The Saharan desert ant (Cataglyphis fortis) takes no chances when it comes to homeland security. It viciously attacks ants from other colonies that get too close to its nest. Now researchers have found that the ant relies on the same internal navigation system it uses for foraging to decide whether an intruder has come too close for comfort. Many animals fly into a defensive rage when they sense competitors edging in on their territory. But in the sandy Sahara, few environmental cues mark territorial boundaries. Behavioral neurobiologists Markus Knaden and Rüdiger Wehner of the University of Zürich in Switzerland wondered whether the sight or smell of the nest primes the ants for a fight or if their internal navigation system puts them on alert. Previous research showed that the desert ants somehow keep track of every step and turn they take when out foraging for food and integrate that information to plot a straight line back home. The system apparently serves the ants well, enabling them to find their way in an environment devoid of landmarks and get back to the nest before shriveling up in the hot sun. To test whether the ants' navigation system also plays a role in aggression, Knaden and Wehner placed a feeder 20 meters from a desert ant nest. Left undisturbed, the ants snatched a bite of food and ran straight back to their nest. But the researchers grabbed the ants as soon as the ants picked up a piece of food and moved them to a 40-meter-square grid 2 kilometers away. There, they turned the ants loose and let them run either 20 meters or only 5 meters before testing their willingness to fight other ants. The ants that ran the whole 20 meters--covering what would have been the distance back to their nest--were far more aggressive than the ones that only ran 5, the team reports in the 2 July issue of Science.

Keyword: Aggression
Link ID: 5743 - Posted: 07.02.2004

ITHACA, N.Y. -- A laser-based microscopy technique may have settled a long-standing debate among neuroscientists about how brain cells process energy -- while explaining what's really happening in PET (positron emission tomography) imaging and offering a better way to observe the damage that strokes and neurodegenerative diseases, such as Alzheimer's, wreak on brain cells. Multi-photon microscopy scans by Cornell University biophysicists of living brain tissue, as reported in the latest issue of Science (July 2, 2004), reveal exactly how and when neurons (the cells that do the thinking) and astrocytes (the starburst-shaped glial cells that service neurons) interact to burn oxygen and glucose, after astrocytes make lactate from glucose in the bloodstream, to meet the extraordinary energy demands of the brain. Based on imaging of two different energy states of NADH (nicotinamide adenine dinucleotide, a coenzyme involved in brain-cell metabolism), the Cornell biophysicists say they have both confirmed and redefined the controversial "astrocyte-neuron lactate shuttle" hypothesis for brain energy metabolism. "Over the past decade scientists have passionately debated whether the activated brain burns glucose completely to water or incompletely to lactate," said Karl A. Kasischke, M.D., lead author of the Science paper titled "Neural Activity Triggers Neuronal Oxidative Metabolism Followed by Astrocytic Glycolysis."

Keyword: Glia
Link ID: 5742 - Posted: 07.02.2004

The remnants of a remarkably petite skull belonging to one of the first human ancestors to walk on two legs have revealed the great physical diversity among these prehistoric populations. But whether the species Homo erectus, meaning "upright man", should be reclassified into several distinct species remains controversial. Richard Potts, from the National Museum of Natural History at the Smithsonian Institute in Washington, DC, and colleagues discovered numerous pieces of a single skull in the Olorgesailie valley, in southern Kenya, between June and August 2003. The bones found suggest the skull is that of a young adult Homo erectus who inhabited the lush mountainside some 930,000 years ago. The prominent brow and temporal bone resemble other Homo erectus specimens found elsewhere in Africa, and in Europe, Indonesia and China. But the skull itself is around 30% smaller, which is likely to have corresponded to a similar difference in body size. The specimen helps fill a gap in the fossil record as very few Homo erectus specimens of this age have been found in Africa so far. © Copyright Reed Business Information Ltd.

Keyword: Evolution
Link ID: 5741 - Posted: 06.24.2010

Scientists have made the first recordings of the human brain's awareness of its own body, using the illusion of a strategically-placed rubber hand to trick the brain. Their findings shed light on disorders of self-perception such as schizophrenia, stroke and phantom limb syndrome, where sufferers may no longer recognize their own limbs or may experience pain from missing ones. In the study published today in Science Express online, University College London's (UCL) Dr Henrik Ehrsson, working with Oxford University psychologists, manipulated volunteers' perceptions of their own body via three different senses - vision, touch and proprioception (position sense). They found that one area of the brain, the premotor cortex, integrates information from these different senses to recognize the body. However, because vision tends to dominate, if information from the senses is inconsistent, the brain "believes" the visual information over the proprioceptive. Thus, someone immersed in an illusion would feel, for example, that a fake limb was part of their own body. In the study, each volunteer hid their right hand beneath a table while a rubber hand was placed in front of them at an angle suggesting the fake hand was part of their body. Both the rubber hand and hidden hand were simultaneously stroked with a paintbrush while the volunteer's brain was scanned using functional magnetic resonance imaging.

