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November 19, 2008, 8:41 PM CT

How brain makes sense of natural scenes

How brain makes sense of natural scenes
Computational neuroresearchers at Carnegie Mellon University have developed a computational model that provides insight into the function of the brain's visual cortex and the information processing that enables people to perceive contours and surfaces, and understand what they see in the world around them.

A type of visual neuron known as simple cells can detect lines, or edges, but the computation they perform is insufficient to make sense of natural scenes, said Michael S. Lewicki, associate professor in Carnegie Mellon's Computer Science Department and the Center for the Neural Basis of Cognition. Edges often are obscured by variations in the foreground and background surfaces within the scene, he said, so more sophisticated processing is necessary to understand the complete picture. But little is known about how the visual system accomplishes this feat.

In a paper published online by the journal Nature, Lewicki and his graduate student, Yan Karklin, outline their computational model of this visual processing. The model employs an algorithm that analyzes the myriad patterns that compose natural scenes and statistically characterizes those patterns to determine which patterns are most likely linked to each other.

The bark of a tree, for instance, is composed of a multitude of different local image patterns, but the computational model can determine that all these local images represent bark and are all part of the same tree, as well as determining that those same patches are not part of a bush in the foreground or the hill behind it.........

Posted by: Daniel      Read more         Source


November 18, 2008, 5:15 AM CT

Gene associated with epilepsy

Gene associated with epilepsy
A University of Iowa-led international research team has found a new gene linked to the brain disorder epilepsy. While the PRICKLE1 gene mutation was specific to a rare form of epilepsy, the study results could help lead to new ideas for overall epilepsy therapy.

The findings, which involved nearly two dozen institutions from six different countries, appear in the Nov. 7 issue of the American Journal of Human Genetics

In epilepsy, nerve cells in the brain signal abnormally and cause repeated seizures that can include strange sensations, severe muscle spasms and loss of consciousness. The seizures may not have lasting effects but can affect activities, such as limiting a person's ability to drive. Most seizures do not cause brain damage but some types of epilepsy lead to physical disabilities and cognitive problems. Medications can control symptoms, but there is no cure.

"The study results were surprising not only because the PRICKLE1 gene had never been linked to epilepsy but also because the gene was not linked to any other human disease," said the study's lead author Alex Bassuk, M.D., Ph.D., assistant professor of pediatrics at the University of Iowa Carver College of Medicine and a pediatric neurologist with University of Iowa Children's Hospital.........

Posted by: Daniel      Read more         Source


November 18, 2008, 5:13 AM CT

Exercise increases brain growth factor

Exercise increases brain growth factor
A new study confirms that exercise can reverse the age-related decline in the production of neural stem cells in the hippocampus of the mouse brain, and suggests that this happens because exercise restores a brain chemical which promotes the production and maturation of new stem cells.

Neural stem cells and progenitor cells differentiate into a variety of mature nerve cells which have different functions, a process called neurogenesis. There is evidence that when fewer new stem or progenitor cells are produced in the hippocampus, it can result in impairment of the learning and memory functions. The hippocampus plays an important role in memory and learning.

The study, "Exercise enhances the proliferation of neural stem cells and neurite growth and survival of neuronal progenitor cells in dentate gyrus of middle-aged mice," was carried out by Chih-Wei Wu, Ya-Ting Chang, Lung Yu, Hsiun-ing Chen, Chauying J. Jen, Shih-Ying Wu, Chen-Peng Lo, Yu-Min Kuo, all of the National Cheng Kung University Medical College in Taiwan. The study appears in the recent issue of the Journal of Applied Physiology, published by The American Physiological Society.

Rise in corticosterone or fall in nerve growth factor?

The scientists built on earlier studies that observed that the production of stem cells in the area of the hippocampus known as the dentate gyrus drops off dramatically by the time mice are middle age and that exercise can slow that trend. In the current study, the scientists wanted to track these changes in mice over time, and find out why they happen.........

Posted by: Daniel      Read more         Source


November 14, 2008, 9:42 PM CT

When You Look at a Face, You Look Nose First

When You Look at a Face, You Look Nose First
While general wisdom says that you look at the eyes first in order to recognize a face, UC San Diego computer researchers now report that you look at the nose first.

The nose may be the where the information about the face is balanced in all directions, or the optimal viewing position for face recognition, the scientists from UC San Diego's Jacobs School of Engineering propose in a paper recently reported in the journal Psychological Science.

The scientists showed that people first look just to the left of the center of the nose and then to the center of the nose when trying to determine if a face is one they have seen recently. These two visual "fixations" near the center of the nose are all you need in order to determine if a face is one that you have seen just a few minutes before. Looking at a third spot on the face does not improve face recognition, the cognitive researchers found.

