Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.Electrophysiology: The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.Membrane Potentials: The voltage differences across a membrane. For cellular membranes they are computed by subtracting the voltage measured outside the membrane from the voltage measured inside the membrane. They result from differences of inside versus outside concentration of potassium, sodium, chloride, and other ions across cells' or ORGANELLES membranes. For excitable cells, the resting membrane potentials range between -30 and -100 millivolts. Physical, chemical, or electrical stimuli can make a membrane potential more negative (hyperpolarization), or less negative (depolarization).Patch-Clamp Techniques: An electrophysiologic technique for studying cells, cell membranes, and occasionally isolated organelles. All patch-clamp methods rely on a very high-resistance seal between a micropipette and a membrane; the seal is usually attained by gentle suction. The four most common variants include on-cell patch, inside-out patch, outside-out patch, and whole-cell clamp. Patch-clamp methods are commonly used to voltage clamp, that is control the voltage across the membrane and measure current flow, but current-clamp methods, in which the current is controlled and the voltage is measured, are also used.Tetrodotoxin: An aminoperhydroquinazoline poison found mainly in the liver and ovaries of fishes in the order TETRAODONTIFORMES, which are eaten. The toxin causes paresthesia and paralysis through interference with neuromuscular conduction.Electric Stimulation: Use of electric potential or currents to elicit biological responses.Sodium Channels: Ion channels that specifically allow the passage of SODIUM ions. A variety of specific sodium channel subtypes are involved in serving specialized functions such as neuronal signaling, CARDIAC MUSCLE contraction, and KIDNEY function.Calcium: A basic element found in nearly all organized tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.Guinea Pigs: A common name used for the genus Cavia. The most common species is Cavia porcellus which is the domesticated guinea pig used for pets and biomedical research.Ventricular Function: The hemodynamic and electrophysiological action of the HEART VENTRICLES.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Potassium Channels: Cell membrane glycoproteins that are selectively permeable to potassium ions. At least eight major groups of K channels exist and they are made up of dozens of different subunits.Neural Conduction: The propagation of the NERVE IMPULSE along the nerve away from the site of an excitation stimulus.Heart: The hollow, muscular organ that maintains the circulation of the blood.Potassium: An element in the alkali group of metals with an atomic symbol K, atomic number 19, and atomic weight 39.10. It is the chief cation in the intracellular fluid of muscle and other cells. Potassium ion is a strong electrolyte that plays a significant role in the regulation of fluid volume and maintenance of the WATER-ELECTROLYTE BALANCE.Heart Conduction System: An impulse-conducting system composed of modified cardiac muscle, having the power of spontaneous rhythmicity and conduction more highly developed than the rest of the heart.Papillary Muscles: Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.Electric Conductivity: The ability of a substrate to allow the passage of ELECTRONS.4-Aminopyridine: One of the POTASSIUM CHANNEL BLOCKERS, with secondary effect on calcium currents, which is used mainly as a research tool and to characterize channel subtypes.Synaptic Transmission: The communication from a NEURON to a target (neuron, muscle, or secretory cell) across a SYNAPSE. In chemical synaptic transmission, the presynaptic neuron releases a NEUROTRANSMITTER that diffuses across the synaptic cleft and binds to specific synaptic receptors, activating them. The activated receptors modulate specific ion channels and/or second-messenger systems in the postsynaptic cell. In electrical synaptic transmission, electrical signals are communicated as an ionic current flow across ELECTRICAL SYNAPSES.Microelectrodes: Electrodes with an extremely small tip, used in a voltage clamp or other apparatus to stimulate or record bioelectric potentials of single cells intracellularly or extracellularly. (Dorland, 28th ed)Pyramidal Cells: Projection neurons in the CEREBRAL CORTEX and the HIPPOCAMPUS. Pyramidal cells have a pyramid-shaped soma with the apex and an apical dendrite pointed toward the pial surface and other dendrites and an axon emerging from the base. The axons may have local collaterals but also project outside their cortical region.Heart Ventricles: The lower right and left chambers of the heart. The right ventricle pumps venous BLOOD into the LUNGS and the left ventricle pumps oxygenated blood into the systemic arterial circulation.Dendrites: Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.Sodium: A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.Purkinje Fibers: Modified cardiac muscle fibers composing the terminal portion of the heart conduction system.Synapses: Specialized junctions at which a neuron communicates with a target cell. At classical synapses, a neuron's presynaptic terminal releases a chemical transmitter stored in synaptic vesicles which diffuses across a narrow synaptic cleft and activates receptors on the postsynaptic membrane of the target cell. The target may be a dendrite, cell body, or axon of another neuron, or a specialized region of a muscle or secretory cell. Neurons may also communicate via direct electrical coupling with ELECTRICAL SYNAPSES. Several other non-synaptic chemical or electric signal transmitting processes occur via extracellular mediated interactions.Potassium Channel Blockers: A class of drugs that act by inhibition of potassium efflux through cell membranes. Blockade of potassium channels prolongs the duration of ACTION POTENTIALS. They are used as ANTI-ARRHYTHMIA AGENTS and VASODILATOR AGENTS.Tetraethylammonium CompoundsRefractory Period, Electrophysiological: The period of time following the triggering of an ACTION POTENTIAL when the CELL MEMBRANE has changed to an unexcitable state and is gradually restored to the resting (excitable) state. During the absolute refractory period no other stimulus can trigger a response. This is followed by the relative refractory period during which the cell gradually becomes more excitable and the stronger impulse that is required to illicit a response gradually lessens to that required during the resting state.Potassium Channels, Voltage-Gated: Potassium channel whose permeability to ions is extremely sensitive to the transmembrane potential difference. The opening of these channels is induced by the membrane depolarization of the ACTION POTENTIAL.Anti-Arrhythmia Agents: Agents used for the treatment or prevention of cardiac arrhythmias. They may affect the polarization-repolarization phase of the action potential, its excitability or refractoriness, or impulse conduction or membrane responsiveness within cardiac fibers. Anti-arrhythmia agents are often classed into four main groups according to their mechanism of action: sodium channel blockade, beta-adrenergic blockade, repolarization prolongation, or calcium channel blockade.Myocytes, Cardiac: Striated muscle cells found in the heart. They are derived from cardiac myoblasts (MYOBLASTS, CARDIAC).Models, Cardiovascular: Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.Arrhythmias, Cardiac: Any disturbances of the normal rhythmic beating of the heart or MYOCARDIAL CONTRACTION. Cardiac arrhythmias can be classified by the abnormalities in HEART RATE, disorders of electrical impulse generation, or impulse conduction.Sodium Channel Blockers: A class of drugs that act by inhibition of sodium influx through cell membranes. Blockade of sodium channels slows the rate and amplitude of initial rapid depolarization, reduces cell excitability, and reduces conduction velocity.Excitatory Postsynaptic Potentials: Depolarization of membrane potentials at the SYNAPTIC MEMBRANES of target neurons during neurotransmission. Excitatory postsynaptic potentials can singly or in summation reach the trigger threshold for ACTION POTENTIALS.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Ion Channels: Gated, ion-selective glycoproteins that traverse membranes. The stimulus for ION CHANNEL GATING can be due to a variety of stimuli such as LIGANDS, a TRANSMEMBRANE POTENTIAL DIFFERENCE, mechanical deformation or through INTRACELLULAR SIGNALING PEPTIDES AND PROTEINS.Delayed Rectifier Potassium Channels: A group of slow opening and closing voltage-gated potassium channels. Because of their delayed activation kinetics they play an important role in controlling ACTION POTENTIAL duration.Tetraethylammonium: A potassium-selective ion channel blocker. (From J Gen Phys 1994;104(1):173-90)Dogs: The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Evoked Potentials: Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported.Calcium Channels: Voltage-dependent cell membrane glycoproteins selectively permeable to calcium ions. They are categorized as L-, T-, N-, P-, Q-, and R-types based on the activation and inactivation kinetics, ion specificity, and sensitivity to drugs and toxins. The L- and T-types are present throughout the cardiovascular and central nervous systems and the N-, P-, Q-, & R-types are located in neuronal tissue.Models, Neurological: Theoretical representations that simulate the behavior or activity of the neurological system, processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.Calcium Channels, L-Type: Long-lasting voltage-gated CALCIUM CHANNELS found in both excitable and nonexcitable tissue. They are responsible for normal myocardial and vascular smooth muscle contractility. Five subunits (alpha-1, alpha-2, beta, gamma, and delta) make up the L-type channel. The alpha-1 subunit is the binding site for calcium-based antagonists. Dihydropyridine-based calcium antagonists are used as markers for these binding sites.Myocardium: The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.Myocardial Contraction: Contractile activity of the MYOCARDIUM.Heart Atria: The chambers of the heart, to which the BLOOD returns from the circulation.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Ion Channel Gating: The opening and closing of ion channels due to a stimulus. The stimulus can be a change in membrane potential (voltage-gated), drugs or chemical transmitters (ligand-gated), or a mechanical deformation. Gating is thought to involve conformational changes of the ion channel which alters selective permeability.Motor Neurons: Neurons which activate MUSCLE CELLS.Sinoatrial Node: The small mass of modified cardiac muscle fibers located at the junction of the superior vena cava (VENA CAVA, SUPERIOR) and right atrium. Contraction impulses probably start in this node, spread over the atrium (HEART ATRIUM) and are then transmitted by the atrioventricular bundle (BUNDLE OF HIS) to the ventricle (HEART VENTRICLE).Atrial Function: The hemodynamic and electrophysiological action of the HEART ATRIA.Voltage-Sensitive Dye Imaging: Optical imaging techniques used for recording patterns of electrical activity in tissues by monitoring transmembrane potentials via FLUORESCENCE imaging with voltage-sensitive fluorescent dyes.Endocardium: The innermost layer of the heart, comprised of endothelial cells.Calcium Signaling: Signal transduction mechanisms whereby calcium mobilization (from outside the cell or from intracellular storage pools) to the cytoplasm is triggered by external stimuli. Calcium signals are often seen to propagate as waves, oscillations, spikes, sparks, or puffs. The calcium acts as an intracellular messenger by activating calcium-responsive proteins.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Electrophysiological Phenomena: The electrical properties, characteristics of living organisms, and the processes of organisms or their parts that are involved in generating and responding to electrical charges.Hippocampus: A curved elevation of GRAY MATTER extending the entire length of the floor of the TEMPORAL HORN of the LATERAL VENTRICLE (see also TEMPORAL LOBE). The hippocampus proper, subiculum, and DENTATE GYRUS constitute the hippocampal formation. Sometimes authors include the ENTORHINAL CORTEX in the hippocampal formation.Calcium Channel Blockers: A class of drugs that act by selective inhibition of calcium influx through cellular membranes.Neural Inhibition: The function of opposing or restraining the excitation of neurons or their target excitable cells.Interneurons: Most generally any NEURONS which are not motor or sensory. Interneurons may also refer to neurons whose AXONS remain within a particular brain region in contrast to projection neurons, which have axons projecting to other brain regions.Pericardium: A conical fibro-serous sac surrounding the HEART and the roots of the great vessels (AORTA; VENAE CAVAE; PULMONARY ARTERY). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers.Anura: An order of the class Amphibia, which includes several families of frogs and toads. They are characterized by well developed hind limbs adapted for jumping, fused head and trunk and webbed toes. The term "toad" is ambiguous and is properly applied only to the family Bufonidae.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Quinidine: An optical isomer of quinine, extracted from the bark of the CHINCHONA tree and similar plant species. This alkaloid dampens the excitability of cardiac and skeletal muscles by blocking sodium and potassium currents across cellular membranes. It prolongs cellular ACTION POTENTIALS, and decreases automaticity. Quinidine also blocks muscarinic and alpha-adrenergic neurotransmission.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Long QT Syndrome: A condition that is characterized by episodes of fainting (SYNCOPE) and varying degree of ventricular arrhythmia as indicated by the prolonged QT interval. The inherited forms are caused by mutation of genes encoding cardiac ion channel proteins. The two major forms are ROMANO-WARD SYNDROME and JERVELL-LANGE NIELSEN SYNDROME.Animals, Newborn: Refers to animals in the period of time just after birth.Presynaptic Terminals: The distal terminations of axons which are specialized for the release of neurotransmitters. Also included are varicosities along the course of axons which have similar specializations and also release transmitters. Presynaptic terminals in both the central and peripheral nervous systems are included.Ether-A-Go-Go Potassium Channels: A family of voltage-gated potassium channels that are characterized by long N-terminal and C-terminal intracellular tails. They are named from the Drosophila protein whose mutation causes abnormal leg shaking under ether anesthesia. Their activation kinetics are dependent on extracellular MAGNESIUM and PROTON concentration.Reaction Time: The time from the onset of a stimulus until a response is observed.Neurotransmitter Agents: Substances used for their pharmacological actions on any aspect of neurotransmitter systems. Neurotransmitter agents include agonists, antagonists, degradation inhibitors, uptake inhibitors, depleters, precursors, and modulators of receptor function.Barium: An element of the alkaline earth group of metals. It has an atomic symbol Ba, atomic number 56, and atomic weight 138. All of its acid-soluble salts are poisonous.Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)Neocortex: The largest portion of the CEREBRAL CORTEX in which the NEURONS are arranged in six layers in the mammalian brain: molecular, external granular, external pyramidal, internal granular, internal pyramidal and multiform layers.Cells, Cultured: Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others.Lidocaine: A local anesthetic and cardiac depressant used as an antiarrhythmia agent. Its actions are more intense and its effects more prolonged than those of PROCAINE but its duration of action is shorter than that of BUPIVACAINE or PRILOCAINE.Muscle Contraction: A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.Cesium: A member of the alkali metals. It has an atomic symbol Cs, atomic number 50, and atomic weight 132.91. Cesium has many industrial applications, including the construction of atomic clocks based on its atomic vibrational frequency.Ganglia, Spinal: Sensory ganglia located on the dorsal spinal roots within the vertebral column. The spinal ganglion cells are pseudounipolar. The single primary branch bifurcates sending a peripheral process to carry sensory information from the periphery and a central branch which relays that information to the spinal cord or brain.Neuromuscular Junction: The synapse between a neuron and a muscle.gamma-Aminobutyric Acid: The most common inhibitory neurotransmitter in the central nervous system.Electrocardiography: Recording of the moment-to-moment electromotive forces of the HEART as projected onto various sites on the body's surface, delineated as a scalar function of time. The recording is monitored by a tracing on slow moving chart paper or by observing it on a cardioscope, which is a CATHODE RAY TUBE DISPLAY.Ventricular Fibrillation: A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST.Differential Threshold: The smallest difference which can be discriminated between two stimuli or one which is barely above the threshold.Shal Potassium Channels: A shaker subfamily of potassium channels that participate in transient outward potassium currents by activating at subthreshold MEMBRANE POTENTIALS, inactivating rapidly, and recovering from inactivation quickly.Sotalol: An adrenergic beta-antagonist that is used in the treatment of life-threatening arrhythmias.Cardiac Pacing, Artificial: Regulation of the rate of contraction of the heart muscles by an artificial pacemaker.Muscles: Contractile tissue that produces movement in animals.Aminopyridines: Pyridines substituted in any position with an amino group. May be hydrogenated, but must retain at least one double bond.Synaptic Potentials: The voltages across pre- or post-SYNAPTIC MEMBRANES.Strontium: An element of the alkaline earth family of metals. It has the atomic symbol Sr, atomic number 38, and atomic weight 87.62.Cnidarian Venoms: Venoms from jellyfish; CORALS; SEA ANEMONES; etc. They contain hemo-, cardio-, dermo- , and neuro-toxic substances and probably ENZYMES. They include palytoxin, sarcophine, and anthopleurine.Sodium-Calcium Exchanger: An electrogenic ion exchange protein that maintains a steady level of calcium by removing an amount of calcium equal to that which enters the cells. It is widely distributed in most excitable membranes, including the brain and heart.Sensory Receptor Cells: Specialized afferent neurons capable of transducing sensory stimuli into NERVE IMPULSES to be transmitted to the CENTRAL NERVOUS SYSTEM. Sometimes sensory receptors for external stimuli are called exteroceptors; for internal stimuli are called interoceptors and proprioceptors.Decapodiformes: A superorder of CEPHALOPODS comprised of squid, cuttlefish, and their relatives. Their distinguishing feature is the modification of their fourth pair of arms into tentacles, resulting in 10 limbs.Biological Clocks: The physiological mechanisms that govern the rhythmic occurrence of certain biochemical, physiological, and behavioral phenomena.Nerve Fibers, Unmyelinated: A class of nerve fibers as defined by their nerve sheath arrangement. The AXONS of the unmyelinated nerve fibers are small in diameter and usually several are surrounded by a single MYELIN SHEATH. They conduct low-velocity impulses, and represent the majority of peripheral sensory and autonomic fibers, but are also found in the BRAIN and SPINAL CORD.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Cobalt: A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.Nerve Fibers: Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM.Ganglia: Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.Apamin: A highly neurotoxic polypeptide from the venom of the honey bee (Apis mellifera). It consists of 18 amino acids with two disulfide bridges and causes hyperexcitability resulting in convulsions and respiratory paralysis.Nifedipine: A potent vasodilator agent with calcium antagonistic action. It is a useful anti-anginal agent that also lowers blood pressure.Astacoidea: A superfamily of various freshwater CRUSTACEA, in the infraorder Astacidea, comprising the crayfish. Common genera include Astacus and Procambarus. Crayfish resemble lobsters, but are usually much smaller.Kinetics: The rate dynamics in chemical or physical systems.Cochlear Nerve: The cochlear part of the 8th cranial nerve (VESTIBULOCOCHLEAR NERVE). The cochlear nerve fibers originate from neurons of the SPIRAL GANGLION and project peripherally to cochlear hair cells and centrally to the cochlear nuclei (COCHLEAR NUCLEUS) of the BRAIN STEM. They mediate the sense of hearing.Ranvier's Nodes: Regularly spaced gaps in the myelin sheaths of peripheral axons. Ranvier's nodes allow saltatory conduction, that is, jumping of impulses from node to node, which is faster and more energetically favorable than continuous conduction.Isoproterenol: Isopropyl analog of EPINEPHRINE; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant.Procaine: A local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block. (From Martindale, The Extra Pharmacopoeia, 30th ed, p1016).Sciatic Nerve: A nerve which originates in the lumbar and sacral spinal cord (L4 to S3) and supplies motor and sensory innervation to the lower extremity. The sciatic nerve, which is the main continuation of the sacral plexus, is the largest nerve in the body. It has two major branches, the TIBIAL NERVE and the PERONEAL NERVE.Egtazic Acid: A chelating agent relatively more specific for calcium and less toxic than EDETIC ACID.Bicuculline: An isoquinoline alkaloid obtained from Dicentra cucullaria and other plants. It is a competitive antagonist for GABA-A receptors.Shaw Potassium Channels: A shaker subfamily that is prominently expressed in NEURONS and are necessary for high-frequency, repetitive firing of ACTION POTENTIALS.Excitatory Amino Acid Antagonists: Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists.Periodicity: The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian).Peripheral Nerves: The nerves outside of the brain and spinal cord, including the autonomic, cranial, and spinal nerves. Peripheral nerves contain non-neuronal cells and connective tissue as well as axons. The connective tissue layers include, from the outside to the inside, the epineurium, the perineurium, and the endoneurium.Ion Transport: The movement of ions across energy-transducing cell membranes. Transport can be active, passive or facilitated. Ions may travel by themselves (uniport), or as a group of two or more ions in the same (symport) or opposite (antiport) directions.Neuronal Plasticity: The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.Nodose Ganglion: The inferior (caudal) ganglion of the vagus (10th cranial) nerve. The unipolar nodose ganglion cells are sensory cells with central projections to the medulla and peripheral processes traveling in various branches of the vagus nerve.Mechanoreceptors: Cells specialized to transduce mechanical stimuli and relay that information centrally in the nervous system. Mechanoreceptor cells include the INNER EAR hair cells, which mediate hearing and balance, and the various somatosensory receptors, often with non-neural accessory structures.NAV1.5 Voltage-Gated Sodium Channel: A voltage-gated sodium channel subtype that mediates the sodium ion PERMEABILITY of CARDIOMYOCYTES. Defects in the SCN5A gene, which codes for the alpha subunit of this sodium channel, are associated with a variety of CARDIAC DISEASES that result from loss of sodium channel function.Ulnar Nerve: A major nerve of the upper extremity. In humans, the fibers of the ulnar nerve originate in the lower cervical and upper thoracic spinal cord (usually C7 to T1), travel via the medial cord of the brachial plexus, and supply sensory and motor innervation to parts of the hand and forearm.Barium Compounds: Inorganic compounds that contain barium as an integral part of the molecule.Sarcoplasmic Reticulum: A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.Organ Culture Techniques: A technique for maintenance or growth of animal organs in vitro. It refers to three-dimensional cultures of undisaggregated tissue retaining some or all of the histological features of the tissue in vivo. (Freshney, Culture of Animal Cells, 3d ed, p1)Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Extracellular Space: Interstitial space between cells, occupied by INTERSTITIAL FLUID as well as amorphous and fibrous substances. For organisms with a CELL WALL, the extracellular space includes everything outside of the CELL MEMBRANE including the PERIPLASM and the cell wall.GABA Antagonists: Drugs that