New Jersey, that trick your brain into thinking circular patterns that shift across a screen are actually spinning. Make sure you are close to the screen to see the full effect. In the first animation, the top and bottom halves of the shape should look like they are rotating in opposite directions. They switch directions as the motion of the pattern changes from left to right. In the second version of the illusion, a block covers half of the shape. This time it looks like the spokes of a wheel are rotating as the whole pattern travels left and right across the screen. In the final animation, two gears connected by a chain appear to be rotating together. If you're convinced that these shapes are actually turning, try tracking each of the short lines, and you'll see that it's an illusion. The physical trajectory of each line segment is purely horizontal and none of the circles are rotating. Do you know why our brains trick us in this way? If you think you know the answer, let us know in the comments below and we will reveal all next week. © Copyright Reed Business Information Ltd.

Keyword: Vision
Link ID: 15070 - Posted: 03.05.2011

By Nina Bai When asked recently on The Today Show how he cured himself of his addiction, Two and a Half Men sitcom star Charlie Sheen replied, "I closed my eyes and made it so with the power of my mind." Until last month, he was the highest paid actor on TV, despite his well-known bad-boy lifestyle and persistent problems with alcohol and cocaine. After the rest of his season's shows were canceled by producers, Sheen has gone on an interview tear with many bizarre statements, including that he is on a "winning" streak. His claims of quitting a serious drug habit on his own, however, is perhaps one of his least eccentric statements. A prevailing view of substance abuse, supported by both the National Institute on Drug Abuse and Alcoholics Anonymous, is the disease model of addiction. The model attributes addiction largely to changes in brain structure and function. Because these changes make it much harder for the addict to control substance use, health experts recommend professional treatment and complete abstinence. But some in the field point out that many if not most addicts successfully recover without professional help. A survey by Gene Heyman, a research psychologist at McLean Hospital in Massachusetts, found that between 60 to 80 percent of people who were addicted in their teens and 20s were substance-free by their 30s, and they avoided addiction in subsequent decades. Other studies on Vietnam War veterans suggest that the majority of soldiers who became addicted to narcotics overseas later stopped using them without therapy. © 2011 Scientific American

Keyword: Drug Abuse
Link ID: 15069 - Posted: 03.05.2011

By Clara Moskowitz The latest neuroscience research is presenting intriguing evidence that the brains of certain kinds of criminals are different from those of the rest of the population. While these findings could improve our understanding of criminal behavior, they also raise moral quandaries about whether and how society should use this knowledge to combat crime. In one recent study, scientists examined 21 people with antisocial personality disorder – a condition that characterizes many convicted criminals. Those with the disorder "typically have no regard for right and wrong. They may often violate the law and the rights of others," according to the Mayo Clinic. Brain scans of the antisocial people, compared with a control group of individuals without any mental disorders, showed on average an 18 percent reduction in the volume of the brain's middle frontal gyrus, and a 9 percent reduction in the volume of the orbital frontal gyrus — two sections in the brain's frontal lobe. Another brain study, published in the September 2009 Archives of General Psyciatry, compared 27 psychopaths — people with severe antisocial personality disorder — to 32 non-psycopaths. In the psychopaths, the researchers observed deformations in another part of the brain called the amygdala, with the psychopaths showing a thinning of the outer layer of that region called the cortex and, on average, an 18-percent volume reduction in this part of brain. © 2011 LiveScience.com.

Keyword: Aggression; Emotions
Link ID: 15068 - Posted: 03.05.2011

by Rowan Hooper Neuroengineer Ed Boyden is best known for his pioneering work on optogenetics, which allows brain cells to be controlled using light. A speaker at the TED2011 conference this week, his vision, he tells Rowan Hooper, is nothing less than to understand the brain, treat neural conditions and figure out the basis of human existence. Give us your elevator pitch. I run the synthetic neurobiology group. We develop software, electrical and optical tools to allow people to analyse brain dynamics. Unlike a computer, the brain is made of thousands of different types of cell, and we don't know how they work. We need to be able to turn the cells on and off to see how they cooperate to implement brain computations, and how they go awry in brain disorders. What we're doing is making genetically encoded neurons that we can turn on and off with light. By shining light on these cells we can activate them and see what they do. What brain functions will this allow you to study? Scientists now have unprecedented abilities to perturb and record from the brain, and that's allowing us to go after complex ideas like thought and memory. Our tools will help us parse out emotion, memory, attention and consciousness. Put psychology and neuroscience together with neuroengineering, and some of the biggest questions in neuroscience become tractable. Tell us about your tools. The core idea is to take molecules that sense light and convert it into electrical energy, and put them in neurons. We can take a given class of brain cells and develop a virus to deliver genes to these cells. Then we can shine light on these cells and activate them and see what they do. © Copyright Reed Business Information Ltd.

