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December 9, 2007, 5:18 PM CT

Neurons in the frontal lobe may be responsible

Neurons in the frontal lobe may be responsible
You study the menu at a restaurant and decide to order the steak rather than the salmon. But when the waiter tells you about the lobster special, you decide lobster trumps steak. Without reconsidering the salmon, you place your orderall because of a trait called transitivity.

Transitivity is the hallmark of rational economic choice, says Camillo Padoa-Schioppa, a postdoctoral researcher in HMS Professor of Neurobiology John Assads lab. As per transitivity, if you prefer A to B and B to C, then you ought to prefer A to C. Or, if you prefer lobster to steak, and steak to salmon, then you will prefer lobster to salmon.

Padoa-Schioppa is lead author on a paper that suggests this trait might be encoded at the level of individual neurons. The study, which appears online Dec. 9 in Nature Neuroscience, shows that some neurons in a part of the brain called the orbitofrontal cortex encode economic value in a menu invariant way. That is, the neurons respond the same to steak regardless if its offered against salmon or lobster.

People make choices by assigning values to different options. If the values are menu invariant preferences will be transitive. The activity of these neurons does not vary with the menu options, suggesting that these neurons could be responsible for transitivity, Padoa-Schioppa explains.........

Posted by: Daniel      Read more         Source


December 2, 2007, 8:56 PM CT

Short, long sleep duration and increased mortality

Short, long sleep duration and increased mortality
A study reported in the December 1 issue of the journal SLEEP is the first to show that both a decrease and an increase in sleep duration are linked to an elevated risk of mortality by cardiovascular and non-cardiovascular means, respectively.

The study, authored by Jane E. Ferrie, PhD, of the University College London Medical School in London, U.K., focused on 10,308 participants between 35 and 55 years of age. Baseline screening (Phase 1), conducted between 1985 and 1988, involved a clinical examination and a self-administered questionnaire. Data collection at Phase 3 (1992-1993) also included a clinical examination (8,104 participants) and questionnaire (8,642 participants).

As per the results, U-shaped associations were observed between sleep at Phase 1 and Phase 3 and subsequent all-cause, cardiovascular and non-cardiovascular mortality. A decrease in sleep duration among participants sleeping six, seven or eight hours at baseline was linked to a 110 percent excess risk of cardiovascular mortality. However, an increase in sleep duration among those sleeping seven or eight hours at baseline was linked to a 110 percent excess risk of non-cardiovascular mortality. Adjustment for the socio-demographic factors, existing mortality and health-related behaviors measured left these associations largely unchanged.........

Posted by: Janet      Read more         Source


December 2, 2007, 8:18 PM CT

A real attention grabber

A real attention grabber
The person youre speaking with may be looking at you, but are they really paying attention" Or has the person covertly shifted their attention, without moving their eyes" Dr. Brian Corneil, of the Centre for Brain and Mind at The University of Western Ontario in London, Canada has found a way of actually measuring covert attention. His research Neuromuscular consequences of reflexive covert orienting is posted on the Advance Online Publication of "Nature Neuroscience".

Our results demonstrate for the first time that covert attention can be measured in real-time via recordings of muscle activity in the neck, says Corneil, an assistant professor of physiology & pharmacology and psychology. This finding may fundamentally change how attention is measured, grounding it in an objective and straightforward technique.

Until now, measuring attention was based on indirect measures of changes in reaction time, or stimulus detection. In furthering our understanding of how the brain works, Corneil has discovered that neck muscles are recruited during covert orienting, even in the absence of eye movements. This finding could help in assessing the effectiveness of therapies for stroke or other neurodegenerative disorders such as Parkinsons disease.........

Posted by: Daniel      Read more         Source


November 29, 2007, 3:57 PM CT

Club drugs inflict damage to brain

Club drugs inflict damage to brain
What do suffering a traumatic brain injury and using club drugs have in common".

University of Florida scientists say both may trigger a similar chemical chain reaction in the brain, leading to cell death, memory loss and potentially irreversible brain damage.

A series of studies at UF over the past five years has shown using the popular club drug Ecstasy, also called MDMA, and other forms of methamphetamine lead to the same type of brain changes, cell loss and protein fluctuations in the brain that occur after a person endures a sharp blow to the head, as per findings a UF researcher presented at a Society for Neuroscience conference held in San Diego this month.

Using methamphetamine is like inflicting a traumatic brain injury on yourself, said Firas Kobeissy, a postdoctoral associate in the College of Medicine department of psychiatry. We observed that a lot of brain cells are being injured by these drugs. Thats alarming to society now. People dont seem to take club drugs as seriously as drugs such as heroin or cocaine.