bind to but do not activate GABA RECEPTORS, thereby blocking the actions of endogenous GAMMA-AMINOBUTYRIC ACID and GABA RECEPTOR AGONISTS.Calcium Channels, T-Type: A heterogenous group of transient or low voltage activated type CALCIUM CHANNELS. They are found in cardiac myocyte membranes, the sinoatrial node, Purkinje cells of the heart and the central nervous system.Median Nerve: A major nerve of the upper extremity. In humans, the fibers of the median nerve originate in the lower cervical and upper thoracic spinal cord (usually C6 to T1), travel via the brachial plexus, and supply sensory and motor innervation to parts of the forearm and hand.Electromyography: Recording of the changes in electric potential of muscle by means of surface or needle electrodes.Cadmium: An element with atomic symbol Cd, atomic number 48, and atomic weight 114. It is a metal and ingestion will lead to CADMIUM POISONING.Leeches: Annelids of the class Hirudinea. Some species, the bloodsuckers, may become temporarily parasitic upon animals, including man. Medicinal leeches (HIRUDO MEDICINALIS) have been used therapeutically for drawing blood since ancient times.Nervous System Physiological Phenomena: Characteristic properties and processes of the NERVOUS SYSTEM as a whole or with reference to the peripheral or the CENTRAL NERVOUS SYSTEM.6-Cyano-7-nitroquinoxaline-2,3-dione: A potent excitatory amino acid antagonist with a preference for non-NMDA iontropic receptors. It is used primarily as a research tool.Aplysia: An opisthobranch mollusk of the order Anaspidea. It is used frequently in studies of nervous system development because of its large identifiable neurons. Aplysiatoxin and its derivatives are not biosynthesized by Aplysia, but acquired by ingestion of Lyngbya (seaweed) species.Torsades de Pointes: A malignant form of polymorphic ventricular tachycardia that is characterized by HEART RATE between 200 and 250 beats per minute, and QRS complexes with changing amplitude and twisting of the points. The term also describes the syndrome of tachycardia with prolonged ventricular repolarization, long QT intervals exceeding 500 milliseconds or BRADYCARDIA. Torsades de pointes may be self-limited or may progress to VENTRICULAR FIBRILLATION.Rhodanine2-Amino-5-phosphonovalerate: The D-enantiomer is a potent and specific antagonist of NMDA glutamate receptors (RECEPTORS, N-METHYL-D-ASPARTATE). The L form is inactive at NMDA receptors but may affect the AP4 (2-amino-4-phosphonobutyrate; APB) excitatory amino acid receptors.Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Ryanodine: A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.Nerve Endings: Branch-like terminations of NERVE FIBERS, sensory or motor NEURONS. Endings of sensory neurons are the beginnings of afferent pathway to the CENTRAL NERVOUS SYSTEM. Endings of motor neurons are the terminals of axons at the muscle cells. Nerve endings which release neurotransmitters are called PRESYNAPTIC TERMINALS.Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Electric Capacitance: The ability of a substrate to retain an electrical charge.KCNQ1 Potassium Channel: A voltage-gated potassium channel that is expressed primarily in the HEART.Electrophysiologic Techniques, Cardiac: Methods to induce and measure electrical activities at specific sites in the heart to diagnose and treat problems with the heart's electrical system.Small-Conductance Calcium-Activated Potassium Channels: A major class of calcium-activated potassium channels that are found primarily in excitable CELLS. They play important roles in the transmission of ACTION POTENTIALS and generate a long-lasting hyperpolarization known as the slow afterhyperpolarization.Acetanilides: Compounds based on N-phenylacetamide, that are similar in structure to 2-PHENYLACETAMIDES. They are precursors of many other compounds. They were formerly used as ANALGESICS and ANTIPYRETICS, but often caused lethal METHEMOGLOBINEMIA.Potassium Channels, Inwardly Rectifying: Potassium channels where the flow of K+ ions into the cell is greater than the outward flow.Anesthetics, Local: Drugs that block nerve conduction when applied locally to nerve tissue in appropriate concentrations. They act on any part of the nervous system and on every type of nerve fiber. In contact with a nerve trunk, these anesthetics can cause both sensory and motor paralysis in the innervated area. Their action is completely reversible. (From Gilman AG, et. al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed) Nearly all local anesthetics act by reducing the tendency of voltage-dependent sodium channels to activate.Brain Stem: The part of the brain that connects the CEREBRAL HEMISPHERES with the SPINAL CORD. It consists of the MESENCEPHALON; PONS; and MEDULLA OBLONGATA.Voltage-Gated Sodium Channels: A family of membrane proteins that selectively conduct SODIUM ions due to changes in the TRANSMEMBRANE POTENTIAL DIFFERENCE. They typically have a multimeric structure with a core alpha subunit that defines the sodium channel subtype and several beta subunits that modulate sodium channel activity.Rana pipiens: A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.Purkinje Cells: The output neurons of the cerebellar cortex.Electrodes: Electric conductors through which electric currents enter or leave a medium, whether it be an electrolytic solution, solid, molten mass, gas, or vacuum.Nerve Net: A meshlike structure composed of interconnecting nerve cells that are separated at the synaptic junction or joined to one another by cytoplasmic processes. In invertebrates, for example, the nerve net allows nerve impulses to spread over a wide area of the net because synapses can pass information in any direction.Sural Nerve: A branch of the tibial nerve which supplies sensory innervation to parts of the lower leg and foot.NAV1.6 Voltage-Gated Sodium Channel: A voltage-gated sodium channel subtype found widely expressed in neurons of the central and peripheral nervous systems. Defects in the SCN8A gene which codes for the alpha subunit of this sodium channel are associated with ATAXIA and cognitive deficits.Acetylcholine: A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.Chlorides: Inorganic compounds derived from hydrochloric acid that contain the Cl- ion.Muscle Cells: Mature contractile cells, commonly known as myocytes, that form one of three kinds of muscle. The three types of muscle cells are skeletal (MUSCLE FIBERS, SKELETAL), cardiac (MYOCYTES, CARDIAC), and smooth (MYOCYTES, SMOOTH MUSCLE). They are derived from embryonic (precursor) muscle cells called MYOBLASTS.Physical Stimulation: Act of eliciting a response from a person or organism through physical contact.Nerve Fibers, Myelinated: A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves.Verapamil: A calcium channel blocker that is a class IV anti-arrhythmia agent.Muscle, Smooth: Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed)Tubocurarine: A neuromuscular blocker and active ingredient in CURARE; plant based alkaloid of Menispermaceae.Veratridine: A benzoate-cevane found in VERATRUM and Schoenocaulon. It activates SODIUM CHANNELS to stay open longer than normal.Piperidines: A family of hexahydropyridines.KCNQ Potassium Channels: A family of delayed rectifier voltage-gated potassium channels that share homology with their founding member, KCNQ1 PROTEIN. KCNQ potassium channels have been implicated in a variety of diseases including LONG QT SYNDROME; DEAFNESS; and EPILEPSY.Strophanthidin: 3 beta,5,14-Trihydroxy-19-oxo-5 beta-card-20(22)-enolide. The aglycone cardioactive agent isolated from Strophanthus Kombe, S. gratus and other species; it is a very toxic material formerly used as digitalis. Synonyms: Apocymarin; Corchorin; Cynotoxin; Corchorgenin.Optics and Photonics: A specialized field of physics and engineering involved in studying the behavior and properties of light and the technology of analyzing, generating, transmitting, and manipulating ELECTROMAGNETIC RADIATION in the visible, infrared, and ultraviolet range.Pyridinium CompoundsMollusca: A phylum of the kingdom Metazoa. Mollusca have soft, unsegmented bodies with an anterior head, a dorsal visceral mass, and a ventral foot. Most are encased in a protective calcareous shell. It includes the classes GASTROPODA; BIVALVIA; CEPHALOPODA; Aplacophora; Scaphopoda; Polyplacophora; and Monoplacophora.Nociceptors: Peripheral AFFERENT NEURONS which are sensitive to injuries or pain, usually caused by extreme thermal exposures, mechanical forces, or other noxious stimuli. Their cell bodies reside in the DORSAL ROOT GANGLIA. Their peripheral terminals (NERVE ENDINGS) innervate target tissues and transduce noxious stimuli via axons to the CENTRAL NERVOUS SYSTEM.Mexiletine: Antiarrhythmic agent pharmacologically similar to LIDOCAINE. It may have some anticonvulsant properties.Chelating Agents: Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.Vagus Nerve: The 10th cranial nerve. The vagus is a mixed nerve which contains somatic afferents (from skin in back of the ear and the external auditory meatus), visceral afferents (from the pharynx, larynx, thorax, and abdomen), parasympathetic efferents (to the thorax and abdomen), and efferents to striated muscle (of the larynx and pharynx).Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: A subgroup of cyclic nucleotide-regulated ION CHANNELS of the superfamily of pore-loop cation channels that are opened by hyperpolarization rather than depolarization. The ion conducting pore passes SODIUM, CALCIUM, and POTASSIUM cations with a preference for potassium.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Kv1.1 Potassium Channel: A delayed rectifier subtype of shaker potassium channels that is commonly mutated in human episodic ATAXIA and MYOKYMIA.Elapid Venoms: Venoms from snakes of the family Elapidae, including cobras, kraits, mambas, coral, tiger, and Australian snakes. The venoms contain polypeptide toxins of various kinds, cytolytic, hemolytic, and neurotoxic factors, but fewer enzymes than viper or crotalid venoms. Many of the toxins have been characterized.Lanthanum: Lanthanum. The prototypical element in the rare earth family of metals. It has the atomic symbol La, atomic number 57, and atomic weight 138.91. Lanthanide ion is used in experimental biology as a calcium antagonist; lanthanum oxide improves the optical properties of glass.Glutamic Acid: A non-essential amino acid naturally occurring in the L-form. Glutamic acid is the most common excitatory neurotransmitter in the CENTRAL NERVOUS SYSTEM.Cardiac Electrophysiology: The study of the electrical activity and characteristics of the HEART; MYOCARDIUM; and CARDIOMYOCYTES.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Ganglia, Invertebrate: Clusters of neuronal cell bodies in invertebrates. Invertebrate ganglia may also contain neuronal processes and non-neuronal supporting cells. Many invertebrate ganglia are favorable subjects for research because they have small numbers of functional neuronal types which can be identified from one animal to another.Rana temporaria: A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.Cardiac Complexes, Premature: A group of cardiac arrhythmias in which the cardiac contractions are not initiated at the SINOATRIAL NODE. They include both atrial and ventricular premature beats, and are also known as extra or ectopic heartbeats. Their frequency is increased in heart diseases.Ganglia, Sympathetic: Ganglia of the sympathetic nervous system including the paravertebral and the prevertebral ganglia. Among these are the sympathetic chain ganglia, the superior, middle, and inferior cervical ganglia, and the aorticorenal, celiac, and stellate ganglia.Sarcolemma: The excitable plasma membrane of a muscle cell. (Glick, Glossary of Biochemistry and Molecular Biology, 1990)Caffeine: A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.QuinoxalinesFerrets: Semidomesticated variety of European polecat much used for hunting RODENTS and/or RABBITS and as a laboratory animal. It is in the subfamily Mustelinae, family MUSTELIDAE.Rana catesbeiana: A species of the family Ranidae (true frogs). The only anuran properly referred to by the common name "bullfrog", it is the largest native anuran in North America.Heart Rate: The number of times the HEART VENTRICLES contract per unit of time, usually per minute.
(1/21346) Further evidence that prostaglandins inhibit the release of noradrenaline from adrenergic nerve terminals by restriction of availability of calcium.

