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February 26, 2007, 8:51 PM CT

Menstrual Cycle And The Female Brain

Menstrual Cycle And The Female Brain
What influence does the variation in estrogen level have on the activation of the female brain? Using functional Magnetic Resonance Imaging, Jean-Claude Dreher, a researcher at the Cognitive Neuroscience Center (CNRS/Universit Lyon 1), in collaboration with an American team from the National Institute of Mental Health (Bethesda, Maryland) directed by Karen Berman, has identified, for the first time, the neural networks involved in processing reward-related functions modulated by female gonadal steroid hormones. This result, which was published online on January 29, 2007 on the PNAS website, is an important step in better comprehension of certain psychiatric and neurological pathologies.

The human brain has a recompense system that predicts different types of reward (food, money, drugs). The normal functioning of this system plays a fundamental role in a number of cognitive processes such as motivation and learning. This reward system, composed of dopaminergic neurons1 situated in the mesencephalon (a very deep region of the brain) and their projection sites2, is crucial for neural coding of rewards. Its dysfunction can result in disorders such as addictions and is also implicated in various psychiatric and neurological pathologies, such as Parkinson's disease and schizophrenic disorders. A number of studies on animals prove that the dopaminergic3 system is sensitive to gonadal steroid hormones (estrogen, progesterone). For example, female rats self-administer cocaine (a drug that acts on the dopamine system) in higher doses after estrogens have been administered to them. The influence of gonadal steroid hormones on the activation of the reward system remained to be studied in humans. A better knowledge of this influence should make for better understanding of the differences between men and women, especially as observed in the prevalence of certain psychiatric pathologies and in vulnerability to drugs, (for which the dopaminergic system plays an important role.) It is known, for example, that the female response to cocaine is greater in the follicular phase of the menstrual cycle4 than in the luteal phase5.Moreover, schizophrenia tends to appear later in women than in men.........

Posted by: Emily      Read more         Source


February 21, 2007, 9:02 PM CT

Reduced Brain Growth In Alcoholics

Reduced Brain Growth In Alcoholics
The brains of alcohol-dependent individuals are affected not only by their own heavy drinking, but also by genetic or environmental factors linked to their parents drinking, as per a new study by scientists at the National Institute on Alcohol Abuse and Alcoholism (NIAAA), part of the National Institutes of Health (NIH). Scientists found reduced brain growth among alcohol-dependent individuals with a family history of alcoholism or heavy drinking in comparison to those with no such family history. Their report has been published online in Biological Psychiatry at http://www.sciencedirect.com/science/journal/00063223 as an article in press.

"This is interesting new information about how biological and environmental factors might interact to affect children of alcoholics," notes George Kunos M.D., Ph.D., Scientific Director, Division of Intramural Clinical and Biological Research, NIAAA.

A number of studies have shown that alcohol-dependent men and women have smaller brain volumes than non-alcohol-dependent individuals. It is widely believed that this is due to the toxic effects of ethanol, which causes the alcoholics brain to shrink with aging to a greater extent than the non-alcoholics.

"Our study is the first to demonstrate that brain size among alcohol-dependent individuals with a family history of alcoholism is reduced even before the onset of alcohol dependence," explains first author Jodi Gilman, B.S., a NIAAA research fellow and Ph.D. candidate at Brown University working with senior author Daniel Hommer, M.D., of the NIAAA Laboratory of Clinical and Translational Studies (LCTS) and co-author James Bjork, Ph.D., also of the NIAAA/LCTS.........

Posted by: Daniel      Read more         Source


February 20, 2007, 9:10 PM CT

Cause Of Chronic Dizziness

Cause Of Chronic Dizziness
Approximately 9 million to 15 million people in the U.S. suffer from recurrent bouts of dizziness and 3 million experience symptoms of dizziness nearly every day. As per a paper that appears in the recent issue of Archives of OtolaryngologyHead & Neck Surgery, scientists at the University of Pennsylvania School of Medicine observed that chronic subjective dizziness (CSD) may have several common causes, including anxiety disorders, migraine, mild traumatic brain injuries, and neurally mediated dysautonomias disorders in the autonomic nervous system, which controls involuntary actions.

Among the various forms of dizziness, clinicians have found CSD to be especially vexing. "Patients with CSD experience persistent dizziness not correlation to vertigo, imbalance, and hypersensitivity to motion, which is heightened in highly visual settings, such as walking in a busy store or driving in the rain," says Jeffrey P. Staab, MD, MS, Assistant Professor, Departments of Psychiatry and Otorhinolaryngology at Penn, and coauthor of the paper.

Staab and coauthor, Michael J. Ruckenstein, MD, Associate Professor Department of Otorhinolaryngology at Penn, studied 345 men and women age 15 to 89 (average age 43.5) who had dizziness for three months or longer due to unknown causes. From 1998 to 2004, the patients were tracked from their referral to Penns balance center through multiple specialty examinations until they were given a diagnosis.........