Keyword: Pain & Touch
Link ID: 5740 - Posted: 07.02.2004

BY JAMIE TALAN Almost one in every six soldiers arriving home from duty in Iraq is showing symptoms of post-traumatic stress disorder, depression or anxiety, according to interviews with more than 6,000 soldiers and Marines before and after deployment. Many said they were aware of their symptoms, but few have sought help. According to the study, published in today's New England Journal of Medicine, the veterans cited fear of the stigma of mental illness - that it could cost them their careers or alter relationships with peers and command officers. "These findings cry out for creative solutions," said Dr. Matthew Friedman, executive director of the Department of Veterans Affairs National Center for PTSD. "We need to figure out ways to get these people into treatment." Post-traumatic stress disorder - once known as shell shock or combat fatigue - was the most reported mental health problem. Overall, about 12 percent of those returning from Iraq reported symptoms, compared to 3 percent to 4 percent of the general population. Copyright © 2004, Newsday, Inc.

Keyword: Stress
Link ID: 5739 - Posted: 06.24.2010

NEW ORLEANS - After seven months of constant, bark-like hiccups, a first-of-its-kind operation has returned normal life to a 50-year-old Texas man. Shane Shafer's speech is now a hoarse whisper — a side effect of the electronic device that cured him, one generally used to treat epilepsy and recently approved for major depression. But for the first time since November, he can eat. He can sleep. He no longer has to make himself gag to make the hiccups stop. He can talk without a bark-like hiccup every three to four seconds. "Even something as simple as a kiss is now performed without a hiccup," said his wife, Lori Shafer. Surgeons implanted the device — a "vagus nerve stimulator" — in Shafer's chest June 23 in New Orleans. It was activated June 24. Copyright © 2004 Yahoo! Inc.

Keyword: Miscellaneous
Link ID: 5738 - Posted: 06.24.2010

LAURA NELSON Jon-Paul Bingham fumbles around for a condom. Big Bertha is waiting. There’s an awkward pause. “It has to be the non-lubricated kind,” he says. Bingham rips open the packet and slips the prophylactic over a small plastic test tube. Big Bertha is one of Bingham’s nine tropical marine cone snails. These colourful creatures are some of the most venomous beasts on the planet. But the powerful poisons they produce can, in tiny doses, help to reveal how nerve cells function — and potentially help to treat conditions from chronic pain to epilepsy. Currently, most neuroscientists obtain their cone snail toxins from dead animals taken from the wild. But Bingham, a biochemist at Clarkson University in upstate New York, believes that the future lies with cone snail farming. Not only might it help conserve wild populations, he says, but it can also yield a wider range of useful toxins. ‘Milking’ the live snails is a hazardous business. One false move and Bingham could be dead in half an hour. Using forceps, he dangles a dead goldfish, the same length as Big Bertha, in front of her. Behind the bait, the condom is stretched over the mouth of the plastic tube. © Nature News Service / Macmillan Magazines Ltd 2004

Keyword: Neurotoxins
Link ID: 5737 - Posted: 06.24.2010

Bees are not as busy as they are made out to be. In fact the insects are lazy, workshy and prone to sleeping on the job, according to new research. Bees sleep for 80 per cent of the night and like to spend long periods "resting their wings", an award-winning German zoologist has found. Prof Randolf Menzel, from the Free University in Berlin, said that the popular image of bees as the ultimate hard workers was inaccurate. "Bees are not particularly hard working. Instead they sleep a lot and are actually quite lazy," he said. "They spend up to 80 per cent of the night sleeping rather than working in the hive - and during the day they often sit around in the hive resting their wings and doing not much else." Although we see bees buzzing around tirelessly in spring and summer, pollinating flowers and producing honey-filled hives, the common belief in a bee's busy nature is based on a misconception, he said. © Copyright of Telegraph Group Limited 2004.

