Andrew Bennett Hellman The body's internal clock helps to regulate a water-storing hormone so that nightly dehydration or trips to the toilet are not the norm, research suggests. In an article published in Nature Neuroscience today, neurophysiologists Eric Trudel and Charles Bourque at the Research Institute of the McGill University Health Centre in Montreal, Canada, propose a mechanism by which the body's circadian system, or internal clock, controls water regulation1. By allowing cells that sense water levels to activate cells that release vasopressin, a hormone that instructs the body to store water, the circadian system keeps the body hydrated during sleep. "We've known for years that there's a rhythm of vasopressin that gets high when you're sleeping. But no one knew how that occurred. And this group identified a very concrete physiological mechanism of how it occurs," says Christopher Colwell, a neuroscientist who studies sleep and circadian rhythms at the David Geffen School of Medicine at the University of California, Los Angeles. The body regulates its water content mainly by balancing water intake through thirst with water loss through urine production. People don't drink during sleep, so the body has to minimize water loss to remain sufficiently hydrated. Scientists knew that low water levels excite a group of cells called osmosensory neurons, which direct another set of neurons to release vasopressin into the bloodstream. Vasopressin levels increase during sleep; clock neurons, meanwhile, get quieter. © 2010 Nature Publishing Group,

Keyword: Biological Rhythms; Hormones & Behavior
Link ID: 13816 - Posted: 06.24.2010

By Karen Weintraub Ana can sit on the couch for only about five minutes before it’s time to move. First she rides her bright blue unicycle a few times around the dining room table. Then she gets on a swing hung from the doorway and pumps until her feet can touch the ceiling. A few minutes later she’s doing laps around the table on her RipStik - a skateboard-like balance board. Then she runs outside and climbs the back fence (more fun than going through the gate), to jump on a trampoline. After mastering a flip, she manages to climb back into the house through an open window. Life with Ana, who turns 11 this month, is action-packed. The fifth-grader has sensory processing disorder - her brain doesn’t process information from her five senses in a typical way - leaving her unable to sit still (her muscles just have to move), wear socks (they’re too irritating), concentrate in a busy classroom (so much to look at and hear), or be in the same room with a hot pizza (the aroma is overpowering). “You know when you wake up in the morning, if you don’t have your coffee and your car doesn’t work and you get to the office and someone’s given you a new project that’s due today instead of tomorrow - that’s what it’s like for these kids every day,’’ her mother, Pauline Pimlott, said. Getting help for such kids can be tough. Insurance often won’t pick up the tab, because sensory processing disorder isn’t officially recognized by the American Psychiatric Association, which writes the definitive manual on disabilities such as autism, dyslexia, and attention-deficit hyperactivity disorder. Ana has received specialized occupational therapy on and off for years, but at $175 an hour, it’s too expensive to do often, her mother says. © 2010 NY Times Co.

Keyword: Pain & Touch; Development of the Brain
Link ID: 13815 - Posted: 06.24.2010

By Manfred Dworschak Neurologists are employing brain electrodes to try to establish contact with people in vegetative and minimally conscious states. This could be the last hope for Belgian Rom Houben, who has been trapped in his own body for 23 years. Attempts to let him communicate by means of a keyboard have failed. Day after day, Marie-Aurélie Bruno attaches caps wired with embedded electrodes to her patients' shaved heads. The neuropsychologist at the University of Liège in Belgium is looking for signals in the quivering readouts of the brain's electrical activity, where there might be a hidden message. Bruno's patients are in a condition marked by both a "vegetative state" (VS) and a "minimally conscious state" (MCS). Most of the time, they seem completely withdrawn from the world, though their eyes remain open. Only occasionally does a blink of the eye or a squeeze of the hand reveal that some of these patients retain a small amount of consciousness. Listening in on their brains directly could allow better access to them. "In some individual cases, we might even be able to establish a channel of communication," says Steven Laureys, director of the research group in Liège. The technique the group is using has its origins in the laboratory of Niels Birbaumer, a neurologist at the University of Tübingen in southwestern Germany. "It has worked out pretty well for us," he says of the treatment he uses on patients with "locked-in syndrome" -- that is, ones who are verifiably fully conscious but paralyzed from head to foot. With the help of electrodes, some patients are able to communicate via a computer. A variety of letters appear on the screen in quick succession. By briefly concentrating on the word "yes," the test subjects can indicate the desired letter. Sometimes they manage this within a few seconds; sometimes it takes a full minute. © DER SPIEGEL 7/2010

