When you spot a celebrity on a magazine cover, your brain recognizes the image in an instant--an effect that seems to occur because of a single neuron. A recent study indicates that our brains employ far fewer cells to interpret a given image than previously believed, and the findings could help neuroscientists determine how memories are formed and stored. Exactly how the human brain works to record and remember an image is the subject of much debate and speculation. In previous decades, two extreme views have emerged. One says that millions of neurons work in concert, piecing together various bits of information into one coherent picture, whereas the other states that the brain contains a separate neuron to recognize each individual object and person. In the 1960s neurobiologist Jerome Lettvin named the latter idea the "grandmother cell" theory, meaning that the brain has a neuron devoted just for recognizing each family member. Lose that neuron, and you no longer recognize grandma. Experts long ago dismissed this latter view as overly simplistic. But Rodrigo Quian Quiroga of the University of Leicester in England and his colleagues decided to investigate just how selective single neurons might be. The team looked at eight patients who each had 64 tiny electrodes implanted in their brains before epilepsy surgery (a procedure to pinpoint the source of their seizures). Many of the electrodes were placed in the hippocampus, an area critical for the storage of long-term memories. © 1996-2005 Scientific American, Inc.

Keyword: Vision
Link ID: 8010 - Posted: 06.24.2010

With, or without us, our world continues to change at an incredible pace. The twentieth century has seen cars getting closer and closer to the supposed futuristic fantasies of the manufacturers of the 1950's; computers that, less than 40 years ago filled a whole office, now sit nicely on each of our desks; scientists are making breakthroughs in fighting diseases that only decades ago hadn't even been identified yet. In order to keep pace with our ever-changing environment we all have to learn to adapt, and as the father of the theory of evolution Charles Darwin declared, adaptation can mean survival. So as a race are we still evolving? It seems that we are. Researchers have shown that mutations, or variants, in two genes thought to regulate brain size have only arisen recently in the long history of evolution of the planet and appear to be spreading quickly in large swaths of the world's population. Armed with this fresh evidence, one researcher argues that our brains are still evolving. "We've caught evolution in action, in the sense that here is a new variant in each one of these two genes that arose very recently," says human geneticist Bruce Lahn, from the University of Chicago and an investigator at the Howard Hughes Medical Institute. "Our findings just added another piece of evidence to the idea of evolution, that as a species we're still evolving, even as a very complex species we're still evolving. We can see that at the level of genes, that is, our genes are still in the process of changing." © ScienCentral, 2000-2005.

Keyword: Evolution; Development of the Brain
Link ID: 8009 - Posted: 06.24.2010

The patient came into the doctor's office in a wheelchair, weighted down by a diagnosis of Parkinson's disease, taking medication for the disorder and insisting she was unable to stand or walk. Thirty minutes later, after jogging down the hallway, she strolled out the door. No Parkinson's patient was she. Rather, she was a perfect example of a person with "fear of falling gait," said neurologist and Parkinson's expert Roger Kurlan, M.D., of the University of Rochester Medical Center. Kurlan has seen enough cases of the condition, where a person is so afraid of falling that the mind actually affects the ability to walk, that he wrote about the disorder in the September issue of Cognitive and Behavioral Neurology to cue other physicians about the condition. In the case reported in the journal, Kurlan describes an elderly woman who had an increasingly difficult time walking. The difficulties began shortly after her husband died, when she tripped and fell, breaking a wrist and bruising her leg. Her inability to walk led her doctor to diagnose Parkinson's disease, and she was prescribed the Parkinson's medication levodopa to treat her symptoms. Despite treatment, she ended up in a wheelchair, unable to walk, and she was sent to Kurlan, an expert in movement disorders like Parkinson's. A thorough physical exam turned up nothing abnormal, but the woman refused to try to stand up on her own, even pushing herself down into her chair as Kurlan and a nurse tried to convince her to attempt to stand up. With enough persuasion, though, and with several people available to help her up, the woman finally did rise.