Keyword: Miscellaneous
Link ID: 15067 - Posted: 03.05.2011

NEW YORK — People who regularly use ibuprofen to ease their aches and pains may be less likely to develop Parkinson's disease than those who do not use the painkiller, researchers reported Wednesday. In a study of more than 136,000 U.S. men and women, researchers found that the more ibuprofen tablets people took each week, the lower their odds of developing Parkinson's, a disorder in which movement-regulating brain cells degenerate over time. Ibuprofen, sold as name-brands like Advil and Motrin in the U.S., is a non-steroidal anti-inflammatory drug (NSAID). But the study found no connection between Parkinson's risk and other NSAIDS, like aspirin or naproxen (Aleve), or with acetaminophen (Tylenol). Experts caution, however, that the findings do not prove that ibuprofen itself can help ward off Parkinson's. "It's too early to recommend use of ibuprofen to prevent or treat Parkinson's disease," lead researcher Dr. Xiang Gao, of Harvard Medical School in Boston, told Reuters Health in an email. Instead, Gao said, the findings lay the groundwork for clinical trials to look at whether the painkiller, which costs only a few cents per pill, might help slow SOURCE: http://bit.ly/Q5TNl Neurology, online March 2, 2011. Copyright 2011 Thomson Reuters

Keyword: Parkinsons
Link ID: 15066 - Posted: 03.03.2011

By Katherine Harmon Wandering the neighborhood randomly is not usually the best strategy to find a great dinner—especially if you live in a place where such meals are few and far between. The resulting trajectory, known in mathematics as "a random walk," does not always make for the best use of time and energy, particularly in locations where resources can be scarce, such as the open ocean. But a more purposeful "directed walk" to a destination takes a pretty sophisticated memory and spatial sense (or a device with GPS) that many animals don't have. New research, however, shows that thresher and tiger sharks are actually quite adept at highly directed swimming, with tiger sharks finning it over to a familiar spot from six to eight kilometers away within a home territory that covers hundreds or even thousands of square kilometers. Demonstrating that an animal is traveling directly to a desired destination—rather than stumbling on it accidentally—is challenging, given communication barriers and the fact that even straight paths are not always part of a purposeful travel pattern. To find out whether sharks were always circling their home range randomly or were intentionally returning to a place they remembered to offer food, shelter or mates, a team of researchers used fractal analysis to assess old GPS tracking data from three shark species: tiger sharks (Galeocerdo cuvier), thresher sharks (Alopias vulpinus) and blacktip reef sharks (Carcharhinus melanopterus). Tracking for each individual shark lasted for at least seven hours. © 2011 Scientific American,

Keyword: Animal Migration
Link ID: 15065 - Posted: 03.03.2011

A new mouse model closely resembles how the human body reacts to early HIV infection and is shedding light on nerve cell damage related to the disease, according to researchers funded by the National Institutes of Health. The study in today’s Journal of Neuroscience demonstrates that HIV infection of the nervous system leads to inflammatory responses, changes in brain cells, and damage to neurons. This is the first study to show such neuronal loss during initial stages of HIV infection in a mouse model. The study was conducted by a team of scientists from the University of Nebraska Medical Center, Omaha, and the University of Rochester Medical Center, N.Y. It was supported by the National Institute on Drug Abuse (NIDA), the National Institute of Neurological Disorders and Stroke, the National Institute of Mental Health, and the National Center for Research Resources. "This research breakthrough should help us move forward in learning more about how HIV affects important brain functioning in its initial stages, which in turn could lead us to better treatments that can be used early in the disease process," said Dr. Nora D. Volkow, director of NIDA. "The work contained within this study is the culmination of a 20-year quest to develop a rodent model of the primary neurological complications of HIV infection in humans," said Dr. Howard Gendelman, one of the primary study authors. "Previously, the rhesus macaque was the only animal model for the study of early stages of HIV infection. However, its use was limited due to expense and issues with generalizing results across species. Relevant rodent models that mimic human disease have been sorely needed."

Keyword: Miscellaneous
Link ID: 15064 - Posted: 03.03.2011

By Tina Hesman Saey A naturally occurring genetic variant may predict who will do well after a stroke and who won’t. People who have two copies of a particular version of the Tp53 gene have a poor prognosis after stroke and brain hemorrhages, researchers in Spain report online February 28 in the Journal of Experimental Medicine. The difference between the two versions of the gene amounts to one small change: swapping proline out for arginine as the 72nd link in a chain of amino acids that make up a protein called p53. The arginine-containing variant of p53 had previously been shown to help protect against cancer by increasing apoptosis, a cell suicide program that gets rid of damaged cells before they can turn nasty. Brain cells can also undergo apoptosis after a stroke, but there it’s a bad thing, leading to more widespread damage. Angeles Almeida, a molecular biologist at the University Hospital of Salamanca, and her colleagues wanted to know if the variant works as vigorously in the brain as in cancer cells, so they tested nerve cells that make either the arginine variant or the proline version. “We saw that the difference was huge,” Almeida says. Cells with the arginine version of p53 had four times greater capacity to undergo apoptosis than cells with the proline variant did. And that molecular difference carries over into consequences for the whole brain. The researchers tested the DNA of stroke and brain hemorrhage victims to see if the version of p53 the people carried could affect their prognosis. The variant did not affect the chance of having a stroke or brain hemorrhage, but did correlate with how well patients had recovered three months after the brain injuries, the team found. © Society for Science & the Public 2000 - 2011