Posted by: Daniel      Read more         Source


February 15, 2007, 7:11 AM CT

Alzheimers Research Initiated At UCSB

Alzheimers Research Initiated At UCSB
Michael Bowers, a professor in the Department of Chemistry and Biochemistry, developed this project, which is being funded by the National Institutes of Health. Bowerss laboratory will receive $1.3 million of the total $9 million project grant, plus biological samples worth an additional $500,000. The grant covers a five-year period. Four institutions are involved.

Bowers is using specialized chemical research methods and applying them to biology. His research will depend upon the study of rare peptides, or strings of amino acids, that are difficult to produce. These will be provided by co-investigator David Teplow, a professor at UCLAs David Geffen School of Medicine, who has been involved in Alzheimers research for over 10 years. Joan-Emma Shea, also a professor in UCSBs Department of Chemistry and Biochemistry, heads the theoretical modeling aspect of the project.

Until about five or six years ago, everyone assumed that the large amyloid plaques, or neurofibrillary tangles, that were found in the brains of Alzheimers victims were the cause of the disease, said Bowers. However, recent scientific discoveries indicate that these large, insoluble aggregates might merely be markers of the disease they do not cause the disease. Rather, smaller soluble oligomers, or peptide complexes, are now felt to be the causative agents, and I find that very interesting.........

Posted by: Daniel      Read more         Source


February 12, 2007, 9:11 PM CT

Be around friends to impair your memory

Be around friends to impair your memory
Youre watching a basketball game with some buddies and decide to order pizza during the commercial. Scientists from Indiana University observed that people in a group setting exposed to brand information such as an ad for Pizza Hut -- have a hard time recalling the brands competitors. In other words, being around friends when deciding where to order takeout might cause you to forget completely about that local pizza place youve been wanting to try.

"When groups of individuals are exposed to brands in the shopping environment, their memory for other brands within the same product category is impaired," write Charles D. Lindsey and H. Shanker Krishnan (Indiana University). "The current research examines retrieval in a collaborative group setting, which is a novel context for brand memory research".

Appearing in the recent issue of the Journal of Consumer Research, the study observed that this effect is magnified for very familiar brands. Lindsey and Krishnan argue that this happens because individuals in the group are exposed not only to the advertisement but also to mentions of the brand by other members of the group.

"The practical implications of this research imply that a group premium (over and above the standard market share premium) seems to exist for advertising brands during programming where a higher percentage of viewers are group-based," conclude the authors.........

Posted by: Daniel      Read more         Source


February 7, 2007, 5:00 AM CT

Children who sleep less more likely to be overweight

Children who sleep less more likely to be overweight
Research indicates that getting inadequate sleep has negative effects on children's social and emotional well-being and school performance. Now a Northwestern University study finds it also increases their risk of being overweight.

The study -- conducted in two waves of data collection approximately five years apart -- is the first nationally representative, longitudinal investigation of the relationship between sleep, Body Mass Index (BMI) and overweight status in children aged 3 to 18.

"Our study suggests that earlier bedtimes, later wake times and later school start times could be an important and relatively low-cost strategy to help reduce childhood weight problems," says Emily Snell. Snell is co-author of "Sleep and the Body Mass Index and Overweight Status of Children and Adolescents" in the Jan./Feb. issue of Child Development.

"We found even an hour of sleep makes a big difference in weight status," said Snell, a Northwestern doctoral student in human development and social policy. "Sleeping an additional hour reduced young children's chance of being overweight from 36 percent to 30 percent, while it reduced older children's risk from 34 percent to 30 percent."

The Northwestern study not only differs from most other investigations of the effects of sleep on children's weight in its five-year approach. It also helps disentangle the issue of whether sleep actually affects weight or whether children who already are overweight are simply poor sleepers. In addition, it takes into account the possible effects of other variables including race, ethnicity and income.........

Posted by: JoAnn      Read more         Source


February 5, 2007, 9:32 PM CT

Two Brains: Connected?

Two Brains: Connected?
The nerve cells of the brain are inter-connected to a complex network. All brain activities are the result of the "firing" of nerve cells, when they send electrical pulses - like a Morse code - to other cells of the brain. This process depends on the exact dynamics of the neuronal activity. When the brain receives sensory input, calculates or remembers, it processes information encoded in a series of neuronal impulses in different nerve cells. Eventhough no two people have the same brain, they can still share the same thought. Thus, only to a certain extent is the dynamics of neuronal activity dependent on the structure of neuronal networks. For networks far simpler than that of the human brain this idea also applies: different structures can display the same functionality. Raoul-Martin Memmesheimer and Marc Timme, scientists at the Max Planck Institute for Dynamics and Self-Organization and the Bernstein Center for Computational Neuroscience Gottingen, have developed a mathematical method to describe the set of all networks that exhibit a given dynamics. With this, they provide scientists with a tool which can be used to investigate the connection between structure and function of a neuronal network.