Keyword: Parkinsons
Link ID: 8008 - Posted: 10.08.2005

Howard Florey Institute scientists in Melbourne have found that fluoxetine (commonly marketed as ProzacŪ) not only improves depression in Huntington's disease, but also improves learning and memory. Dr Anthony Hannan and his team also found that fluoxetine restores the brain's process of neurogenesis - the birth of new neurons - to normal levels, which helps delay the onset of the inherited fatal disease. People with Huntington's disease have progressive motor problems, cognitive deficits (dementia) and psychiatric symptoms (the most common is depression) that usually start to appear in mid-life. There is no cure and death usually results within 10 to 20 years of symptom onset, or faster in the childhood-onset form of the disease. The disease is caused by a mutation in a single gene and when this defective gene is passed from parent to child, 50 percent of the offspring will inherit the disorder, which can be detected by genetic testing. Dr Hannan said this discovery was an important step in developing effective treatments to delay the onset of symptoms and the progression of Huntington's disease. "Now that we've found fluoxetine improves memory problems, or dementia, as well as depression in mice with Huntington's disease, further research can be conducted to see if the drug has the same benefits in humans with the disease," Dr Hannan said.

Keyword: Huntingtons; Learning & Memory
Link ID: 8007 - Posted: 10.07.2005

By Jay Michaelson There was a time when I didn't have a memory. It was the spring of 2001, after I suffered a Grade 3 concussion when a tow truck hit a taxi in which I was riding. For six months, I forgot conversations as soon as they were over, lost track of names and addresses, and often found myself on the street, or the subway, without any idea where I was headed or why. Of course, everyone forgets things: We've all had the experience of walking into the kitchen and then losing track of why we came, or fumbling for the name of someone we've met a dozen times. But this was different. This was a complete erasure of linear time. Every moment was new, without history, and grounded in the past only by the detailed notes I kept for myself. After about six months, the symptoms eventually lifted and my short-term memory returned. I had suffered no retrograde amnesia and should have been back to my "old self." Except that my old self was no longer there. In the six-month space of my memory loss, I had quit my job at the software company I'd founded, unable to keep track of the many meetings, tasks, and personnel of which I was in charge. My longtime girlfriend had left me, prompting me to come to terms with my sexuality and come out to myself and my friends. And fundamentally, something about me had shifted—I had been skeptical, uptight, nervous. But now I was performing poetry at slams, dancing at bonfires in the desert, and traveling to new countries on a whim. At the time, it felt like a rebirth. ©2005 Washingtonpost.Newsweek Interactive Co.

Keyword: Learning & Memory; Depression
Link ID: 8006 - Posted: 06.24.2010

Do you always get what you ask for? A new study finds that when you don't, you might not even notice the difference. Swedish researchers showed a pair of female faces to 120 volunteers for 2 seconds and then asked them to choose which one they thought was more attractive. The researchers then asked the volunteers to explain their choice. The trial was repeated 15 times for each volunteer, using different pairs of faces, but in three of the trials the faces were secretly switched after a decision had been made. Surprisingly, not only were a large number of the volunteers oblivious to the switch when ultimately allowed to take a longer look at their choice, they were actually able to gave detailed explanations for why they preferred the face that, indeed, they had actually rejected. It would be like asking for an apple and then explaining exactly why you wanted the banana you got instead. The researchers call the phenomenon "choice blindness." "She's radiant," gushed one male volunteer about a face he didn't choose. "I would rather have approached her at a bar than the other one. I like earrings!" Another female volunteer said that the face she chose (which in fact she hadn't) looked nicer than the other. © 2005 MSNBC.com

Keyword: Vision; Sexual Behavior
Link ID: 8005 - Posted: 06.24.2010

CINCINNATI--Scientists have found that the site in the brain that controls language in right-handed people shifts with aging--a discovery that might offer hope in the treatment of speech problems resulting from traumatic brain injury or stroke. The shift was documented by researchers led by Jerzy Szaflarski, MD, PhD, assistant professor in the Department of Neurology at the University of Cincinnati (UC) Academic Health Center, and Scott Holland, PhD, professor in the UC departments of biomedical engineering, pediatrics and radiology. Dr. Holland also heads the Pediatric Brain Imaging Research Program at Cincinnati Children's Hospital Medical Center. Their results will be published in the February 2006 edition of the journal Human Brain Mapping. While the site of language activity in right-handed people is originally the left side of the brain, the researchers report, starting as early as age 5 language gradually becomes a function shared by both sides. Between the ages of about 25 to 67, the site becomes more evenly distributed, until language activity can be measured in both hemispheres simultaneously. This, the researchers say, may explain why young children who have had a large portion of one side of the brain surgically removed often recover completely.