Working with UF scientists Dr. Mark Gold, chief of the division of addiction medicine at UFs McKnight Brain Institute and one of the countrys leading experts on addiction medicine, and Kevin Wang, director of the UF Center for Neuroproteomics and Biomarkers Research, Kobeissy compared what happened in the brains of rats given large doses of methamphetamine with what happened to those that had suffered a traumatic brain injury.........

Posted by: Daniel      Read more         Source


November 19, 2007, 8:32 PM CT

Gene therapy normalizes brain function in Parkinson's patients

Gene therapy normalizes brain function in Parkinson's patients
Brain scans used to track changes in a dozen patients who received an experimental gene treatment show that the therapy normalizes brain function - and the effects are still present a year later.

Andrew Feigin, MD, and David Eidelberg, MD, of The Feinstein Institute for Medical Research collaborated with Michael Kaplitt, MD, of Weill Cornell Medical Center in Manhattan and others to deliver genes for glutamic acid decarboxylase (or GAD) into the subthalamic nucleus of the brain in Parkinsons patients. The study was designed as a phase I safety study, and the genes were delivered to only one side of the brain to reduce risk and to better assess the therapy.

A recently published study included the clinical results of the novel gene treatment trial, but this new report from the same study focuses on the power of modern brain scans to show that the gene treatment altered brain activity in a favorable way. This latest study is published this week in the Proceedings of the National Academy of Sciences.

The patients only received the viral vector-carrying genes to the side of the brain that controls movement on the side of their body most affected by the disease. It was a so-called open-label study -- everybody received the gene treatment so the researchers knew that there could be a placebo effect. That is why brain scans were so critical to the experiment. Dr. Eidelberg and colleagues pioneered the technology and used it to identify brain networks in Parkinsons disease and many other neurological disorders.........

Posted by: Daniel      Read more         Source


November 14, 2007, 9:52 PM CT

Cellular machinery that enables neurons to fire

Cellular machinery that enables neurons to fire
Neurons
If you ever had a set of Micronauts toy robots with removable body parts you probably had fun swapping their heads, imagining how it would affect their behavior. Researchers supported by the National Institutes of Health have been performing similar experiments on ion channels pores in our nerve cells to sort out the channels' key functional parts.

In the November 15 issue of Nature, one group of scientists shows that a part of ion channels called the paddle is uniquely transplantable between different channels. Writing in the same issue, another group exploited this property to probe the three-dimensional structure of ion channels on an atomic scale.

"The effects of a number of toxins and therapeutic drugs, as well as some diseases, can be wholly explained by changes in ion channel function," says Story Landis, Ph.D., director of the National Institute of Neurological Disorders and Stroke (NINDS), part of the NIH. "We also know that ion channels are at least a contributing player in epilepsy, chronic pain, Parkinson's disease and other disorders. As we learn more about how channels work, we're able to pursue more approaches to therapy".

Ion channels are proteins that control the flow of electrically charged salt particles (ions) across the nerve cell membrane. It's the opening and closing of these channels that enables nerve cells to fire off bursts of electrical activity. A built-in voltmeter, called a voltage sensor, pops the channel open when the nerve cell is ready to fire. The papers in Nature hone in on a part of the voltage sensor called the paddle, named for its shape.........

Posted by: Daniel      Read more         Source


November 12, 2007, 8:41 PM CT

Towards Spinal Cord Reconstruction Following Injury

Towards Spinal Cord Reconstruction Following Injury
A new study has identified what may be a pivotal first step towards the regeneration of nerve cells following spinal cord injury, using the body's own stem cells.

This seminal study, published in this week's Proceedings of the National Academy of Science, identifies key elements in the body's reaction to spinal injury, critical information that could lead to novel therapies for repairing previously irreversible nerve damage in the injured spinal cord. Very little is known about why, unlike a wound to the skin for example, the adult nervous system is unable to repair itself following spinal injury. This is in contrast to the developing brain and non-mammals which can repair and regenerate after severe injuries. One clue from these systems has been the role of stem cells and their potential to develop into different cell types.

"Because of their regenerative role, it is crucial to understand the movements of stem cells following brain or spinal cord injury," says Dr. Philip Horner, co-lead investigator and neuroscientist at the University of Washington. "We know that stem cells are present within the spinal cord, but it was not known why they could not function to repair the damage. Surprisingly, we discovered that they actually migrate away from the lesion and the question became why - what signal is telling the stem cells to move."........