Understanding how the human brain recognizes faces may help cognitive researchers create more realistic models of the brain-models that could be used as tools to train or otherwise assist people with brain lesions or cognitive challenges, explained Janet Hsiao, the first author on the Psychological Science paper and a postdoctoral researcher in the computer science department at UC San Diego.........

Posted by: Daniel      Read more         Source


November 14, 2008, 9:02 PM CT

How the brain takes care of things

How the brain takes care of things
Store room for future learning: nerve cells retain many of their newly created connections and if necessary, inactivate only transmission of the information. This makes relearning easier.

Image: Max Planck Institute of Neurobiology / Hofer
Thanks to our ability to learn and to remember, we can perform tasks that other living things can not even dream of. However, we are only just beginning to get the gist of what really goes on in the brain when it learns or forgets something. What we do know is that changes in the contacts between nerve cells play an important role. But can these structural changes account for that well-known phenomenon that it is much easier to re-learn something that was forgotten than to learn something completely new? Researchers at the Max Planck Institute of Neurobiology have been able to show that new cell contacts established during a learning process stay put, even when they are no longer required. The reactivation of this temporarily inactivated "stock of contacts" enables a faster learning of things forgotten. (Nature, November 12, 2008).

While an insect still flings itself against the window-pane after dozens of unsuccessful attempts to gain its freedom, our brain is able to learn very complex associations and sequences of movement. This not only helps us to avoid accidents like walking into glass doors, but also enables us to acquire such diverse skills as riding a bicycle, skiing, speaking different languages or playing an instrument. Eventhough a young brain learns more easily, we retain our ability to learn up to an advanced age. For a long time, researchers have been trying to ascertain exactly what happens in the brain while we learn or forget.........

Posted by: Daniel      Read more         Source


November 13, 2008, 10:28 PM CT

Protecting neurons could halt Alzheimer's

Protecting neurons could halt Alzheimer's
Scientists at Southern Methodist University (SMU) and The University of Texas at Dallas (UTD) have identified a group of chemical compounds that slow the degeneration of neurons, a condition behind old-age diseases like Alzheimer's, Parkinson's and amyotrophic lateral sclerosis (ALS).

Their findings are featured in the November 2008 edition of Experimental Biology and Medicine SMU Chemistry Professor Edward R. Biehl and UTD Biology Professor Santosh D'Mello teamed to test 45 chemical compounds. Four were found to be the most potent protectors of neurons, the cells that are core components of the human brain, spinal cord and peripheral nerves.

The most common cause of neurodegenerative disease is aging. Current medications only alleviate the symptoms but do not affect the underlying cause degeneration of neurons. The identification of compounds that inhibit neuronal death is of urgent and critical importance.

The synthesized chemicals identified by Biehl and D'Mello, called "3-substituted indolin-2-one compounds" are derivatives of another compound called GW5074 which was shown to prevent neurodegeneration in a past report published by the D'Mello lab. While effective at protecting neurons from decay or death, GW5074 is toxic to cells at slightly elevated doses, which makes it unsuitable for clinical testing in patients.........

Posted by: Daniel      Read more         Source


November 12, 2008, 10:37 PM CT

Hormone shows promise in reversing Alzheimer's disease

Hormone shows promise in reversing Alzheimer's disease
Saint Louis University scientists have identified a novel way of getting a potential therapy for Alzheimer's disease and stroke into the brain where it can do its work.

"We found a unique approach for delivering drugs to the brain," says William A. Banks, M.D., professor of geriatrics and pharmacological and physiological science at Saint Louis University. "We're turning off the guardian that's keeping the drugs out of the brain".

The brain is protected by the blood-brain barrier (BBB), a gate-keeping system of cells that lets in nutrients and keeps out foreign substances. The blood-brain barrier passes no judgment on which foreign substances are trying to get into the brain to treat diseases and which are trying to do harm, so it blocks them without discrimination.

"The problem in treating a lot of diseases of the central nervous system such as Alzheimer's disease, HIV and stroke is that we can't get drugs past the blood-brain barrier and into the brain," says Banks, who also is a staff doctor at Veterans Affairs Medical Center in St. Louis.

"Our new research shows a way of getting a promising therapy for these types of devastating diseases to where they need to be to work".

The treatment known as PACAP27 -- is a hormone produced by the body that is a general neuro-protectant. PACAP stands for pituitary adenylate cyclase-activating polypeptide. "It is a general protector of the brain against a number of types of insult and injury," Banks says.........