Keyword: Language; Stroke
Link ID: 8004 - Posted: 10.07.2005

When evaluating facial attractiveness, participants may fail to notice a radical change to the outcome of their choice, according to a study by researchers at Lund University, Sweden, and New York University. Equally surprising, the study shows that participants may produce confabulatory reports when asked to describe the reasons behind their choices. The findings appear in the October 7 issue of Science. Researchers showed picture-pairs of female faces to the participants and asked them to choose which face in each pair they found most attractive. In addition, immediately after their choice, they were asked to verbally describe the reasons for choosing the way they did. Unknown to the participants, on certain trials, a card magic trick was used to secretly exchange one face for the other. Thus, on these trials, the outcome of the choice became the opposite of what they intended. The researchers measured whether the participants noticed that something went wrong with their choice, both concurrently, during the experimental task, and retrospectively through a post-experimental interview. Less than 10% of all manipulations were detected immediately by the participants, and counting all forms of detection no more than a fifth of all manipulated trials were exposed. The researchers call this effect choice blindness.

Keyword: Sexual Behavior; Vision
Link ID: 8003 - Posted: 10.07.2005

The central nervous system in adult mammals is notoriously bad at healing itself. Once severed, the axons that connect one neuron to another can't regrow. That's why people regain little, if any, movement or sensation after a spinal cord injury. Now, researchers have made a promising discovery. In the 7 October Science, they identify a class of drugs--including one already on the market for treating cancer--that promote axon regeneration in rodents. In the new study, Zhigang He, and Vuk Koprivica at Children's Hospital in Boston along with colleagues tested about 400 small molecules on cultured rodent neurons, hoping to identify ones that promoted the growth of new axonlike extensions. Most of the compounds did nothing, but several compounds that blocked a cell surface protein called the epidermal growth factor receptor (EGFR) had impressive effects. To test the compounds on nerve injuries in live animals, the researchers crushed an optic nerve in adult mice then packed the nerve with foam soaked with one of the EGFR blockers. Two weeks after the injury, the treated mice showed a ninefold increase in axon regeneration compared to untreated animals. Additional work by He's team suggests that the compounds block two kinds of molecular signals: inhibitory molecules embedded in the myelin insulation on axons and inhibitory signals spewed out by support cells that form a scar around the site of injury. "It's a really unexpected finding," says Marie Filbin, a neurobiologist at Hunter College in New York City. She and other experts say they never suspected that EGFR might have a role in thwarting regeneration. The study "identifies a novel target for therapeutic interventions," Filbin says. © 2005 by the American Association for the Advancement of Science.

Keyword: Regeneration; Trophic Factors
Link ID: 8002 - Posted: 06.24.2010

Researchers have discovered a new form of synaptic plasticity, the changes to nerve cells in the brain that underlie learning and memory. The phenomenon, the scientists say, may help govern how a single neuron integrates and processes multiple stimuli. The researchers, led by HHMI investigators Lily Jan and Yuh Nung Jan at the University of California San Francisco, published their findings in the October 7, 2005, issue of the journal Cell. Coauthors on the paper include the Jans' colleagues at UCSF and Robert B. Darnell, an HHMI investigator at The Rockefeller University. Scientists have long known that long-term potentiation (LTP) can strengthen the connections between neurons, so that a nerve cell more readily responds to a signal from its neighbor. This heightened sensitivity can persist for several hours. LTP is best studied in excitatory synapses, where a neurotransmitter molecule is released by one cell and tends to triggers an electrical impulse in the receiving cell. Lily Jan compares the phenomenon to Pavlov's famous experiment in which ringing a bell while feeding a dog causes the dog to associate the two stimuli. LTP, she says, “reminds you of that. If you have two different excitatory inputs and they happen at the same time, it can cause a very long-lasting change.” © 2005 Howard Hughes Medical Institute.

