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.Immunological Synapses: The interfaces between T-CELLS and ANTIGEN-PRESENTING CELLS. Supramolecular organization of proteins takes place at these synapses involving various types of immune cells. Immunological synapses can have several functions including LYMPHOCYTE ACTIVATION; enhancing, balancing, or terminating signaling; or directing cytokine secretion.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.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.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.Electrical Synapses: Specialized junctions between NEURONS which connect the cytoplasm of one neuron to another allowing direct passage of an ion current.Neuronal Plasticity: The capacity of the NERVOUS SYSTEM to change its reactivity as the result of successive activations.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.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.Synaptic Vesicles: Membrane-bound compartments which contain transmitter molecules. Synaptic vesicles are concentrated at presynaptic terminals. They actively sequester transmitter molecules from the cytoplasm. In at least some synapses, transmitter release occurs by fusion of these vesicles with the presynaptic membrane, followed by exocytosis of their contents.Dendrites: Extensions of the nerve cell body. They are short and branched and receive stimuli from other NEURONS.Receptors, AMPA: A class of ionotropic glutamate receptors characterized by their affinity for the agonist AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid).Dendritic Spines: Spiny processes on DENDRITES, each of which receives excitatory input from one nerve ending (NERVE ENDINGS). They are commonly found on PURKINJE CELLS and PYRAMIDAL CELLS.Long-Term Potentiation: A persistent increase in synaptic efficacy, usually induced by appropriate activation of the same synapses. The phenomenological properties of long-term potentiation suggest that it may be a cellular mechanism of learning and memory.Electric Stimulation: Use of electric potential or currents to elicit biological responses.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.Receptors, N-Methyl-D-Aspartate: A class of ionotropic glutamate receptors characterized by affinity for N-methyl-D-aspartate. NMDA receptors have an allosteric binding site for glycine which must be occupied for the channel to open efficiently and a site within the channel itself to which magnesium ions bind in a voltage-dependent manner. The positive voltage dependence of channel conductance and the high permeability of the conducting channel to calcium ions (as well as to monovalent cations) are important in excitotoxicity and neuronal plasticity.Neural Inhibition: The function of opposing or restraining the excitation of neurons or their target excitable cells.Neuromuscular Junction: The synapse between a neuron and a muscle.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.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.Synaptic Membranes: Cell membranes associated with synapses. Both presynaptic and postsynaptic membranes are included along with their integral or tightly associated specializations for the release or reception of transmitters.gamma-Aminobutyric Acid: The most common inhibitory neurotransmitter in the central nervous system.Nerve Tissue ProteinsLong-Term Synaptic Depression: A persistent activity-dependent decrease in synaptic efficacy between NEURONS. It typically occurs following repeated low-frequency afferent stimulation, but it can be induced by other methods. Long-term depression appears to play a role in MEMORY.Axons: Nerve fibers that are capable of rapidly conducting impulses away from the neuron cell body.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.Excitatory Amino Acid Antagonists: Drugs that bind to but do not activate excitatory amino acid receptors, thereby blocking the actions of agonists.Purkinje Cells: The output neurons of the cerebellar cortex.Mossy Fibers, Hippocampal: Axons of certain cells in the DENTATE GYRUS. They project to the polymorphic layer of the dentate gyrus and to the proximal dendrites of PYRAMIDAL CELLS of the HIPPOCAMPUS. These mossy fibers should not be confused with mossy fibers that are cerebellar afferents (see NERVE FIBERS).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.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.Animals, Newborn: Refers to animals in the period of time just after birth.Action Potentials: Abrupt changes in the membrane potential that sweep along the CELL MEMBRANE of excitable cells in response to excitation stimuli.