Keyword: Attention; Language
Link ID: 13814 - Posted: 06.24.2010

By JONAH LEHRER The Victorians had many names for depression, and Charles Darwin used them all. There were his “fits” brought on by “excitements,” “flurries” leading to an “uncomfortable palpitation of the heart” and “air fatigues” that triggered his “head symptoms.” In one particularly pitiful letter, written to a specialist in “psychological medicine,” he confessed to “extreme spasmodic daily and nightly flatulence” and “hysterical crying” whenever Emma, his devoted wife, left him alone. While there has been endless speculation about Darwin’s mysterious ailment — his symptoms have been attributed to everything from lactose intolerance to Chagas disease — Darwin himself was most troubled by his recurring mental problems. His depression left him “not able to do anything one day out of three,” choking on his “bitter mortification.” He despaired of the weakness of mind that ran in his family. “The ‘race is for the strong,’ ” Darwin wrote. “I shall probably do little more but be content to admire the strides others made in Science.” Darwin, of course, was wrong; his recurring fits didn’t prevent him from succeeding in science. Instead, the pain may actually have accelerated the pace of his research, allowing him to withdraw from the world and concentrate entirely on his work. His letters are filled with references to the salvation of study, which allowed him to temporarily escape his gloomy moods. “Work is the only thing which makes life endurable to me,” Darwin wrote and later remarked that it was his “sole enjoyment in life.” Copyright 2010 The New York Times Company

Keyword: Depression; Evolution
Link ID: 13813 - Posted: 06.24.2010

By RONI CARYN RABIN Surgery on blocked neck arteries has long been considered the best procedure for preventing a stroke. Now a large North American study has found that a less invasive approach may be just as safe and effective, but other researchers are not so sure. The findings, released Friday at a medical meeting in San Antonio, have the potential to make the less invasive procedure — inserting a small tube called a stent in the carotid artery — a more appealing option for many patients. Yet just a day earlier, European investigators reported dismal results from another international trial involving carotid stents, published online Thursday by the British medical journal The Lancet. In that study, patients treated with stents suffered almost double the rate of complications as those treated surgically, leading the British researchers to conclude that surgical treatment of carotid blockages, called endarterectomy, remains the treatment of choice. The disparate findings — which could help determine whether Medicare expands coverage to cover the stent procedure — left scientists trying to explain why two fairly similar clinical trials came to such starkly different conclusions. Copyright 2010 The New York Times Company

Keyword: Stroke
Link ID: 13812 - Posted: 06.24.2010

DYING ear cells have been revived with a shot of gene therapy. Ear cells have a hair-like structure that enables them to pick up sound vibrations. They are vital for hearing in mammals but are easily damaged by loud noise, which can lead to deafness. A gene called Math1 has already been used to generate new hair cells in guinea pigs, from the supporting cells that surround them. Now David He at Creighton University in Omaha, Nebraska, and colleagues have shown that the same gene can repair guinea pigs' existing, damaged hair cells - as long as you get to them in time. He's team exposed guinea pigs to the audio equivalent of 200 rounds of gunfire. After this, the animals couldn't hear anything quieter than a chainsaw. When the researchers injected the animals with a Math1-loaded virus in one ear, hearing recovered almost completely. The team tested the guinea pigs' hearing by monitoring the electrical activity in their brainstems in response to various noises. Then they viewed the newly grown cells in samples under a microscope. The hair cells also expressed a green protein, showing they had taken up the gene. Although the gene is only temporarily expressed, this is enough to make proteins that repair the cells for life, he says. However, cells could only be saved if they were treated within 10 days of being damaged. He presented the work at the Association for Research in Otolaryngology meeting in Anaheim, California. © Copyright Reed Business Information Ltd.

Keyword: Hearing; Regeneration
Link ID: 13811 - Posted: 06.24.2010

Athletes who wear red could have a subtle advantage, say Canadian researchers, who have found that the eye perceives red as moving faster than other colours. Mazyar Fallah, a professor of kinesiology and health science at York University, says wearing red might confer a slight advantage in sports such as figure-skating and gymnastics, where judging is involved. Fallah points to International Skating Union rules, which include a base score for each element. "These are based on criteria, which include speed on the ice," Fallah told CBC Radio's Quirks & Quarks. "So, if you're wearing red instead of blue doing exactly the same routine, then [the judges'] eyes move a little faster. "And maybe that subconscious effect … will actually cause them to bump you up one point more than they would if you were wearing blue." Fallah said the experiment, conducted with Illia Tchernikov at York's Centre for Vision Research, doesn't show that red skating costumes result in higher scores, only that the eye moves faster when tracking red objects. "We don't know for certain that this is actually happening … but if it were me, I'd wear red every time," he said. In the experiment, published this week in the journal PLoS One, five participants took part in thousands of tests where they watched coloured dots moving on a computer screen. © CBC 2010