Keyword: Learning & Memory
Link ID: 8001 - Posted: 06.24.2010

Known as "the cocktail party problem," the ability of the brain's auditory processing centers to sort a babble of different sounds, like cocktail party chatter, into identifiable individual voices has long been a mystery. Now, researchers analyzing how both humans and monkeys perceive sequences of tones have created a model that can predict the central features of this process, offering a new approach to studying its mechanisms. The research team--Christophe Micheyl, Biao Tian, Robert Carlyon, and Josef Rauschecker--published their findings in the October 6, 2005, issue of Neuron. For both the humans and the monkeys, the researchers used an experimental method in which they played repetitive triplet sequences of tones of two alternating frequencies. Researchers know that when the frequencies are close together and alternate slowly, the listener perceives a single stream that sounds like a galloping horse. However when the tones are at widely separated frequencies or played in rapid succession, the listener perceives two separate streams of beeps. Importantly, at intermediate frequency separations or speeds, after a few seconds the listeners' perceptions can shift from the single galloping sounds to the two streams of beeps. The researchers could use this phenomenon to explore the neurobiology of perception of auditory streams, because they could explore how perception altered with the same stimulus.

Keyword: Hearing
Link ID: 8000 - Posted: 10.06.2005

Roxanne Khamsi It may not be considered manly for humans to cry. But when male mice shed a tear, they seem to be trying to prove their masculinity. So say Japanese researchers who have discovered that male mice release pheromones in the fluid that moistens their eyes. "Nobody expected that sex-specific pheromones would exist in tears," says Kazushige Touhara of the University of Tokyo in Chiba. Pheromones, the chemicals that convey messages about everything from fear to sexual desire, are most common in sweat in humans, and in urine in mice. It is not clear whether mice ever cry for the same reasons as humans; in this study, their tears were just the result of a basic physiological response that keeps a mouse's eyes wet and comfortable. Touhara says the pheromones in these secretions are probably picked up by females when they groom the faces of their fellow mice. These sexy cues may help females to work out which of their companions are male and therefore potential mates, Touhara and his team report in Nature1. In most vertebrates, pheromones seem to trigger nerve cells in the vomeronasal organs, which are situated in the hard palate between the nose and mouth. Some studies have found evidence for such an organ in the developing human fetus, but the presence of a functioning one in human adults remains controversial. ©2005 Nature Publishing Group

Keyword: Sexual Behavior; Chemical Senses (Smell & Taste)
Link ID: 7999 - Posted: 06.24.2010

When you jaywalk, your ability to keep track of that oncoming truck despite your constantly changing position can be a lifesaver. But scientists do not understand how such constant updating of depth and distance takes place, suspecting that the brain receives information not just from the eye but also from the motion-detecting vestibular system in the middle ear. In studies with monkeys reported in the October 6, 2005, issue of Neuron, Nuo Li and Dora Angelaki of Washington University School of Medicine in St. Louis have demonstrated how such depth motion is updated and strongly implicated the vestibular system in that process. In their experiments, the researchers trained the monkeys to perform memory-guided eye movements. The animals were first shown a light a fixed distance away from their head. Then the researchers flashed one of eight other, closer "world-fixed" target lights. Next, with the room lights turned off, the monkeys were moved either forward or backward and the fixed-distance light flashed, signaling the monkeys that they should look at where they remembered the world-fixed light had flashed. Finally, the room lights and target light were turned on, so the monkey could make any corrective eye movement to the re-lit target. For comparison, the researchers also conducted experiments in which the monkeys were not moved.

Keyword: Miscellaneous
Link ID: 7998 - Posted: 10.06.2005

New studies in mice have shown that immature stem cells that proliferate to form brain tissues can function for at least a year — most of the life span of a mouse — and give rise to multiple types of neural cells, not just neurons. The discovery may bode well for the use of these neural stem cells to regenerate brain tissue lost to injury or disease. Alexandra L. Joyner, a Howard Hughes Medical Institute investigator at New York University School of Medicine, and her former postdoctoral fellow, Sohyun Ahn, who is now at the National Institute of Child Health and Human Development, published their findings in the October 6, 2005, issue of the journal Nature. They said the technique they used to trace the fate of stem cells could also be used to understand the roles of stem cells in tissue repair and cancer progression. Joyner said that previous studies by her lab and others had shown that a regulatory protein called Sonic hedgehog (Shh) orchestrates the activity of an array of genes during development of the brain. Scientists also knew that Shh played a role in promoting the proliferation of neural stem cells. However, Joyner said the precise role of Shh in regulating stem cell self-renewal — the process whereby stem cells divide and maintain an immature state that enables them to continue to generate new cells — was unknown. In the studies published in Nature, Joyner and Ahn developed genetic techniques that enabled them to label neural stem cells in adult mice that are responding to Shh signaling at any time point so they could study which stem cells respond to Shh. © 2005 Howard Hughes Medical Institute.

