That means when the dopamine released by one nerve cell is not entirely absorbed by the receiving nerve cell, the leftover dopamine is blocked from reentering the original nerve cell and stays in the gap between the two nerve cells.
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B cells are thought to be a key contributor to myelin (nerve cell insulation) and nerve cell damage, which can result in disability for patients with MS, said Dr. Peter Chin, group medical director for neuroscience at Genentech, the company that makes the drug.
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"The effects tended to be things having to do with neural development and nerve cell development," Greenhouse said.
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Grey matter, which is made up of nerve cell bodies, is involved in sensory perception and muscle control.
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A year ago, Smith changed Taser's name to Axon Enterprise, referring to the conductive fibre of a nerve cell.
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The therapy, known as active nerve cell cluster stimulation, was used on patients within 24 hours of an ischemic stroke.
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When GABA receptors are activated they can cause the firing in a nerve cell to slow down or shut off completely.
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When the researchers stimulated the bees' antennae with an electric field, there was no change in the antennae's nerve cell activity.
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He revealed in March 2017 that he had amyotrophic lateral sclerosis, the degenerative nerve-cell disorder known as Lou Gehrig's disease.
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Researchers say that the compound binds to a receptor in the brain and makes the nerve cell linked to seizures less active.
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When the virus enters the body, it travels up the nerves and hangs out in the ganglia, a bundle of nerve cell bodies.
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Dr Khizroev and his team use magnetoelectric particles so tiny that they can interact with the electric field generated by an individual nerve cell.
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In the angry mice, just before they literally were about to stick their noses in another mouse's business, nerve cell activity in the VMHvl spiked.
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J&J's esketamine, used in combination with a newly prescribed antidepressant, works by restoring the nerve cell connections in the brain, leading to an improvement in depression symptoms.
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Zika can cause "neurodevelopmental abnormalities," which include a wide range of health problems related to nerve cell development: problems walking, swallowing, hearing, seeing, cerebral palsy and epileptic seizures.
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That's because the compound activates nerve-cell surface receptors responsible for morphine's painkilling effects without activating receptors involved in controlling breathing or in releasing the pleasure-related chemical dopamine.
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The fruit fly, for example, with its rapid reproduction, helped scientists understand genetics; the squid, with its peculiarly gigantic axon fibers, allowed scientists to examine the workings of a single nerve cell.
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When a stem cell divides, each new cell can either remain a stem cell or become another kind of cell, such as a nerve cell, a skin cell or a red blood cell.
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The study, published Wednesday in the journal Nature, reports that a specific type of neuron or nerve cell, in a certain brain region helps galvanize whether or not a risky choice is made.
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There is an instructive connection between a nerve cell-assaulting virus and al Qaeda's attacks on 22011/220: They both represent trust, or the lack thereof, with violation of duty to the American people.
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Each electrode records voltage changes in the nerve cell nearest to it and transmits those changes to the top of the probe through a conductive channel (one per electrode) that acts like a wire.
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Uses for bioluminescence molecules would be similar to those of the green fluorescent protein, which has been used to follow the fate of HIV infections, visualize tumors and track nerve-cell damage in Alzheimer's disease.
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Neurofilament light chain is a protein found in blood that provides structural support to nerve fibres in the brain, and increases may be associated with nerve cell damage, Roche said in a statement on Tuesday.
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This starts a domino effect that makes the nerve cell send pain signals in response to lower levels of heat, which it senses using the same molecule that detects the substance that makes chili peppers burn.
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Although the monkey's spinal cord was not re-fused, the team says it may be possible if the spinal cord is cut cleanly in a bath of polyethylene glycol (PEG), a chemical that preserves nerve cell membranes.
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NfL is a "marker in the blood which gives an indication of nerve cell loss in the brain," explained lead researcher Mathias Jucker, professor of cell biology of neurological diseases at the German Center for Neurodegenerative Diseases.
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Amyloid plaques are starch-like deposits found outside nerve cells, and neurofibrillary tangles are hair-like clumps found inside nerve cells, and the traditional thinking was that these deposits led to nerve cell death and ultimately, symptoms of Alzheimer's.
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Ruby was eventually diagnosed with a form of epilepsy – a disorder in which nerve cell activity in the brain is disturbed, causing seizures – and cerebral palsy; a congenital disorder with symptoms of exaggerated reflexes, floppy or rigid limbs, and involuntary motions.
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Dr. Hideya Sakaguchi, study co-author and postdoctoral fellow at Kyoto University (currently at the Salk Institute), explained in an email that the important thing here is not just the creation of a mini-brain but that a tool was developed to detect nerve cell activity.
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Under the proposed research framework, Alzheimer's would be characterized by three factors: evidence of two abnormal proteins associated with Alzheimer's - beta amyloid and tau - and evidence of neurodegeneration or nerve cell death, all of which can be seen through brain imaging or tests of cerebral spinal fluid.
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CMT usually strikes adolescents or young adults, affecting roughly 1 in 2,500 people in the US. It's caused by genetic mutations, according to the National Institute of Neurological Disorders and Stroke:A nerve cell communicates information to distant targets by sending electrical signals down a long, thin part of the cell called the axon.
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In 1978, having obtained a Ph.D. in biology at Indiana University, Allis began to tackle a problem that had long troubled geneticists and cell biologists: if all the cells in the body have the same genome, how does one become a nerve cell, say, and another a blood cell, which looks and functions very differently?
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In the late 1990s, stem cells from human embryos were isolated and cultured for the first time, revealing that unlike adult stem cells, which could give rise only to cell types found in their tissue of origin (a blood stem cell in the bone marrow might generate a neutrophil, for instance, but wouldn't differentiate into a nerve cell in the brain), embryonic stem cells harbored the potential to become any cell type in the body.
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Neurotransmitters are chemical messengers that transmit a message from a nerve cell across the synapse to a target cell. The target can be another nerve cell, or a muscle cell, or a gland cell. They are chemicals made by the nerve cell specifically to transmit the message. Neurotransmitters are released from synaptic vesicles in synapses into the synaptic cleft, where they are received by neurotransmitter receptors on the target cell.
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The lack of myelin resulting from the lack of acid ceramidase break down leads to nerve cell damage.
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Processes extending from an astrocyte can enwrap several nerve cell bodies or synapse with hundreds of neuronal dendrites.
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The sympathetic ganglia, or autonomic ganglia, are the ganglia of the sympathetic nervous system. Ganglia are 20,000 to 30,000 afferent and efferent nerve cell bodies that run along on either side of the spinal cord. Afferent nerve cell bodies bring information from the body to the brain and spinal cord, while efferent nerve cell bodies bring information from the brain and spinal cord to the rest of the body. The cell bodies create long sympathetic chains that are on either side of the spinal cord.
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The diagram on the right shows a nerve cell with a damaged myelin sheath, being the cause of multiple sclerosis.
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The beginning of a new neural impulse goes as follows: # An exchange of ions (charged atoms) across the nerve cell membrane sends a depolarizing current towards the end of the nerve cell (cell terminus). # When the depolarizing current arrives at the nerve cell terminus, the neurotransmitter acetylcholine (ACh), which is held in vesicles, is released into the space between the two nerves (synapse). It moves across the synapse to the postsynaptic receptors. # ACh binds to the receptors and transfers the signal to the target cell, and after a short time, it is destroyed by acetylcholinesterase.
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Presence of ChAT in a nerve cell classifies this cell as a "cholinergic" neuron. In humans, the choline acetyltransferase enzyme is encoded by the CHAT gene.
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An autonomic ganglion is a cluster of nerve cell bodies (a ganglion) in the autonomic nervous system. The two types are sympathetic ganglion and parasympathetic ganglion.
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The ASAH1 Gene codes for acid ceramidase which is an enzyme found in lysosomes. The lysosome breaks down acid ceramidase and the fatty acid component is then used to produce myelin. Myelin is a coating around the nerves in the body which help transfer signals from nerve cell to nerve cell and increase transmission rate. In patients with SMA-PME, the cermidase function is reduced to only be 33.33% effective.
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U.S. National Institutes of Health. Retrieved 2018-10-09. Diagram of two different nerve cells. The diagram on the left shows a nerve cell that is healthy and normally-functioning.
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Totawa, New Jersey: Humana Press. describe the application of neuroanatomical data of the developing human cerebral cortex to computational models. Sterratt, D., Graham, B., Gillies, A., & Willshaw, D. (2011) discuss aspects of the nervous system of computational modeling in the development of nerve cell morphology, cell physiology, cell patterning, patterns of ocular dominance, and connection between nerve cell and muscle, and retinotopic maps. Carreira-Perpinan, M. A. & Goodhill, G. J. (2002)Carreira-Perpinan, M. A., & Goodhill, G. J. (2002).
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Palladin's precise biological role is poorly understood, but it has been shown to play a role in cytoskeletal organization, embryonic development, cell motility, scar formation in the skin, and nerve cell development.
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The neuroadaptive processes involved in tolerance, dependence, and withdrawal mechanisms implicate both the GABAergic and the glutamatergic systems. Gamma-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter of the central nervous system; roughly one-quarter to one- third of synapses use GABA. GABA mediates the influx of chloride ions through ligand-gated chloride channels called GABAA receptors. When chloride enters the nerve cell, the cell membrane potential hyperpolarizes thereby inhibiting depolarization, or reduction in the firing rate of the post-synaptic nerve cell.
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Signals pass across the synapses from one nerve cell to the next as discrete (digital) packets of chemicals, which are then summed within the nerve cell in an analog fashion by building an electro-chemical potential until its threshold is reached, whereupon it discharges and sends out a series of digital packets to the next nerve cell. The advantages are at least threefold: noise within the system is minimized (and tends not to be additive), no common grounding system is required, and there is minimal degradation of the signal even if there are substantial differences in activity of the cells along a path (only the signal delays tend to vary). The individual nerve cells are analogous to analog computers; the synapses are analogous to digital computers. Hybrid computers should be distinguished from hybrid systems.
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The word comes from the Greek νεύρον (neuron, which refers to the nerve cell) and εύρισκω ("euriskein" heuristic, which refers to a problem-solving procedure that is often characterized by its informal, intuitive and speculative features).
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The nervous system is the system of neurons, or nerve cells, that relay electrical signals through the brain and body. A nerve cell receives signals from other nerve cells through tree-branch-like extensions called dendrites and passes signals on through a long extension called an axon (or nerve fiber). Synapses are places where one cell's axon passes information to another cell's dendrite by sending chemicals called neurotransmitters across a small gap called a synaptic cleft. Synapses occur in various locations, including ganglia (singular: ganglion), which are masses of nerve cell bodies.
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Tangles are insoluble twisted fibers that build up inside the nerve cell. Though many older people develop some plaques and tangles, the brains of AD patients have them to a much greater extent and in different brain locations.
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By studying structures in 3D hydrogels, researchers can identify new models of nerve cell mechanoproperties. For example, LaPlaca et al. developed a new model showing that strain may play a role in cell culture (LaPlaca et al. 2005).
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When sphingolipids are not made, an accumulation of toxic byproducts can also lead to nerve cell death. This gradual destruction of nerve cells results in loss of sensation and muscle weakness in people with hereditary sensory neuropathy type 1.
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In the autonomic nervous system there are both sympathetic and parasympathetic ganglia which contain the cell bodies of postganglionic sympathetic and parasympathetic neurons respectively. A pseudoganglion looks like a ganglion, but only has nerve fibers and has no nerve cell bodies.
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Kim identified the cancer cell growth inhibition mechanism of magnetic-based cell division difference. Dispersed by the static magnetic field, the core protein GCP3 in spindle formation, during cell division cycle, was identified for the first time in the world. This contributed to establish the scientific basis on the availability to the magnetic field for future anti-cancer therapy. From Harvard MGH research exchanges, the treatment of nerve cell to nerve cell turning the magnetic field grow into the direction perpendicular to the magnetic field that can be used in a certain direction based on research data.