1 Guinea-pig vasa deferentia were continuously superfused after labelling the transmitter stores with [3H](-)-noradrenaline. Release of [3H]-(-)-noradrenaline was induced by transmural nerve stimulation. 2 Prostglandin E2 (14 nM) drastically reduced the release of [3H]-(-)-noradrenaline, while tetraethylammonium (2 mM), rubidium (6 mM), phenoxybenzamine (3 muM) each in the presence or absence of Uptake 1 or 2 blockade, and prolonged pulse duration (from 0.5 to 2.0 ms) all significantly increased the release of [3H]-(-)-noradrenaline per nerve impulse. 3 The inhibitory effect of prostaglandin E2 on evoked release of [3H]-(-)-noradrenaline was significantly reduced by tetraethylammonium, rubidium and prolonged pulse duration, whilst it was actually enhanced by phenoxybenzamine. This indicates that increased release of noradrenaline per nerve impulse does not per se counteract the inhibitory effect of prostaglandin E2. 4 It is concluded that tetraethylammonium, rubidium and prolonged pulse duration counteracted the inhibitory effect of prostaglandin E2 on T3H]-(-)-noradrenaline release by promoting calcium influx during the nerve action potential. The results are consistent with, and add more weight to the view that prostaglandins inhibit the release of noradrenaline by restriction of calcium availability.  (+info)