Keyword: Vision
Link ID: 13810 - Posted: 06.24.2010

By Nathan Seppa SAN ANTONIO — As many as four in 10 people referred to a clinic with signs of a “ministroke” may have subtle cognitive damage that standard tests miss, a new study shows. The findings, reported by Canadian researchers February 24 at the International Stroke Conference in San Antonio, Texas, suggest that after suffering the ministrokes many patients lose some ability to process abstract thoughts, reason things out and make quick calculations — what doctors call “executive function.” While full-blown strokes cause a clear loss of cognitive function, most often due to a blood vessel blockage in the brain that shows up on an MRI or CT scan, ministrokes are caused by smaller obstructions. They result in more subtle deficits that are less likely to be detected by brain scans or even by patients themselves. Some scientists consider the term ministroke a misnomer, preferring the technical term transient ischemic attack, while others use the terms interchangeably. The symptoms of a ministroke or a full-blown one might start out the same, with numbness in the face or extremities, confusion, vision problems, dizziness or headache. But in a ministroke, these symptoms wane after minutes or hours. In the new study, researchers tested 140 such patients in whom symptoms subsided within 24 hours, indicating they had ministrokes instead of full-blown ones. They gave the subjects a test of cognitive acuity that is routinely given to patients who show up at a clinic or hospital with signs of a stroke. Known as the Mini-Mental Status Exam, the test quickly gauges 30 cognitive functions including short-term recall, attention span, spatial recognition and executive function. © Society for Science & the Public 2000 - 2010

Keyword: Stroke
Link ID: 13809 - Posted: 06.24.2010

By Katie Moisse The same technology that has people swinging imaginary rackets and bowling virtual balls for entertainment at home might help people recovering from strokes, according to research presented February 25 at the American Stroke Association's International Stroke Conference. The pilot study, carried out at the Toronto Rehabilitation Institute at the University of Toronto, suggests that video games for the Nintendo Wii could help stroke victims regain lost motor function. "This is the first randomized clinical study showing that virtual reality using Wii gaming technology is feasible and safe and is potentially effective in enhancing motor function following a stroke,” said the study’s lead investigator, Gustavo Saposnik, in a prepared statement. “But our study results need to be confirmed in a major clinical trial.” The study examined the Wii’s potential for helping patients recover fine motor function (such as finger dexterity) and gross motor function (such as arm movements) two months after a stroke. Twenty patients were randomly assigned to two groups: one played recreational games (such as cards or the block-stacking game Jenga); the other played virtual games such as Wii tennis and Wii Cooking Mama—a simulation game that has players cutting potatoes, peeling onions and shredding cheese. Both groups played for about six hours over the course of the two-week study. © 2010 Scientific American, a division of Nature America

Keyword: Stroke
Link ID: 13808 - Posted: 06.24.2010

By Jennifer Viegas Experts say that a fatal killer whale attack at SeaWorld in Orlando may have been tied to the isolation and breeding of the male marine mammal. Tilikum, the male killer whale that fatally injured trainer Dawn Brancheau in front of a stunned audience at SeaWorld in Orlando on Wednesday, was a breeding "stud" often housed in isolation. Experts believe he did not kill for food, but may have been acting out due to stress and raging hormones. While some reports have been portraying Tilikum as a particularly aggressive orca, a nearly identical incident involving another killer whale male named Ky occurred in July 2004 at the San Antonio SeaWorld. Trainer Steve Aibel, like Brancheau, was pulled underwater by the whale, which also attempted to bite, but Aibel walked away uninjured. He later blamed Ky's "adolescent hormones" for the episode. Marine biologist Nancy Blake told Discovery News that Tilikum could have acted out for similar reasons. "He was used a lot [by SeaWorld] for mating, and could have even been enacting a mating behavior during the incident," explained Blake, a leading expert on killer whales who runs California's Monterey Bay Whale Watch. © 2010 Discovery Communications, LLC.

