With some practice, it's not that hard to balance a baseball bat on the end of your finger. But try to poise a pen or a short stick, and the task becomes rather difficult. That's because a smaller object moves more quickly--at speeds that approach the time required to carry out corrective motions. Now findings published in the October 7 issue of Physical Review Letters suggest that random movements induced by the nervous system can help keep a stick balanced on a fingertip. © 1996-2002 Scientific American, Inc.

Keyword: Movement Disorders
Link ID: 2707 - Posted: 06.24.2010

NewScientist.com news service Circumcised women experience sexual arousal and orgasm as frequently as uncircumcised women, according to a study in Nigeria. The researchers also found no difference in the frequency of intercourse or age of first sexual experience between the two groups of women. These findings remove key arguments used to defend the practice, they say. Friday Okonofua and colleagues at the Women's Health and Action Research Centre in Benin City studied 1836 women, 45 per cent of whom had been circumcised. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior
Link ID: 2706 - Posted: 06.24.2010

By Jennifer Viegas, Discovery News While men today sometimes receive criticism from women about their communication skills, a new book reveals that a male was probably the first human to speak. According to "The Speciation of Modern Homo Sapiens," published last week by The British Academy, a male likely was the first to acquire a gene, called protocadherinXY, believed to play a crucial role in human capacity for language. The book states that the gene emerged as a translocation, or change, of a segment on the Y chromosome, which is associated with men. Tim Crow, who edited the volume and is a professor of psychiatry at the University of Oxford and a member of England's Medical Research Council's External Research Staff, theorizes that the genetic transition might have occurred between 100,000-150,000 years ago, when there appears to have been an "evolutionary jump" that gave rise to modern humans. Crow and many other researchers believe language could have been the catalyst for the break. Copyright © 2002 Discovery Communications Inc.

Keyword: Language; Evolution
Link ID: 2705 - Posted: 06.24.2010

Philippine researchers want to restore a sea snake that has been wiped out on Gato Island by translocating the species from other islands. But new research suggests that this may not work because these snakes have such a strong drive to return to their own islands. "The fidelity of snakes to their home island was absolute," say Sohan Shetty, then at the University of Sydney, Australia, and now at Nanyang Technological University in Singapore, and Richard Shine of the University of Sydney, Australia, in the October issue of Conservation Biology. Widely distributed in the Pacific Ocean, the snakes (yellow-lipped sea kraits) forage for moray and conger eels in the ocean, and typically return to land to digest their prey, mate, lay eggs. The up to 5-foot long snakes are prized for their meat and skins, which are used to make high-quality leather goods, and are easy to catch in huge numbers because they are concentrated on small islands and, although venomous, are so docile that they rarely bite or even try to escape.

Keyword: Animal Migration
Link ID: 2704 - Posted: 09.25.2002

The nature v nurture debate has never been so fierce. Robin McKie and Vanessa Thorpe report on the bitter row between two leading scientists The Observer One is a boor, a scientific dinosaur and 'a hardline left-winger' whose ideas have long since ceased to matter. The other is a 'wicked' individual whose ideas could lead more children to be assaulted by abusive parents. That is how two leading scientists have denounced each other over their claims to know the causes of human aggression. Violence is in the air and, it appears, at its roots. In his book They F*** You Up British psychologist Oliver James argues family influences are critical. Neuroscientist Steven Pinker says nothing matters more than our genes. Both are openly abusive about each other's stance. Hence, the accusation of one of Pinker's allies that James is 'fucked-up' while he has retorted in turn that his opponent is telling lies. Guardian Unlimited © Guardian Newspapers Limited 2002

Keyword: Development of the Brain
Link ID: 2703 - Posted: 06.24.2010

Scientists have developed a drug which may help addicts wean themselves off cocaine in the same way methadone helps heroin addicts. Nocaine has been developed by US researchers. Tests on animals showed it provided some of cocaine's effects, but at a much lower level. Researchers at Washington DC's Georgetown University Medical Center's Drug Discovery Program say it appears to blunt the effects of withdrawal. Safety trials are expected to begin in humans early next year. Experts warn cocaine use can cause heart problems, chest pain and respiratory failure; strokes, seizure, and headaches; and abdominal pain and nausea, (C) BBC

Keyword: Drug Abuse
Link ID: 2702 - Posted: 09.24.2002

In order to study molecular dynamics and cell interactions successfully, scientists need a way to track the movements of specific cells and cell components. Currently, proteins isolated from jellyfish that emit fluorescent green light are widely used for this purpose. Now researchers have isolated a molecule from a common coral species that fluoresces in three colors. They described the protein in a report published online this week by the Proceedings of the National Academy of Sciences. © 1996-2002 Scientific American, Inc. All rights reserved.