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.Receptors, Glutamate: Cell-surface proteins that bind glutamate and trigger changes which influence the behavior of cells. Glutamate receptors include ionotropic receptors (AMPA, kainate, and N-methyl-D-aspartate receptors), which directly control ion channels, and metabotropic receptors which act through second messenger systems. Glutamate receptors are the most common mediators of fast excitatory synaptic transmission in the central nervous system. They have also been implicated in the mechanisms of memory and of many diseases.Post-Synaptic Density: Cytoskeleton specialization at the cytoplasmic side of postsynaptic membrane in SYNAPSES. It is involved in neuronal signaling and NEURONAL PLASTICITY and comprised of GLUTAMATE RECEPTORS; scaffolding molecules (e.g., PSD95, PSD93), and other proteins (e.g., CaCMKII).Synaptophysin: A MARVEL domain-containing protein found in the presynaptic vesicles of NEURONS and NEUROENDOCRINE CELLS. It is commonly used as an immunocytochemical marker for neuroendocrine differentiation.Vesicular Glutamate Transport Protein 1: A vesicular glutamate transporter protein that is predominately expressed in TELENCEPHALON of the BRAIN.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.Synaptic Potentials: The voltages across pre- or post-SYNAPTIC MEMBRANES.Guanylate Kinase: Catalyzes the ATP-dependent PHOSPHORYLATION of GMP to generate GDP and ADP.Motor Neurons: Neurons which activate MUSCLE CELLS.Cerebellum: The part of brain that lies behind the BRAIN STEM in the posterior base of skull (CRANIAL FOSSA, POSTERIOR). It is also known as the "little brain" with convolutions similar to those of CEREBRAL CORTEX, inner white matter, and deep cerebellar nuclei. Its function is to coordinate voluntary movements, maintain balance, and learn motor skills.Inhibitory Postsynaptic Potentials: Hyperpolarization of membrane potentials at the SYNAPTIC MEMBRANES of target neurons during NEUROTRANSMISSION. They are local changes which diminish responsiveness to excitatory signals.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.Synapsins: A family of synaptic vesicle-associated proteins involved in the short-term regulation of NEUROTRANSMITTER release. Synapsin I, the predominant member of this family, links SYNAPTIC VESICLES to ACTIN FILAMENTS in the presynaptic nerve terminal. These interactions are modulated by the reversible PHOSPHORYLATION of synapsin I through various signal transduction pathways. The protein is also a substrate for cAMP- and CALCIUM-CALMODULIN-DEPENDENT PROTEIN KINASES. It is believed that these functional properties are also shared by synapsin II.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.Neural Pathways: Neural tracts connecting one part of the nervous system with another.Receptors, Metabotropic Glutamate: Cell surface proteins that bind glutamate and act through G-proteins to influence second messenger systems. Several types of metabotropic glutamate receptors have been cloned. They differ in pharmacology, distribution, and mechanisms of action.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.Cell Adhesion Molecules, Neuronal: Surface ligands that mediate cell-to-cell adhesion and function in the assembly and interconnection of the vertebrate nervous system. These molecules promote cell adhesion via a homophilic mechanism. These are not to be confused with NEURAL CELL ADHESION MOLECULES, now known to be expressed in a variety of tissues and cell types in addition to nervous tissue.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.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.Microscopy, Electron: Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.Pyridinium CompoundsCA1 Region, Hippocampal: One of four subsections of the hippocampus described by Lorente de No, located furthest from the DENTATE GYRUS.Microscopy, Electron, Transmission: Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen.Receptors, Presynaptic: Neurotransmitter receptors located on or near presynaptic terminals or varicosities. Presynaptic receptors which bind transmitter molecules released by the terminal itself are termed AUTORECEPTORS.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)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.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.Mice, Inbred C57BLMice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Excitatory Amino Acid Agents: Drugs used for their actions on any aspect of excitatory amino acid neurotransmitter systems. Included are drugs that act on excitatory amino acid receptors, affect the life cycle of excitatory amino acid transmitters, or affect the survival of neurons using excitatory amino acids.