By introducing expression of a special green-algae gene into neurons of the tiny, transparent nematode C. elegans, researchers have been able to elicit specific behavioral responses by simply illuminating animals with blue light. The work paves the way for better understanding of how neurons communicate with each other, and with muscles, to regulate behavior in intact, living organisms. Generally speaking, detailed information about the activity and function of specific neurons during particular behaviors has been difficult to achieve in undissected animals. The new findings are reported by Alexander Gottschalk and colleagues at Goethe-University Frankfurt and at the Max Planck Institute for Biophysical Chemistry, also in Frankfurt. In their new study, the researchers employed a light-sensitive protein from the green alga Chlamydomonas reinhardtii. This protein, channelrhodopsin-2 (ChR2), sits in cell membranes, where it gates the flow of certain ions from one side of the membrane to the other. Such so-called channel proteins play central roles in the activities of neurons and muscle cells, and while some channel proteins are sensitive to chemicals or electrical signals, ChR2 and its relatives are controlled directly by certain wavelengths of light, making them ideal for remote control in the laboratory. In their experiments, the researchers took advantage of the light sensitivity of the algal channel protein by introducing expression of a modified form of ChR2 in specific C. elegans neurons and muscle cells. The researchers found that when this form of ChR2 was expressed in muscle cells, blue-light activation of the protein was sufficient to cause strong contraction of the muscle. They found that muscle contraction was simultaneous with light exposure.

Keyword: Pain & Touch
Link ID: 8329 - Posted: 12.20.2005

By Stacey Colino, Special to The Washington Post Like most teenagers, Andrew Solomon was often at the mercy of his moods -- but in his case this situation persisted into his thirties. "During my up periods, I'm lucid and articulate," said Solomon, author of the partly autobiographical "The Noonday Demon: An Atlas of Depression," which won the National Book Award for nonfiction in 2001. "I have clarity and can see patterns in my work, and I can write loads of publishable material in one night. I'm also very affectionate with people I care about." But when his moods would turn, as they invariably did, he could withdraw or have angry outbursts. Once, after an annoying phone call, he slammed down the phone so hard it broke. Another time, when an acquaintance who frequently drank too much showed up at his home tipsy and immediately poured herself a cocktail, Solomon "smashed the glass and yelled at her that she had to leave immediately," he recalls. After such explosions, he would "spend the next week apologizing." Yet it wasn't until three years ago that Solomon, now 42, learned there is a word for the mood swings that have affected him since his youth: cyclothymia. Cyclothymic disorder, as it is sometimes known, is a milder cousin of bipolar disorder. Like bipolar disorder, cyclothymia has high and low phases, though the highs are not as high and the lows not as low. It can be crippling nonetheless. And it is a risk factor for bipolar disease itself, with up to 50 percent of those with cyclothymia eventually developing bipolar disorder. Major depression is also a higher risk. © 2005 The Washington Post Company

Keyword: Depression; Schizophrenia
Link ID: 8328 - Posted: 06.24.2010

Morphine and other opioids work wonders for pain. Unfortunately, their effectiveness declines over time while their addictiveness grows, meaning patients need the drug even as it affords them less and less relief. But new research into the cellular workings of opioids offers a promising new pathway to improved pain relief--without the addiction--by triggering one receptor and blocking another. Medicinal chemist Philip Portoghese of the University of Minnesota and his colleagues began by studying two of the four major opioid receptors in the cells of the central nervous system. Each bears the name of a Greek letter and the chemists focused on the Mu and Delta receptors. Previous research had shown that drugs that linked up with Mu receptors lasted longer with less addiction when combined with drugs that blocked Delta receptors. But it was not known whether the two channels worked separately or in concert to improve the overall effect. So Portoghese and his colleagues built a drug that triggered the Mu receptor while blocking the Delta receptor--dubbed MDAN, for Mu Delta agonist antagonist. They administered various versions of the drug to mice and then tested their sensitivity to pain by focusing a hot light on their tails and recording the time it took the animals to move them. The MDAN drug proved roughly 50 times more effective than morphine in blocking pain, the researchers report in this week's online edition of the Proceedings of the National Academy of Sciences. But MDAN still paled in comparison to drugs designed purely to stimulate the Mu receptor, which exhibit more than 100 times the pain blocking potential of morphine. The MDAN drugs had another benefit, however: the mice did not develop any dependence. © 1996-2005 Scientific American, Inc

