Posts tagged nervous system
Articles and news from the latest research reports.
Genetic cause discovered for rare disorder of motor neurones
Scientists have identified an underlying genetic cause for a rare disorder of motor neurones, and believe this may help find causes of other related diseases.
Disorders of motor neurones are a group of progressive neuromuscular disorders that damage the nervous system, causing muscle weakness and wasting. These diseases affect many thousands of people in the UK. A number are inherited but the causes of the majority remain unknown, and there are no cures.
The new study has discovered a gene mutation that causes a rare disorder of motor neurones called distal hereditary motor neuropathy (dHMN). The researchers say their findings raise a possibility that mutations of the same gene or genes with similar roles might underlie other disorders of motor neurones. This could open up the potential for new treatment options, not only for dHMN but also for the wider group of these disorders.
dHMN principally affects muscles of the hands and feet, and sometimes causes a hoarse voice. Symptoms usually begin during adolescence although this can vary from infancy to the mid-thirties.
The study to investigate possible genetic causes of dHMN was led by Professor Andrew Crosby and Dr Meriel McEntagart at St George’s, University of London. It has been published in the American Journal of Human Genetics.
The Hazards of Growing Up Painlessly
The girl who feels no pain was in the kitchen, stirring ramen noodles, when the spoon slipped from her hand and dropped into the pot of boiling water. It was a school night; the TV was on in the living room, and her mother was folding clothes on the couch. Without thinking, Ashlyn Blocker reached her right hand in to retrieve the spoon, then took her hand out of the water and stood looking at it under the oven light. She walked a few steps to the sink and ran cold water over all her faded white scars, then called to her mother, “I just put my fingers in!” Her mother, Tara Blocker, dropped the clothes and rushed to her daughter’s side. “Oh, my lord!” she said — after 13 years, that same old fear — and then she got some ice and gently pressed it against her daughter’s hand, relieved that the burn wasn’t worse.
“I showed her how to get another utensil and fish the spoon out,” Tara said with a weary laugh when she recounted the story to me two months later. “Another thing,” she said, “she’s starting to use flat irons for her hair, and those things get superhot.”
Tara was sitting on the couch in a T-shirt printed with the words “Camp Painless But Hopeful.” Ashlyn was curled on the living-room carpet crocheting a purse from one of the skeins of yarn she keeps piled in her room. Her 10-year-old sister, Tristen, was in the leather recliner, asleep on top of their father, John Blocker, who stretched out there after work and was slowly falling asleep, too. The house smelled of the homemade macaroni and cheese they were going to have for dinner. A South Georgia rainstorm drummed the gutters, and lightning illuminated the batting cage and the pool in the backyard.
Without lifting her eyes from the crochet hooks in her hands, Ashlyn spoke up to add one detail to her mother’s story. “I was just thinking, What did I just do?” she said.
Life without the Neurobeachin Protein
Scientists at Freie Universität, Universität Hohenheim, and Katholieke Universiteit Leuven Breed Fruit Flies for First Time without the Neurobeachin Protein and Facilitate Study of Nervous Diseases in Humans
In experiments on the brain of the fruit fly Drosophila, scientists at Freie Universität Berlin have advanced the research on brain function and diseases in humans. Neuroscientists in the Emmy Noether Junior Research Group “Biological Memory Systems” headed by Dr. Martin Schwärzel and based at Freie Universität succeeded in breeding fruit flies without the neurobeachin protein. Among other things, BEACH proteins affect the development and function of the brain in animals and humans. The results were published in the most recent issue of The Journal of Neuroscience. In the future such animal models could be of particular importance for the understanding of certain diseases in humans, such as autism. Scientists from the University of Hohenheim and the Belgian Katholieke Universiteit Leuven were also involved.
Up to now there were no animal models suitable for understanding the significance of neurobeachin proteins in the functioning of the nervous system, for example in memory formation. Mice that are lacking the neurobeachin protein die shortly after birth. Fruit flies, on the other hand, can be alive and well without neurobeachin. The scientists also found in experiments on the flies that neurobeachin has a function in learning as the flies exhibit characteristic learning disabilities due to the absence of the protein.
The flies were also found to have a number of other abnormalities with regard to the development and function of the nervous system. Through a “genetic rescue experiment,” the researchers were able to localize the distribution of these defects in the brain. The function of the lacking neurobeachin gene was reintroduced in certain areas of the nervous system. With this procedure, the researchers were able to show, among other things, that certain features of the neurobeachin protein in flies and mice are identical.