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.Green Fluorescent Proteins: Protein analogs and derivatives of the Aequorea victoria green fluorescent protein that emit light (FLUORESCENCE) when excited with ULTRAVIOLET RAYS. They are used in REPORTER GENES in doing GENETIC TECHNIQUES. Numerous mutants have been made to emit other colors or be sensitive to pH.Membrane Proteins: Proteins which are found in membranes including cellular and intracellular membranes. They consist of two types, peripheral and integral proteins. They include most membrane-associated enzymes, antigenic proteins, transport proteins, and drug, hormone, and lectin receptors.Retinal Bipolar Cells: INTERNEURONS of the vertebrate RETINA containing two processes. They receive inputs from the RETINAL PHOTORECEPTOR CELLS and send outputs to the RETINAL GANGLION CELLS. The bipolar cells also make lateral connections in the retina with the RETINAL HORIZONTAL CELLS and with the AMACRINE CELLS.Neurons, Afferent: Neurons which conduct NERVE IMPULSES to the CENTRAL NERVOUS SYSTEM.Cerebellar Cortex: The superficial GRAY MATTER of the CEREBELLUM. It consists of two main layers, the stratum moleculare and the stratum granulosum.Exocytosis: Cellular release of material within membrane-limited vesicles by fusion of the vesicles with the CELL MEMBRANE.Vesicular Glutamate Transport Protein 2: A vesicular glutamate transporter protein that is predominately expressed in the DIENCEPHALON and lower brainstem regions of the CENTRAL NERVOUS SYSTEM.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Receptors, GABA-A: Cell surface proteins which bind GAMMA-AMINOBUTYRIC ACID and contain an integral membrane chloride channel. Each receptor is assembled as a pentamer from a pool of at least 19 different possible subunits. The receptors belong to a superfamily that share a common CYSTEINE loop.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.Vesicular Inhibitory Amino Acid Transport Proteins: A family of vesicular neurotransmitter transporter proteins that sequester the inhibitory neurotransmitters GLYCINE; GAMMA-AMINOBUTYRIC ACID; and possibly GAMMA-HYDROXYBUTYRATE into SECRETORY VESICLES.2-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.Excitatory Amino Acid Agonists: Drugs that bind to and activate excitatory amino acid receptors.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.Microscopy, Immunoelectron: Microscopy in which the samples are first stained immunocytochemically and then examined using an electron microscope. Immunoelectron microscopy is used extensively in diagnostic virology as part of very sensitive immunoassays.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.QuinoxalinesNeuropil: A dense intricate feltwork of interwoven fine glial processes, fibrils, synaptic terminals, axons, and dendrites interspersed among the nerve cells in the gray matter of the central nervous system.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.Cerebral Cortex: The thin layer of GRAY MATTER on the surface of the CEREBRAL HEMISPHERES that develops from the TELENCEPHALON and folds into gyri and sulchi. It reaches its highest development in humans and is responsible for intellectual faculties and higher mental functions.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).Receptors, Cholinergic: Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.Goldfish: Common name for Carassius auratus, a type of carp (CARPS).alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid: An IBOTENIC ACID homolog and glutamate agonist. The compound is the defining agonist for the AMPA subtype of glutamate receptors (RECEPTORS, AMPA). It has been used as a radionuclide imaging agent but is more commonly used as an experimental tool in cell biological studies.Miniature Postsynaptic Potentials: Postsynaptic potentials generated from a release of neurotransmitters from a presynaptic nerve terminal in the absence of an ACTION POTENTIAL. They may be m.e.p.p.s (miniature EXCITATORY POSTSYNAPTIC POTENTIALS) or m.i.p.p.s (miniature INHIBITORY POSTSYNAPTIC POTENTIALS).Mice, Transgenic: Laboratory mice that have been produced from a genetically manipulated EGG or EMBRYO, MAMMALIAN.Microscopy, Confocal: A light microscopic technique in which only a small spot is illuminated and observed at a time. An image is constructed through point-by-point scanning of the field in this manner. Light sources may be conventional or laser, and fluorescence or transmitted observations are possible.Retina: The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.Cell Communication: Any of several ways in which living cells of an organism communicate with one another, whether by direct contact between cells or by means of chemical signals carried by neurotransmitter substances, hormones, and cyclic AMP.Immunohistochemistry: Histochemical localization of immunoreactive substances using labeled antibodies as reagents.