Keyword: Pain & Touch; Drug Abuse
Link ID: 8327 - Posted: 06.24.2010

Our ability to understand speech or decide which fruit in the store is freshest depends on the brain's dexterity in integrating information over time. The prefrontal cortex, where working memory resides, plays a critical role in helping us make these countless everyday decisions. A novel computational study by Brandeis researchers in this week's issue of the Proceedings of the National Academy of Sciences proposes for the first time a neuronal model for the mechanisms underlying a time-related task in this complex decision-making process. Essentially, the study shows that neurons in the prefrontal cortex fire with greater or lesser intensity to finely control, or inhibit behavior, based on a neuronal feedback signal, or circuit mechanism. Such integral feedback control is probably at work in many regulatory areas of the body, such as temperature control and feelings of satiety to prevent overeating, but this is the first time this mechanism has been suggested as a role of neuronal firing. The findings provide a framework for understanding how neurons operate in a part of the brain that controls behavior and which is often compromised in people with mental health problems such as schizophrenia, a disease that can entail problems with short-term memory tasks and misperceptions about the immediate environment.

Keyword: Learning & Memory
Link ID: 8326 - Posted: 12.20.2005

Darwin’s fingerprints can be found all over the human genome. A detailed look at human DNA has shown that a significant percentage of our genes have been shaped by natural selection in the past 50,000 years, probably in response to aspects of modern human culture such as the emergence of agriculture and the shift towards living in densely populated settlements. One way to look for genes that have recently been changed by natural selection is to study mutations called single-nucleotide polymorphisms (SNPs) – single-letter differences in the genetic code. The trick is to look for pairs of SNPs that occur together more often than would be expected from the chance genetic reshuffling that inevitably happens down the generations. Such correlations are known as linkage disequilibrium, and can occur when natural selection favours a particular variant of a gene, causing the SNPs nearby to be selected as well. Robert Moyzis and his colleagues at the University of California, Irvine, US, searched for instances of linkage disequilibrium in a collection of 1.6 million SNPs scattered across all the human chromosomes. They then looked carefully at the instances they found to distinguish the consequences of natural selection from other phenomena, such as random inversions of chunks of DNA, which can disrupt normal genetic reshuffling. © Copyright Reed Business Information Ltd.

Keyword: Evolution
Link ID: 8325 - Posted: 06.24.2010

On average, twins of people who have been diagnosed with dementia score lower on cognitive tests than do the twins of people without dementia, new research has found. The study, which included more than 100 Swedish twins age 65 and older, also found that, on average, identical twins of people with dementia have poorer cognitive skills than do fraternal (non-identical) twins of people with dementia. The researchers suggest that these differences in thinking skills reflect a genetic risk for dementia. However, they emphasize that cognitive changes and elevated genetic risk do not always predict that twins or siblings of people with dementia will eventually develop dementia themselves. The research, reported in the December 2005 issue of the Journal of Geriatric Psychiatry and Neurology, was led by Margaret Gatz, Ph.D., of the University of Southern California and the Karolinska Institute in Sweden. The study was funded by the National Institute on Aging (NIA), a component of the National Institutes of Health, U.S. Department of Health and Human Services, and a Zenith Award from the Alzheimer's Association. The University of Southern California Alzheimer's Disease Center is one of more than 30 Alzheimer's Disease Centers nationwide supported by the NIA. "This research is intriguing because it associates genetic risk for dementia with twins' cognitive deficits, even in the absence of dementia," says Neil Buckholtz, Ph.D., chief of the Dementias of Aging Branch of NIA's Neuroscience and Neuropsychology of Aging Program. "The differences in cognitive deficits between identical and fraternal twins are also important, suggesting that the twins who were more similar genetically had the greater risk."