(2/21346) Effect of electrotonic potentials on pacemaker activity of canine Purkinje fibers in relation to parasystole.

Isolated false tendons excised form dog hearts were mounted in a three-chamber tissue bath. Isotonic sucrose solution was perfused in the central chamber to provide a region of depressed conductivity between the fiber segments in chambers 1 and 3, which were perfused with Tyrode's solution. The electrotonic influence of spontaneous or driven responses evoked in chamber 3 during the first half of the spontaneous cycle of a chamber 1 peacemaker delayed the next spontaneous discharge. This effect changed to acceleration when the chamber 3 segment fired during the second half of the spontaneous cycle. We found that subthreshold depolarizing current pulses 50-300 msec applied across the sucrose gap caused similar degrees of delay or acceleration. Furthermore, hyperpolarizing currents caused the reverse pattern. The results indicate that the discharge pattern of a parasystolic focus may be altered by the electrotonic influence of activity in the surrounding tissue. The significance of these findings is considered in relation to the mechanism of production of parasystolic rhythms.  (+info)

(3/21346) Low resting potential and postnatal upregulation of NMDA receptors may cause Cajal-Retzius cell death.

Using in situ patch-clamp techniques in rat telencephalic slices, we have followed resting potential (RP) properties and the functional expression of NMDA receptors in neocortical Cajal-Retzius (CR) cells from embryonic day 18 to postnatal day 13, the time around which these cells normally disappear. We find that throughout their lives CR cells have a relatively depolarized RP (approximately -50 mV), which can be made more hyperpolarized (approximately -70 mV) by stimulation of the Na/K pump with intracellular ATP. The NMDA receptors of CR cells are subjected to intense postnatal upregulation, but their similar properties (EC50, Hill number, sensitivity to antagonists, conductance, and kinetics) throughout development suggest that their subunit composition remains relatively homogeneous. The low RP of CR cells is within a range that allows for the relief of NMDA channels from Mg2+ blockade. Our findings are consistent with the hypothesis that CR cells may degenerate and die subsequent to uncontrolled overload of intracellular Ca2+ via NMDA receptor activation by ambient glutamate. In support of this hypothesis we have obtained evidence showing the protection of CR cells via in vivo blockade of NMDA receptors with dizocilpine.  (+info)

(4/21346) Activity-dependent metaplasticity of inhibitory and excitatory synaptic transmission in the lamprey spinal cord locomotor network.

Paired intracellular recordings have been used to examine the activity-dependent plasticity and neuromodulator-induced metaplasticity of synaptic inputs from identified inhibitory and excitatory interneurons in the lamprey spinal cord. Trains of spikes at 5-20 Hz were used to mimic the frequency of spiking that occurs in network interneurons during NMDA or brainstem-evoked locomotor activity. Inputs from inhibitory and excitatory interneurons exhibited similar activity-dependent changes, with synaptic depression developing during the spike train. The level of depression reached was greater with lower stimulation frequencies. Significant activity-dependent depression of inputs from excitatory interneurons and inhibitory crossed caudal interneurons, which are central elements in the patterning of network activity, usually developed between the fifth and tenth spikes in the train. Because these interneurons typically fire bursts of up to five spikes during locomotor activity, this activity-dependent plasticity will presumably not contribute to the patterning of network activity. However, in the presence of the neuromodulators substance P and 5-HT, significant activity-dependent metaplasticity of these inputs developed over the first five spikes in the train. Substance P induced significant activity-dependent depression of inhibitory but potentiation of excitatory interneuron inputs, whereas 5-HT induced significant activity-dependent potentiation of both inhibitory and excitatory interneuron inputs. Because these metaplastic effects are consistent with the substance P and 5-HT-induced modulation of the network output, activity-dependent metaplasticity could be a potential mechanism underlying the coordination and modulation of rhythmic network activity.  (+info)

(5/21346) Ionic currents underlying spontaneous action potentials in isolated cerebellar Purkinje neurons.

Acutely dissociated cell bodies of mouse Purkinje neurons spontaneously fired action potentials at approximately 50 Hz (25 degrees C). To directly measure the ionic currents underlying spontaneous activity, we voltage-clamped the cells using prerecorded spontaneous action potentials (spike trains) as voltage commands and used ionic substitution and selective blockers to isolate individual currents. The largest current flowing during the interspike interval was tetrodotoxin-sensitive sodium current (approximately -50 pA between -65 and -60 mV). Although the neurons had large voltage-dependent calcium currents, the net current blocked by cobalt substitution for calcium was outward at all times during spike trains. Thus, the electrical effect of calcium current is apparently dominated by rapidly activated calcium-dependent potassium currents. Under current clamp, all cells continued firing spontaneously (though approximately 30% more slowly) after block of T-type calcium current by mibefradil, and most cells continued to fire after block of all calcium current by cobalt substitution. Although the neurons possessed hyperpolarization-activated cation current (Ih), little current flowed during spike trains, and block by 1 mM cesium had no effect on firing frequency. The outward potassium currents underlying the repolarization of the spikes were completely blocked by 1 mM TEA. These currents deactivated quickly (<1 msec) after each spike. We conclude that the spontaneous firing of Purkinje neuron cell bodies depends mainly on tetrodotoxin-sensitive sodium current flowing between spikes. The high firing rate is promoted by large potassium currents that repolarize the cell rapidly and deactivate quickly, thus preventing strong hyperpolarization and restoring a high input resistance for subsequent depolarization.  (+info)

(6/21346) Somatic recording of GABAergic autoreceptor current in cerebellar stellate and basket cells.

Patch-clamp recordings were performed from stellate and basket cells in rat cerebellar slices. Under somatic voltage clamp, short depolarizing pulses were applied to elicit action potentials in the axon. After the action potential, a bicuculline- and Cd2+-sensitive current transient was observed. A similar response was obtained when eliciting axonal firing by extracellular stimulation. With an isotonic internal Cl- solution, the peak amplitude of this current varied linearly with the holding potential, yielding an extrapolated reversal potential of -20 to 0 mV. Unlike synaptic or autaptic GABAergic currents obtained in the same preparation, the current transient had a slow rise-time and a low variability between trials. This current was blocked when 10 mM BAPTA was included in the recording solution. In some experiments, the current transient elicited axonal action potentials. The current transient was reliably observed in animals aged 12-15 d, with a mean amplitude of 82 pA at -70 mV, but was small and rare in the age group 29-49 d. Numerical simulations could account for all properties of the current transient by assuming that an action potential activates a distributed GABAergic conductance in the axon. The actual conductance is probably restricted to release sites, with an estimated mean presynaptic current response of 10 pA per site (-70 mV, age 12-15 d). We conclude that in developing rats, stellate and basket cell axons have a high density of GABAergic autoreceptors and that a sizable fraction of the corresponding current can be measured from the soma.  (+info)

(7/21346) Inducible genetic suppression of neuronal excitability.

Graded, reversible suppression of neuronal excitability represents a logical goal of therapy for epilepsy and intractable pain. To achieve such suppression, we have developed the means to transfer "electrical silencing" genes into neurons with sensitive control of transgene expression. An ecdysone-inducible promoter drives the expression of inwardly rectifying potassium channels in polycistronic adenoviral vectors. Infection of superior cervical ganglion neurons did not affect normal electrical activity but suppressed excitability after the induction of gene expression. These experiments demonstrate the feasibility of controlled ion channel expression after somatic gene transfer into neurons and serve as the prototype for a novel generalizable approach to modulate excitability.  (+info)

(8/21346) Cerebellar Purkinje cell simple spike discharge encodes movement velocity in primates during visuomotor arm tracking.