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.Thalamus: Paired bodies containing mostly GRAY MATTER and forming part of the lateral wall of the THIRD VENTRICLE of the brain.Signal Transduction: The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway.CA3 Region, Hippocampal: A subsection of the hippocampus, described by Lorente de No, that is located between the HIPPOCAMPUS CA2 FIELD and the DENTATE GYRUS.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.Agrin: A protein component of the synaptic basal lamina. It has been shown to induce clustering of acetylcholine receptors on the surface of muscle fibers and other synaptic molecules in both synapse regeneration and development.Receptors, Kainic Acid: A class of ionotropic glutamate receptors characterized by their affinity for KAINIC ACID.Protein Transport: The process of moving proteins from one cellular compartment (including extracellular) to another by various sorting and transport mechanisms such as gated transport, protein translocation, and vesicular transport.Afferent Pathways: Nerve structures through which impulses are conducted from a peripheral part toward a nerve center.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Cochlear Nucleus: The brain stem nucleus that receives the central input from the cochlear nerve. The cochlear nucleus is located lateral and dorsolateral to the inferior cerebellar peduncles and is functionally divided into dorsal and ventral parts. It is tonotopically organized, performs the first stage of central auditory processing, and projects (directly or indirectly) to higher auditory areas including the superior olivary nuclei, the medial geniculi, the inferior colliculi, and the auditory cortex.GABAergic Neurons: Neurons whose primary neurotransmitter is GAMMA-AMINOBUTYRIC ACID.Biophysics: The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.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.N-Methylaspartate: An amino acid that, as the D-isomer, is the defining agonist for the NMDA receptor subtype of glutamate receptors (RECEPTORS, NMDA).Spinal Cord: A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER.Dentate Gyrus: GRAY MATTER situated above the GYRUS HIPPOCAMPI. It is composed of three layers. The molecular layer is continuous with the HIPPOCAMPUS in the hippocampal fissure. The granular layer consists of closely arranged spherical or oval neurons, called GRANULE CELLS, whose AXONS pass through the polymorphic layer ending on the DENDRITES of PYRAMIDAL CELLS in the hippocampus.Glycine: A non-essential amino acid. It is found primarily in gelatin and silk fibroin and used therapeutically as a nutrient. It is also a fast inhibitory neurotransmitter.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.Vesicular Glutamate Transport Proteins: A family of vesicular neurotransmitter transporter proteins that were originally characterized as sodium dependent inorganic phosphate cotransporters. Vesicular glutamate transport proteins sequester the excitatory neurotransmitter GLUTAMATE from the CYTOPLASM into SECRETORY VESICLES in exchange for lumenal PROTONS.Microtubule-Organizing Center: An amorphous region of electron dense material in the cytoplasm from which the MICROTUBULES polymerization is nucleated. The pericentriolar region of the CENTROSOME which surrounds the CENTRIOLES is an example.Calcium-Calmodulin-Dependent Protein Kinase Type 2: A multifunctional calcium-calmodulin-dependent protein kinase subtype that occurs as an oligomeric protein comprised of twelve subunits. It differs from other enzyme subtypes in that it lacks a phosphorylatable activation domain that can respond to CALCIUM-CALMODULIN-DEPENDENT PROTEIN KINASE KINASE.Receptors, GABA-B: A subset of GABA RECEPTORS that signal through their interaction with HETEROTRIMERIC G-PROTEINS.Auditory Pathways: NEURAL PATHWAYS and connections within the CENTRAL NERVOUS SYSTEM, beginning at the hair cells of the ORGAN OF CORTI, continuing along the eighth cranial nerve, and terminating at the AUDITORY CORTEX.Glutamate Decarboxylase: A pyridoxal-phosphate protein that catalyzes the alpha-decarboxylation of L-glutamic acid to form gamma-aminobutyric acid and carbon