Keyword: Stroke; Genes & Behavior
Link ID: 15063 - Posted: 03.03.2011

by Andrew Moseman Ken Jennings and Brad Rutter are accustomed to making others feel the heat as they blaze through Jeopardy clue after Jeopardy clue. But tonight, the quiz show's two greatest champions will oppose a player who can't be psyched out. It's time for the world to meet Watson. IBM's Jeopardy-playing computer system appears to viewers at home as an avatar of the Earth on a black screen. In fact, it is a system years in the making, and perhaps the most impressive attempt ever to create a question-answering computer that understands the nuances of human language. Watson is not connected to the Internet, but its databases overflow with books, scripts, dictionaries, and whatever other material lead researcher David Ferrucci could pack in. Storing information is the computer's strong suit; the grand artificial intelligence challenge of Jeopardy is the subtlety of words. advertisement | article continues below When the bright lights of Jeopardy go up tonight, there will be no human handler to tell Watson where inside its mighty databases to seek the answers. It must parse each clue and category title to figure out what it's being asked. It must race through its databases, find relevant search terms, and pick out the right response with a high level of confidence. It must understand the puns and geeky quirks of America's Favorite Quiz Show. It must beat two Jeopardy champions to the buzzer. And it too must voice its responses in the form of a question. © 2011, Kalmbach Publishing Co.

Keyword: Intelligence; Robotics
Link ID: 15062 - Posted: 03.03.2011

By Laura Sanders SALT LAKE CITY — When the brain can’t nail an answer, it falls back on reasonable guesses. Now scientists have evidence that this strategy may happen very early in the processing of sensory inputs, a study presented February 27 at the Computational and Systems Neuroscience meeting suggests. The research took advantage of a common misperception of the human brain: People often think that hazy, ill-defined objects are moving more slowly than they really are. The brain’s rationale for this error: “Things in the world don’t tend to move very quickly,” said neuroscientist Ed Vul of the University of California, San Diego, who was not involved in the new study. “They’re not running past you at 60 miles per hour. For the most part, when things are moving, they’re moving slowly.” Researchers already knew that the brain relies on assumptions when it has trouble figuring something out, but it wasn’t clear where in the brain—and when—these assumptions get used. In the new study, Brett Vintch of New York University and Justin Gardner of Riken Brain Science Institute in Japan scanned people’s brains using functional MRI while they judged how fast black and white lines moved on a computer screen. At first, the researchers made the task relatively easy to see how participants’ brains would handle it under normal conditions. Some brain regions grew more active as the volunteers judged speed, and other regions grew less active. The team used a statistical model to decode these brain activity signals and found that some of the most important vision areas in the brain were used to gauge the speed of the object. © Society for Science & the Public 2000 - 2011

Keyword: Attention
Link ID: 15061 - Posted: 03.01.2011

By Bruce Bower A popular “club drug” promises to open a scientific window on the strange world of out-of-body experiences, researchers say. Recreational users of a substance called ketamine often report having felt like they left their bodies or underwent other bizarre physical transformations, according to an online survey conducted by psychologist Todd Girard of Ryerson University in Toronto and his colleagues. Ketamine, an anesthetic known to interfere with memory and cause feelings of detachment from one’s self or body, reduces transmission of the brain chemical glutamate through a particular class of molecular gateways. Glutamate generally jacks up brain activity. Ketamine stimulates sensations of illusory movement or leaving one’s body by cutting glutamate’s ability to energize certain brain areas, the researchers propose in a paper published online February 15 in Consciousness and Cognition. “Ketamine may disrupt patterns of brain activation that coalesce to represent an integrated body and self, leading to out-of-body experiences,” Girard says. National surveys indicate that 1.6 percent of high school seniors in Canada and the United States have used ketamine at least once. An estimated 70 percent of Toronto rave-goers now report taking ketamine at these all-night parties, Girard notes. © Society for Science & the Public 2000 - 2011