Keyword: Sleep
Link ID: 5736 - Posted: 06.24.2010

It sounds like the beginning of a joke: "How do bacteria know what time it is?" The surprising answer, reported today in Nature, is that some of these single-celled entities actually have internal clocks. In a living organism, changes in gene expression, physiology and behavior that follow the cycle of day and night are called circadian rhythms. This oscillation is well known to occur in various mammals, insects, plants and fungi. But in recent years researchers have discovered that some single-celled organisms, too, display circadian rhythms. Irina Mihalcescu of the University Joseph Fourier in Saint Martin d'Heres, France, and her colleagues studied cyanobacteria, or blue-green algae, that had been engineered to light up when a particular regulatory gene turned on. By observing the pattern of illumination under a microscope, the scientists could measure the internal clockwork of individual bacteria. Previous research had found that these photosynthetic bacteria keep a daily schedule even without stimuli from the outside world. Under such constant conditions, Mihalcescu and her co-workers found that the bacteria maintained a specific rhythm even following cell division--that is, the clock-setting was passed on to subsequent generations. To determine whether intercellular interactions influence this synchronicity, the team grew two cell colonies shifted in time by three hours--like New Yorkers and Californians. When the scientists combined the bacteria, individuals resisted changing their clocks even when butting up against those from a different time zone. © 1996-2004 Scientific American, Inc. All rights reserved.

Keyword: Biological Rhythms
Link ID: 5735 - Posted: 06.24.2010

CHAPEL HILL -- Scientists at the University of North Carolina at Chapel Hill have discovered key steps involved in regulating nerve growth and regeneration that may have implications for spinal cord research. The new research, published in the June 24 issue of the journal Neuron, for the first time describes how nerve growth factor (NGF) stimulates a sequence of proteins – a molecular pathway – that promotes nerve growth. "It is the first study to show the link between NGF and the building blocks that form the axon," said Dr. William Snider, professor of neurology and cell and molecular physiology at UNC's School of Medicine and director of the UNC Neuroscience Center. Axons are long tendrils, or processes, that extend from nerve cells to form connections with other nerve cells, muscles and the skin. Injury to the peripheral nervous system – that portion of the nervous system outside the brain and spinal cord – typically results in spontaneous regeneration and repair. However, this is not the case with the spinal cord, where disruption of connections from injury leads to paralysis

Keyword: Regeneration
Link ID: 5734 - Posted: 06.24.2010

By Rossella Lorenzi, Discovery News — Males do not listen, at least if they are Manx shearwater sea birds, new research has shown. Puffinus puffinus, best known as Manx shearwaters for their habit of gliding on stiff wings along the troughs of waves, marry for life and share the incubation of a single egg. The chick is then raised by both parents who feed it with regurgitated food. Scientists at Leeds and Cardiff universities put microphones into the burrows of nesting shearwaters and discovered that males regularly provide more food to their offspring than the females. “ Males return to the nest at least once every four days, bringing back food with predictable regularity, regardless of the chick's cries. ” The reason is not that they are better parents, said Keith Hamer of Leeds University's biology department — they just don't listen to the begging calls of their chicks. Copyright © 2004 Discovery Communications Inc.

Keyword: Animal Communication; Sexual Behavior
Link ID: 5733 - Posted: 06.24.2010

Individuals who suffer from severe depression have more nerve cells in the part of the brain that controls emotion, researchers at UT Southwestern Medical Center at Dallas have found. Studies of postmortem brains of patients diagnosed with major depressive disorder (MDD) showed a 31 percent greater than average number of nerve cells in the portion of the thalamus involved with emotional regulation. Researchers also discovered that this portion of the thalamus is physically larger than normal in people with MDD. Located in the center of the brain, the thalamus is involved with many different brain functions, including relaying information from other parts of the brain to the cerebral cortex. The findings, published in today's issue of The American Journal of Psychiatry, are the first to directly link a psychiatric disorder with an increase in total regional nerve cells, said Dr. Dwight German, professor of psychiatry at UT Southwestern. "This supports the hypothesis that structural abnormalities in the brain are responsible for depression," he said. "Often people don't understand why mentally ill people behave in odd ways. They may think they have a weak will or were brought up in some unusual way.