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A pseudoganglion is a localized thickening of the main part or trunk of a nerve that has the appearance of a ganglion but has only nerve fibers and no nerve cell bodies. Pseudoganglia are found in the teres minor muscle and radial nerve.
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Between the fetal stage and 18 months, a baby experiences rapid growth of a substance called gray matter. Gray matter is the darker tissue of the brain and spinal cord, consisting mainly of nerve cell bodies and branching dendrites.Google definition. (2013, November 12).
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Mice have been used as an experimental system to investigate possible mechanisms by which levels of sex steroid hormones might regulate nervous system function. During the part of the mouse estrous cycle when progesterone is highest, the level of nerve-cell GABA receptor subtype delta was high. Since these GABA receptors are inhibitory, nerve cells with more delta receptors are less likely to fire than cells with lower numbers of delta receptors. During the part of the mouse estrous cycle when estrogen levels are higher than progesterone levels, the number of delta receptors decrease, increasing nerve cell activity, in turn increasing anxiety and seizure susceptibility.
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Numerous theories have been proposed to explain post-polio syndrome. Despite this, no absolutely defined causes of PPS are known. The most widely accepted theory of the mechanism behind the disorder is "neural fatigue". A motor unit is a nerve cell (or neuron) and the muscle fibers it activates.
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Similar to the mechanism of ethanol's effect, the increase of gas dissolved in nerve cell membranes may cause altered ion permeability properties of the neural cells' lipid bilayers. The partial pressure of a gas required to cause a measured degree of impairment correlates well with the lipid solubility of the gas: the greater the solubility, the less partial pressure is needed. An early theory, the Meyer-Overton hypothesis, suggested that narcosis happens when the gas penetrates the lipids of the brain's nerve cells, causing direct mechanical interference with the transmission of signals from one nerve cell to another. More recently, specific types of chemically gated receptors in nerve cells have been identified as being involved with anesthesia and narcosis.
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It may be spread to an infant during childbirth. After infection, the viruses are transported along sensory nerves to the nerve cell bodies, where they reside lifelong. Causes of recurrence may include: decreased immune function, stress, and sunlight exposure. Oral and genital herpes is usually diagnosed based on the presenting symptoms.
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Pathfinding is important for axon growth to the right destination (e.g. another nerve cell or a muscle). Significant for this mechanism is the L1CAM gene, a cell surface glycoprotein of the immunoglobulin superfamily. Mutations leading to a loss-of-function in L1CAM are also found in other X-linked syndromes.
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Inhibition of the sodium/potassium ATPase protein present in the plasma membrane of the nerve cell is caused by glycidamide.Lehning, E. J., Persaud, A., Dyer, K. R., Jortner, B. S., & LoPachin, R. M. (1998). Biochemical and morphologic characterization of acrylamide peripheral neuropathy. Toxicology and Applied Pharmacology, 151(2), 211-221.
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In Alzheimer's disease, changes in tau protein lead to the disintegration of microtubules in brain cells. The tau hypothesis proposes that tau protein abnormalities initiate the disease cascade. In this model, hyperphosphorylated tau begins to pair with other threads of tau. Eventually, they form neurofibrillary tangles inside nerve cell bodies.
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In order to fully assume the function of the damaged hippocampus, the prosthesis must be able to communicate with the existing tissue in a bidirectional manner. in other words, the implant must be able to receive information from the brain and give an appropriate and compressible feedback to the surrounding nerve cell.
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A few others argued that it merely accelerated remission in those patients who would undergo remission anyway. The consensus at the time was somewhere in between, claiming a success rate of about 50% in patients who had been ill for less than a year (about double the spontaneous remission rate) with no influence on relapse. Sakel suggested the therapy worked by "causing an intensification of the tonus of the parasympathetic end of the autonomic nervous system, by blockading the nerve cell, and by strengthening the anabolic force which induces the restoration of the normal function of the nerve cell and the recovery of the patient." The shock therapies in general had developed on the erroneous premise that epilepsy and schizophrenia rarely occurred in the same patient.
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The mid frequency projections end up in between the two extremes; in this way the tonotopic organization that is established in the cochlea is preserved in the cochlear nuclei. This tonotopic organization is preserved because only a few inner hair cells synapse on the dendrites of a nerve cell in the spiral ganglion, and the axon from that nerve cell synapses on only a very few dendrites in the cochlear nucleus. In contrast with the VCN that receives all acoustic input from the auditory nerve, the DCN receives input not only from the auditory nerve but it also receives acoustic input from neurons in the VCN (T stellate cells). The DCN is therefore in a sense a second order sensory nucleus.
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In mammals there are seven known type I receptors and five type II receptors. There are three activins: Activin A, Activin B and Activin AB. Activins are involved in embryogenesis and osteogenesis. They also regulate many hormones including pituitary, gonadal and hypothalamic hormones as well as insulin. They are also nerve cell survival factors.
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The connection between dopamine and psychosis is generally believed to be complex. While dopamine receptor D2 suppresses adenylate cyclase activity, the D1 receptor increases it. If D2-blocking drugs are administered, the blocked dopamine spills over to the D1 receptors. The increased adenylate cyclase activity affects genetic expression in the nerve cell, which takes time.
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5 mg Valium Roche packaging Australia Diazepam is a long-acting "classical" benzodiazepine. Other classical benzodiazepines include chlordiazepoxide, clonazepam, lorazepam, oxazepam, nitrazepam, temazepam, flurazepam, bromazepam, and clorazepate. Diazepam has anticonvulsant properties. Benzodiazepines act via micromolar benzodiazepine binding sites as calcium channel blockers and significantly inhibit depolarization-sensitive calcium uptake in rat nerve cell preparations.
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Image of a Nissl-stained histological section through the rodent hippocampus showing various classes of cells (neurons and glia). Motor nerve cell from ventral horn of medulla spinalis of rabbit. The angular and spindle-shaped Nissl bodies are well shown. A Nissl body, also known as Nissl substance and Nissl material, is a large granular body found in neurons.
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With vocabularies in Latin and English and illustrations. Philadelphia: P. Blakiston's Son & Co. of the official Latin anatomic nomenclature of 1895, Nomina Anatomica. The name of the locus coeruleus is derived from its azure appearance in unstained brain tissue. The color is due to light scattering from neuromelanin in noradrenergic (producing or activated by norepinephrine) nerve cell bodies.
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An axon (from Greek ἄξων áxōn, axis), or nerve fiber (or nerve fibre: see spelling differences), is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action potentials away from the nerve cell body. The function of the axon is to transmit information to different neurons, muscles, and glands. In certain sensory neurons (pseudounipolar neurons), such as those for touch and warmth, the axons are called afferent nerve fibers and the electrical impulse travels along these from the periphery to the cell body, and from the cell body to the spinal cord along another branch of the same axon. Axon dysfunction has caused many inherited and acquired neurological disorders which can affect both the peripheral and central neurons.
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In addition to their structural role in axons, neurofilaments are also cargoes of axonal transport. Most of the neurofilament proteins in axons are synthesized in the nerve cell body, where they rapidly assemble into neurofilament polymers within about 30 minutes. These assembled neurofilament polymers are transported along the axon on microtubule tracks powered by microtubule motor proteins. The filaments move bidirectionally, i.e.
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1 micron) unmyelinated regions of the axon between adjacent long (c. 0.2 mm – >1 mm) myelinated internodes. Once it reaches the axon terminal, this electrical signal provokes the release of a chemical message or neurotransmitter that binds to receptors on the adjacent post-synaptic cell (e.g., nerve cell in the CNS or muscle cell in the PNS) at specialised regions called synapses.
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In some areas of the brain, gyri are fewer in number but wider than normal (pachygyri). Other areas lack gyri entirely (agyri). Normally, during the third and fourth months of pregnancy, the brain cells in the baby multiply and move to the surface of the brain to form the cortex. Lissencephaly is caused by a failure of this nerve cell migration.
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Diagram showing cortical pathways In general, neurons receive information either at their dendrites or cell bodies. The axon of a nerve cell is, in general, responsible for transmitting information over a relatively long distance. Therefore, most neural pathways are made up of axons. If the axons have myelin sheaths, then the pathway appears bright white because myelin is primarily lipid.
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This is a perikaryon of a nerve cell, displayed here because of the obvious cytoplasmic granules. The granules, which appear almost black due to their high electron density, take up a large portion of the endoplasm. They are suspended in cytosol - the fluid component of the cytoplasm. The term granule refers to a small particle within the endoplasm, typically the secretory vesicles.
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The nerve fibre is a thread-like extension of a nerve cell that includes the axon which may or may not be encased in a myelinated sheath. The androgenic nerve fibre when myelinated increases the speed of transmission for an action potential across the length of the cell. The gaps in the sheath along the axon are call the node of ranvier.
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In humans, the nerve cell bodies of the pars compacta are coloured black by the pigment neuromelanin. The degree of pigmentation increases with age. This pigmentation is visible as a distinctive black stripe in brain sections and is the origin of the name given to this volume of the brain. The neurons have particularly long and thick dendrites (François et al.).
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Studies have shown that animals raised in complex environments have a greater volume of capillaries per nerve cell—and therefore a greater supply of blood to the brain—than the caged animals, regardless of whether the caged animal lived alone or with companions. Overall, these studies depict an orchestrated pattern of increased capacity in the brain that depends on experience.
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Many pesticides are enzyme inhibitors. Acetylcholinesterase (AChE) is an enzyme found in animals, from insects to humans. It is essential to nerve cell function through its mechanism of breaking down the neurotransmitter acetylcholine into its constituents, acetate and choline. This is somewhat unusual among neurotransmitters as most, including serotonin, dopamine, and norepinephrine, are absorbed from the synaptic cleft rather than cleaved.
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Anosmin-1 is encoded by a gene ANOS1 (earlier called ADMLX, KAL, KAL1, KALIG1). In human it is located on the X chromosome at Xp22.3 and is affected in some male individuals with Kallmann syndrome. This gene codes for a protein of the extracellular matrix named anosmin-1, which is involved in the migration of certain nerve cell precursors (neuroendocrine GnRH cells) during embryogenesis.
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General structures of sphingolipids Cerebrosides is the common name for a group of glycosphingolipids called monoglycosylceramides which are important components in animal muscle and nerve cell membranes. They consist of a ceramide with a single sugar residue at the 1-hydroxyl moiety. The sugar residue can be either glucose or galactose; the two major types are therefore called glucocerebrosides (a.k.a. glucosylceramides) and galactocerebrosides (a.k.a. galactosylceramides).
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The enteric nervous system functions to control the gastrointestinal system. Both autonomic and enteric nervous systems function involuntarily. Nerves that exit from the cranium are called cranial nerves while those exiting from the spinal cord are called spinal nerves. At the cellular level, the nervous system is defined by the presence of a special type of cell, called the neuron, also known as a "nerve cell".
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Patch clamp of a nerve cell within a slice of brain tissue. The pipette in the photograph has been marked with a slight blue color. Many patch clamp amplifiers do not use true voltage clamp circuitry, but instead are differential amplifiers that use the bath electrode to set the zero current (ground) level. This allows a researcher to keep the voltage constant while observing changes in current.
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Chronic exposure to these hormones results in an acceleration of the aging process, which is associated with "gradual, but often dramatic, changes over time in almost every physiological system in the human body. Combined, these changes result in decreased efficiency and resiliency of physiological function." Chronic stress and chronic heavy alcohol use cause a similar premature aging effect, including nerve cell degeneration in the hippocampus.
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Axoplasm is the cytoplasm within the axon of a neuron (nerve cell). For some neuronal types this can be more than 99% of the total cytoplasm. Axoplasm has a different composition of organelles and other materials than that found in the neuron's cell body (soma) or dendrites. In axonal transport (also known as axoplasmic transport) materials are carried through the axoplasm to or from the soma.