Keyword: Development of the Brain
Link ID: 2701 - Posted: 06.24.2010

NewScientist.com news service We are more unique than previously thought, according to new comparisons of human and chimpanzee DNA. It has long been held that we share 98.5 per cent of our genetic material with our closest relatives. That now appears to be wrong. In fact, we share less than 95 per cent of our genetic material, a three-fold increase in the variation between us and chimps. The new value came to light when Roy Britten of the California Institute of Technology became suspicious about the 98.5 per cent figure. Ironically, that number was originally derived from a technique that Britten himself developed decades ago at Caltech with colleague Dave Kohne. By measuring the temperature at which matching DNA of two species comes apart, you can work out how different they are. © Copyright Reed Business Information Ltd.

Keyword: Evolution; Development of the Brain
Link ID: 2700 - Posted: 06.24.2010

By RICHARD A. FRIEDMAN, M.D. Most young gay and bisexual American men who were found to be infected with the AIDS virus in a recent study were unaware of their infection, according to a finding reported recently at the 14th International AIDS Conference in Barcelona by Dr. Duncan MacKellar, an epidemiologist at the Centers for Disease Control and Prevention. The study surveyed 5,719 men, ages 15 to 29, of whom 573 were discovered to be H.I.V.-positive. Of those 573 men, 77 percent did not know that they were infected. Despite having engaged in frequent high-risk sex like unprotected anal intercourse, most of these men still believed that they were at low risk of contracting H.I.V. How can one explain such potentially fatal self-destructive behavior? After all, the route of H.I.V. transmission and safer sexual practices are well known. Copyright 2002 The New York Times Company

Keyword: Sexual Behavior
Link ID: 2699 - Posted: 09.24.2002

By ANDREW POLLACK IRVINE, Calif. — In a closetlike room at the "Leg Lab" here, salamanders stare blankly out of clear plastic drinking cups. The lab is so named because many of the animals have had, or will have, a leg cut off. But the salamanders recover, with perfect new limbs growing back in weeks. Salamanders are the superstars of regeneration. They can grow back not only limbs but also tails, parts of their hearts and the retinas and lenses in their eyes. Humans cannot do any of that. So scientists here hope that the salamander's tricks may one day be applied to people. "I really do believe it's just a matter of time before you're going to regenerate an arm or at least a finger," said Dr. David M. Gardiner, a biologist who runs the laboratory at the University of California at Irvine with Dr. Susan V. Bryant, the dean of biological sciences and his wife. "I'd like to see that in my lifetime." Copyright 2002 The New York Times Company

Keyword: Regeneration
Link ID: 2698 - Posted: 06.24.2010

By NICHOLAS WADE Most people have around 100 billion nerve cells in their brain. But the roundworm, down at the other end of the scale of animal complexity, figures out everything it needs to know about life with exactly 302 neurons. Researchers have now gained what seems to be a major insight into how nature builds brains of such different capabilities. They have discovered a gene that apparently determines the brain's size. The gene has come to light through study of a disease known as microcephaly, in which people are born with a head and brain significantly smaller than usual. Patients are in general only mildly retarded but have far fewer neurons. The microcephalic patients might not have come to clinical attention but for a dam that was completed in 1967 in the Mirpur Province of Pakistani-controlled Kashmir. Some 50,000 Pakistanis were displaced by the rising waters, and many emigrated to Bradford, in the British midlands. The emigrants included some large families with many marriages between close relatives, a circumstance that can make genetic disease more evident. Copyright 2002 The New York Times Company