Keyword: Stem Cells
Link ID: 7997 - Posted: 06.24.2010

By DONALD G. McNEIL Jr. The Food and Drug Administration proposed new rules yesterday to prevent the spread of mad cow disease by banning brains and spinal cords from older cows in all animal feed. "This reduces a very, very low risk to even lower," said Dr. Stephen F. Sundlof, the agency's director of veterinary medicine, in announcing the changes. But the rules are not as strict as those the agency proposed last year and never adopted, and critics promptly denounced them as inadequate. The new proposal still allows chickens, pigs and other noncattle animals to be fed material that some scientists consider potentially infectious, including the brains and spinal cords of young animals, and the eyes, tonsils, intestines and nerves of older ones. Cows can potentially ingest that material because they can be given chicken feed and droppings swept up from the floors of poultry farms, scrapings from restaurant plates, and a calf milk replacement made from cow blood and fat. In the rules proposed in early 2004, poultry litter and plate waste would have been banned. The F.D.A. and the meat industry are "totally committed to continuing the practice of feeding slaughterhouse waste to cows," said John Stauber, the author of "Mad Cow U.S.A." (1997) and a critic of the meat industry who has called for a ban on feeding all animal protein to livestock. Copyright 2005 The New York Times Company

Keyword: Prions
Link ID: 7996 - Posted: 10.05.2005

While we need maps to navigate long distances, each fall millions of monarch butterflies migrate up to 3,000 miles south to their overwintering grounds in central Mexico without losing their way. "Monarchs absolutely have to be able to see ultraviolet light in order to navigate, and if this is blocked in some way they lose their sense of direction," says ecologist and evolutionary biologist Adriana Briscoe from the University of California, Irvine. Briscoe says what North American migratory monarch butterflies (Danaus plexippus) use as a cue to keep them on track despite clouds, wind and fog along the way has long been a mystery. Previous research showed that monarchs use the sun as one of the celestial cues for deciding which direction to fly in. In particular, they use a type of light that humans can't see called polarized light — produced primarily by the scattering of sunlight through the atmosphere. "We also knew that they had an internal clock which they used to also calibrate their sense of direction," Briscoe explains. But how the butterflies put all this together to navigate was not understood. Now Briscoe, working in collaboration with an international team of researchers, has found that when the skies of certain U.S. states fill each fall with the flitter of up to a hundred million monarchs, these incredible butterflies are using the sun's ultraviolet, or UV, light as a compass to tell them where they are and which direction to fly — the same type of light that cancer-conscious people shy away from. © ScienCentral, 2000-2005.

Keyword: Vision; Animal Migration
Link ID: 7995 - Posted: 06.24.2010

By Jon McClellan, M.D. Consumer, professional, legislative and regulatory organizations are increasingly calling for the development and adoption of evidence-based therapies, based on demands for quality services and expectations that outpouring of dollars and time are rewarded by beneficial outcomes. In child and adolescent mental health, growing public concerns over safety, in particular with psychotropic medications, and the recognition that psychiatric impairment is a major factor within other social service systems has further fueled the demand for empirically based interventions. Randomized, controlled trials (RCTs) with adequate sample sizes and defined study populations are the standard for characterizing an intervention as evidence-based (Cochrane Collaboration, 2002). A listing of all RCTs in child and adolescent psychiatry is beyond the scope of this commentary (for a review, see McClellan and Werry [2003]). This review will outline interventions with the best research support. Fortunately, although the literature remains limited, the number of well-conducted studies is increasing. An estimated 6% of young people under the age of 20 in the United States receive prescriptions for psychotropic medication. This represents approximately a threefold increase since 1987 (Zito et al., 2003), and includes a substantial rise in prescriptions for preschoolers (Zito et al., 2000). The majority of prescriptions are off-label (i.e., not U.S. Food and Drug Administration-approved). Pediatricians and family practice physicians issue the majority of prescriptions for psychotropic drugs, in part due to the scarcity of child psychiatrists (Goodwin et al., 2001). © 2005 Psychiatric Times.