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Key elements of this communication are chemicals known as neurotransmitters, which carry messages from one nerve cell, or neuron, to another. Neurotransmitters are released by neurons and attach themselves to receptors on parts of neighboring cells. Some neurotransmitters may make the receiving cell more sensitive, while others tend to make the receiving cell less sensitive. Laboratory studies suggest that an imbalance between these chemicals may underlie myoclonus.
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White matter is composed of bundles, which connect various grey matter areas (the locations of nerve cell bodies) of the brain to each other, and carry nerve impulses between neurons. Myelin acts as an insulator, which allows electrical signals to jump, rather than coursing through the axon, increasing the speed of transmission of all nerve signals.Klein, S.B., & Thorne, B.M. Biological Psychology. Worth Publishers: New York. 2007.
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Prenatal exposure of BaP to rats is known to affect learning and memory in rodent models. Pregnant rats eating BaP were shown to negatively affect the brain function in the late life of their offspring. At a time when synapses are first formed and adjusted in strength by activity, BaP diminished NMDA receptor-dependent nerve cell activity measured as mRNA expression of the NMDA NR2B receptor subunit..
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Preganglionic nerve cells in the sympathetic nervous system (all of which come from the lateral grey column), use the neurotransmitter acetylcholine, while postganglionic sympathetic nerve cells use norepinephrine. Grey matter in the brain and spinal cord is any accumulation of cell bodies and neuropil (neuropil is tissue rich in nerve cell bodies and dendrites). White matter consists of nerve tracts (groups of axons) and commissures (tracts that cross the brain's midline).
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Neurotransmitters are endogenous chemicals that transmit signals across a synapse from one neuron (nerve cell) to another "target" cell (often another neuron). Neurotransmitters can cause inhibitory or excitatory effects on the "target" cell they are affecting."Neurotransmitter" at Dorland's Medical Dictionary Alcohol increases the effect of the neurotransmitter GABA (gamma- Aminobutyric acid) in the brain. GABA causes slow actions and inaudible verbal communication that often occur in alcoholics.
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The eventual exhaustion of muscles leads to respiratory failure and death. A separate class of nerve agents are related to Tetrodotoxin, frequently abbreviated as TTX, is a potent neurotoxin with no known antidote. Tetrodotoxin blocks action potentials in nerves by binding to the voltage-gated, fast sodium channels in nerve cell membranes, essentially preventing any affected nerve cells from firing by blocking the channels used in the process.
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A cholinergic neuron is a nerve cell which mainly uses the neurotransmitter acetylcholine (ACh) to send its messages. Many neurological systems are cholinergic. Cholinergic neurons provide the primary source of acetylcholine to the cerebral cortex, and promote cortical activation during both wakefulness and rapid eye movement sleep. The cholinergic system of neurons has been a main focus of research in aging and neural degradation, specifically as it relates to Alzheimer's disease.
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Schematic of an anatomically accurate single pyramidal neuron, the primary excitatory neuron of cerebral cortex, with a synaptic connection from an incoming axon onto a dendritic spine. A neuron or nerve cell is an electrically excitable cell that communicates with other cells via specialized connections called synapses. It is the main component of nervous tissue in all animals except sponges and placozoa. Plants and fungi do not have nerve cells.
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They also form para- or pre-vertebral gangalia of gross anatomy. The efferent nerve cell bodies bring information from the brain to the body regarding perceptions of danger. This perception of danger can instigate the fight-or-flight response associated with the sympathetic nervous system. The fight-or-flight response is adaptive when there is a real and present danger which can be avoided or diminished through increased sympathetic activity.
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Humans have far fewer active odor receptor genes than other primates and other mammals. In mammals, each olfactory receptor neuron expresses only one functional odor receptor. Odor receptor nerve cells function like a key–lock system: if the airborne molecules of a certain chemical can fit into the lock, the nerve cell will respond. There are, at present, a number of competing theories regarding the mechanism of odor coding and perception.
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Victor had injected two other eggs with NGF, which were given to two families who work at Chimera through the fertility clinic there. They both inexplicably die at age three because of brain edema. Victor later finds out they had been given the antibiotic Cephaloclor, which causes the nerve cell growth process to begin again. This causes their brains to grow too large for their skulls, killing them.
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Using these radiotracers, she discovered that smokers have reduced levels of MAO in their brains and lungs. This may account for some of the behavioral and epidemiological features of smoking, such as the high rate of smoking in individuals with depression and drug addiction, two conditions involving poor nerve-cell communication, and has led to many studies on reduced MAO and smoking. Fowler holds eight patents for radiolabeling procedures.
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Critical to the proper folding and function of the neural plate is N-cadherin, a type of cadherin protein associated with the nervous system. N-cadherin is critical to holding neural plate cells together. Additionally, cells destined to become neural plate cells express nerve cell adhesion molecule (NCAM) to further neural plate cohesion. Another cadherin, E-cadherin, is expressed by ectodermal cells in the process of neural plate development.
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It found that an average of 75 percent of the lateral column cells were lost in people with progressive autonomic failure. Multiple system atrophy (MSA) is an adult onset disorder that is a sporadic and progressive. It is characterized by a combination of ataxia, parkinsonism, and autonomic dysfunction. A study did a comparison with the lateral grey column nerve cell count between 15 cases of patients with MSA and a control group.
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Type V consists of the nuclear lamins, and type VI consists of the protein nestin. The type IV intermediate filament genes all share two unique introns not found in other intermediate filament gene sequences, suggesting a common evolutionary origin from one primitive type IV gene. Any proteinaceous filament that extends in the cytoplasm of a nerve cell is also termed a neurofibril. This name is used in the neurofibrillary tangles of some neurodegenerative diseases.
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Otto Friedrich Karl Deiters (1834-1863) Otto Friedrich Karl Deiters (; November 15, 1834 - December 5, 1863) was a German neuroanatomist. He was born in Bonn, studied at the University of Bonn, and spent most of his professional career in Bonn. He is remembered for his microscopic research of the brain and spinal cord. Around 1860, Deiters provided the most comprehensive description of a nerve cell that was known to exist at the time.
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Internal to this peripheral region is the gray, butterfly-shaped central region made up of nerve cell bodies. This central region surrounds the central canal, which is an anatomic extension of the spaces in the brain known as the ventricles and, like the ventricles, contains cerebrospinal fluid. The spinal cord has a shape that is compressed dorso-ventrally, giving it an elliptical shape. The cord has grooves in the dorsal and ventral sides.
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The hypothalamus is the most important part of the brain for sexual functioning. This is a small area at the base of the brain consisting of several groups of nerve cell bodies that receives input from the limbic system. Studies have shown that within lab animals, destruction of certain areas of the hypothalamus causes the elimination of sexual behavior. The hypothalamus is important because of its relationship to the pituitary gland, which lies beneath it.
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It is of foremost importance for these sodium channels to function properly, as they are essential for the propagation of an action potential. Without this ability, the nerve cell becomes unable to transmit signals and the region of the body that it enervates is cut off from the nervous system. This may lead to paralysis of the affected region, as in the case of saxitoxin. Saxitoxin binds reversibly to the sodium channel.
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Traces of are found in all potassium, and it is the most common radioisotope in the human body. Potassium ions are vital for the functioning of all living cells. The transfer of potassium ions across nerve cell membranes is necessary for normal nerve transmission; potassium deficiency and excess can each result in numerous signs and symptoms, including an abnormal heart rhythm and various electrocardiographic abnormalities. Fresh fruits and vegetables are good dietary sources of potassium.
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Typical action potential frequency is between 4 and 12 Hz. An electrical stimulation can artificially elicit this action potential by changing the electric potential across a nerve cell membrane (this also includes the nerve axon) by inducing electrical charge in the immediate vicinity of the outer membrane of the cell.M.R. Popovic and T.A. Thrasher, "Neuroprostheses", in Encyclopedia of Biomaterials and Biomedical Engineering, G.E. Wnek and G.L. Bowlin, Eds.: Marcel Dekker, Inc., vol.
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One of Nissl's university professors was Bernhard von Gudden. His assistant, Sigbert Josef Maria Ganser suggested that Nissl write an essay on the pathology of the cells of the cortex of the brain. When the medical faculty offered a competition for a prize in neurology in 1884, Nissl undertook the brain-cortex study. He used alcohol as a fixative and developed a staining technique that allowed the demonstration of several new nerve-cell constituents.
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In 1907 the zoologist Ross Granville Harrison demonstrated the growth of frog nerve cell processes in a medium of clotted lymph. It is made up of lymph nodes and vessels. In 1913, E. Steinhardt, C. Israeli, and R. A. Lambert grew vaccinia virus in fragments of tissue culture from guinea pig corneal grown in lymph.Steinhardt, E; Israeli, C; and Lambert, R.A. (1913) "Studies on the cultivation of the virus of vaccinia" J. Inf Dis.
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Exocytosis of a vesicle. 8. Recaptured neurotransmitter. Axon terminals (also called synaptic boutons, terminal boutons, or end-feet) are distal terminations of the telodendria (branches) of an axon. An axon, also called a nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses called action potentials away from the neuron's cell body, or soma, in order to transmit those impulses to other neurons, muscle cells or glands.
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Fetomaternal microchimerism has been shown in experimental investigations of whether fetal cells can cross the blood brain barrier in mice. The properties of these cells allow them to cross the blood brain barrier and target injured brain tissue. This mechanism is possible because umbilical cord blood cells express some proteins similar to neurons. When these umbilical cord blood cells are injected in rats with brain injury or stroke, they enter the brain and express certain nerve cell markers.
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Robert Cantu, a Professor of Neurology and Neurosurgery and Co-Founder of the CTE Center at the Boston University School of Medicine, believes that children under 14 should not play tackle football. Their brains are not fully developed, and myelin (nerve cell insulation) is at greater risk in shear when the brain is young. Myelination is completed at about 15 years of age. Children also have larger heads relative to their body size and weaker necks.
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Strychnine is a neurotoxin which acts as an antagonist of glycine and acetylcholine receptors. It primarily affects the motor nerve fibers in the spinal cord which control muscle contraction. An impulse is triggered at one end of a nerve cell by the binding of neurotransmitters to the receptors. In the presence of an inhibitory neurotransmitter, such as glycine, a greater quantity of excitatory neurotransmitters must bind to receptors before there will be an action potential generated.
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In cross-section, the peripheral region of the cord contains neuronal white matter tracts containing sensory and motor axons. Internal to this peripheral region is the grey matter, which contains the nerve cell bodies arranged in the three grey columns that give the region its butterfly-shape. This central region surrounds the central canal, which is an extension of the fourth ventricle and contains cerebrospinal fluid. The spinal cord is elliptical in cross section, being compressed dorsolaterally.
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Major dopamine pathways. As part of the reward pathway, dopamine is manufactured in nerve cell bodies located within the alt=A labelled line drawing of dopamine pathways superimposed on a drawing of the human brain. Inside the brain, dopamine plays important roles in executive functions, motor control, motivation, arousal, reinforcement, and reward, as well as lower-level functions including lactation, sexual gratification, and nausea. The dopaminergic cell groups and pathways make up the dopamine system which is neuromodulatory.
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After gaining her Masters, Reddick began teaching biology at Spelman in 1937. She became the first female biology instructor at Morehouse College in 1939. In 1942, Reddick was awarded a second Rockefeller education fellowship by Radcliffe College, the women's coordinate for Harvard University at that time. Reddick studied techniques for transplanting tissues and nerve cell differentiation in chick embryos there for two years, gaining a second master's degree in biology in 1943 and being awarded a PhD in 1944.
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Obidoxime is a member of the oxime family used to treat nerve gas poisoning. Oximes are drugs known for their ability to reverse the binding of organophosphorus compounds to the enzyme acetylcholinesterase (AChE). AChE is an enzyme that removes acetylcholine from the synapse after it creates the required stimulation on the next nerve cell. If it gets inhibited, acetylcholine is not removed after the stimulation and multiple stimulations are made, resulting in muscle contractions and paralysis.