Pathophysiological, lesion, and electrophysiological studies suggest that the cerebellar cortex is important for controlling the direction and speed of movement. The relationship of cerebellar Purkinje cell discharge to the control of arm movement parameters, however, remains unclear. The goal of this study was to examine how movement direction and speed and their interaction-velocity-modulate Purkinje cell simple spike discharge in an arm movement task in which direction and speed were independently controlled. The simple spike discharge of 154 Purkinje cells was recorded in two monkeys during the performance of two visuomotor tasks that required the animals to track targets that moved in one of eight directions and at one of four speeds. Single-parameter regression analyses revealed that a large proportion of cells had discharge modulation related to movement direction and speed. Most cells with significant directional tuning, however, were modulated at one speed, and most cells with speed-related discharge were modulated along one direction; this suggested that the patterns of simple spike discharge were not adequately described by single-parameter models. Therefore, a regression surface was fitted to the data, which showed that the discharge could be tuned to specific direction-speed combinations (preferred velocities). The overall variability in simple spike discharge was well described by the surface model, and the velocities corresponding to maximal and minimal discharge rates were distributed uniformly throughout the workspace. Simple spike discharge therefore appears to integrate information about both the direction and speed of arm movements, thereby encoding movement velocity.  (+info)

*  Nav1.2
They are responsible for the generation and propagation of action potentials in neurons and muscle. This gene encodes one ...
*  Nav1.7
... is a voltage-gated sodium channel and plays a critical role in the generation and conduction of action potentials and is ... threshold that produces most of the transmembrane current responsible for the depolarizing phase of action potentials. The ... Stimulation of the nociceptor nerve endings produces "generator potentials", which are small changes in the voltage across the ... Stimulation of the nociceptor nerve endings produces "generator potentials", small changes in the voltage across the neuronal ...
*  Quantitative models of the action potential
As an example, the cardiac action potential illustrates how differently shaped action potentials can be generated on membranes ... Op-amp circuits that realize the FHN and van der Pol models of the action potential have been developed by Keener. A hybrid of ... The simplest models of the action potential are the "flush and fill" models (also called "integrate-and-fire" models), in which ... In neurophysiology, several mathematical models of the action potential have been developed, which fall into two basic types. ...
*  Compound muscle action potential
The compound muscle action potential (CMAP) or compound motor action potential is an electromyography investigation (electrical ... have prolonged compound muscle action potential. Goodman BP; et al. (2009). "Prolonged compound muscle action potential ... The CMAP idealizes the summation of a group of almost simultaneous action potentials from several muscle fibers in the same ...
*  Action potential
The action potential in a normal skeletal muscle cell is similar to the action potential in neurons. Action potentials result ... of Arizona A cartoon illustrating the action potential Action potential propagation Production of the action potential: voltage ... The cardiac action potential differs from the neuronal action potential by having an extended plateau, in which the membrane is ... Action potentials in neurons are also known as "nerve impulses" or "spikes", and the temporal sequence of action potentials ...
*  Atrial action potential
... the atrial action potential are action potentials that occur in the heart atrium. They are similar to ventricular action ... Cardiac action potential Vigmond E.J, Tsoi V, Yin Y, Page P, & Vinet A. (2009). Estimating Atrial Action Potential Duration ... Also, in comparison to the ventricular action potential, atrial action potentials have a more gradual repolarization period. ... Vigmond E.J, Tsoi V, Yin Y, Page P, & Vinet A. (2009). Estimating Atrial Action Potential Duration from Electrograms. IEEE ...
*  Pacemaker action potential
A pacemaker action potential is the kind of action potential that provides a reference rhythm for the network. This contrasts ... Some pacemaker action potentials generate rhythms for the heart beat (sino-atrial node) or the circadian rhythm in the ... with pacemaker potential or current which drives rhythmic modulation of firing rate. ...
*  Action potential pulse
The action potential pulse is a model of the speed an action potential that is dynamically dependant upon the position and ... The action potential pulse model takes into account entropy and the conduction speed of the action potential along an axon. It ... In addition a soliton pulse is known to flow at the same rate and follow the action potential. From measurements of the speed ... An action potential pulse is a mathematically and experimentally correct Synchronized Oscillating Lipid Pulse coupled with an ...
*  Cardiac action potential
... of a cardiac action potential Interactive mathematical models of cardiac action potential and other generic action potentials. ... The cardiac action potential differs from action potentials found in other types of electrically excitable cells, such as ... Outlined below are the five phases of the ventricular myocyte action potential, with reference also to the SAN action potential ... Unlike the action potential in skeletal muscle cells, the cardiac action potential is not initiated by nervous activity. ...
*  Ventricular action potential
This current is observed in human and dog action potentials, but not in guinea pig action potentials. Repolarization is ... which is close to the potassium reversal potential. When an action potential is generated, the membrane potential rises above ... The beginning of the action potential, phase 0, specialized membrane proteins (voltage-gated sodium channels) in the cell ... and channels that open quickly but are inactivated until the end of the action potential (rapid delayed rectifier channels). ...
*  Brain
When an action potential, traveling along an axon, arrives at a synapse, it causes a chemical called a neurotransmitter to be ... Some neurons emit action potentials constantly, at rates of 10-100 per second, usually in irregular patterns; other neurons are ... These axons transmit signals in the form of electrochemical pulses called action potentials, which last less than a thousandth ... Neurotransmitters are chemicals that are released at synapses when an action potential activates them-neurotransmitters attach ...
*  Dendrite
... is their ability to send action potentials back into the dendritic arbor. Known as back-propagating action potentials, these ... a train of back-propagating action potentials artificially generated at the soma can induce a calcium action potential (a ... returning the electrochemical gradient to the resting potential. After an action potential has occurred, there is a transient ... An action potential propagates the electrical activity along the membrane of the neuron's dendrites to the cell body and then ...
*  Pathophysiology of Parkinson's disease
The activated motor neurons then transmit their signals, via action potential, to motor neurons in the legs. However, when a ... doi:10.1186/1750-1326-4-20 Barnett MW, Larkman PM; Larkman (June 2007). "The action potential". Pract Neurol 7 (3): 192-7. PMID ... Role and Therapeutic Potential of VEGF in the Nervous System. Physiological Reviews, 89(2), 607-648. doi:10.1152/physrev. ...
*  Neuron
... changing the membrane potential. Thin neurons and axons require less metabolic expense to produce and carry action potentials, ... an all-or-none electrochemical pulse called an action potential is generated and this change in cross-membrane potential ... decreasing the probability of an action potential firing as the voltage becomes more negative (recall that for an action ... The sheath enables action potentials to travel faster than in unmyelinated axons of the same diameter, whilst using less energy ...
*  Spike potential
Spike potentials are one of the action potentials, which occur in electrical activity of smooth muscle contraction in animals. ... These are true action potentials. In the human gut they occur automatically when the resting membrane potential of the ... The spike potentials last 10 to 40 times as long in gastrointestinal muscle as the action potentials in large nerve fibers, ... gastrointestinal smooth muscle becomes more positive than about -40 millivolts (the normal resting membrane potential in the ...
*  Plant perception (physiology)
... action potentials) to environmental stimuli. These action potentials can influence processes such as actin-based cytoplasmic ... Pickard, B. G. (1973). "Action Potentials in Higher Plants". Botanical Review. 39 (2): 172-201. doi:10.1007/BF02859299. JSTOR ... Zimmermann, M. R.; Maischak, H.; Mithofer, A.; Boland, W.; Felle, H. H. (2009). "System Potentials, a Novel Electrical Long- ... use sophisticated cost-benefit analysis and take tightly controlled actions to mitigate and control diverse environmental ...
*  Seema Goel
Goel's pieces were Excitaory response; action potential and aspiration. Goel portrays human-human, human-animal and human-place ... action potential (2005) aspiration (2005) "Wool Is 44% Carbon". Leonardo. 45 (2): 186-187. 2012. Retrieved 13 March 2016. " ...