(Source: fu-berlin.de)
Researchers at the doorstep of stem cell therapies for MS, other myelin disorders
When the era of regenerative medicine dawned more than three decades ago, the potential to replenish populations of cells destroyed by disease was seen by many as the next medical revolution. However, what followed turned out not to be a sprint to the clinic, but rather a long tedious slog carried out in labs across the globe required to master the complexity of stem cells and then pair their capabilities and attributes with specific diseases.
In a review article appearing today in the journal Science, University of Rochester Medical Center scientists Steve Goldman, M.D., Ph.D., Maiken Nedergaard, Ph.D., and Martha Windrem, Ph.D., contend that researchers are now on the threshold of human application of stem cell therapies for a class of neurological diseases known as myelin disorders – a long list of diseases that include conditions such as multiple sclerosis, white matter stroke, cerebral palsy, certain dementias, and rare but fatal childhood disorders called pediatric leukodystrophies.
"Stem cell biology has progressed in many ways over the last decade, and many potential opportunities for clinical translation have arisen," said Goldman. "In particular, for diseases of the central nervous system, which have proven difficult to treat because of the brain’s great cellular complexity, we postulated that the simplest cell types might provide us the best opportunities for cell therapy."
The common factor in myelin disorders is a cell called the oligodendrocyte. These cells arise, or are created, by another cell found in the central nervous system called the glial progenitor cell. Both oligodendrocytes and their “sister cells” – called astrocytes – share this same parent and serve critical support functions in the central nervous systems.
(Source: eurekalert.org)
Aggressive Brain Tumors Can Originate From a Range of Nervous System Cells
Scientists have long believed that glioblastoma multiforme (GBM), the most aggressive type of primary brain tumor, begins in glial cells that make up supportive tissue in the brain or in neural stem cells. In a paper published October 18 in Science, however, researchers at the Salk Institute for Biological Studies have found that the tumors can originate from other types of differentiated cells in the nervous system, including cortical neurons.
GBM is one of the most devastating brain tumors that can affect humans. Despite progress in genetic analysis and classification, the prognosis of these tumors remains poor, with most patients dying within one to two years of diagnosis. The Salk researcher’s findings offer an explanation for the recurrence of GBM following treatment and suggest potential new targets to treat these deadly brain tumors.
"One of the reasons for the lack of clinical advances in GBMs has been the insufficient understanding of the underlying mechanisms by which these tumors originate and progress," says Inder Verma, a professor in Salk’s Laboratory of Genetics and the Irwin and Joan Jacobs Chair in Exemplary Life Science.
To better understand this process, Verma’s team harnessed the power of modified viruses, called lentiviruses, to disable powerful tumor suppressor genes that regulate the growth of cells and inhibit the development of tumors. With these tumor suppressors deactivated, cancerous cells are given free rein to grow out of control.
Immune cells of the blood might replace dysfunctional brain cells
Blood-circulating immune cells can take over the essential immune surveillance of the brain, this is shown by scientists of the German Center for Neurodegenerative Diseases (DZNE) and the Hertie Institute for Clinical Brain Research in Tübingen. Their study, now published in PNAS, might indicate new ways of dealing with diseases of the nervous system.
The immune system is comprised of multiple cell types each capable of specialized functions to protect the body from invading pathogens and promote tissue repair after injury. One cell type, known as monocytes, circulates throughout the organism in the blood and enters tissues to actively phagocytose (eat!) foreign cells and assist in tissue healing. While monocytes can freely enter most bodily tissues, the healthy, normal brain is different as it is sequestered from circulating blood by a tight network of cells known as the blood brain barrier. Thus, the brain must maintain a highly specialized, resident immune cell, known as microglia, to remove harmful invaders and respond to tissue damage.
In certain situations, such as during disease, monocytes can enter the brain and also contribute to tissue repair or disease progression. However, the potential for monocytes to actively replace old or injured microglia is under considerable debate. To address this, Nicholas Varvel, Stefan Grathwohl and colleagues from the German Center for Neurodegenerative Diseases (DZNE) Tübingen and the Hertie Institute for Clinical Brain Research in Tübingen used a transgenic mouse model in which almost all brain microglia cells (>95%) can be removed within two weeks. This was done by introducing a so-called suicide gene into microglia cells and administering a pharmaceutical agent that leads to acute death of the cells. Surprisingly, after the ablation of the microglia, the brain was rapidly repopulated by blood-circulating monocytes. The monocytes appeared similar, but not identical to resident microglia. The newly populated monocytes, evenly dispersed throughout the brain, responded to acute neuronal injury and other stimuli — all activities normally assumed by microglia. Most interestingly, the monocytes were still present in the brain six months - nearly a quarter of the life of a laboratory mouse - after initial colonization.