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Insects have a complex nervous system which incorporates a variety of internal physiological information as well as external sensory information. As in the case of vertebrates, the basic component is the neuron or nerve cell. This is made up of a dendrite with two projections that receive stimuli and an axon, which transmits information to another neuron or organ, like a muscle. As with vertebrates, chemicals (neurotransmitters such as acetylcholine and dopamine) are released at synapses.
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As the nerve cell matures, these type III IFs are replaced by more complex type IV neurofilaments expanding the diameter of axons in order to attain normal velocities of action potentials. The exact function of peripherin is unknown. Expression of peripherin in development is greatest during the axonal growth phase and decreases postnatally, which suggests a role in neurite elongation and axonal guidance during development. Expression is also increased after axonal injury, such as peripheral axotomy in motor neurons and dorsal root ganglia.
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General structures of sphingolipids Sphingomyelin (SPH, ˌsfɪŋɡoˈmaɪəlɪn) is a type of sphingolipid found in animal cell membranes, especially in the membranous myelin sheath that surrounds some nerve cell axons. It usually consists of phosphocholine and ceramide, or a phosphoethanolamine head group; therefore, sphingomyelins can also be classified as sphingophospholipids. In humans, SPH represents ~85% of all sphingolipids, and typically make up 10–20 mol % of plasma membrane lipids. Sphingomyelin was first isolated by German chemist Johann L.W. Thudicum in the 1880s.
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L1 protein is located all over the nervous system on the surface of neurons. It is placed along the cellular membrane so that one end of the protein remains inside the nerve cell while the other end stays on the outer surface of the neurone. This position allows the protein to activate chemical signals which spread through the neurone. There are a wide variety of cells which express the protein L1, not only neuronal cells but also some non-neuronal ones.
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Each 'layer' of the microfluidic device (cells seeded in ECM, a hydrogel sheath, and finally a calcium chloride solution). The seeded cells culture within the hydrogel sheath for several days, and then the sheath is removed with viable cell fibers. Various cell types were inserted into the ECM core, including myocytes, endothelial cells, nerve cell fibers, and epithelial cell fibers. This group then showed that these fibers can be woven together to fabricate tissues or organs in a mechanism similar to textile weaving.
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Peripheral nervous system diseases may be further categorized by the type of nerve cell (motor, sensory, or both) affected by the disorder. Effective treatment of these diseases is often prevented by lack of understanding of the underlying molecular and genetic pathology. Epigenetic therapy is being investigated as a method of correcting the expression levels of misregulated genes in neurodegenerative diseases. Neurodengenerative diseases of motor neurons can cause degeneration of motor neurons involved in voluntary muscle control such as muscle contraction and relaxation.
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Vitamin B12 deficiency can lead to anemia and neurological disorders. A mild deficiency may not cause any discernible symptoms, but as the deficiency becomes more significant, symptoms of anemia may result, such as weakness, fatigue, light-headedness, rapid heartbeat, rapid breathing and pale color to the skin. It may also cause easy bruising or bleeding, including bleeding gums, gastrointestinal side effects including sore tongue, stomach upset, weight loss, and diarrhea or constipation. If the deficiency is not corrected, nerve cell damage can result.
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Those axons that become myelinated accumulate more neurofilaments, which drives the expansion of their caliber. After an axon has grown and connected with its target cell, the diameter of the axon may increase as much as fivefold. This is caused by an increase in the number of neurofilaments exported from the nerve cell body as well as a slowing of their rate of transport. In mature myelinated axons, neurofilaments can be the single most abundant cytoplasmic structure and can occupy most of the axonal cross-sectional area.
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Foix–Alajouanine syndrome, also called subacute ascending necrotizing myelitis, is a disease caused by an arteriovenous malformation of the spinal cord. The patients present with symptoms indicating spinal cord involvement (paralysis of arms and legs, numbness and loss of sensation and sphincter dysfunction), and pathological examination reveals disseminated nerve cell death in the spinal cord and abnormally dilated and tortuous vessels situated on the surface of the spinal cord. Surgical treatment can be tried in some cases. If surgical intervention is contraindicated, corticosteroids may be used.
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Tectin is the brand name of a pain killing drug currently in development by WEX Pharmaceuticals Inc. The drug is a purified version of the main toxin in the pufferfish, tetrodotoxin, a very potent neurotoxin which shuts down electrical signaling in nerves by blocking sodium channels on nerve cell membranes. Tectin holds promise to relieve severe pain when other standard pain relievers are found to be ineffective. It is also being researched as a drug to relieve the symptoms of withdrawal in opiate addicts.
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In neuroanatomy, a nucleus (plural form: nuclei) is a cluster of neurons in the central nervous system, located deep within the cerebral hemispheres and brainstem. The neurons in one nucleus usually have roughly similar connections and functions. Nuclei are connected to other nuclei by tracts, the bundles (fascicles) of axons (nerve fibers) extending from the cell bodies. A nucleus is one of the two most common forms of nerve cell organization, the other being layered structures such as the cerebral cortex or cerebellar cortex.
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He suggested an idea similar to Hebb in which coincidental activation in time causes the potential connections to be transformed into actual excitatory connections. Inhibitory connections arise when the excitation of one input coincides in time with a decease in its associated connection. He described the process: "The plastic changes would be related to the formation and multiplication of new synaptic junctions between the axon terminals of one nerve cell and the soma (i.e. the body and the dendrites) of the other"Konorski J. (1948).
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However, they can also cause more troublesome forms of herpes simplex. As neurotropic and neuroinvasive viruses, HSV-1 and -2 persist in the body by hiding from the immune system in the cell bodies of neurons. After the initial or primary infection, some infected people experience sporadic episodes of viral reactivation or outbreaks. In an outbreak, the virus in a nerve cell becomes active and is transported via the neuron's axon to the skin, where virus replication and shedding occur and cause new sores.
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Phencyclidine is an NMDA receptor antagonist that blocks the activity of the NMDA receptor to cause anaesthesia and analgesia without causing cardiorespiratory depression. NMDA is an excitatory receptor in the brain, when activated normally the receptor acts as an ion channel and there is an influx of positive ions through the channel to cause nerve cell depolarisation. Phencyclidine enters the ion channel and binds, reversibly and non-competitively, inside the channel pore to block the entry of positive ions to the cell, thereby inhibiting cell depolarisation.
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Neuromuscular junctions are the focal point where a motor neuron attaches to a muscle. Acetylcholine, (a neurotransmitter used in skeletal muscle contraction) is released from the axon terminal of the nerve cell when an action potential reaches the microscopic junction called a synapse. A group of chemical messengers cross the synapse and stimulate the formation of electrical changes, which are produced in the muscle cell when the acetylcholine binds to receptors on its surface. Calcium is released from its storage area in the cell's sarcoplasmic reticulum.
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An impulse from a nerve cell causes calcium release and brings about a single, short muscle contraction called a muscle twitch. If there is a problem at the neuromuscular junction, a very prolonged contraction may occur, such as the muscle contractions that result from tetanus. Also, a loss of function at the junction can produce paralysis. Skeletal muscles are organized into hundreds of motor units, each of which involves a motor neuron, attached by a series of thin finger-like structures called axon terminals.
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Alain Prochiantz has been working since the early 1980s in the field of molecular neurobiology, particularly on the processes of morphogenesis and nerve cell differentiation. He did his first major work at the Collège de France with Jacques Glowinski on the development and in vitro maturation of dopaminergic neurons in the mesencephalon.Effect of striatal cells on in vitro maturation of mesencephalic dopaminergic neurones grown in serum-free conditions. par di Porzio U, Daguet MC, Glowinski J, Prochiantz A. dans Nature du 27 novembre 1980;288(5789):370-3.
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Proper myelination is critical for carrying electrical signals, or data, from one nerve cell to the next. When myelin becomes damaged, it can cause numerous neurological problems, many of which are seen in patients with SSADH deficiency. Thus, Ren and Mody's work in the relationship between increased levels of GHB and myelin expression may further show the significance of this pathway in terms of the neurological deficits seen in SSADH deficiency. Glutamine metabolism may also play a role in the pathophysiology of SSADH deficiency.
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Somatic Cell Nuclear Transfer (SCNT) is the process by which the nucleus of an oocyte (egg cell) is removed and is replaced with the nucleus of a somatic (body) cell (examples include skin, heart, or nerve cell). The two entities fuse to become one and factors in the oocyte cause the somatic nucleus to reprogram to a pluripotent state. The cell contains genetic information identical to the donated somatic cell. After stimulating this cell to begin dividing, in the proper conditions an embryo will develop.
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Nakanishi has also been able to detail the structure of receptors for Substance P, Substance K, neurotensin and endothelin. The work with Substance K represented the first time that the structure of a peptide receptor had been elucidated. Modifying a technique invented by a National Cancer Institute colleague, Nakanishi has applied cell ablation to the study of neuroscience. In Nakanishi's version of cell ablation, he is able to eliminate specific nerve cell types one at a time, which aids in the study of brain function, dysfunction and compensation.
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Unlike dynamic metabolic simulation, FBA assumes that the internal concentration of metabolites within a system stays constant over time and thus is unable to provide anything other than steady-state solutions. It is unlikely that FBA could, for example, simulate the functioning of a nerve cell. Since the internal concentration of metabolites is not considered within a model, it is possible that an FBA solution could contain metabolites at a concentration too high to be biologically acceptable. This is a problem that dynamic metabolic simulations would probably avoid.
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Anterograde degeneration in the nervous system, also known as Wallerian degeneration, is a process of deterioration down the axon of a nerve cell away from the cell body. This degeneration is the result of damage or injury to a nerve fiber, and it causes the affected fiber to appear “coagulated” or “curdled.” It was discovered by Ludwig Turck that anterograde degeneration can be used to trace axonal pathways in the nervous system. It was also found that the coagulated fragments produced by anterograde degeneration have a high affinity for impregnation by silver.
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Myelin is formed in the central nervous system (CNS; brain, spinal cord and optic nerve) by glial cells called oligodendrocytes and in the peripheral nervous system (PNS) by glial cells called Schwann cells. In the CNS, axons carry electrical signals from one nerve cell body to another. In the PNS, axons carry signals to muscles and glands or from sensory organs such as the skin. Each myelin sheath is formed by the concentric wrapping of an oligodendrocyte (CNS) or Schwann cell (PNS) process (a limb-like extension from the cell body) around the axon.
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Driven by his pioneering neuropathological findings of early prenatal cytoarchitectural malformations in the brains of patients with schizophrenic psychoses, he is one of the fathers of the neurodevelopmental theory of these psychoses. In 1986 with C. Jakob, he reported on cortical and subcortical developmental disturbances in schizophrenic psychoses, particularly in the entorhinal area. These cytoarchitectural abnormalities were mainly or exclusively localized in the upper cortical layers of the limbic allocortex, including circumscribed malformations, nerve cell alterations as well as cytoarchitectural deviations attributable to disruptions of neural migration in the second trimester of gestation.
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The cellular membrane pinches in a procession known as pinocytosis and allows entry of the virus into the cell by way of an endosome. The virus then uses the acidic environment, which is necessary, of that endosome and binds to its membrane simultaneously, releasing its five proteins and single strand RNA into the cytoplasm. Once within a muscle or nerve cell, the virus undergoes replication. The L protein then transcribes five mRNA strands and a positive strand of RNA all from the original negative strand RNA using free nucleotides in the cytoplasm.
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Neurofibrillary tangles, paired helical filaments containing over- phosphorylated tau protein, are located within the nerve cell. Early symptoms of AD include difficulty remembering names and events, while later symptoms include impaired judgment, disorientation, confusion, behavior changes, and difficulty speaking, swallowing, and walking. After initial diagnosis, a person with AD can live, on average, an additional 3 to 10 years with the disease. In 2013, it was estimated that 5.2 million Americans of all ages had AD. Environmental factors such as head trauma, high cholesterol, and type 2 diabetes can increase the likelihood of AD.