Posted by: Daniel      Read more         Source


November 8, 2007, 9:52 PM CT

Tracking Nerve-Cell Development in Live Human Brain

Tracking Nerve-Cell Development in Live Human Brain
A team of researchers including scientists at Cold Spring Harbor Laboratory (CSHL) have identified and validated the first biomarker that permits neural stem and progenitor cells (NPCs) to be tracked, non-invasively, in the brains of living human subjects. This important advance could lead to significantly better diagnosis and monitoring of brain tumors and a range of serious neurological and psychiatric disorders.

The biomarker is a lipid molecule whose presence the researchers were able consistently to detect in a part of the brain called the hippocampus where new nerve cells are known to be generated. The marker was not detected in the cortex and other parts of the brain where this process, called neurogenesis, does not occur in healthy adults.

As elsewhere in the body, the rise of new cells in the brain is a process that can be traced to stem cells, which, through mechanisms still only partly grasped, give birth to "daughter" progenitor cells that undergo repeated division and maturation into "adult" cells. As recently as a few years ago, most researchers did not think that new nerve cells were created anywhere in the adult brain.

The newly discovered marker can be detected when NPCs - stem-like "progenitor" cells - are actively dividing, a mark that new nerve cells are being created. "Until now, there was no way to identify and track these cells in living people, to get a dynamic picture of neurogenesis," said Grigori Enikolopov, Ph.D.........

Posted by: Daniel      Read more         Source


November 8, 2007, 9:47 PM CT

Discovery That May Lead To Safe Treatment For High Blood Pressure

Discovery That May Lead To Safe Treatment For High Blood Pressure
Jason Koski/University Photography
Frank Schroeder inserts a natural product sample into a nuclear magnetic resonance spectrometer in the Department of Chemistry and Chemical Biology. NMR spectroscopy has evolved into the most important tool for identifying new biologically active compounds.
For more than 40 years, scientists have suspected there must be a natural hormone that could safely flush sodium out of the body and could be harnessed to develop more effective and safer therapys for high blood pressure, or hypertension. Currently, drugs that lower sodium levels all have serious side effects because they also reduce potassium levels.

Scientists at Cornell and the Boyce Thompson Institute for Plant Research (BTI) have used a new technique and identified a hormone from human urine -- a xanthurenic-acid derivative -- that seems able to do the job. The discovery opens the door to developing novel medications to control sodium levels and treat hypertension.

Frank Schroeder, an assistant scientist at BTI and co-author of the paper, which appeared in a recent issue of Proceedings of the National Academy of Sciences, developed a new technique for analyzing complex mixtures of small molecules, making it possible to finally identify the hormone.

Previous to the discovery, scientists knew that a human steroid called aldosterone activates the kidney to reabsorb sodium and excrete potassium, which led them to suspect that there must be another hormone that would trigger the kidney to do the opposite: excrete sodium and reabsorb potassium. A number of had tried to find such a hormone in human urine, but urine contains a mix of hundreds of molecules, and the correct one could not be isolated, probably because the suspected hormone breaks down easily during traditional chemical analysis.........

Posted by: Daniel      Read more         Source


November 7, 2007, 9:32 PM CT

How the brain sends eyeballs bouncing

How the brain sends eyeballs bouncing
All vision, including reading this sentence, depends on a constant series of infinitesimal jumps by the eyeball that centers the retina on target objectswords or phrases in the case of reading. Such jumps, or saccades, are critical to vision because only the small central region of the retina, called the fovea, produces the clear image necessary for perception. Such saccades take place several times a second and are generated within a brain region known as the frontal eye field (FEF).

In studies with monkeys, Robert Schafer and Tirin Moore have taken an important step in understanding how circuitry of the FEF generates saccadeswith the FEFs attentional circuitry governing the motor circuitry that produces saccades. The scientists published their findings in the November 8, 2007, issue of the journal Neuron, published by Cell Press.

In a preview of the paper in the same issue of Neuron, Stefan Everling wrote that the scientists findings are exciting, because they demonstrate that attention and action interact more closely in the FEF than previously thought, and they suggest a mechanism by which attention can modulate saccade motor commands. Everling is at the University of Western Ontario in Canada.

In their experiments, Schafer and Moore took advantage of a well-known optical phenomenon involving the influence of the motion of a drifting grating on saccades that target the grating. The moving grating causes a motion-induced bias of saccades; for example, if the eye makes a saccade to a grating that is drifting upward, that saccade to the grating is biased to land higher than it would if the grating were stationary.........

Posted by: Mike      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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