*  Heart arrhythmia
Normally, the action potential impulse will spread through the heart quickly enough that each cell will respond only once. ... All of the cells in the heart have the ability to initiate an action potential; however, only some of these cells are designed ... Tachyarrhythmias are the result of spontaneous action potentials arise from cardiac muscle cells. Cardiac arrhythmia are often ... Shen, H; Choe, W (April 2011). "Spontaneous high-frequency action potential". Science China. Life sciences. 54 (4): 311-35. doi ...
*  Inhibitory postsynaptic potential
... reverse potential of the postsynaptic potential, action potential threshold voltage, ionic permeability of the ion channel, as ... If the electrochemical potential of the ion is more negative than that of the action potential threshold then the resultant ... IPSPs always want to keep the membrane potential more negative than the action potential threshold and can be seen as a " ... Depolarization can also occur due to an IPSP if the reverse potential is between the resting threshold and the action potential ...
*  Antidromic
For most neurons, their dendrites, soma, or axons are depolarized forming an action potential that moves from the starting ...
*  Alan Lloyd Hodgkin
Hodgkin, A. L.; Huxley, A. F. (1939). "Action Potentials Recorded from Inside a Nerve Fibre". Nature. 144 (3651): 710-711. ... With Andrew Fielding Huxley, Hodgkin worked on experimental measurements and developed an action potential theory representing ... With Huxley, he established the propagation mechanism of nerve impulse called "action potentials", the electrical impulses ... 1963 Action Potential Paper[permanent dead link] Imperial War Museum Interview. ...
*  Catecholaminergic polymorphic ventricular tachycardia
Underlying mechanism and threshold for triggered action potentials". Circ. Res. 87: 774-778. doi:10.1161/01.res.87.9.774. Jiang ... causing a prolonged Ca2+ leak which triggers early action potentials. With reduced SR Ca2+ buffering capacity, is a faster ... SOICR leads to spontaneous and inappropriate action potentials, generating arrhythmias. A Ryr2 mutation may increase ...
*  Histrionicotoxins
This blocks action potentials and slows neural function. Histrionicotoxin has been shown to bind competitively with many local ... studies of the effects of histrionicotoxin on end-plate potential have shown that the compound hinders membrane potential ... Masukawa, Leona M.; Albuquerque, Edson X. (1978). "Voltage- and time-dependent action of histrionicotoxin on the endplate ...
*  Somatosensory system
They react in quick action potentials, especially to vibrations around 250 Hz (even up to centimeters away). They are the most ... They respond in quick action potentials, unlike Merkel. They are responsible for the ability to read Braille and feel gentle ... All of these receptors are activated upon pressures that squish their shape causing an action potential. All afferent touch/ ... "Action Observation Activates Premotor and Parietal Areas in a Somatotopic Manner: An FMRI Study." Wiley Online Library. Jan. ...
*  Low-threshold spikes
As with the action potentials that follow them, LTS vary little in amplitude or shape at different holding potentials. This ... The spike is typically crowned by a burst of two to seven action potentials, which is known as a low-threshold burst. LTS are ... An excitatory postsynaptic potential (EPSP) opens the channels, thus generating a LTS. The LTS triggers Na+-dependent action ... LTS result in the neuron reaching the threshold for an action potential. LTS is a large depolarization due to an increase in ...
*  New Melones Dam
The potential water yield, and thus the supply contracts, of the Melones Project were calculated based on stream flow data ... The Wild and Scenic Rivers Act "prohibits federal support for actions such as the construction of dams or other instream ... One potential solution has been outlined in a 2016 agreement between the Bureau of Reclamation, the local water districts and a ... "Chapter 2: Water Resources" (PDF). Draft Revised Substitute Environmental Document in Support of Potential Changes to the Water ...
*  Slow-wave potential
Uterine muscle seems to generate action potentials spontaneously. In gastrointestinal smooth muscle, the slow-wave threshold ... A slow wave potential is a rhythmic electrophysiological event in the gastrointestinal tract. The normal conduction of slow ... Another potential coupling mechanism is the "Peg and Socket" theory which demonstrates that the membranes of smooth muscle ... In physiology, the slow-wave threshold is the potential which must be reached before a slow wave can be propagated in smooth ...
Compound muscle action potential - Wikipedia  Compound muscle action potential - Wikipedia
The compound muscle action potential (CMAP) or compound motor action potential is an electromyography investigation (electrical ... 2009). "Prolonged compound muscle action potential duration in critical illness myopathy". Muscle Nerve. 40 (6): 1040-2. doi: ... have prolonged compound muscle action potential.[1]. References[edit]. *^ Goodman BP; et al. ( ... The CMAP idealizes the summation of a group of almost simultaneous action potentials from several muscle fibers in the same ...
more infohttps://en.wikipedia.org/wiki/Compound_muscle_action_potential
Compound Motor Action Potential Interexaminer Variability in Photoguided Placement of the Recording Electrodes  Compound Motor Action Potential Interexaminer Variability in Photoguided Placement of the Recording Electrodes
... Axelson, Hans W ... In this study, we explored whether the interexaminer variability of the compound motor action potential (CMAP) amplitude is ...
more infohttp://uu.diva-portal.org/smash/record.jsf?pid=diva2:539929
PLOS ONE: The Relative Influences of Phosphometabolites and pH on Action Potential Morphology during Myocardial Reperfusion: A...  PLOS ONE: The Relative Influences of Phosphometabolites and pH on Action Potential Morphology during Myocardial Reperfusion: A...
... action potential amplitude (APA), and depolarization of the resting membrane potential were more severe when ATP and PCr ... can result when ischemic tissue exhibits decreased excitability and/or changes of action potential duration (APD), conditions ... or phosphometabolite-related processes play a more significant role in generating changes in excitability and action potential ... availability during reperfusion may be more beneficial than perturbing pH recovery with regard to mitigating action potential ...
more infohttp://journals.plos.org/plosone/article/related?id=10.1371/journal.pone.0047117&imageURI=info:doi/10.1371/journal.pone.0047117.g011
Mathematical modelling of mechanical effects on action potential duration in heterogeneous myocardium - Physiology, Anatomy and...  Mathematical modelling of mechanical effects on action potential duration in heterogeneous myocardium - Physiology, Anatomy and...
Mathematical modelling of mechanical effects on action potential duration in heterogeneous myocardium ... Mathematical modelling of mechanical effects on action potential duration in heterogeneous myocardium ...
more infohttps://www.dpag.ox.ac.uk/publications/345968
Action potential - Wikipedia  Action potential - Wikipedia
The action potential in a normal skeletal muscle cell is similar to the action potential in neurons. Action potentials result ... of Arizona A cartoon illustrating the action potential Action potential propagation Production of the action potential: voltage ... The cardiac action potential differs from the neuronal action potential by having an extended plateau, in which the membrane is ... Action potentials in neurons are also known as "nerve impulses" or "spikes", and the temporal sequence of action potentials ...
more infohttps://en.wikipedia.org/wiki/Action_potential
Atrial action potential - Wikipedia  Atrial action potential - Wikipedia
... the atrial action potential are action potentials that occur in the heart atrium. They are similar to ventricular action ... Cardiac action potential Vigmond E.J, Tsoi V, Yin Y, Page P, & Vinet A. (2009). Estimating Atrial Action Potential Duration ... Also, in comparison to the ventricular action potential, atrial action potentials have a more gradual repolarization period. ... Vigmond E.J, Tsoi V, Yin Y, Page P, & Vinet A. (2009). Estimating Atrial Action Potential Duration from Electrograms. IEEE ...
more infohttps://en.wikipedia.org/wiki/Atrial_action_potential
action potential | PNAS  action potential | PNAS
Role of sodium channel subtype in action potential generation by neocortical pyramidal neurons Efrat Katz, Ohad Stoler, Anja ... Optical magnetic detection of single-neuron action potentials using quantum defects in diamond John F. Barry, Matthew J. Turner ... Covariation of axon initial segment location and dendritic tree normalizes the somatic action potential Mustafa S. Hamada, ...
more infohttps://www.pnas.org/keyword/action-potential
Action Potential  Action Potential
The beginning sounds like something I'd be humming to myself and never quite satisfied with, but made actually good. That not-quite-pointless multiple notes rather than one longer note ...
more infohttps://www.newgrounds.com/audio/listen/493642
Action potentials - Wikiversity  Action potentials - Wikiversity
Neuronal action potential[edit]. This animated gif illustrates action potential propagation in an axon. Three types of ion ... Cardiac action potential[edit]. Estimations of the number of ions involved in generating the upstroke of the action potential[ ... The voltage across the capacitor is the membrane potential (see action potential for an example of a membrane RC circuit). ... approaching the sodium equilibrium potential. The positive-inside voltage during the action potential in the initial segment ...