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His interest was drawn toward experimental research, and so enrolled in the department of natural sciences where he joined the laboratory for two years, the same which had once been used by Arthur Van Gehuchten. It was during this time that he made his first scientific contributions: two publications on the histology of the nerve cell. After having a conversation with Désiré Mercier, founder of Leuven's laboratory of experimental psychology, was when he finally decided to dedicate himself to psychology. He began working under Armand Thiéry, who had been the laboratory director since 1894.
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Bipolar cells are also found in the spinal ganglia, when the cells are in an embryonic condition. Sometimes the extensions, also called processes, come off from opposite poles of the cell, and the cell then assumes a spindle shape. In some cases where two fibers are apparently connected with a cell, one of the fibers is really derived from an adjoining nerve cell and is passing to end in a ramification around the ganglion cell, or, again, it may be coiled helically around the nerve process which is issuing from the cell.
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In the brain, cytoplasmic polyadenylation is active during learning and could play a role in long-term potentiation, which is the strengthening of the signal transmission from a nerve cell to another in response to nerve impulses and is important for learning and memory formation. Cytoplasmic polyadenylation requires the RNA-binding proteins CPSF and CPEB, and can involve other RNA- binding proteins like Pumilio. Depending on the cell type, the polymerase can be the same type of polyadenylate polymerase (PAP) that is used in the nuclear process, or the cytoplasmic polymerase GLD-2.
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Giant axonal neuropathy results from mutations in the GAN gene, which codes for the protein gigaxonin. This alters the shape of the protein, changing how it interacts with other proteins when organizing the structure of the neuron. Neurons affected by the altered protein accumulate excess neurofilaments in the axon, the long extension from the nerve cell that transmits its signal to other nerve cells and to muscles. These enlarged or 'giant' axons cannot transmit signals properly, and eventually deteriorate, resulting in the range of neurological anomalies associated with the disorder.
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In the brain, messages are passed from a nerve cell to another via a chemical synapse, a small gap between the cells. The presynaptic cell that sends the information releases neurotransmitters including serotonin into that gap. The neurotransmitters are then recognized by receptors on the surface of the recipient postsynaptic cell, which upon this stimulation, in turn, relays the signal. About 10% of the neurotransmitters are lost in this process; the other 90% are released from the receptors and taken up again by monoamine transporters into the sending presynaptic cell, a process called reuptake.
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The building consists of two glass-clad and steel-framed pavilions, separated by a central yard, and connected to each other by a multi-coloured glass walkway. The glass cladding of the pavilions includes some coloured panels designed by the artist Bruce McLean, depicting images inspired by molecular science. The walkway also provides access to the Neuron Pod, a free standing steel structure located at the northern end of the central yard. The pod is modelled on a nerve cell, and covered with hundred of plastic filaments, designed to look like hairs.
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First, after a period of nerve cell injury, SGCs are known to up-regulate GFAP and to undergo cell division. They have the ability to release chemoattractants, which are analogous to those released by Schwann cells and contribute to the recruitment and proliferation of macrophages. Additionally, several research groups have found that SGC coupling increases after nerve damage, which has an effect on the perception of pain, likely for several reasons. Normally, the gap junctions between SGCs are used in order to redistribute potassium ions between adjacent cells.
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A follower neuron is a nerve cell that arises in the developmental stage of the brain and which growth and orientation is intrinsically related to pioneer neurons. These neurons can also be called later development neurons or follower cells. In the early stages of brain development, pioneer neurons define axonal trajectories that are later used as scaffolds by follower neurons, which project their growth cones and fasciculate with pioneer axons, forming a fiber tract Chédotal A and Richards LJ (2010). Wiring the Brain: The Biology of Neuronal Guidance.
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When a nerve is stimulated, i.e., when sufficient electrical charge is provided to a nerve cell, a localized depolarization of the cell wall occurs resulting in an action potential that propagates toward both ends of the axon. Typically, one "wave" of action potentials will propagate along the axon towards the muscle (orthodromic propagation) and concurrently, the other "wave" of action potentials will propagate towards the cell body in the central nervous system (antidromic propagation). While the direction of propagation in case of the antidromic stimulation and the sensory nerve stimulation is the same, i.e.
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Interleukin 6 (IL6), also referred to as B-cell stimulatory factor-2 (BSF-2) and interferon beta-2, is a cytokine involved in a wide variety of biological functions. It plays an essential role in the final differentiation of B cells into immunoglobulin- secreting cells, as well as inducing myeloma/plasmacytoma growth, nerve cell differentiation, and, in hepatocytes, acute-phase reactants. A number of other cytokines may be grouped with IL6 on the basis of sequence similarity. These include granulocyte colony-stimulating factor (GCSF) and myelomonocytic growth factor (MGF).
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The term dendrites was first used in 1889 by Wilhelm His to describe the number of smaller "protoplasmic processes" that were attached to a nerve cell. German anatomist Otto Friedrich Karl Deiters is generally credited with the discovery of the axon by distinguishing it from the dendrites. Some of the first intracellular recordings in a nervous system were made in the late 1930s by Kenneth S. Cole and Howard J. Curtis. Swiss Rüdolf Albert von Kölliker and German Robert Remak were the first to identify and characterize the axon initial segment.
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Twenty-four hours into arm regeneration, the body wall of the arm is still contracted and the aboral side of the arm has folded to the oral side. A thin epithelial layer has begun to form and the stump has begun to reform due to dedifferentiated epidermal cells. At this stage, the radial nerve cell has also begun to heal. 72 hours into arm regeneration, the aboral arm wall is still covering the wound site, however, now the body wall has relaxed and the papullae began to inflate again.
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New research indicates different biological mechanisms may underlie some mental health disorders, only indirectly related to neurotransmitters and the monoamine chemical imbalance hypothesis. Recent research indicates a biological "final common pathway" may exist which both electroconvulsive therapy and most current antidepressant drugs have in common. These investigations show recurrent depression may be a neurodegenerative disorder, disrupting the structure and function of brain cells, destroying nerve cell connections, even killing certain brain cells, and precipitating a decline in overall cognitive function. In this new biological psychiatry viewpoint, neuronal plasticity is a key element.
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In vertebrates, a neuroblast or primitive nerve cell is a postmitotic cell that does not divide further, and which will develop into a neuron after a migration phase. In invertebrates such as Drosophila, neuroblasts are neural progenitor cells which divide asymmetrically to produce a neuroblast, and a daughter cell of varying potency depending on the type of neuroblast. Vertebrate neuroblasts differentiate from radial glial cells and are committed to becoming neurons. Neural stem cells, which only divide symmetrically to produce more neural stem cells, transition gradually into radial glial cells.
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Patients exhibiting type II CS often have shortened and/or misfolded CSB that disrupt gene expression and transcription. The characteristic biological effect of malfunctioning ERCC6 is nerve cell death, resulting in premature aging and growth defects. The extent to which malfunctioning CSB hinders oxidative repair heavily influences patients' neurological functioning. The two subforms of the disorder (the latter of which corresponds to ERCC6 defects) - CS-A and CS-B - both cause problems in the oxidative repair, though CS-B patients more often exhibit nerve system problems stemming from damage to this pathway.
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Both MAP2 and tau have been shown to stabilize microtubules by binding to the outer surface of the microtubule protofilaments. A single study has suggested that MAP2 and tau bind on the inner microtubule surface on the same site in tubulin monomers as the drug Taxol, which is used in treating cancer, but this study has not been confirmed. MAP2 binds in a cooperative manner, with many MAP2 proteins binding a single microtubule to promote stabilization. Tau has the additional function of facilitating bundling of microtubules within the nerve cell.
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The most clinical experience has been with electrical stimulation. Neuromodulation, whether electrical or magnetic, employs the body's natural biological response by stimulating nerve cell activity that can influence populations of nerves by releasing transmitters, such as dopamine, or other chemical messengers such as the peptide Substance P, that can modulate the excitability and firing patterns of neural circuits. There may also be more direct electrophysiological effects on neural membranes as the mechanism of action of electrical interaction with neural elements. The end effect is a "normalization" of a neural network function from its perturbed state.
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When in the nanoscale, iron oxides will remain permanently magnetized at lengths greater than 50 nm and will become magnetized at lengths smaller than 50 nm. Since these platelets have been observed in collections of 5-10, they are thought to form dipoles local to the dendrite they are present in. These local magnetic changes then cause a mechanical response along the membrane of the nerve cell, leading to a change in ion concentrations. This ion concentration, with respect to the other dendrite clusters is believed to form the magnetic sense.
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If it is of threshold strength or over, a spike (a nervous impulse) of maximum magnitude is set up. Either the single fibre does not respond with spike production, or it responds to the utmost of its ability under the conditions at the moment. This property of the single nerve fibre is termed the all-or-none relationship. This relationship holds only for the unit of tissue; for nervous tissue the unit is the nerve cell, for skeletal muscle the unit is the individual muscle fiber and for the heart the unit is the entire auricles or the entire ventricles.
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In normal neuromuscular function, a nerve impulse is carried down the axon (the long projection of a nerve cell) from the spinal cord. At the nerve ending in the neuromuscular junction, where the impulse is transferred to the muscle cell, the nerve impulse leads to the opening of voltage-gated calcium channels (VGCC), the influx of calcium ions into the nerve terminal, and the calcium-dependent triggering of synaptic vesicle fusion with plasma membrane. These synaptic vesicles contain acetylcholine, which is released into the synaptic cleft and stimulates the acetylcholine receptors on the muscle. The muscle then contracts.
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In addition to his administrative and teaching duties, he continued to work actively on muscle contraction, and also made theoretical contributions to other work in the department, such as that on animal reflectors. In 1963, he was jointly awarded the Nobel Prize in Physiology or Medicine for his part in discoveries concerning the ionic mechanisms of the nerve cell. In 1969 he was appointed to a Royal Society Research Professorship, which he held in the Department of Physiology at University College London. In 1980, Huxley was elected as President of the Royal Society, a post he held until 1985.
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Scheme of path of the recurrent laryngeal nerve in giraffe In mammals, the left recurrent laryngeal nerve is longer than the right; in the giraffe it is over longer. These nerves are longer in the giraffe than in any other living animal; the left nerve is over long. Each nerve cell in this path begins in the brainstem and passes down the neck along the vagus nerve, then branches off into the recurrent laryngeal nerve which passes back up the neck to the larynx. Thus, these nerve cells have a length of nearly in the largest giraffes.
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Julian Hart Lewis FRS (12 August 1946 - 30 April 2014) was an English developmental biologist and researcher whose work shed light on the nature of cellular timing mechanisms and their role in animal development. He showed that the Notch ligand (a molecule involved in cell-to-cell communication) controls the timing of nerve cell differentiation and the synchronised cycling of neighbouring cell activity. He modelled the cellular oscillatory circuit that determines the segmentation of the developing body, and clarified the importance of delay kinetics in setting the frequency of those oscillations. He was an undergraduate at Balliol College, Oxford from 1964.
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A number of ionotropic receptors have been identified as contributing to anoxic depolarization of nerve cell membranes. They include the NMDA receptors, AMPA receptors, P2X7 purinergic receptors, pannexin channels (Panx1), transient receptor potential (TRP) channels, and acid-sensing ion channels (ASICs). During brain ischemia, glutamate is released in excess from the presynaptic terminal, leading to the uncontrollable opening of the glutamate receptors, including the NMDA and AMPA receptors, which allows for an excessive influx of Ca2+ into the intracellular environment. Purinergic and NMDA receptors activate the pannexin-1 channels, which become hyperactive and allow the release of ATP from the intracellular environment.