Keyword: Alzheimers; Genes & Behavior
Link ID: 8324 - Posted: 12.20.2005

By THE ASSOCIATED PRESS ANCHORAGE, (AP) - Lloyd Leavitt shrugs off the subzero freeze that blankets the town of Barrow, Alaska, each winter. It is the weeks of endless night that get to him, filling him with insatiable cravings for carbohydrates, sleep and natural light. "There comes a time when you don't know if it's morning or evening; you get confused," said Mr. Leavitt, who has lived all his 49 years in Barrow, the nation's highest-latitude community. Mr. Leavitt has plenty of company when it comes to dealing with Alaska's dark side. No matter how far south you go, the state is still far north of the rest of the country. That means abbreviated days that get increasingly short as you travel farther north. Winter brings shorter days and extreme cold in other states as well. But Alaska is the American vortex of seasonal blues. No wonder residents here eagerly await the passing of winter solstice, the psychological turning point toward spring. The sun will not rise again in Barrow for another month after the solstice, which falls on Wednesday. For those in Barrow, a largely Inupiat Eskimo town of 4,500, that day marks the countdown to daylight, which is celebrated in a three-day April festival. Copyright 2005The New York Times Company

Keyword: Depression; Biological Rhythms
Link ID: 8323 - Posted: 12.19.2005

By Robert Roy Britt After hitting a 565-foot home run, Mickey Mantle once said, "I just saw the ball as big as a grapefruit." During a slump, Joe "Ducky" Medwick of the St. Louis Cardinals said he was "swinging at aspirins." A new study puts some science behind those perceptions. Researchers found a correlation between batting averages of softball players and how big or small they perceived the ball to be. After games at several softball fields in Charlottesville, Va., the researchers asked 47 players to pick from eight different-sized circles the one that best represented the size of the ball they had been trying to hit. "Only people who hit .500 or above pointed at the big circle," said Jessica Witt, a cognitive psychology doctoral candidate at the University of Virginia. The softball players literally see the ball as larger, the study concludes. "It's not in their minds. It's in perception," Witt told LiveScience. Witt was not surprised. She competed last July for the gold medal-winning U.S. Ultimate Frisbee team at the 2005 World Games in Duisburg, Germany. She has experienced a similar effect. © 2005 MSNBC.com

Keyword: Vision
Link ID: 8322 - Posted: 06.24.2010

By Clifford Singer, M.D., and Alison Bahr, M.A. Changes in sleep are inevitable as people age, though some sleep symptoms may be due to diseases rather than aging itself (Foley et al., 1999). For example, 41% of a study sample of older adults with ≥4 medical conditions considered themselves to be fair or poor sleepers as compared to 22% with one to three conditions and only 10% of those with none (Foley et al., 2004). In this same study, poor sleep was most strongly associated with heart disease, depression, arthritis and obesity. However, even healthy seniors experience reductions in slow-wave sleep ("deep sleep") and have lower sleep efficiency with more nighttime awakenings than younger adults (Bliwise, 1993). Patients with Alzheimer's disease (AD) may have the same sleep disturbances seen in other seniors, and, early in the course of AD, their sleep may not differ markedly from age-matched controls (Vitiello et al., 1990). In some cases, however, the sleep disturbance may be a marker for early AD. For example, investigators have reported that insomnia is an independent risk factor for cognitive decline over a three-year follow-up period (Cricco et al., 2001). Sleep-related problems generally increase as AD progresses (Moe et al., 1995). Patients with AD experience more frequent nighttime awakenings, daytime sleep increases, and both slow-wave sleep and rapid eye movement (REM) sleep are decreased (Bliwise, 1993; Prinz et al., 1982; Vitiello and Borson, 2001; Vitiello et al., 1992). Subjective sleep disturbances occur in up to 54% of patients with AD who live in the community (Carpenter et al., 1995; Chen et al., 2000; Hart et al., 2003; McCurry et al., 1999). McCurry et al. (1999) reported that 24% of caregivers report being awakened at night by the patient with AD and 40% report that patients with AD sleep more than usual. © 2005 Psychiatric Times.