dioxide. The enzyme is found in bacteria and in invertebrate and vertebrate nervous systems. It is the rate-limiting enzyme in determining GAMMA-AMINOBUTYRIC ACID levels in normal nervous tissues. The brain enzyme also acts on L-cysteate, L-cysteine sulfinate, and L-aspartate. EC Receptor Modulators: Compounds that interact with and modulate the activity of CANNABINOID RECEPTORS.Phosphinic Acids: Inorganic or organic derivatives of phosphinic acid, H2PO(OH). They include phosphinates and phosphinic acid esters.Perforant Pathway: A pathway of fibers that originates in the lateral part of the ENTORHINAL CORTEX, perforates the SUBICULUM of the HIPPOCAMPUS, and runs into the stratum moleculare of the hippocampus, where these fibers synapse with others that go to the DENTATE GYRUS where the pathway terminates. It is also known as the perforating fasciculus.Bicuculline: An isoquinoline alkaloid obtained from Dicentra cucullaria and other plants. It is a competitive antagonist for GABA-A receptors.Benzothiadiazines: Heterocyclic compounds of a ring with SULFUR and two NITROGEN atoms fused to a BENZENE ring. Members inhibit SODIUM-POTASSIUM-CHLORIDE SYMPORTERS and are used as DIURETICS.Learning: Relatively permanent change in behavior that is the result of past experience or practice. The concept includes the acquisition of knowledge.Biophysical Processes: Physical forces and actions in living things.Receptors, GABA: Cell-surface proteins that bind GAMMA-AMINOBUTYRIC ACID with high affinity and trigger changes that influence the behavior of cells. GABA-A receptors control chloride channels formed by the receptor complex itself. They are blocked by bicuculline and usually have modulatory sites sensitive to benzodiazepines and barbiturates. GABA-B receptors act through G-proteins on several effector systems, are insensitive to bicuculline, and have a high affinity for L-baclofen.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.Quaternary Ammonium Compounds: Derivatives of ammonium compounds, NH4+ Y-, in which all four of the hydrogens bonded to nitrogen have been replaced with hydrocarbyl groups. These are distinguished from IMINES which are RN=CR2.Neuropeptides: Peptides released by NEURONS as intercellular messengers. Many neuropeptides are also hormones released by non-neuronal cells.Ganglia: Clusters of multipolar neurons surrounded by a capsule of loosely organized CONNECTIVE TISSUE located outside the CENTRAL NERVOUS SYSTEM.Amacrine Cells: INTERNEURONS of the vertebrate RETINA. They integrate, modulate, and interpose a temporal domain in the visual message presented to the RETINAL GANGLION CELLS, with which they synapse in the inner plexiform layer.Central Nervous System: The main information-processing organs of the nervous system, consisting of the brain, spinal cord, and meninges.Brain-Derived Neurotrophic Factor: A member of the nerve growth factor family of trophic factors. In the brain BDNF has a trophic action on retinal, cholinergic, and dopaminergic neurons, and in the peripheral nervous system it acts on both motor and sensory neurons. (From Kendrew, The Encyclopedia of Molecular Biology, 1994)Dose-Response Relationship, Radiation: The relationship between the dose of administered radiation and the response of the organism or tissue to the radiation.Picrotoxin: A noncompetitive antagonist at GABA-A receptors and thus a convulsant. Picrotoxin blocks the GAMMA-AMINOBUTYRIC ACID-activated chloride ionophore. Although it is most often used as a research tool, it has been used as a CNS stimulant and an antidote in poisoning by CNS depressants, especially the barbiturates.Neural Cell Adhesion Molecules: Cell adhesion molecule involved in a diverse range of contact-mediated interactions among neurons, astrocytes, oligodendrocytes, and myotubes. It is widely but transiently expressed in many tissues early in embryogenesis. Four main isoforms exist, including CD56; (ANTIGENS, CD56); but there are many other variants resulting from alternative splicing and post-translational modifications. (From Pigott & Power, The Adhesion Molecule FactsBook, 1993, pp115-119)Neuroglia: The non-neuronal cells of the nervous system. They not only provide physical support, but also respond to injury, regulate the ionic and chemical composition of the extracellular milieu, participate in the BLOOD-BRAIN BARRIER and BLOOD-RETINAL BARRIER, form the myelin insulation of nervous pathways, guide neuronal migration during development, and exchange metabolites with neurons. Neuroglia have high-affinity transmitter uptake systems, voltage-dependent and transmitter-gated ion channels, and can release transmitters, but their role in signaling (as in many other functions) is unclear.Rats, Long-Evans: An outbred strain of rats developed in 1915 by crossing several Wistar Institute white females with a wild gray male. Inbred strains have been derived from this original outbred strain, including Long-Evans cinnamon rats (RATS, INBRED LEC) and Otsuka-Long-Evans-Tokushima Fatty rats (RATS, INBRED OLETF), which are models for Wilson's disease and non-insulin dependent diabetes mellitus, respectively.Nerve Regeneration: Renewal or physiological repair of damaged nerve tissue.