Keyword: Depression
Link ID: 5732 - Posted: 07.01.2004

By Charles Choi, United Press International NEW YORK, (UPI) -- Implantable microchips that stimulate nerve cells with puffs of chemicals instead of pulses of electricity are being developed to serve as prosthetic retinas for the blind, scientists told United Press International. The microchips also could be used as medicine-delivering implants for treating diseases such as Parkinson's. "It's a very new way to interface with the brain," said lead researcher Harvey Fishman, director of the Stanford Ophthalmic Tissue Engineering Laboratory in California. Implantable devices that electrically stimulate nerve cells are commonplace, including cochlear implants that help deaf patients hear and deep brain stimulating electrodes that help Parkinson's patients cope with their symptoms. "When you're stimulating something electrically, you're doing so very indiscriminately," Fishman told UPI. "And you're not stimulating the nerve cell or muscle the way it's normally stimulated." Copyright © 2001-2004 United Press International

Keyword: Vision; Parkinsons
Link ID: 5731 - Posted: 06.24.2010

Alex Proyas never got a high school diploma - a fact he blames on Isaac Asimov. It was Asimov's short story "Nightfall" that derailed Proyas' academic career. "It's a wonderful vision of how the world can suddenly descend into anarchy," says Proyas, 41, describing the chaos that ensues in "Nightfall" when all six of a planet's suns set for the first time in 2,049 years. "I tried to convince my English teachers to assign us some science fiction, but they wouldn't. It opened a rift between my creative desires and what the system wanted me to explore." So Proyas quit school and took his education upon himself, reading the works of Asimov, Ray Bradbury, Arthur C. Clarke, and Philip K. Dick. It makes sense then that Proyas' career as a film director has been defined by fantasy. His 1994 movie The Crow, based on the James O'Barr comic book, immediately gained cult status after Brandon Lee (the only son of kung fu master Bruce Lee) was killed in a freakish accident on set. In 1998, he directed Dark City, a visually rich and haunting movie about the surreal wanderings of an amnesiac accused of murder. "I like movies made for adolescent grown-ups," says Proyas. "A few decades ago, it was still true that the golden age of science fiction readers was 12, but in my lifetime, it's become a mainstream genre." This July, Proyas turns again to his favored genre with I, Robot, an adaptation of Asimov's nine-story collection of the same name. "This is the definitive movie about robots," says Proyas. "It's the most faithful cinematic reworking of Asimov's stories to date, true to the spirit and ideas, yet reenvisioned." The film takes place in Chicago in the year 2035, just as the NS-5 automated domestic assistant comes to market. The all-purpose personal robot is expected to have such wide appeal that it will shift the ratio of humans to bots from about 15 to 1 to 5 to 1. But the release is tarnished when an NS-5 named Sonny is accused of murder. © Copyright© 1993-2004 The Condé Nast Publications Inc.

Keyword: Robotics
Link ID: 5730 - Posted: 06.24.2010

Few ailments sound scarier than mad cow disease and its human counterparts. They incubate silently for years, slowly eating the brain away and leaving it full of holes. So it's not surprising that many people want the U.S. Department of Agriculture to test all cattle for the illness, formally called bovine spongiform encephalopathy (BSE). Certainly testing all 35 million cattle slaughtered annually would reopen trade with Japan, which has refused American beef since the discovery of a mad cow in Washington State last December. It might prevent BSE-free countries from dominating the export market. And consumers might simply feel better about their steaks, roasts and burgers. Too bad there's not much science to back up the proposal. Commercial "rapid tests" are not designed to detect the disease reliably in most slaughtered bovines. They work best on those that have lived long enough to build up in their brains a detectable amount of prions, the proteins at the root of BSE. Typically those animals are older than 30 months or have symptoms, such as an inability to stand (called downer cattle). Most U.S. bovines, however, reach slaughter weight before 24 months of age--before the tests can accurately detect incubating BSE. Most European countries recognize those limitations and target cattle 30 months and older. But using current kits on all slaughtered animals, at least 80 percent of which are younger than 30 months, may give misleading assurance about the safety of beef. © 1996-2004 Scientific American, Inc.

Keyword: Prions
Link ID: 5729 - Posted: 06.24.2010

By Larry O'Hanlon — Elephants may be listening with their feet as well as with their ears, say researchers who are studying how well super-low frequency elephant song moves through the ground. For about 20 years it's been known that African elephants sing out and respond to calls so low that they are beyond human hearing. Until now, however, no one was sure if the rumbling calls were also moving through the Earth as seismic waves, possibly helping elephants communicate when there is too much noise above ground. "They are trying to prove the concept is possible," said elephant researcher Katy Payne of the Cornell University Bioacoustics Research Program, referring to a team of Stanford University researchers who have published a paper on seismic elephant infrasound calls in the current issue of Geophysical Research Letters. "We have several experiments going on right now to try to determine whether elephants perceive seismic cues via bone through their toenails and foot bones to their middle ear bones, or through vibration-detecting cells in the bottom of the foot," said Stanford's Caitlin O'Connell-Rodwell, now studying the matter in Namibia. Copyright © 2004 Discovery Communications Inc.