more infohttps://en.wikiversity.org/wiki/Action_potentials
mouse : Action Potential  mouse : Action Potential
Action Potential is a forum operated by neuroscience editors at Nature for the entire neuroscience community. We'll discuss ... This is a great article; I am pleased to see Action Potential and, importantly, Nature tackling the issue of gender…. ... Read ...
more infohttp://blogs.nature.com/actionpotential/tag/mouse
orientation selectivity : Action Potential  orientation selectivity : Action Potential
Action Potential is a forum operated by neuroscience editors at Nature for the entire neuroscience community. We'll discuss ... This is a great article; I am pleased to see Action Potential and, importantly, Nature tackling the issue of gender…. ... Read ...
more infohttp://blogs.nature.com/actionpotential/tag/orientation-selectivity
Action potential - Wikipedia  Action potential - Wikipedia
The action potential in a normal skeletal muscle cell is similar to the action potential in neurons.[56] Action potentials ... Thus, the cell fires, producing an action potential.[4][7][8][note 1] The frequency at which a neuron elicits action potentials ... Action potential propagation. *Production of the action potential: voltage and current clamping simulations[permanent dead link ... Cardiac action potentialsEdit. Main articles: Cardiac action potential, Electrical conduction system of the heart, Cardiac ...
more infohttps://en.m.wikipedia.org/wiki/Action_potentials
action potential | Definition, Steps, & Facts | Britannica.com  action potential | Definition, Steps, & Facts | Britannica.com
In the neuron an action potential produces the nerve impulse, and in the muscle cell it produces the contraction required for ... Action potential, the brief (about one-thousandth of a second) reversal of electric polarization of the membrane of a nerve ... When depolarization reaches the threshold potential, it triggers an action potential. Generation of the action potential brings ... More About Action potential. 9 references found in Britannica articles. Assorted References. *definition* In resting potential ...
more infohttps://www.britannica.com/science/action-potential
Synaptically triggered action potentials in dendrites.  - PubMed - NCBI  Synaptically triggered action potentials in dendrites. - PubMed - NCBI
Synaptically triggered action potentials in dendrites.. Regehr W1, Kehoe JS, Ascher P, Armstrong C. ... We tested the hypothesis that action potentials originate in apical dendrites of pyramidal cells. Layer V somata were voltage ... We conclude that Na+ action potentials are initiated in the apical dendrite in response to synaptic input. ...
more infohttps://www.ncbi.nlm.nih.gov/pubmed/8338663?dopt=Abstract
The action potential of Dionaea muscipula Ellis | SpringerLink  The action potential of Dionaea muscipula Ellis | SpringerLink
The intention of this investigation was to acquire more concise information about the nature of the action potential of Dionaea ... firing action potentials with pronounced after-hyperpolarizations. The action potentials are strictly dependent on Ca2+. Their ... Action potential Dionaea Plasma membrane (freeze etching) Resting potential Sensory cell Abbreviations. DNP. 2,4-dinitrophenol ... Gaffey, C.T., Mullins, L.J. (1958) Ion fluxes during the action potential in Chara. J. Physiol. 144, 505-524Google Scholar ...
more infohttps://link.springer.com/article/10.1007%2FBF00394867?LI=true
Abstract Action Potential Models for Toxin Recognition  Abstract Action Potential Models for Toxin Recognition
... James Peterson and Taufiquar Khan ... We use generated families of action potentials from a classic Hodgkin-Huxley model to verify our methodology and build toxin ... We focus on event detection in action potential via abstraction of information content into a low dimensional feature vector ... present a robust methodology using mathematical pattern recognition schemes to detect and classify events in action potentials ...
more infohttps://www.hindawi.com/journals/cmmm/2005/913532/abs/
The Action Potential Scheme | OMNINOGGINOMNINOGGIN  The Action Potential Scheme | OMNINOGGINOMNINOGGIN
It is this action potential that allows us to have any sort of feelings in our senses! No k ... How does an Action Potential start?. The action potential is triggered when the stimulus causes a depolarization. The axon end ... Can multiple action potential happen at the same time?. No. The action potential once started needs to be completed before it ... will cause another action potential. This is reasoned by the fact that the action potential initiation is dependent on the ...
more infohttp://omninoggin.com/anatomy/the-action-potential-scheme/
motor unit action potential duration (repost)  motor unit action potential duration (repost)
I find myself needing a mathematical rule for determining the 'end' ,, of a motor unit action potential. For example, I could ... motor unit action potential duration (repost). Venkatesh Murthy venk at stein.u.washington.edu Tue Jan 12 23:27:44 EST 1993 * ... If you want to get more detailed, you can fit a regression line to the last consistent 'turn' in your action potential and ... I'm assuming you need this so that you can isolate different action potential shapes from the same electrode. Let me know if ...
more infohttp://www.bio.net/bionet/mm/neur-sci/1993-January/011666.html
The Ionic Basis for the Action Potential  The Ionic Basis for the Action Potential
If you know the author of The Ionic Basis for the Action Potential, please help us out by filling out the form below and ... The Ionic Basis for the Action Potential "In the following discussion, we look carefully at how each ion contributes to changes ... in membrane potential during an "action potential" by following what happens to sodium, potassium, and chloride conductances." ... Disciplines with similar materials as The Ionic Basis for the Action Potential. ...
more infohttps://www.merlot.org/merlot/viewMaterial.htm?id=87834
  • Patients that suffer from critical illness myopathy , which is a frequent cause of weakness seen in patients in hospital intensive care units , have prolonged compound muscle action potential. (wikipedia.org)
  • Jitter measurement with a CNE have risks, such as the triggering and/or jittering potentials being compound signals due to summation, and showing extra phases rather than a clear single-fiber action potential (18). (thefreedictionary.com)
  • 1. Absolute refractory period means there is absolutely no stimuli, no matter how strong, will cause another action potential. (omninoggin.com)
  • 2. Relative refractory period means the duration of an action potential that may be able to be depolarized again because of another stimuli. (omninoggin.com)
  • The specific differences in the types of ion channels expressed and mechanisms by which they are activated results in differences in the configuration of the action potential waveform, as shown in figure 2. (wikipedia.org)
  • The tricky part will be to see how many consistent 'turns' you have in the action potential waveform and to see you include all such turns. (bio.net)
  • Investigation into the membranes of axons have shown that the spaces in between the channels are sufficiently large, such that cable theory cannot apply to them, because it depends upon the capacitance potential of a membrane to be transferred almost instantly to other areas of the membrane surface. (wikipedia.org)
  • Another potential coupling mechanism is the "Peg and Socket" theory which demonstrates that the membranes of smooth muscle cells have the ability either form physical narrow "sockets" or "pegs" to lock onto other smooth muscle cells and/or interstitial cells of Cajal. (wikipedia.org)
  • You just viewed The Ionic Basis for the Action... . (merlot.org)
  • If you know the author of The Ionic Basis for the Action Potential , please help us out by filling out the form below and clicking Send. (merlot.org)
  • In the generation of the action potential, stimulation of the cell by neurotransmitters or by sensory receptor cells partially opens channel-shaped protein molecules in the membrane. (britannica.com)
  • We conclude that Na+ action potentials are initiated in the apical dendrite in response to synaptic input. (nih.gov)
  • The second response is a burst mode, in which the cell is hyperpolarized and typically responds with LTS and their associated bursts of action potentials. (wikipedia.org)
  • The paper discusses a potential therapeutic strategy involving the upregulation of the dopamine receptor D2R that may be beneficial in the treatment of cocaine abuse and addiction. (nature.com)
  • It is shown by microelectrode measurements that, besides the sensory cells, all the major tissues of the trap lobes are excitable, firing action potentials with pronounced after-hyperpolarizations. (springer.com)
  • The resting potentials of sensory cells (-161±7 mV) and mesophyll cells (-155±8 mV) are of the same magnitude. (springer.com)
  • Sometimes called a propagated potential because a wave of excitation is actively transmitted along the nerve or muscle fibre, an action potential is conducted at speeds that range from 1 to 100 metres (3 to 300 feet) per second, depending on the properties of the fibre and its environment . (britannica.com)
  • The intention of this investigation was to acquire more concise information about the nature of the action potential of Dionaea muscipula Ellis and the different types of cells generating and conducting it. (springer.com)