Keyword: Aggression; Sexual Behavior
Link ID: 13807 - Posted: 06.24.2010

By HENRY FOUNTAIN If you’ve seen one damselfish, you’ve seen them all. That may be true for people, who have a difficult time telling some damselfish species apart. But the fish themselves see it differently, according to a study in Current Biology. They can use ultraviolet facial patterns to tell one species from another. Ulrike E. Siebeck of the University of Queensland in Australia and colleagues studied Pomacentrus amboinensis and P. moluccensis, two species of damselfish capable of seeing light at the ultraviolet end of the spectrum. They are also highly territorial: P. amboinensis males, for example, will chase off unfamiliar members of their species because they are seen as competitors, but go easier on P. moluccensis intruders. To people, the two species of reef fish look practically identical. But under UV light they are revealed to have distinctly different patterns in the scales around the eyes. “These are really fine, intricate patterns that we can’t see at all,” Dr. Siebeck said. The question for her and her colleagues was whether the patterns, and the ability to see them, had an effect on behavior. In a series of experiments in which, among other things, they placed fish inside a glass chamber equipped with UV filters, they showed that P. amboinensis used the patterns to discriminate between the two species. Copyright 2010 The New York Times Company

Keyword: Vision
Link ID: 13806 - Posted: 06.24.2010

By ABIGAIL ZUGER, M.D. Picture a cupped hand. A capsule and a pill lie in the palm. The hand is extended toward a small child. The caption reads, “Take your vitamins.” It’s better than a Rorschach test, that image: most people will erupt with a passionate visceral reaction, especially if they deduce that the proffered medications are not vitamins at all, but strong psychoactive drugs like Ritalin and Prozac. For some, the picture symbolizes the best kind of parenting, proactive and nurturing. For others, it is an evocative summary of everything that is wrong with our culture, as pushy parents blithely dose hapless children with unnecessary medication in the name of conformity and achievement. The journalist Judith Warner was a die-hard member of the second camp, and wanted to spread the word. Six years ago, she happily landed a book contract to explore and document the overmedication of American youth. Readers of Domestic Disturbances, the online column Ms. Warner wrote for The New York Times until December, will be familiar with what happened next. She sallied forth to interview all the pushy parents, irresponsible doctors and overmedicated children she could find — and lo, she could barely find any. After several years of dead ends, missed deadlines and worried soul-searching, she was forced to reconsider her premise and start all over again. Copyright 2010 The New York Times Company

Keyword: ADHD; Depression
Link ID: 13805 - Posted: 06.24.2010

By Katherine Harmon Would you feel better if, besides giving you a pill, your doctor also explained some potential benefits? It's quite likely, according to research from placebo effect studies from the past couple of decades. But an international group of researchers, led by Damien Finniss of the University of Sydney Pain Management and Research Institute in Australia, wanted to take a closer look at just how such an approach affects patients—and doctors who might make use of it. "The placebo effect is a genuine psychobiological event attributable to the overall therapeutic context," the researchers explained in their review article published online February 18 in The Lancet. In other words, the effect is real but heavily dependent not just on the existence of possible treatment, but perhaps even more so on the environment in which it is administered. Several types of placebo effects have been identified—from the psychological (conditioning and expectation) to the neurobiological (opioid release and changes in metabolic activity in the brain). But few studies have charted precisely how the clinical context of a placebo or treatment administration changes its effect. Some studies have shown the effect of "nocebos," which patients are told their treatments might increase discomfort. Others have shown that receiving acupuncture, whether it is real, faked (with retracting needles) or done incorrectly, can better relieve back pain than traditional treatments. But the ethical slope is a slippery one, the researchers conceded, often making further research difficult without ample deception or withholding real treatment from people who need it. © 2010 Scientific American, a division of Nature America,

Keyword: Pain & Touch
Link ID: 13804 - Posted: 06.24.2010

By Laura Sanders SAN DIEGO — Quantity, not quality, of sleep may determine how well older people’s brains function the next day, research reported February 21 at the annual meeting of the American Association for the Advancement of Science suggests. For youngsters, though, quality may be more important. The study shows that sleep affects young and old brains differently, and may ultimately lead to new ways to offset age-related cognitive decline. The link between sleep and learning has been well-established, comments Matthew Walker of the University of California, Berkeley. “It’s critical to sleep before learning. Sleep almost prepares the brain like a dry sponge to soak up new information.” Contrary to common beliefs, older adults don’t sleep substantially less than younger adults. From age 35 to 85, people really lose only about an hour of nightly sleep, psychologist Sean Drummond of the University of California, San Diego said at the meeting. Rather, the thing that changes is something called sleep efficiency — a measure of the portion of time spent tossing, turning or lying awake in bed. “The biggest, most common, most robust change is that we spend more time awake in the middle of the night,” Drummond said. In the new study, 33 adults with a mean age of 67 and 29 adults with a mean age of 27 slept in a lab while Drummond and his colleagues measured the duration and quality of their sleep. The next day, the researchers tested participants’ brain activity and performance on a learning and memory task. © Society for Science & the Public 2000 - 2010