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Synaptotagmin, a transmembrane protein found in neurosecretory vesicles, functions as a calcium sensor triggering vesicle fusion and neurotransmitter release. Stimulation of a neuron results in an increase in intracellular calcium concentration. After binding calcium ion to a region in its cytosolic domain, vesicular synaptotagmin promotes quick or slow neurotransmitter release from the presynaptic neuron via interaction with regulatory and fusion related proteins such as members of the SNARE complex. Südhof also discovered RIMs and Muncs (most notably Munc13 and Munc18), soluble proteins which aid in the fusion of neurotransmitter vesicles to the nerve cell membrane and play an important role in synaptic plasticity.
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Poliovirus attacks specific neurons in the brainstem and the anterior horn cells of the spinal cord, generally resulting in the death of a substantial fraction of the motor neurons controlling skeletal muscles. In an effort to compensate for the loss of these neurons, surviving motor neurons sprout new nerve terminals to the orphaned muscle fibers. The result is some recovery of movement and the development of enlarged motor units. The neural fatigue theory proposes that the enlargement of the motor neuron fibers places added metabolic stress on the nerve cell body to nourish the additional fibers.
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The pathway for erythropoietin in both the central and peripheral nervous systems begins with the binding of Epo to EpoR. This leads to the enzymatic phosphorylation of PI3-K and NF-κB and results in the activation of proteins that regulate nerve cell apoptosis. Recent research shows that Epo activates JAK2 cascades which activate NF-κB, leading to the expression of CIAP and c-IAP2, two apoptosis-inhibiting genes. Research conducted in rat hippocampal neurons demonstrates that the protective role of Epo in hypoxia-induced cell death acts through extracellular signal-regulated kinases ERK1, ERK2 and protein kinase Akt-1/PKB.
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After a Campylobacter infection, the body produces antibodies of the IgA class; only a small proportion of people also produce IgG antibodies against bacterial substance cell wall substances (e.g. lipooligosaccharides) that crossreact with human nerve cell gangliosides. It is not currently known how this process escapes central tolerance to gangliosides, which is meant to suppress the production of antibodies against the body's own substances. Not all antiganglioside antibodies cause disease, and it has recently been suggested that some antibodies bind to more than one type of epitope simultaneously (heterodimeric binding) and that this determines the response.
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The virus usually first infects muscle cells close to the site of infection, where they are able to replicate without being 'noticed' by the host's immune system. Once enough virus has been replicated, they begin to bind to acetylcholine receptors at the neuromuscular junction. The virus then travels through the nerve cell axon via retrograde transport, as its P protein interacts with dynein, a protein present in the cytoplasm of nerve cells. Once the virus reaches the cell body it travels rapidly to the central nervous system (CNS), replicating in motor neurons and eventually reaching the brain.
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The brain and the spinal cord are the essential components of the central nervous system and it is responsible for the integration of the signals received from the afferent nerves and initiates action. The nerve cells, known as neurons, carry impulses throughout the body and the nerve impulses are carried along the axon. These microscopic nerve fibers, where the action potential occurs, are protected by a white, fatty tissue that surrounds and insulates it, known as the myelin sheath. This insulation helps the axon of a nerve cell with the conduction and speed of the signal along the axon.
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Also, a good model must take into account the fact that the expression of a single nerve cell is negligible, since the processes are carried by groups of neurons interacting in network. Once installed, the device must assume all (or at least most) of the function of the damaged hippocampus for a prolonged period of time. First, the artificial neurons must be able to work together in network just like real neurons. Then, they must be able, working and effective synaptics connections with the existing neurons of the brain; therefore a model for silicon/neurons interface will be required.
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An adrenergic nerve fibre is a neuron for which the neurotransmitter is either adrenaline (epinephrine), noradrenaline or dopamine. These neurotransmitters are released at a location known as the synapse, which is a junction point between the axon of one nerve cell and the dendrite of another. The neurotransmitters are first released from the axon and then bind to the receptor site on the dendrite. Adrenergic nerve terminals are found in the secondary neurons of the sympathetic nervous system, one of two deviations of the autonomic nervous system which is responsible for the fight-or-flight response.
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Inflammation associated with nerve cell destruction often alters the color and appearance of the gray matter in the spinal column, causing it to appear reddish and swollen. Other destructive changes associated with paralytic disease occur in the forebrain region, specifically the hypothalamus and thalamus. The molecular mechanisms by which poliovirus causes paralytic disease are poorly understood. Early symptoms of paralytic polio include high fever, headache, stiffness in the back and neck, asymmetrical weakness of various muscles, sensitivity to touch, difficulty swallowing, muscle pain, loss of superficial and deep reflexes, paresthesia (pins and needles), irritability, constipation, or difficulty urinating.
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Tetrodotoxin is a sodium channel blocker. It inhibits the firing of action potentials in neurons by binding to the voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the neuron. This prevents the nervous system from carrying messages and thus muscles from contracting in response to nervous stimulation. Its mechanism of action, selective blocking of the sodium channel, was shown definitively in 1964 by Toshio Narahashi and John W. Moore at Duke University, using the sucrose gap voltage clamp technique.
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The cell bodies of the neurons produce the enzymes that synthesize dopamine, and they are then transmitted via the projecting axons to their synaptic destinations, where most of the dopamine is produced. Dopaminergic nerve cell bodies in such areas as the substantia nigra pars compacta tend to be pigmented due to the presence of the black pigment melanin. Dopaminergic pathways are involved in many functions such as executive function, learning, reward, motivation, and neuroendocrine control. Dysfunction of these pathways and nuclei may be involved in multiple diseases and disorders such as Parkinson's disease, attention deficit hyperactivity disorder, addiction, and restless legs syndrome (RLS).
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Franz von Leydig's work on neural tissue influenced Norwegian zoologist and polar explorer Fridtjof Nansen (1861–1931), who along with Wilhelm His, Sr. (1831–1904) and Auguste-Henri Forel (1848–1931), were the first to establish the anatomical entity of the nerve cell. Chief among Leydig's discoveries is the interstitial cell ("Leydig cells"), a body enclosed in a smooth endoplasmic reticulum and holding lipid granules and crystals, which occur adjacent to the seminiferous tubules of the testes. The cells produce the male hormone testosterone. Leydig had described the interstitial cells in his detailed account of the male sex organs.
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He has identified a number of key genes that are responsible for nerve cell degeneration and early-onset forms of Alzheimer's disease. He splits his time between the University of Cambridge and the University of Toronto where he has research labs.Peter St George-Hyslop Professor Takanori Shibata was awarded the 2018 Ryman Prize in recognition of his more than 25 years of ground-breaking research into new technology to help older people. Professor Shibata, an artificial intelligence (AI) and robotics pioneer, was presented with the prize by the Right Honourable Jacinda Ardern, Prime Minister of New Zealand.
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A flow map of the axon reflex. Stimulation of the axon can cause electric flow to all effector tissues the neuron innervates, as well as back to the soma of the neuron; this is distinct from a normal neuron firing only down the axon. The axon reflex (or the flare response) is the response stimulated by peripheral nerves of the body that travels away from the nerve cell body and branches to stimulate target organs. Reflexes are single reactions that respond to a stimulus making up the building blocks of the overall signaling in the body's nervous system.
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Hodgkin was nominated for the Nobel Prize in Physiology or Medicine in 1953 by Lord Adrian. In October 1961, he was told by Swedish journalists that he, Huxley, and Eccles had been awarded the Nobel Prize. This turned out to be a false alarm, however, when shortly thereafter it was announced that the 1961 Prize was awarded to Georg von Békésy. It was only two years later that Hodgkin, Huxley, and Eccles were finally awarded the Prize "for their discoveries concerning the ionic mechanisms involved in excitation and inhibition in the peripheral and central portions of the nerve cell membrane".
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In June 2012, a new drug candidate named "Rhosin" was synthesized by researchers at the Cincinnati Children's Hospital, a drug with the full intention to inhibit cancer proliferation and promote nerve cell regeneration. This inhibitor specifically targets Rho GTPases to prevent cell growth related to cancer. When tested on breast cancer cells, Rhosin inhibited growth and the growth of mammary spheres in a dose dependent manner, functioning as targets for RhoA while simultaneously maintaining the integrity of normal cellular processes and normal breast cells. These promising results indicate Rhosin's general effectiveness in preventing breast cancer proliferation via RhoA targeting.
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Within the jugular foramen, there are two glossopharyngeal ganglia that contain nerve cell bodies that mediate general, visceral, and special sensation. The visceral motor fibers pass through both ganglia without synapsing and exit the inferior ganglion with CN IX general sensory fibers as the tympanic nerve. Before exiting the jugular foramen, the tympanic nerve enters the petrous portion of the temporal bone and ascends via the inferior tympanic canaliculus to the tympanic cavity. Within the tympanic cavity the tympanic nerve forms a plexus on the surface of the promontory of the middle ear to provide general sensation.
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A neuron (also known as a neurone or nerve cell) is an excitable cell in the nervous system that processes and transmits information by electrochemical signaling. Neurons are the core components of the brain, the vertebrate spinal cord, the invertebrate ventral nerve cord and the peripheral nerves. A number of specialized types of neurons exist: sensory neurons respond to touch, sound, light and numerous other stimuli affecting cells of the sensory organs that then send signals to the spinal cord and brain. Motor neurons receive signals from the brain and spinal cord that cause muscle contractions and affect glands.
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You couldn't even attempt to > build a quantum computer out of ordinary nerve signals, because they're just > too big and in an environment that's too disorganized. Ordinary nerve > signals have to be treated classically. But if you go down to the level of > the microtubules, then there's an extremely good chance that you can get > quantum-level activity inside them. For my picture, I need this quantum- > level activity in the microtubules; the activity has to be a large scale > thing that goes not just from one microtubule to the next but from one nerve > cell to the next, across large areas of the brain.
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Vance has also worked on the transport of lipids and cholesterol to growing neurons. She discovered defects in cholesterol transport in neurons lacking the protein associated with Niemann–Pick disease type C, NPC1, and found that these defects can be addressed by treatment with cyclodextrin. She observed that growing neurons in vitro take up and use components from low-density lipoprotein and very low-density lipoprotein particles, and identified a role for lipoproteins provided by glial cells in stimulating nerve cell growth and protecting neurons from apoptosis. In 2018 she was awarded the Wilhelm Bernhard International Lifetime Achievement Prize by the European Molecular Biology Organization.
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Chalfie's lab uses the nematode C. elegans to investigate aspects of nerve cell development and function. The wealth of developmental, anatomical, genetic, and molecular information available for C. elegans provides a powerful and multifaceted approach to these studies. He has published over 100 papers of which at least 25 have over 100 citations. He traces his work on green fluorescent protein to a 1988 seminar from Paul Brehm about bioluminescent organisms, which led to some crucial experiments in 1992, detailed in his paper "Green fluorescent protein as a marker for gene expression", which is among the 20 most-cited papers in the field of Molecular Biology & Genetics.
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Between the two layers of cells is a liquid-filled interior space, which, except for the immediate zones of contact with the ventral and dorsal sides, is pervaded by a star-shaped fibre syncytium: a fibrous network that consists essentially of a single cell but contains numerous nuclei that, while separated by internal crosswalls (septa), do not have true cell membranes between them. Similar structures are also found in the sponges (Porifera) and many fungi. On both sides of the septa are liquid-filled capsules that cause the mentioned separating structures to resemble synapses, i.e. nerve-cell junctions that occur in fully expressed form only in animals with tissues (Eumetazoa).
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Nervonic acid is particularly abundant in the white matter of animal brains and in peripheral nervous tissue where nervonyl sphingolipids are enriched in the myelin sheath of nerve fibers. In the same way, recent studies have concluded that nervonic acid is implicated as an intermediate in the biosynthesis of nerve cell myelin. This acid is an important member of the group of the cerebrosides, which are fatty acids of the glycosphingolipids group, important components of the muscles and the central nervous system and peripheral. Indeed, it is one of the major fatty acids in brain sphingolipids, normally accounting for approximately 40% of the total fatty acids in sphingolipids.