Keyword: Alzheimers; Sleep
Link ID: 8321 - Posted: 06.24.2010

By Ewald Horwath, M.D., and Sara Siris Nash, M.D. Patients with HIV infection are at risk of developing psychiatric symptoms and disorders similar to those seen in the general population. Even before infection, people at risk for HIV may come from certain populations--such as injection-drug users and others with substance abuse or dependence--in whom there is a higher than average risk for psychiatric illness (Pillard, 1988; Rounsaville et al., 1982). Symptoms of anxiety and depression may be related to apprehension about disease progression and death and sadness from the loss of health, friends and income (Forstein, 1984; Nichols, 1985; Ostrow, 1987). Several studies have found a substantial risk for DSM-III major depression and adjustment disorders with anxious or depressed mood, which may occur during asymptomatic infection (Dilley et al., 1985; Holland and Tross, 1985). In addition, patients living with an underlying mental illness--especially severe and persistent mental or mood disorders--are at a disproportionately increased risk of developing infection with HIV due to sexual and substance use behaviors (Carey et al., 2004). Shortly after the initial HIV infection, the virus enters the central nervous system and may cause meningitis or encephalitis. Other serious CNS complications tend to occur late in the course of disease, when immune function has significantly declined, though studies have reported conflicting results as to the predictive value of CD4 counts in assessing cognitive and motor performance (Bornstein et al., 1991; Goethe et al., 1989; Koralnik et al., 1990; McArthur et al., 1989; Miller et al., 1990; Saykin et al., 1988). Viral load is more closely associated with the degree of cognitive impairment. © 2005 Psychiatric Times.

Keyword: Miscellaneous
Link ID: 8320 - Posted: 06.24.2010

Bruce Bower Preliminary evidence indicates that people can quell either temporary or chronic physical pain by learning to use their minds to reduce activity in a key brain area. Brain-imaging technology now enables individuals to use mental exercises to control a neural region that contributes to pain perception, say neuroscientist Sean C. Mackey of Stanford University and his colleagues. Both healthy volunteers and chronic-pain patients "learned to control their brains and, through that, their pain," Mackey holds. "However, significantly more testing must be done before this can be considered a treatment for chronic pain." The new findings appear in the Dec. 20 Proceedings of the National Academy of Sciences. Mackey's team studied 32 healthy volunteers, ages 18 to 37. First, each volunteer reported when an adjustable heat pulse applied to a leg produced pain that he or she rated as 7 out of 10, with 10 being equivalent to "the worst pain imaginable." Brain imaging of participants, using a functional magnetic resonance imaging (fMRI) scanner, showed that this level of pain was accompanied by pronounced blood flow—a sign of intense neural activity—in an area called the rostral anterior cingulate cortex. ©2005 Science Service.

Keyword: Pain & Touch
Link ID: 8319 - Posted: 06.24.2010

By Jennifer Viegas, Discovery News — Circus tigers increase their pacing ahead of performances, according to a new study whose authors believe that such behavior indicates the big cats positively anticipate their time on stage. The authors received cooperation and assistance from Feld Entertainment, Inc., the owners of Ringling Brothers and Barnum and Bailey Circus. Previously, the researchers analyzed other repetitive behavior, such as weaving, in circus elephants and came to a similar conclusion, which suggested the animals perked up before performing. "Elephants actually fight to do their act when they are held back," said Ted Friend, one of the researchers. "If the elephants are kept out of the ring, they will do their act outside." Friend, a professor in the Department of Animal Science at Texas A&M University, added, "That is what the elephants are accustomed to do. It's like humans going to work every day." He and his colleagues videotaped four tigers before and after performances for five days in 2002 and for four days in 2003. The researchers determined that pacing increased before performances. © 2005 Discovery Communications Inc.

Keyword: Learning & Memory; Emotions
Link ID: 8318 - Posted: 06.24.2010

Claire Ainsworth The seeds of sudden infant death syndrome seem to be planted in part by conditions in the mother's womb. The finding shows it is not just genetic factors that determine whether babies are predisposed to the tragic condition. And although it will not change doctors' advice to parents, it may shed some light on the causes of these mysterious deaths. Cot death, or sudden infant death syndrome (SIDS), is the name for the unexplained death of a baby, usually in its sleep. The condition strikes 1 in 2,000 babies in the developed world. Most cases are isolated. But it is known that a woman who has had one baby die from SIDS is five times more likely than other women to have a second baby die. This was once thought to cast suspicion on a mother's ability to care for her children. But it is now accepted that there are biological reasons for this recurrence, although it hasn't been clear what these are. To investigate, a team led by Gordon Smith, an obstetrician at the University of Cambridge, UK, studied the medical records of more than a quarter of a million women in Scotland. They compared three groups: those who had given birth to two surviving children; those whose first baby had died from SIDS, but whose second child did not; and those who first child did not die, but whose second baby did. ©2005 Nature Publishing Group