Posted by: Daniel      Read more         Source


November 12, 2008, 10:18 PM CT

In the war against diseases, nerve cells need their armor

In the war against diseases, nerve cells need their armor
In a new study, scientists at the Montreal Neurological Institute (MNI), McGill University, and the Universit de Montral have discovered an essential mechanism for the maintenance of the normal structure of myelin, the protective covering that insulates and supports nerve cells (neurons). Up until now, very little was known about myelin maintenance. This new information provides vital insight into diseases such as Multiple Sclerosis (MS) and other progressive demyelinating diseases in which myelin is destroyed, causing irreversible damage and disrupting the nerve cells' ability to transmit messages. The research, published recently in the Journal of Neuroscience, is the first to identify a role for the protein netrin-1, previously characterized only in the developing nervous system, with this critical function in the adult nervous system. This research was funded by the MS Society of Canada and the Canadian Institutes of Health Research.

Netrin-1, a protein deriving its name from the ancient Indian language, Sanskrit, word for 'one who guides,' is known to guide and direct nerve cell axons to their targets. In the molecular biological studies conducted by the team, they observed that blocking the function of netrin-1 and one of its receptors in adult neural tissue causes the disruption of myelin. "We've known for just over 10 years that netrin is essential for normal development of the nervous system, and we also knew that netrin was present in the adult brain, but we didn't know why. It is fascinating that netrin-1 has such a vital role in maintaining the structure of myelin in the adult nervous system," says Dr. Tim Kennedy, a neuroscientist at the MNI and the senior investigator of this study, "continuing to pursue the implications of that are incredibly exciting." "Our mission is to find a cure as quickly as possible and enhance quality of life," says Karen Lee, assistant vice-president of research programs for the MS Society of Canada. "We are pleased to be involved in funding work that supports our mission and feel that this research takes us closer to understanding the players and processes that could aid in remyelination."........

Posted by: Daniel      Read more         Source


November 11, 2008, 12:09 AM CT

Protein can nurture or devastate brain cells

Protein can nurture or devastate brain cells
Dr. Amelia Eisch (right) and colleagues from psychiatry, including Dr. Diane Lagace, uncovered a beneficial mechanism of the Cdk5 protein, which is also thought to kill brain cells and contribute to diseases such as Alzheimer's.
Scientists at UT Southwestern Medical Center have uncovered new insights into the "Dr. Jekyll and Mr. Hyde" nature of a protein that stimulates stem-cell maturation in the brain but, paradoxically, can also lead to nerve-cell damage.

In two separate studies in mice scheduled to appear online this week and in an upcoming issue of the Proceedings of the National Academy of Sciences, UT Southwestern research teams studied the protein Cdk5 and discovered both helpful and detrimental mechanisms it elicits in nerve cells.

Dr. Amelia Eisch, assistant professor of psychiatry at UT Southwestern, and her colleagues uncovered a beneficial mechanism of the helpful "Dr. Jekyll" side of the Cdk5 protein, which is also thought to kill brain cells and contribute to neurodegenerative diseases such as Alzheimer's. In the current study, Dr. Eisch observed that Cdk5, together with its activating partner molecule p35, helps immature nerve cells become fully functional.

In a separate study, Dr. James Bibb, associate professor of psychiatry at.

UT Southwestern, found yet another harmful action of the Cdk5 protein. It can stunt learning and reduce motor control.

Cdk5 is a kinase, which means its job is to interact with all sorts of other proteins inside cells and modify them through a process called protein phosphorylation. Whether Cdk5 nurtures or devastates depends on the state of its partner and the proteins it modifies.........

Posted by: Daniel      Read more         Source


October 27, 2008, 10:30 PM CT

Brain stimulation improves dexterity

Brain stimulation improves dexterity
Applying electrical stimulation to the scalp and the underlying motor regions of the brain could make you more skilled at delicate tasks. Research published recently in the open access journal BMC Neuroscience shows that a non-invasive brain-stimulation technique, transcranial direct current stimulation (tDCS), is able to improve the use of a person's non-dominant hand.

Drs. Gottfried Schlaug and Bradley Vines from Beth Israel Deaconess Medical Center and Harvard Medical School, tested the effects of using tDCS over one side or both sides of the brain on sixteen healthy, right-handed volunteers, as well as testing the effect of simply pretending to carry out the procedure. The volunteers were not aware of which of the three procedures they were receiving. The test involved using the fingers of the left hand to key in a series of numbers displayed on a computer screen.

The results were striking; stimulating the brain over both the right and left motor regions ('dual hemisphere' tDCS) resulted in a 24% improvement in the subjects' scores. This was significantly better than stimulating the brain only over one motor region or using the sham therapy (16% and 12% improvements, respectively).

tDCS involves attaching electrodes to the scalp and passing a weak direct current through the scalp and skull to alter the excitability of the underlying brain tissue. The therapy has two principal modes depending on the direction in which the current runs between the two electrodes. Brain tissue that underlies the positive electrode (anode) becomes more excitable and the reverse is true for brain tissue that underlies the negative electrode (cathode). No relevant negative side effects have been reported with this type of non-invasive brain stimulation. It is not to be confused with electroconvulsive treatment, which uses currents around a thousand times higher.........

Posted by: Daniel      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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