A common approach in scientific research is to investigate the structure of a system in order to then draw conclusions about its function. Memmesheimer and Timme now took the reverse perspective. "For some simple networks we know the activity dynamics, that is, their function, but not their exact structure", explains Memmesheimer. "Any given dynamics can normally be created by a variety of different networks. We have developed a method to mathematically pin down this diversity". This procedure resembles juggling with a number of unknown quantities and requires great computational power. Already in a network of 1000 neurons (where each neuron can be connected to any other) there are a million possible contacts between any two neurons and consequently an unimaginably large number of possible networks. Each combination can have either an inhibiting or an activating effect on the downstream neuron and, in addition to this, can differ in its intensity and reaction time. The entirety of all possible networks of a defined dynamics resembles a complex figure in a multidimensional space. Here, every point on the surface specifies the data mandatory to determine a network with the desired dynamics. Memmesheimer and Timme have now worked out a mathematical description for this figure.........

Posted by: Daniel      Read more         Source


January 31, 2007, 8:12 PM CT

MRI Better Than CT For Diagnosis Of Stroke

MRI Better Than CT For Diagnosis Of Stroke
Results from the most comprehensive study to compare two imaging techniques for the emergency diagnosis of suspected acute stroke show that magnetic resonance imaging (MRI) can provide a more sensitive diagnosis than computed tomography (CT) for acute ischemic stroke. The difference between MRI and CT was attributable to MRI's superiority for detection of acute ischemic stroke - the most common form of stroke, caused by a blood clot. The study was conducted by physicians at the National Institute of Neurological Disorders and Stroke (NINDS), a part of the National Institutes of Health (NIH). Findings are reported in the January 27, 2007 edition of The Lancet[1].

"These NIH research findings on acute stroke imaging are directly applicable to real-world clinical practice," said NIH Director Elias A. Zerhouni, M.D. "The patients involved in this study were the typical cross-section of suspected stroke patients that come into emergency rooms on a daily basis".

Furthermore, the study has good news for patients, as per Walter J. Koroshetz, M.D., NINDS Deputy Director. "This study shows that approximately 25 percent of stroke patients who come to the hospital within three hours of onset, the time frame for approved clot-busting treatment, have no detectable signs of damage. In other words, brain injury may be completely avoided in some stroke victims by quick re-opening of the blocked blood vessel," said Dr. Koroshetz.........

Posted by: Daniel      Read more         Source


January 24, 2007, 6:34 PM CT

Gene That May Predispose To Schizophrenia

Gene That May Predispose To Schizophrenia
In a new study from The American Journal of Human Genetics, a research team lead by Xinzhi Zhao and Ruqi Tang (Shanghai Jiao Tong University) present evidence that genetic variation may indicate predisposition to schizophrenia. Specifically, their findings identify the chitinase 3-like 1 gene as a potential schizophrenia-susceptibility gene and suggest that the genes involved in biological response to adverse conditions are likely associated with schizophrenia.

Analyzing two separate cohorts of Chinese patients with schizophrenia, the scientists observed a positive association between schizophrenia and genetic variations in the promoter region of the chitinase 3-like 1 (CHI3L1) gene, an association that was significant in both population-based and family-based investigations.

The CHI3L1 gene acts as a survival factor in response to adverse environments, countering various types of physiological stress, such as inflammation, nutrient deprivation, and oxygen deficiency, all of which may induce high expression of CHI3L1. The gene is located on chromosome 1q32.1, a region that has been previously shown to have a weak related to schizophrenia.

Many environmental factors, including prenatal exposure to disease, have been reported as risk factors of schizophrenia. However, the scientists argue that sensitivity to environmental stressors varies widely among individuals, and "at least part of this variation may be genetic in origin and/or involve gene-environment factors," they write.........

Posted by: JoAnn      Read more         Source


January 16, 2007, 5:03 AM CT

Growth Hormone Is Not The Anti-aging Bullet

Growth Hormone Is Not The Anti-aging Bullet Pituitary gland is the source of growth hormone
A review of published data on use of human growth hormone (GH) by healthy elderly people observed that the synthetic hormone was linked to small changes in body composition but not in body weight or other clinically important outcomes.

Further, people who took GH had increased rates of unhealthy side effects such as soft tissue swelling, joint pain, carpal tunnel syndrome, and, in men, abnormal breast development. They were also somewhat more likely to develop diabetes.

The review, "The Safety and Efficacy of Growth Hormone in the Healthy Elderly," was reported in the Jan. 16, 2007, issue of Annals of Internal Medicine and is available on the Web at www.annals.org on that day.

"Growth hormone has been widely promoted as an anti-aging treatment," said Hau Liu, MD, a research fellow in endocrinology and health policy at Stanford University and an author of the review.

"But the scant clinical experience of GH in the healthy elderly suggests that eventhough GH may minimally alter body composition, it does not improve other clinically relevant outcomes such as bone density, cholesterol levels, stamina, and longevity in this population.

"And it's linked to high rates of adverse events.

"So, on the basis of available evidence, we cannot recommend growth hormone use for anti-aging in the healthy elderly."........

Posted by: Janet      Read more         Source



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Did you know?
The drug Ativan is better than Valium or Dilantin for controlling severe epileptic seizures, according to a new review of studies.Ativan, or lorazepam, and Valium, or diazepam, are both benzodiazepines, the currently preferred class of drugs for treating severe epileptic seizures. Dilantin, or phenytoin, is an anticonvulsant long used for the treatment of epileptic seizures.

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