Keyword: Evolution; Development of the Brain
Link ID: 2697 - Posted: 09.24.2002

Big brains gave humans an evolutionary edge, but how did they grow so big? An important clue may come, ironically, from a gene that has been found to stunt the cerebral cortex in people with microcephaly. A team led by biologist Geoffrey Woods of the University of Leeds, U.K., found the brain-shrinking gene, called ASPM, by sequencing the DNA of people afflicted with primary microcephaly, a familial disease that stunts the growth of the cerebral cortex during development. The researchers discovered that in microcephalic people, chunks of the protein encoded by ASPM are missing because of mutations in the gene. To determine where in the body ASPM is active, they screened different fetal tissues and found the gene expressed in the progenitor cells that produce cerebral cortex neurons. Previous work with fruit flies suggests how the gene might influence brain size. The fruit fly version of ASPM organizes the spindle fibers that separate chromosome pairs into the two halves of dividing neuronal progenitor cells. The orientation of these fibers determines how many neurons a progenitor cell will produce, and the more neurons produced, the larger the brain. Humans with microcephaly probably have fewer cortical neurons because mutant ASPM disrupts cell division in the progenitor cells, says Christopher Walsh, a neurobiologist at Harvard University and co-author of the new study, which is published online 23 September by Nature Genetics. Copyright © 2002 by the American Association for the Advancement of Science.

Keyword: Evolution; Development of the Brain
Link ID: 2696 - Posted: 06.24.2010

Attention Deficit Hyperactivity Disorder (ADHD) is a neuropsychiatric condition characterized by hyperactive-impulsive behavior and persistent inattention. Individuals with this condition experience social and academic dysfunction. It is postulated that a developmental failure in the brain mechanism underlies self-control and inhibition in ADHD. ADHD affects approximately 3 to 6% of children from different geographical regions worldwide. Boys are affected more frequently than girls, with the ratio ranging from 3:1 to 9:1. Family studies have indicated a strong genetic component in susceptibility to ADHD. An approximate five to six fold increase in the frequency of ADHD among first-degree relatives when compared with the general population was observed. A number of twin studies have estimated the heritability of ADHD to range from 39% to 91% for various symptoms of the disorder. Synaptosomal-associated protein 25 (SNAP-25) is a protein which is expressed highly and specifically in the nerve cells. The gene encodes a protein essential for synaptic vesicle fusion and neurotransmitter release. Animal model studies have shown that the coloboma mouse mutant has a hyperactive phenotype similar to that of ADHD. This model was shown to be the result of a deletion of the SNAP-25 gene.

Keyword: ADHD; Genes & Behavior
Link ID: 2695 - Posted: 09.24.2002

Copyright © 2002 AP Online The Associated Press WASHINGTON - There are more differences between a chimpanzee and a human being than once believed, according to a new genetic study. Biologists have long held that the genes of chimps and humans are about 98.5 percent identical. But Roy Britten, a biologist at the California Institute of Technology, said in a study published this week that a new way of comparing the genes shows that the genetic similarity between humans and chimps is only about 95 percent. Copyright © 2001 Nando Media

Keyword: Evolution; Genes & Behavior
Link ID: 2694 - Posted: 06.24.2010

Movements faster than your reaction time stop a stick falling off your finger. PHILIP BALL There's more to balancing tricks than quick reactions. Most of the tiny movements we make to balance a stick on a fingertip happen faster than our typical response time, say Juan Cabrera and John Milton of the University of Chicago, thanks to noise in our nervous system.1 Cabrera and Milton think that this mechanism could apply to any problem of balance. Random movements may explain how a tightrope walker stays aloft, for instance. Robotics engineers could make their machines more stable by injecting a little noise into their systems. Using fast cameras that detect infrared light, Cabrera and Milton filmed the motion of a stick with reflective ends, balanced on end on a person's fingertip. Light reflected from the ends enabled them to measure fluctuations in the stick's angle from the vertical. © Nature News Service / Macmillan Magazines Ltd 2002

Keyword: Movement Disorders
Link ID: 2693 - Posted: 06.24.2010

Had an out-of-body experience? Scientists believe they know why BY JEFFREY KLUGER Shamans teach that out-of-body experiences are best achieved through meditation, reflection and transcendental calm. Scientists believe they have found a less celestial source: the right angular gyrus of the brain. The new thinking is the result of the case of a woman, 43, who was undergoing treatment for epilepsy originating in her brain's right hemisphere. A team of researchers at the University Hospitals of Geneva and Lausanne wrote in Nature last week that to pinpoint the problem, it implanted electrodes in the suspect region to record seizures and used a weak current to map the brain. The doctors — and the patient — then got a surprise. When the current was applied to a particular spot, the woman experienced a sense of lightness, as if she were floating above herself. More remarkably, she seemed to see part of her body as if she were viewing it from the ceiling. When the doctors asked her to move her limbs, she experienced other illusions: one arm seemed shorter than the other; her legs seemed to fly toward her face; if she closed her eyes, her upper body felt as if it were flying toward her legs. Copyright © 2002 Time Inc. All rights reserved.