These studies now published in PNAS provide evidence that blood-circulating monocytes can replace brain resident microglia and take over the essential immune surveillance of the brain. Furthermore, the findings highlight a strong homeostatic mechanism to maintain a resident immune cell within the brain. The observation that the monocytes took up long-term residence in the brain raises the possibility that these cells can be utilized to deliver therapeutic agents into the diseased brain or replace microglia when they become dysfunctional. Can monocytes be exploited to combat the consequences of Alzheimer’s disease and other neurodegenerative diseases? The scientists and their colleagues in the research groups headed by Mathias Jucker are now following exactly this research avenue.
(Source: dzne.de)
Attack! Silent watchmen charge to defend the nervous system
In many pathologies of the nervous system, there is a common event - cells called microglia are activated from surveillant watchmen into fighters. Microglia are the immune cells of the nervous system, ingesting and destroying pathogens and damaged nerve cells. Until now little was known about the molecular mechanisms of microglia activation despite this being a critical process in the body. Now new research from the Montreal Neurological Institute and Hospital – The Neuro - at McGill University provides the first evidence that mechanisms regulated by the Runx1 gene control the balance between the surveillant versus activated microglia states. The finding, published in the Journal of Neuroscience, has significant implications for understanding and treating neurological conditions.
Risk-Sensitivity in Bayesian Sensorimotor Integration
Information processing in the nervous system during sensorimotor tasks with inherent uncertainty has been shown to be consistent with Bayesian integration. Bayes optimal decision-makers are, however, risk-neutral in the sense that they weigh all possibilities based on prior expectation and sensory evidence when they choose the action with highest expected value. In contrast, risk-sensitive decision-makers are sensitive to model uncertainty and bias their decision-making processes when they do inference over unobserved variables. In particular, they allow deviations from their probabilistic model in cases where this model makes imprecise predictions. Here we test for risk-sensitivity in a sensorimotor integration task where subjects exhibit Bayesian information integration when they infer the position of a target from noisy sensory feedback. When introducing a cost associated with subjects’ response, we found that subjects exhibited a characteristic bias towards low cost responses when their uncertainty was high. This result is in accordance with risk-sensitive decision-making processes that allow for deviations from Bayes optimal decision-making in the face of uncertainty. Our results suggest that both Bayesian integration and risk-sensitivity are important factors to understand sensorimotor integration in a quantitative fashion.
Britain’s first bionic veteran has a new brain-controlled robotic arm that is transforming his life.
Andrew Garthwaite, 25, had his right arm blown clean off by a rocket-propelled grenade during a firefight with the Taliban in Afghanistan in September 2010. In January he had the state-of-the-art limb wired to his nervous system during a six-hour operation in Vienna, Austria.
Now he is getting to grips with his new body part and is able to ride his motorcycle and drive a car again. Mr Gathwaite, who lives with his new wife Kailey, also 25, in South Shields, Tyneside, said:
'It's been incredible. I thought I might never be the same. But my life is starting to get back to normal - I'm on my motorbike and I'm back in a car. I can do things that I never thought I would have been able to do'.
Nervous System: Facts, Function & Diseases
The nervous system is a complex collection of nerves and specialized cells known as neurons that transmit signals between different parts of the body. Vertebrates — animals with backbones and spinal columns — have central and peripheral nervous systems.
The central nervous system is made up of the brain, spinal cord and retina. The peripheral nervous system consists of sensory neurons, ganglia (clusters of neurons) and nerves that connect to one another and to the central nervous system.
Credit: iDesign, Shutterstock
Description of the nervous system
The nervous system is essentially the body’s electrical wiring. It is composed of nerves, which are cylindrical bundles of fibers that start at the brain and central cord and branch out to every other part of the body.
Neurons send signals to other cells through thin fibers called axons, which cause chemicals known as neurotransmitters to be released at junctions called synapses. A synapse gives a command to the cell and the entire communication process typically takes only a fraction of a millisecond.
Sensory neurons react to physical stimuli such as light, sound and touch and send feedback to the central nervous system about the body’s surrounding environment. Motor neurons, located in the central nervous system or in peripheral ganglia, transmit signals to activate the muscles or glands.
Glial cells, derived from the Greek word for “glue,” support the neurons and hold them in place. Glial cells also feed nutrients to neurons, destroy pathogens, remove dead neurons and act as traffic cops by directing the axons of neurons to their targets. Specific types of glial cells (oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system) generate layers of a fatty substance called myelin that wraps around axons and provides electrical insulation to enable them to rapidly and efficiently transmit signals.