Keyword: Hearing
Link ID: 5728 - Posted: 06.24.2010

Using advanced imaging technology, Carnegie Mellon University scientist Eric Ahrens and co-investigators have conducted the first systematic examination of developmental and sex-associated changes in adolescent and adult mouse brains to reveal fundamental differences in key brain structures, such as those important for emotions, learning, and memory. The results, in press with NeuroImage, show that sex hormones alter the development of certain brain structures during puberty and that these effects persist into adulthood. The findings provide a much truer representation of how circulating hormones affect brain structures than could be derived from human imaging for several reasons, according to Ahrens. The animals studied were nearly genetically identical and reared in the same environment -- factors that cannot be controlled in human studies. And the imaging technology, magnetic resonance microscopy, allows high resolution, 3D imaging in the intact, tiny mouse brain. "The finding that specific brain structures change at puberty under the influence of sex hormones should help scientists understand how levels of sex hormones alter the brain's development," said Ahrens, assistant professor of biological sciences. "Researchers could artificially manipulate sex hormones and then use MRM technology to see how the hormones affect brain structures in animal models."

Keyword: Development of the Brain
Link ID: 5727 - Posted: 06.30.2004

Monkeys and apes who are good at deceiving their peers also have the biggest brains relative to their body size. The finding backs the "Machiavellian intelligence" theory, which suggests the benefits of complex social skills fuelled the evolution of large primate brains. Of all the terrestrial mammals, primates have by far the largest brains relative to their body size, with humans having the largest of all. The enlargement is almost exclusively in the neocortex, which makes up more than 80% of the mass of the human brain. Large brains, despite being energetically costly, benefited primates because they conferred complex cognitive skills. But which skills were the priority - was it clever food-finding strategies that were most valuable, for example, or complex social skills? Earlier studies have hinted that social abilities were the key. And now Richard Byrne and Nadia Corp, psychologists at St Andrews University in the UK, have found more direct evidence for this after studying records of primates deceiving each other for personal gain. © Copyright Reed Business Information Ltd.

Keyword: Evolution; Intelligence
Link ID: 5726 - Posted: 06.24.2010

–Bethesda, MD – Concurrent with the national obesity epidemic has been a rise in the discoveries about how the body controls appetite and food intake. In many of the new findings, research has identified a close relationship between the gastrointestinal endocrine system and the brain in regulating food intake. The relationship is expressed in coordination where circulating hormones convey information about food intake and appetite to brain pathways that control eating. A team of researchers has added to this knowledge through their investigation of cholecystokinin (CCK) and glucagon-like-peptide-1 (GLP-1), two pre-absorptive signals that indicate when the appetite is satisfied (“satiety”). Both peptides are classical gastrointestinal hormones that are released into the circulation in response to meal consumption. Earlier research has documented that these peptides participate in controlling the appetite in healthy volunteers, and also in patients with obesity or Type II diabetes. To further explore potential interactions between these two well-known satiety signals, the research team has examined the effects of CCK-33 and GLP-1 and the hormones’ interaction in the control of food intake and satiety in healthy subjects. The authors of the study, “Interaction between GLP-1 and CCK-33 in Inhibiting Food Intake and Appetite in Men,” are Jean-Pierre Gutzwiller, Lukas Degen, Daniel Matzinger, Sven Prestin, and Christoph Beglinger, all from the University Hospital, Basel, Switzerland. Their research appears in the Articles in PresS section of the American Journal of Physiology –Regulatory, Integrative and Comparative Physiology.

Keyword: Obesity
Link ID: 5725 - Posted: 06.24.2010

Electronic skin could give machines a sophisticated sense of touch. PHILIP BALL Robots are about to get more feeling. An electronic skin as sensitive to touch as our own is being developed by scientists in Japan. "Recognition of tactile information will be very important for future generations of robots," says Takao Someya at the University of Tokyo who developed the skin. A sense of touch would help them to identify objects, carry out delicate tasks and avoid collisions. But while a lot of effort has gone into vision and voice recognition for robots, touch sensitivity is still fairly rudimentary. Our own skin contains a battery of touch receptors that produce nerve signals when pressed. For gentle pressures, the main sensors are tiny bulbs of layered tissue called Meissner's corpuscles. Their behaviour is mimicked in plastics such as polyvinylidene fluoride, which generate an electric field when squeezed and are used to make pressure-sensitive pads for computer keyboards and other touch-triggered devices. © Nature News Service / Macmillan Magazines Ltd 2004

Keyword: Robotics; Pain & Touch
Link ID: 5724 - Posted: 06.24.2010