Keyword: Miscellaneous
Link ID: 2692 - Posted: 06.24.2010

DALLAS – – Researchers at UT Southwestern Medical Center at Dallas and their colleagues have uncovered new information that will help brain researchers better understand a person’s tolerance to drugs of abuse and open new avenues of investigation into the relationship of addictive-drug usage and the biological causes of mood disorders. Dr. Michel Barrot, assistant professor of psychiatry at UT Southwestern and lead author of the paper, said researchers used genetically altered mice to show that pain – both physiological and psychological – as well as pleasure can activate changes in the nucleus accumbens, the forebrain structure critical for reward and motivation processes. The findings appeared in a recent issue of Proceedings of the National Academy of Sciences. Senior author Dr. Eric Nestler, chairman of psychiatry at UT Southwestern, had previously established that drugs of abuse activate CREB, a specific binding protein known for playing a role in the plasticity and adaptation of nerves in the nucleus accumbens. This action between a drug and a binding site is involved with the learning processes and can affect the interaction between subject and environment. © 2002 The University of Texas Southwestern Medical Center at Dallas

Keyword: Drug Abuse
Link ID: 2691 - Posted: 06.24.2010

Artificial neuro-stimulation offers hope — and movement — to the paralysed BY THOMAS K. GROSE Our brains constantly and subconsciously send commands to which our bodies react almost simultaneously. And the internal communications network that accomplishes this miraculous feat is the nervous system. But for many stroke patients, a portion of the nerve network crashes, and that often results in paralysis. Researchers have for years tried using artificial stimulation to sidestep the damaged portion of the system, with little success. Nerves don't appreciate being tampered with. But now scientists at Aalborg University in Denmark have developed electrodes that allow for artificial neuro-stimulation, a breakthrough that may help many stroke patients overcome paralysis. Aalborg's initial technology is an implant — like a pacemaker — that "stimulates the nerve to mimic natural movement," explains Thomas Sinkjaer, the professor who is heading the research. It will benefit patients who sustained so much damage that they are beyond rehabilitation therapies and would otherwise remain paralyzed. Artificially stimulating nerves to perform even simple tasks is a challenge. Even a routine movement, like picking up a paper coffee cup, requires a complex set of instructions to the hand to determine, among other things, how much pressure is needed. Too little pressure, and the cup is dropped; too much, and it's crushed. But the sensors Sinkjaer's team developed can pick up nerve impulses sent to and from the brain to determine how much stimulation is needed to control grasp. Copyright © 2002 Time Inc. All rights reserved.

Keyword: Robotics; Regeneration
Link ID: 2690 - Posted: 06.24.2010

Animal experiments a year away, doctors predict ASSOCIATED PRESS — Attempts to restore sight to people with damaged retinas are turning toward signaling the brain the way nature does it, using chemicals to deliver signals to nerve endings. EXPERIMENTS ALREADY under way with retinal implants seek to use electrical signals to make the nerves send information to the brain. But doctors from Michigan and California described a different method Monday, using retinal implants that respond to images by releasing nerve-stimulating chemicals. MSNBC Terms, Conditions and Privacy © 2002

Keyword: Vision
Link ID: 2689 - Posted: 06.24.2010

The number of Scottish adults contracting meningitis has shown a significant increase, according to a charity. The Meningitis Trust for Scotland said the illness has been on the rise in adults in recent years - although most people still believe that it is a child-centred illness. Now the charity has launched a campaign stressing that meningitis does not only affect children. Of the 177 cases of meningitis notified to Scottish health officials in the 12 months to August, 25% patients involved adults. During 2001 there was a 63% increase in meningococcal meningitis - a severe form of the disease - among the over 20s north of the border. That compared to a rise of about 47% in England and Wales. (C) BBC

Keyword: Miscellaneous
Link ID: 2688 - Posted: 09.23.2002