Keyword: Drug Abuse; Attention
Link ID: 15060 - Posted: 03.01.2011

by Ferris Jabr The mind's eye can develop a knack for language in people who have been blind since birth. Functional magnetic resonance imaging (fMRI) measures blood flow in the brain to determine which neurons are most active. Since the 1990s the technology has shown, surprisingly, that the visual cortex flares up even in blind people. More puzzlingly, this activity occurs when they were carrying out language tasks. Rebecca Saxe at the Massachusetts Institute of Technology says the result seemed implausible, because the visual cortex isn't thought to be useful for language tasks. So to investigate, Saxe's team invited both sighted adults and those who had been blind since birth to listen to speech while lying inside an fMRI scanner. The team found that the language processing centres in the brains of all participants behaved almost identically, but the visual cortices of blind participants buzzed with far more activity than those of sighted people. "This was kind of crazy," says team member Evelina Fedorenko, also at MIT. "You have a portion of the brain which is there from birth to do something, but apparently it can acquire a new high-level function like language, which involves super complex cognitive processing." Fedorenko thinks that blind people who get a linguistic boost from their visual cortex might be better at language tasks than sighted people. © Copyright Reed Business Information Ltd.

Keyword: Language; Vision
Link ID: 15059 - Posted: 03.01.2011

By CARL ZIMMER Charles Darwin considered the evolution of the human eye one of the toughest problems his theory had to explain. In “On the Origin of Species,” he wrote that the idea that natural selection could produce such an intricate organ “seems, I freely confess, absurd in the highest possible degree.” But Darwin dispelled that seeming absurdity by laying out a series of steps by which the evolution could take place. Making this sequence all the more plausible was the fact that some of the transitional forms Darwin described actually existed in living invertebrates. Now, a team of American and European researchers report that they have discovered an eye that could represent the first step in this evolution. They have found, in effect, a swimming eyeball. “This is in no way the ancestor of the human eye, but it’s the first time we have had a model of it,” said Yale Passamaneck, a postdoctoral researcher at the University of Hawaii. He and his colleagues report the discovery in the online journal EvoDevo. The researchers made the discovery while studying a species of brachiopods, or lamp shells, which live in shells but are marine worms unrelated to mollusks like clams and oysters. Lamp shells have existed for over half a billion years, but their biology has long remained a mystery — including the simple question of whether they can see. © 2011 The New York Times Company

Keyword: Evolution; Vision
Link ID: 15058 - Posted: 03.01.2011

By CLAUDIA DREIFUS Dr. Emery Neal Brown, 54, is a professor of anesthesiology at Harvard Medical School, a professor of computational neuroscience at M.I.T. and a practicing physician, seeing patients at Massachusetts General Hospital. Between all that, he heads a laboratory seeking to unravel one of medicine’s big questions: how anesthesia works. Q. Anesthesia — what drew you to it? A. I enjoyed my anesthesia rotation at medical school. I could see that it was very fast-paced and that you had to make important decisions quickly. That appealed. Plus: the regular hours. I saw myself doing research, as well as working with patients. You need a predictable schedule — which anesthesiologists have — to manage both. It’s also a very important piece of modern medicine. If you think about what occurs when we do surgery, it’s a very traumatic insult to the body. You’re cutting people open, removing organs or possibly even transplanting them. The anesthesiologist puts people into a condition where they can tolerate such extreme assaults. Q. Is anesthesia like a coma? A. It’s a reversible drug-induced coma, to simplify. As with a coma that’s the result of a brain injury, the patient is unconscious, insensitive to pain, cannot move or remember. However, with anesthesia, once the drugs wear off, the coma wears off. Q. Anesthesia was first demonstrated right here at Massachusetts General Hospital in 1846. Does that historical fact drive your research? A. I think about it a lot. Seriously! © 2011 The New York Times Company

Keyword: Sleep
Link ID: 15057 - Posted: 03.01.2011

By SINDYA N. BHANOO Pilot whales are highly social creatures that communicate extensively with one another through tonal calls. But their ability to make calls is severely diminished when they dive deeper than about 260 feet, researchers report in The Proceedings of The Royal Society B. Until this point, as the whales dive deeper, their calls grow louder, but beyond this the calls become softer. The whales often dive nearly 3,000 feet deep in order to capture their favorite prey — a large, calorie-rich squid. “If they want to be heard by other whales at the surface, you would expect that they would increase their volume, but that is not the case,” said Frants Jensen a biologist at Aarhus University in Denmark and the study’s lead author. Dr. Jensen and his colleagues attached tags to 12 short-finned pilot whales off the Canary Islands and logged the sound, depth and orientation of the animals. Despite the impairment due to depth, the whales continued to produce tonal calls at lower volumes until they reached about 2,600 feet. The researchers believe that at such depths the lungs of the whales collapse, severely reducing their air volume and restricting their ability to generate sound. Still, the whales find their cohorts when they reach the surface. “They manage to find their social group after each dive,” Dr. Jensen said. “It’s a highly effective social system.” © 2011 The New York Times Company

Keyword: Hearing; Animal Communication
Link ID: 15056 - Posted: 03.01.2011