Keyword: Development of the Brain; Sleep
Link ID: 8317 - Posted: 06.24.2010

Mark Peplow A miniature chemistry set the size of a penny looks set to deliver faster, cheaper imaging agents for positron emission tomography (PET) scans, which are used to see inside patients' bodies. The microfluidic chip uses a tiny network of channels to shuttle chemicals around, and has valves and purification filters to perform a sequence of chemical steps. The result can produce a chemical that is crucial for PET scans much more quickly and with fewer reagents than a standard lab. This should make scans simpler and cheaper for hospitals. Microreactors are not a new idea, and are increasingly being used in research laboratories. But many rely on a continuous flow of material from one end of a miniature pipe to the other, without valves and filters. These continuous flow reactors are plagued by cross-contamination of reagents from different chemical steps, says Hsian-Rong Tseng, a pharmacologist at the University of California, Los Angeles, and part of the team that developed the device. This is a significant barrier to using such chips to make pharmaceuticals or other complex chemicals, he says. The valve-based chip is so versatile that it could become one of the first microreactors in widespread use outside the research lab, says Tseng. ©2005 Nature Publishing Group

Keyword: Brain imaging
Link ID: 8316 - Posted: 06.24.2010

When your host offers you red or white wine at her annual holiday party this year, there may be a good reason to choose red. In a series of laboratory tests, researchers in New York found new evidence that an antioxidant found in red wine, called resveratrol, helps clear away the basic building blocks of Alzheimer plaques. The finding, published in the Journal of Biological Chemistry, contributes to the growing body of research that suggests moderate red wine consumption may help prevent a number of diseases, including age-related dementias, heart disease, and cancer. The researchers, led by neurobiologists Philippe Marambaud and Peter Davies, say their study also identifies a previously unknown chemical pathway that may one day be tapped to design new drugs to fight Alzheimer's disease. "This is potentially a protective [compound], a compound that we could give you at age 40 or 50, whatever age you'd like to start, to protect against the development of Alzheimer's disease," says professor Davies from the Albert Einstein College of Medicine, who was the senior author on the paper. The researchers tested several different antioxidants on cells filled with amyloid peptides. © ScienCentral, 2000-2005

Keyword: Alzheimers
Link ID: 8315 - Posted: 06.24.2010

By Mary Beckman SAN FRANCISCO, CALIFORNIA--Some cancers keep to themselves as compact tumors while others aren't content until they've spread through the body. What makes one more aggressive than the other? One explanation, according to new research, is the presence of a protein normally found in neurons. Experts say the work may offer a new target in the fight against colon and other types of cancers. As cells become cancerous, they produce more of a protein called b-catenin. The protein acts like a molecular switch, turning specific genes on and off. Reasoning that b-catenin might turn on other genes that help cancers along, such as those that make them spread, cancer biologists Avri Ben-Ze'ev and Nancy Gavert of the Weizman Institute of Science in Israel and colleagues set about looking for such genes. Colleagues of Ben-Ze'ev had examined the effect of turning off b-catenin on other, unrelated functions within cells. In the current study, they scanned some of the genes involved in these processes and found a gene called L1CAM, whose protein is well-known to wire nerve cells together. To determine whether L1CAM has a role in cancer, the researchers looked for its protein in normal skin cells, cultured noncancerous cells, and aggressive melanomas from 11 patients. While the normal cells contained no L1CAM protein, the cancers harbored quite a lot. When the team blocked the activity of L1CAM in cultured human colon cancer cells, the cells' growth slowed dramatically. © 2005 American Association for the Advancement of Science.