Keyword: Sleep; Development of the Brain
Link ID: 13803 - Posted: 06.24.2010

By Lisa Grossman Karen Emmorey, a cognitive neuroscientist at San Diego State University, has been looking at how the brains of deaf people interpret American Sign Language. She showed 10 subjects pictures of objects that have actions associated with them — a cup for “drink,” say, or a broom for “sweep.” She asked participants to either sign the word that goes with the picture or to pantomime using the object. In some cases, like “drink,” the word and the gesture are the same: Subjects pretended to hold a cup in one hand and brought it to their mouths. For other words, like “sweep,” the sign and the pantomime look different. By taking positron emission tomography images of the brain as subjects signed, Emmorey found that the brain broadcast participants’ intentions: Different regions of the brain lit up when the deaf subjects signed than when they pantomimed, even when the word and gesture were identical. "For sign production we find language regions engaged,” Emmorey said February 19 at the American Association for the Advancement of Science meeting. But when subjects were pantomiming, the brain regions that lit up were those associated with grasping, manipulation and motor planning. “The fact that many signs are iconic doesn’t change the fundamental organization of language, nor does it change the neural systems that underlie language,” she said. The work has been submitted for consideration for publication in Language and Cognitive Processes. © Society for Science & the Public 2000 - 2010

Keyword: Language
Link ID: 13802 - Posted: 06.24.2010

Taking a mid-afternoon nap may prepare the brain to learn new things, early research suggests. Researchers in the U.S. studied 39 young adults who were divided into two groups. At noon, study participants took a memory test that required them to remember faces linked to names. Of those in the study, 20 took a nap for 100 minutes. All of the volunteers were then retested at 6 p.m. Those who stayed awake did about 10 per cent worse on the tests compared with those who napped, Matthew Walker of University of California at Berkeley said. He presented the preliminary findings Sunday at the American Association of the Advancement of Science meeting in San Diego. The more hours we spend awake, the more sluggish the brain becomes, the study suggests. Normally, the ability to learn declines between noon and 6 p.m., but a nap seemed to fight off the decline. "After about 1:30, I notice my last class of the day I just want the day to be over," Marquis Majore said during reading week at the University of Regina. "It's hard to concentrate and stay focused in class." Previous data from the same team showed pulling an all-nighter also reduces the brain's ability to cram in new facts by nearly 20 per cent. Walker's team showed that fact-based memories are temporarily stored in a region of the brain called the hippocampus before being sent to the brain's prefrontal cortex, which may have more storage space. © CBC 2010

Keyword: Sleep; Learning & Memory
Link ID: 13801 - Posted: 06.24.2010

By Raymond A. Levy and J. Stuart Ablon A remarkably important event has just occurred in the world of psychology: A leading, peer-reviewed journal has published the strongest evidence yet that psychodynamic psychotherapy -- “talk therapy” -- works. In fact, it not only works, it keeps working long after the sessions stop. Full disclosure: We report this not as disinterested observers, but as psychotherapists and researchers on the process and efficacy of therapy. Our book, “Handbook of Evidence-Based Psychodynamic Psychotherapy,” summarized the body of research through last year and another will follow late this year. Still, we can state as fact: The movement to establish an evidence base for psychodynamic therapy has taken a giant new step forward. This new academic paper reports positive findings about the form of therapy that began with Sigmund Freud and has historically been utilized more than any other psychotherapy treatment. What does modern psychodynamic psychotherapy look like? Its distinctive features include several basic building blocks: A focus on emotion and relationships; identification of recurring themes and patterns; discussion of past experiences; a focus on the therapy relationship; exploration of attempts to avoid distressing thoughts and feelings; and exploration of fantasy life. Overall, the paper found, psychodynamic psychotherapy demonstrates efficacy at least equivalent to other psychotherapy treatments commonly labeled as “empirically supported” and “evidence based.” And in fact, it notes, psychodynamic therapy's "active ingredients" are shared by many other forms of therapy as well. © 2010 Scientific American,