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The membranous myelin sheath that surrounds and electrically insulates many nerve cell axons is particularly rich in sphingomyelin, suggesting its role as an insulator of nerve fibers. The plasma membrane of other cells is also abundant in sphingomyelin, though it is largely to be found in the exoplasmic leaflet of the cell membrane. There is, however, some evidence that there may also be a sphingomyelin pool in the inner leaflet of the membrane. Moreover, neutral sphingomyelinase-2 – an enzyme that breaks down sphingomyelin into ceramide - has been found to localise exclusively to the inner leaflet, further suggesting that there may be sphingomyelin present there.
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Golgi-stained neurons in human hippocampal tissue Actin filaments in a mouse cortical neuron in culture Numerous microscopic clumps called Nissl bodies (or Nissl substance) are seen when nerve cell bodies are stained with a basophilic ("base-loving") dye. These structures consist of rough endoplasmic reticulum and associated ribosomal RNA. Named after German psychiatrist and neuropathologist Franz Nissl (1860–1919), they are involved in protein synthesis and their prominence can be explained by the fact that nerve cells are very metabolically active. Basophilic dyes such as aniline or (weakly) haematoxylin highlight negatively charged components, and so bind to the phosphate backbone of the ribosomal RNA.
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The silver chromate precipitate, as a reaction product, selectively stains only some cellular components randomly, sparing other cell parts. The silver chromate particles create a stark black deposit on the soma (nerve cell body) as well as on the axon and all dendrites, providing an exceedingly clear and well-contrasted picture of neuron against a yellow background. This makes it easier to trace the structure of the nerve cells in the brain for the first time. Since cells are selective stained in black, he called the process la reazione nera ("the black reaction"), but today it is called Golgi's method or the Golgi stain.
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Finally, they counterintuitively found that the longer and heavier the male's tail feathers were, the faster they were able to shake their feathers. In a follow-up study published in 2018, Kane and Dakin found that the vibrations sent out by males rattling their trains are actually felt by females on the crest of their head, which vibrates in turn. They found that at the base of the a female's crest feathers lies a tiny feather known as a filoplume, which acts as a mechanical sensor. When the crest feathers begin vibrating, the filoplume triggers a nerve cell, translating the physical vibrations of the plume into neuronal signal.
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Myelin is a lipid-rich (fatty) substance that surrounds nerve cell axons (the nervous system's "wires") to insulate them and increase the rate at which electrical impulses (called action potentials) are passed along the axon. The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However, unlike the plastic covering on an electrical wire, myelin does not form a single long sheath over the entire length of the axon. Rather, each myelin sheath insulates the axon over a single long section and, in general, each axon comprises multiple long myelinated sections separated from each other by short myelin sheath-gaps called nodes of Ranvier.
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Proneural gene expression in the neuroectodermal cells that constitutes the proneural clusters turns them competent to delaminate as neuroblasts. Although neuroblasts are the precursors of Drosophila’s central nervous system (CNS), the proneural gene expression are also involved in control specification and morphogenesis of stomatogastric nerve cell precursors. These genes are expressed and required during all phases of the stomatogastric nervous system (SNS) development to regulate the number, pattern and structural characteristics of the SNS subpopulations. The proper balance between proneural and neurogenic gene expression in the SNS placodes is involved in the control of a complex sequence of morphogenetic movements (delamination, invagination and dissociation) by which these placodes give rise to the different SNS subpopulations.
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By the late 1950s, working at General Automation, Ovshinsky brought together these disparate studies in an invention. Crossing scientific disciplines that academics traditionally hold separate, including neurophysiology and cybernetics, Stan invented, and Herb Ovshinsky helped build, a mechanical model of a nerve cell – an amorphous thin-film switch they called the Ovitron. Stan patented the device and the brothers disclosed it publicly in 1959 in New York City. In an attempt to model the learning ability of nerve cells, which Stan recognized as deriving from the plasticity of the cell's membrane, he drew on his knowledge of surfaces and materials to fashion very thin layers of amorphous material, thus pioneering the use of nanostructures.
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He was considered for a Nobel prize for his work on nerve-cell outgrowth, which helped form the modern functional understanding of the nervous system, and he contributed to surgical tissue transplant technique. During the first world war, Harrison studied embryology and the symmetries of development. By means of the dissection of embryos followed by transplantation and rotatation of the limb bud he demonstrated that the main axes of the developing limb are determined independently and at slightly different times, determination of the anteroposterior (anterior-posterior) axis preceding that of the dorsoventral (dorsal-ventral) axis. Harrison dissected Ambystoma puncatatum (salamander) embryos and transplanted limb buds to determine whether the limbs developed independently or according to instructions from host cells.
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Dendrites (from Greek δένδρον déndron, "tree"), also dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project. Electrical stimulation is transmitted onto dendrites by upstream neurons (usually via their axons) via synapses which are located at various points throughout the dendritic tree. Dendrites play a critical role in integrating these synaptic inputs and in determining the extent to which action potentials are produced by the neuron. Dendritic arborization, also known as dendritic branching, is a multi-step biological process by which neurons form new dendritic trees and branches to create new synapses.
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Tetrodotoxin binds to what is known as site 1 of the fast voltage-gated sodium channel. Site 1 is located at the extracellular pore opening of the ion channel. The binding of any molecules to this site will temporarily disable the function of the ion channel, thereby blocking the passage of sodium ions into the nerve cell (which is ultimately necessary for nerve conduction); neosaxitoxin and several of the conotoxins also bind the same site. The use of this toxin as a biochemical probe has elucidated two distinct types of voltage-gated sodium channels present in mammals: tetrodotoxin-sensitive voltage-gated sodium channels (TTX-s Na+ channels) and tetrodotoxin-resistant voltage-gated sodium channels (TTX-r Na+ channels).
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In rat hippocampal neurons, Pur-alpha is found in the cytoplasm together with mRNA transcripts, in a complex including non- coding RNAs, Pur-beta, fragile X mental retardation proteins and microtubule- associated proteins. This complex is transported by a kinesin motor to sites of translation at junctions of nerve cell dendrites. Recently PURA mutations have been found in multiple patients with brain disorders of a similar phenotype including hypotonia, developmental delay, movement disorders, and seizure or seizure-like movements. This spectrum of brain disorders is similar to the phenotype of a central nervous system syndrome termed the 5q31.3 microdeletion syndrome, and is the basis for a proposed PURA Syndrome based on PURA mutations rather than just deletions.
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Alexander Hill (1856 – 28 February 1929) was a medical doctor and professor who was Master of Downing College, Cambridge from 1888 to 1907 and Vice- Chancellor of the University of Cambridge from 1897 to 1899. He was Principal of Southampton University College from 1913 to 1920.Royal College of Surgeons, Biography of Fellows, 13 April 2012, accessed 24 August 2013The University of Southampton (1962) A. Temple Patterson, Southampton University Press, ASIN: B0000CLFGC A brain specialist, he was the first person to use the term 'neuron' in English to describe the nerve cell and its processes, in his 1891 translation of a German paper summarizing the lectures of Heinrich Wilhelm Gottfried von Waldeyer-Hartz.
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The earliest reports of purinergic signalling date back to 1929, when the Hungarian physiologist Albert Szent-Györgyi observed that purified adenine compounds produced a temporary reduction in heart rate when injected into animals. In the 1960s, the classical view of autonomic smooth muscle control was based upon Dale's principle, which asserts that each nerve cell can synthesize, store, and release only one neurotransmitter. It was therefore assumed that a sympathetic neuron releases noradrenaline only, while an antagonistic parasympathetic neuron releases acetylcholine only. Although the concept of cotransmission gradually gained acceptance in the 1980s, the belief that a single neuron acts via a single type of neurotransmitter continued to dominate the field of neurotransmission throughout the 1970s.
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A serum sodium level of less than 135 mEq/L qualifies as hyponatremia, which is considered severe when the serum sodium level is below 125 mEq/L. The renin–angiotensin system and the atrial natriuretic peptide indirectly regulate the amount of signal transduction in the human central nervous system, which depends on sodium ion motion across the nerve cell membrane, in all nerves. Sodium is thus important in neuron function and osmoregulation between cells and the extracellular fluid; the distribution of sodium ions are mediated in all animals by sodium–potassium pumps, which are active transporter solute pumps, pumping ions against the gradient, and sodium-potassium channels. Sodium channels are known to be less selective in comparison to potassium channels.
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In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target effector cell. Santiago Ramón y Cajal proposed that neurons are not continuous throughout the body, yet still communicate with each other, an idea known as the neuron doctrine. The word "synapse" – from the Greek synapsis (), meaning "conjunction", in turn from ( ("together") and ("to fasten")) – was introduced in 1897 by the English neurophysiologist Charles Sherrington in Michael Foster's Textbook of Physiology. Sherrington struggled to find a good term that emphasized a union between two separate elements, and the actual term "synapse" was suggested by the English classical scholar Arthur Woollgar Verrall, a friend of Foster.
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Van Gehuchten adopted Waldeyer’s coinage for the nerve cell, but spelt this in French as ‘le neurone' rather than 'le neuron'. It is believed that the reason for adding the ‘e’ at the end of the word relates to the interplay between linguistics and phonetics: the final ‘n’ in ‘neuron’ would have been ‘sounded’ in the classical Greek, and also in Waldeyer’s German coinage, and, to do the same in French, there needed to be an ‘e’ placed at the end of the word. Without this, ‘neuron’ would have rhymed with ‘maison’ and the link with the original Greek would have been lost. 50px Text was copied from this source, which is available under a Creative Commons Attribution 4.0 International License.
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" The results were reported on by the Daily Telegraph, which noted that the study did not prove that the MMR vaccine caused autism; rather, "autism may be responsible for the unusual response to the MMR antibodies." Singh's findings on autism have been criticized by other scientists as flawed, unreproducible, or dubious. Mary Ramsay of the Health Protection Agency wrote that the evidence for the "specific" MMR-type antibody Singh claims to have detected was "not credible." Paul Offit wrote in Autism's False Prophets that "...a closer look at Singh's science revealed two critical flaws: children with autism didn't have evidence of nerve cell damage, and, according to measles experts, the test that Singh had used to detect measles antibodies didn't actually detect them.
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She also developed another radiotracer, as these "tagged" molecules are called, that first showed that cocaine's distribution in the human brain parallels its effects on behavior. Fowler played a central role in the development of a fluorine-18-labeled glucose molecule (FDG) enabling human brain glucose metabolism to be measured noninvasively. This positron-emitting molecule, together with positron emission tomography (PET) imaging, has become a mainstay for brain-imaging studies in schizophrenia, aging and cancer. Another of her major accomplishments was the development of the first radiotracers to map monoamine oxidase (MAO), a brain enzyme that regulates the levels of other nerve-cell communication chemicals and one of the two major enzymes involved in neurotransmitter regulation in the brain and peripheral organs.
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Behavioral studies suggest that the IPS is associated with impairments of basic numerical magnitude processing and that there is a pattern of structural and functional alternations in the IPS and in the PFC in dyscalculia. Children with developmental dyscalculia were found to have less gray matter in the left IPS. Studies have shown that electrical activity in a particular group of nerve cells in the intraparietal sulcus spiked when, and only when, volunteers were performing calculations. Outside experimental settings it was also found that when a patient mentioned a number—or even a quantitative reference, such as "some more", "many" or "bigger than the other one"—there was a spike of electrical activity in the same nerve-cell population of the intraparietal sulcus that was activated when the patient was doing calculations under experimental conditions.
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This album contained 14 new songs, 14 new versions of old songs and nine songs recorded live; alongside the album the band released its first video, of the song Lo que ustedes se merecen (What you deserve). The band also did a short tour in Colombia, performing in Medellín, Bogotá and Cali simultaneously with the release of the album in these cities. Later the same year the band released its second video, of the song Neurona (Nerve cell). In March and April 2004, the band toured the United States, there they had fifteen performances in Boston, Baltimore, New York City (where they performed in the famous CBGB, and during which the band recorded a live album), New Jersey, Miami (where they filmed the video of the song Explotados ("Exploited")), Monterrey, Berkeley and San Francisco.