Keyword: Genes & Behavior; Development of the Brain
Link ID: 8314 - Posted: 06.24.2010

by MELISSA CALHOUN ATHENS, Ohio -- Bats have an “ear” for flying in the dark because of a remarkable auditory talent that allows them to determine their physical environment by listening to echoes. But an Ohio University neurobiology professor says bats have a “feel” for it, too. John Zook’s studies of bat flight suggest that touch-sensitive receptors on bats’ wings help them maintain altitude and catch insects in midair. His preliminary findings, presented at the recent Society for Neuroscience meeting, revive part of a long-forgotten theory that bats use their sense of touch for nighttime navigation and hunting. The theory that bats fly by feel was first proposed in the 1780s by French biologist Georges Cuvier, but faded in the 1930s when researchers discovered echolocation, a kind of biological sonar found in bats, dolphins and a few other animals. Bats use echolocation to identify and navigate their environment by emitting calls and listening to the echoes that return from various objects. Zook believes the touch-sensitive receptors on bats’ wings work in conjunction with echolocation to make bats better, more accurate nocturnal hunters. Echolocation helps bats detect their surroundings, while the touch-sensitive receptors help them maintain their flight path and snag their prey. © 2005 Ohio University.

Keyword: Pain & Touch
Link ID: 8313 - Posted: 06.24.2010

Scientists have managed to protect and regenerate the part of the brain that is damaged in Parkinson’s disease, by genetically engineering cells to bypass the blood-brain barrier. The study was conducted in animals, but the approach could one day be used to treat brain conditions in humans, the researchers say. The blood-brain barrier protects the brain from harmful substances, but also prevents drugs from entering, so experimental treatments have involved injecting drugs directly into the brain. Now Clive Svensden at the University of Wisconsin-Madison, US, and colleagues have devised an alternative – implanting cells that act as a Trojan horse, churning out the drug from inside the brain’s fortress. The team took human neural progenitor cells (hNPCs) from fetal tissue at 10 to 15 weeks’ gestation. These have a lot in common with stem cells, though they have already differentiated into specific neural cells. The researchers genetically modified the cells to produce a growth molecule called glial cell line-derived neurotrophic factor (GDNF). This is produced naturally by the brain at around eight weeks’ gestation in humans, but by 20 weeks it has all gone. Previous studies show that GDNF increases the survival and function of dopamine-producing cells, which are progressively destroyed in Parkinson’s disease. © Copyright Reed Business Information Ltd.

Keyword: Stem Cells; Parkinsons
Link ID: 8312 - Posted: 06.24.2010

Will the 3-hour special-effects-loaded remake of King Kong be a box office smash or a complete turkey? For movie producers, getting such questions right can be worth millions, and now they have a computer system to help them work it out before a film is even made. The idea comes from Ramesh Sharda, an information scientist at Oklahoma State University in Stillwater, who has trained an artificial neural network to recognise what makes a successful movie (Expert Systems with Applications, vol 30, p 243). Using data on 834 movies released between 1998 and 2002, Sharda found that the neural network can judge a film based on seven key parameters: the "star value" of the cast, the movie's age rating, the time of release against that of competitive movies, the film's genre, the degree of special effects used, whether it is a sequel or not, and the number of screens it is expected to open in. This allowed it to place a movie in one of nine categories, ranging from "flop" (total takings less than $1 million) to "blockbuster" (over $200 million). The system cannot take into account the intricacies of the plot, but Sharda says it can nonetheless get the revenue category spot-on 37 per cent of the time, and correct to within one category either side 75 per cent of the time. This is enough to make the system a "powerful decision aid", Sharda says. © Copyright Reed Business Information Ltd.

Keyword: Learning & Memory
Link ID: 8311 - Posted: 06.24.2010

Usually squids simply drop their eggs on the sea floor and leave them to survive on their own, although some species of octopus are known to guard their clutch. But scientists captured on film the parental care lavished by Gonatus onyx on its eggs. Biologist Brad Seibel, now at the University of Rhode Island, US, suspected that Gonatus onyx might do more than most for its offspring when in 1995 he and colleagues dredged up both an adult and a separate egg sac in the same net while probing the seas. A year later, he captured another adult and many baby squids in the same net, which led him and colleagues to hypothesise that the squid might be brooding its eggs until hatching. “But without direct observations, there were many that were sceptical,” he told New Scientist. Working with Bruce Robison and Steven Haddock at the Monterey Bay Aquarium Research Institute in California, US, Seibel has now captured images of the protective parent by delving to depths of 2500 metres in a submersible. You can view a video of the squid hatching its young by clicking here (mpg format, 6MB), and see the squid with its cumbersome egg sac fleeing from the submersible here (mpg format, 6MB). © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior
Link ID: 8310 - Posted: 06.24.2010