Keyword: ADHD; Depression
Link ID: 7994 - Posted: 06.24.2010

By Arline Kaplan Repetitive transcranial magnetic stimulation (rTMS), which allows for direct activation of neurons, will play an ever-expanding role in depression and schizophrenia treatment, according to recent reports from Mark S. George, M.D., and Alan L. Schneider, M.D. George, who is distinguished professor of psychiatry, radiology and neurology, and director of the Brain Stimulation Laboratory at the Medical University of South Carolina College of Medicine, provided updates on rTMS research at the 2005 American Psychiatric Association annual meeting. "We call this electrodeless electrical stimulation," George said at a symposium. "Electrical energy in a coil induces a magnetic field, and the field passes unimpeded through the skin and skull and induces an electrical current in the brain." The physiological effects of TMS depend upon the site and frequency of stimulation (Ontario Ministry of Health and Long-Term Care, 2004). The frequency of cortical stimulation varies. Rapid-rate or repetitive TMS usually refers to the application of TMS for a train of minutes at frequencies >1 Hz and is commonly used in treatment studies. Transcranial magnetic stimulation at ≤1 Hz is referred to as slow or low-frequency TMS. The ability to stimulate the brain at either high or low frequency is important, because high-frequency rTMS (e.g., 20 Hz) may increase cerebral blood flow and neuronal excitability in the region of the cortex under the coil, but low-frequency rTMS (≤1 Hz) may have the opposite effect. © 2005 Psychiatric Times

Keyword: Schizophrenia; Depression
Link ID: 7993 - Posted: 06.24.2010

By David W. Loring, Ph.D. Epilepsy is a major public health concern, with prevalence estimated to be slightly less than 1% (Annegers, 1996). Each year, 25,000 to 40,000 children in the United States alone experience their first unprovoked seizure (Hirtz et al., 2003). Depending on the type of seizure (e.g., generalized versus focal) or specific epilepsy syndrome (e.g., juvenile myoclonic epilepsy, benign rolandic epilepsy), there are several recommended medications with demonstrated clinical efficacy from which to choose (Hirtz et al., 2003). Selection of a specific medication, however, is often based upon clinical experience due to the absence of adequate antiepileptic drug (AED) pediatric clinical trials. Antiepileptic drugs decrease membrane excitability, increase postsynaptic inhibition or alter synchronization of neural networks to decrease excessive neuronal excitability associated with seizure development. Common side effects of decreasing neuronal excitability, however, are slowed motor and psychomotor speed, poorer attention and mild memory impairment (Meador, 2005). Unlike adults, cognitive side effects in children occur against the backdrop of normal cognitive and psychosocial development, and treatment decisions made in childhood may have lifelong implications. Adults who developed epilepsy during their childhood tend to have less education, decreased rates of employment and employment at lower job levels, lower rates of marriage, poorer physical health, and increased incidence of psychiatric disorders (Jalava and Sillanpaa 1997a, 1997b; Jalava et al., 1997; Sillanpaa et al., 1998). Importantly, these long-term effects are also present in adults who are no longer taking medications. © 2005 Psychiatric Times.

Keyword: Epilepsy
Link ID: 7992 - Posted: 06.24.2010

Five years ago Karen Reed, from East Yorkshire, was slimmer of the year - but she had a secret. For the past 28 years she has been bulimic. Her daily life revolves around bingeing on vast amounts of food and then making herself sick. The condition has taken a terrible toll on Karen's health. The acid from her stomach has burnt a hole in her oesophagus and dissolved away most of her teeth. "I was 15 when I first made myself sick, I'm 43 now," said Karen. "I can't remember what it feels like to be normal, this is normal for me, throwing up two, three times a day is normal." But it is not just Karen who is suffering. Her eldest daughter Jess, who is 17 and a part time model, is also bulimic. "For me it was always a need to lose weight and it was a very effective way I found," she said. "The first time I threw up I saw on the scales it made me lose a few pounds so I kept it going. It was something that progressed and got worse and now it has such a detrimental effect on my life." Bulimia is treated as a psychological disorder in the UK but Karen and Jess say they have had therapy without success. A BBC documentary team has followed them as they try and get hold of an experimental drug which they believe could cure them of their eating disorder. (C)BBC

Keyword: Anorexia & Bulimia
Link ID: 7991 - Posted: 10.04.2005