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However, the issues are complex, as neovascular growth is not always beneficial, since it plays a role in tumor growth, and also the damage from wet macular degeneration, a disease for which smoking (a major source of carbon monoxide in the blood, several times more than natural production) increases the risk from 4 to 6 times. There is a theory that, in some nerve cell synapses, when long-term memories are being laid down, the receiving cell makes carbon monoxide, which back-transmits to the transmitting cell, telling it to transmit more readily in future. Some such nerve cells have been shown to contain guanylate cyclase, an enzyme that is activated by carbon monoxide. Studies involving carbon monoxide have been conducted in many laboratories throughout the world for its anti-inflammatory and cytoprotective properties.
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The nervous system is defined by the presence of a special type of cell—the neuron (sometimes called "neurone" or "nerve cell"). Neurons can be distinguished from other cells in a number of ways, but their most fundamental property is that they communicate with other cells via synapses, which are membrane-to-membrane junctions containing molecular machinery that allows rapid transmission of signals, either electrical or chemical. Many types of neuron possess an axon, a protoplasmic protrusion that can extend to distant parts of the body and make thousands of synaptic contacts; axons typically extend throughout the body in bundles called nerves. Even in the nervous system of a single species such as humans, hundreds of different types of neurons exist, with a wide variety of morphologies and functions.
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John E. Heuser (born August 29, 1942) is an American Professor of Biophysics in the department of Cell Biology and Physiology at the Washington University School of Medicine as well as a Professor at the Institute for Integrated Cell-Matieral Sciences (iCeMS) at Kyoto University. Heuser created quick- freeze deep-etch electron microscopy (a variant of cell unroofing), a pioneering technique that lets biologists take detailed pictures of fleeting events inside living cells. For decades, Heuser has used this technique to capture details of the molecular mechanisms that underlie many basic biological activities, including nerve cell signal transmission, muscle contraction, and most recently, the fusion of viruses with cells during the spread of infection. He compares quick-freeze deep-etch electron microscopy to using a stroboscopic flash to freeze the action in a photograph.
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In these experiments, membrane potentials including action potentials of neurons are measured with extra- or intracellular electrodes in single-unit recording, with multielectrode arrays, or by employing the patch clamp technique, which enables measurements of membrane potentials in different parts of a given nerve cell. Besides these electrophysiological methods, which are constantly undergoing refinement, numerous optical methods are employed at the CIN to make individual cells or cell clusters visible in vitro or in vivo, and to observe their behaviour in realtime: fluorescence microscopy, most importantly making use of confocal or 2-photon microscopes. The most recent innovation in optical methods is the localisation of protein molecules in neuronal compartments by combining super-resolution microscopy with a molecule-specific marking technique. Super resolution microscopy can reach resolutions below the Abbe limit of conventional light microscopy.
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The high voltage radio frequency (RF) discharges from the output terminal of a Tesla coil pose a unique hazard not found in other high voltage equipment: when passed through the body they often do not cause the painful sensation and muscle contraction of electric shock, as lower frequency AC or DC currents do. The nervous system is insensitive to currents with frequencies over 10 – 20 kHz. It is thought that the reason for this is that a certain minimum number of ions must be driven across a nerve cell's membrane by the imposed voltage to trigger the nerve cell to depolarize and transmit an impulse. At radio frequencies, there is insufficient time during a half-cycle for enough ions to cross the membrane before the alternating voltage reverses.
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He was an advocate of the existence of dendritic spines, although he did not recognize them as the site of contact from presynaptic cells. He was a proponent of polarization of nerve cell function and his student, Rafael Lorente de Nó, would continue this study of input-output systems into cable theory and some of the earliest circuit analysis of neural structures. By producing excellent depictions of neural structures and their connectivity and providing detailed descriptions of cell types he discovered a new type of cell, which was subsequently named after him, the interstitial cell of Cajal (ICC). This cell is found interleaved among neurons embedded within the smooth muscles lining the gut, serving as the generator and pacemaker of the slow waves of contraction which move material along the gastrointestinal tract, mediating neurotransmission from motor neurons to smooth muscle cells.
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Current source density analysis (which could more accurately be called current source and sink density analysis) is the practice of placing a microelectrode in proximity to a nerve or a nerve cell to detect current sourcing from, or sinking into, their plasma membranes. When positive charges, for example, flow quickly across a plasma membrane to the inside of a cell (sink) this creates a transient cloud of negativity in the vicinity of the sink. This is because the flow of positive charges into the interior of the cell leaves behind uncompensated negative charges. A nearby micro-electrode with substantial tip resistance (on the order of 1 MΩ) can detect that negativity because a voltage difference will develop across the tip of the electrode (between the negativity outside the electrode, and the electroneutral environment inside the electrode).
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In the human brainstem, the solitary nucleus (SN) (nucleus of the solitary tract, nucleus solitarius, nucleus tractus solitarii) is a series of purely sensory nuclei (clusters of nerve cell bodies) forming a vertical column of grey matter embedded in the medulla oblongata. Through the center of the SN runs the solitary tract, a white bundle of nerve fibers, including fibers from the facial, glossopharyngeal and vagus nerves, that innervate the SN. The SN projects to, among other regions, the reticular formation, parasympathetic preganglionic neurons, hypothalamus and thalamus, forming circuits that contribute to autonomic regulation. Cells along the length of the SN are arranged roughly in accordance with function; for instance, cells involved in taste are located In the rostrum part, while those receiving information from cardio-respiratory and gastrointestinal processes are found in the caudal part.
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The pathogenic mutation is a hexanucleotide repeat expansion (a series of six nucleotides repeated over and over); people with 30 repeats are normal, while people with hundreds or thousands of repeats can have familial ALS, frontotemporal dementia, or sometimes sporadic ALS. The three mechanisms of disease associated with these C9orf72 repeats are deposition of RNA transcripts in the nucleus, translation of the RNA into toxic dipeptide repeat proteins in the cytoplasm, and decreased levels of the normal C9orf72 protein. Excitotoxicity, or nerve cell death caused by high levels of intracellular calcium due to excessive stimulation by the excitatory neurotransmitter glutamate, is a mechanism thought to be common to all forms of ALS. Motor neurons are more sensitive to excitotoxicity than other types of neurons because they have a lower calcium-buffering capacity and a type of glutamate receptor (the AMPA receptor) that is more permeable to calcium.
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The presenilins are components of a proteolytic complex involved in APP processing and degradation. Although amyloid beta monomers are harmless, they undergo a dramatic conformational change at sufficiently high concentration to form a beta sheet-rich tertiary structure that aggregates to form amyloid fibrils that deposit outside neurons in dense formations known as senile plaques or neuritic plaques, in less dense aggregates as diffuse plaques, and sometimes in the walls of small blood vessels in the brain in a process called amyloid angiopathy or congophilic angiopathy. AD is also considered a tauopathy due to abnormal aggregation of the tau protein, a microtubule-associated protein expressed in neurons that normally acts to stabilize microtubules in the cell cytoskeleton. Like most microtubule-associated proteins, tau is normally regulated by phosphorylation; however, in AD patients, hyperphosphorylated tau accumulates as paired helical filaments that in turn aggregate into masses inside nerve cell bodies known as neurofibrillary tangles and as dystrophic neurites associated with amyloid plaques.
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Research through knockout mice, or mice with the MAG gene removed, has shown that this glycoprotein serves heavily in the formation of myelin but also show that early development of the peripheral nervous system is relatively normal even without the presence of MAG. The knockout mice generally show many motor deficits, however, as they age caused by the degeneration of the myelinated axons further suggesting the need for these glycoproteins in maintenance of the sheaths. While it is still unclear as to the exact mechanism or pathway by which MAG affects myelination, studies suggest that MAG serves in a receptor role to begin a signaling cascade begun by activation from an external source. MAG has also been shown to bind as a ligand to a receptor on the axonal surface which suggests that the external stimulus activating the creation of myelin comes from the nerve cell or cells that these glycoproteins are bound to.
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All parts of the nervous system have the same elementary property; sensibility. Thus sensibility belongs as much to the lower centres of the spinal cord as to the brain, the former, more elementary, form contributing to the subconscious region of mental life, while the higher functions of the nervous system, which make up our conscious mental life, are more complex modifications of this fundamental property of nerve substance. The nervous organism acts as a whole, particular mental operations cannot be referred to definite regions of the brain, and the hypothesis of nervous activity by an isolated pathway from one nerve cell to another is altogether illusory. By insisting on the complete coincidence between the regions of nerve action and sentience, that these are but different aspects of one thing, he was able to attack the doctrine of animal and human automatism which affirms that feeling or consciousness is merely an incidental concomitant of nerve action in no way essential to the chain of physical events.
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Amyloid beta monomers are soluble and contain short regions of beta sheet and polyproline II helix secondary structures in solution, though they are largely alpha helical in membranes; however, at sufficiently high concentration, they undergo a dramatic conformational change to form a beta sheet-rich tertiary structure that aggregates to form amyloid fibrils. These fibrils deposit outside neurons in dense formations known as senile plaques or neuritic plaques, in less dense aggregates as diffuse plaques, and sometimes in the walls of small blood vessels in the brain in a process called cerebral amyloid angiopathy. AD is also considered a tauopathy due to abnormal aggregation of the tau protein, a microtubule-associated protein expressed in neurons that normally acts to stabilize microtubules in the cell cytoskeleton. Like most microtubule-associated proteins, tau is normally regulated by phosphorylation; however, in Alzheimer's disease, hyperphosphorylated tau accumulates as paired helical filaments that in turn aggregate into masses inside nerve cell bodies known as neurofibrillary tangles and as dystrophic neurites associated with amyloid plaques.
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Within the CNS, nerve cell bodies are generally organized into functional clusters, called nuclei. Axons within the CNS are grouped into tracts. There are 33 spinal cord nerve segments in a human spinal cord: 8 cervical segments forming 8 pairs of cervical nerves (C1 spinal nerves exit spinal column between occiput and C1 vertebra; C2 nerves exit between posterior arch of C1 vertebra and lamina of C2 vertebra; C3-C8 spinal nerves through IVF above corresponding cervica vertebra, with the exception of C8 pair which exit via IVF between C7 and T1 vertebra) 12 thoracic segments forming 12 pairs of thoracic nerves (exit spinal column through IVF below corresponding vertebra T1-T12) 5 lumbar segments forming 5 pairs of lumbar nerves (exit spinal column through IVF, below corresponding vertebra L1-L5) 5 sacral segments forming 5 pairs of sacral nerves (exit spinal column through IVF, below corresponding vertebra S1-S5) 3 coccygeal segments joined up becoming a single segment forming 1 pair of coccygeal nerves (exit spinal column through the sacral hiatus).
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Early in his career, Pfaff developed techniques to discover both estrogen and androgen receptors in rat brains. Within 15 years, it was clear that the limbic/hypothalamic system he discovered in rat brains was universal among vertebrate brains as well. His laboratory worked out the first nerve cell circuit for a mammalian behavior, discovered hormone- sensitive genes in the brain; and integrated these findings to show how specific gene expression in a small part of the brain can regulate behavior. Pfaff also discovered that the nerve cells which control all reproductive processes—neurons that express the gene for the peptide called Gonadotropin- releasing hormone (GnRH)—are not born in the brain (as are most neurons), but in the nose, from which they migrate into the brain. Pfaff also formulated a concept of the fundamental brain processes, “generalized brain arousal” (GA), and studied the development of arousal-related neurons, their anatomy, and neurophysiology. Pfaff’s lab has published more than 900 research papers, and he has written or edited more than 25 books.
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