Keyword: Depression
Link ID: 13800 - Posted: 06.24.2010

By Laura Sanders SAN DIEGO — Disrupting a gene implicated in schizophrenia early in development leads to brain anomalies and behavioral defects later in life, a new study in mice finds. The results, presented February 22 at the annual meeting of the American Association for the Advancement of Science, may help researchers understand how early developmental problems contribute to schizophrenia — a disease that typically shows up after adolescence. In humans, mutations in a gene called DISC1 cause flaws in networks of brain cells early in development, scientists believe, long before symptoms of schizophrenia appear. Researchers led by Akira Sawa of Johns Hopkins University School of Medicine in Baltimore developed a new technique to diminish DISC1 activity in mice that are still developing in the womb. The method temporarily reduces DISC1 activity in brain cells in the mice’s prefrontal cortex, a region known to be important for schizophrenia. Sawa and colleagues disturbed DISC1 very early in development and tested the mice later. The mice’s brain chemistry and behavior seemed normal at 28 days. But at 56 days, Sawa and colleagues saw a big change. “After adolescence, we start to observe a dramatic difference in behavior, neurochemistry and information processing,” Sawa says. Mice that had reduced DISC1 activity in the womb had lower levels of dopamine in the prefrontal cortex at 56 days, the team found. DISC1 might be interfering with the normal development of dopamine-producing neurons, leading to the reduction of the chemical signal, Sawa says. What’s more, these mice performed worse on behavioral measures that require information processing. © Society for Science & the Public 2000 - 2010

Keyword: Schizophrenia; Genes & Behavior
Link ID: 13799 - Posted: 06.24.2010

By Victoria Gill Teaching stroke patients to sing "rewires" their brains, helping them recover their speech, say scientists. By singing, patients use a different area of the brain from the area involved in speech. If a person's "speech centre" is damaged by a stroke, they can learn to use their "singing centre" instead. Researchers presented these findings at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Diego. An ongoing clinical trial, they said, has shown how the brain responds to this "melodic intonation therapy". Gottfried Schlaug, a neurology professor at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, US, led the trial. The therapy is already established as a medical technique. Researchers first used it when it was discovered that stroke patients with brain damage that left them unable to speak were still able to sing. Professor Schlaug explained that his was the first study to combine this therapy with brain imaging - "to show what is actually going on in the brain" as patients learn to sing their words. Most of the connections between brain areas that control movement and those that control hearing are on the left side of the brain. "But there's a sort of corresponding hole on the right side," said Professor Schlaug. For some reason, it's not as endowed with these connections, so the left side is used much more in speech. If you damage the left side, the right side has trouble [fulfilling that role]." But as patients learn to put their words to melodies, the crucial connections form on the right side of their brains. Previous brain imaging studies have shown that this "singing centre" is overdeveloped in the brains of professional singers. (C)BBC

Keyword: Stroke; Language
Link ID: 13798 - Posted: 02.23.2010

By Matt Walker The first monogamous amphibian has been discovered living in the rainforest of South America. Genetic tests have revealed that male and females of one species of Peruvian poison frog remain utterly faithful. More surprising is the discovery that just one thing - the size of the pools of water in which they lay their tadpoles - prevents the frogs straying. That constitutes the best evidence yet documented that monogamy can have a single cause, say scientists. Details of the frog's sex life is published in the journal The American Naturalist. "This is the first discovery of a truly monogamous amphibian," says biologist Dr Jason Brown, then of East Carolina University in Greenville, North Carolina, who made the discovery with colleagues Dr Victor Morales and Professor Kyle Summers. The monogamous frog species Ranitomeya imitator, known as the mimic poison frog, is already known to science. In recent years, Dr Brown and his colleagues have extensively studied many of its habits, which were filmed by the BBC natural history documentary series Life in Cold Blood. After mating, a female mimic poison frog lays her eggs on the surface of leaves. The male frog then takes away the tadpoles that hatch, carrying them one by one on his back to pools of water which collect in bromeliad leaves high up in the branches of trees. Each of half a dozen babies are put into their own tiny pool, which he then looks after. When the tadpoles become hungry, the male calls to his female partner who arrives to lay a non-fertile egg in each pool, which the tadpole eats as food. But while the male and female frogs appear to act in unison, new experiments have revealed the extent of their fidelity. (C)BBC

Keyword: Sexual Behavior
Link ID: 13797 - Posted: 02.22.2010