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.Endocannabinoids: Fatty acid derivatives that have specificity for CANNABINOID RECEPTORS. They are structurally distinct from CANNABINOIDS and were originally discovered as a group of endogenous CANNABINOID RECEPTOR AGONISTS.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.Neurogenesis: Formation of NEURONS which involves the differentiation and division of STEM CELLS in which one or both of the daughter cells become neurons.Luminescent Proteins: Proteins which are involved in the phenomenon of light emission in living systems. Included are the "enzymatic" and "non-enzymatic" types of system with or without the presence of oxygen or co-factors.Receptor Aggregation: Chemically stimulated aggregation of cell surface receptors, which potentiates the action of the effector cell.Intracellular Signaling Peptides and Proteins: Proteins and peptides that are involved in SIGNAL TRANSDUCTION within the cell. Included here are peptides and proteins that regulate the activity of TRANSCRIPTION FACTORS and cellular processes in response to signals from CELL SURFACE RECEPTORS. Intracellular signaling peptide and proteins may be part of an enzymatic signaling cascade or act through binding to and modifying the action of other signaling factors.Analysis of Variance: A statistical technique that isolates and assesses the contributions of categorical independent variables to variation in the mean of a continuous dependent variable.Carrier Proteins: Transport proteins that carry specific substances in the blood or across cell membranes.Visual Pathways: Set of cell bodies and nerve fibers conducting impulses from the eyes to the cerebral cortex. It includes the RETINA; OPTIC NERVE; optic tract; and geniculocalcarine tract.Endocytosis: Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis.Memory: Complex mental function having four distinct phases: (1) memorizing or learning, (2) retention, (3) recall, and (4) recognition. Clinically, it is usually subdivided into immediate, recent, and remote memory.Parvalbumins: Low molecular weight, calcium binding muscle proteins. Their physiological function is possibly related to the contractile process.Protein Subunits: Single chains of amino acids that are the units of multimeric PROTEINS. Multimeric proteins can be composed of identical or non-identical subunits. One or more monomeric subunits may compose a protomer which itself is a subunit structure of a larger assembly.Larva: Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.Chelating Agents: Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS.Electric Capacitance: The ability of a substrate to retain an electrical charge.Somatosensory Cortex: Area of the parietal lobe concerned with receiving sensations such as movement, pain, pressure, position, temperature, touch, and vibration. It lies posterior to the central sulcus.Superior Colliculi: The anterior pair of the quadrigeminal bodies which coordinate the general behavioral orienting responses to visual stimuli, such as whole-body turning, and reaching.Mutation: Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.Synaptotagmins: A family of vesicular transport proteins characterized by an N-terminal transmembrane region and two C-terminal calcium-binding domains.Sensory Deprivation: The absence or restriction of the usual external sensory stimuli to which the individual responds.Receptors, Neurotransmitter: Cell surface receptors that bind signalling molecules released by neurons and convert these signals into intracellular changes influencing the behavior of cells. Neurotransmitter is used here in its most general sense, including not only messengers that act to regulate ion channels, but also those which act on second messenger systems and those which may act at a distance from their release sites. Included are receptors for neuromodulators, neuroregulators, neuromediators, and neurohumors, whether or not located at synapses.Receptors, Antigen, T-Cell: Molecules on the surface of T-lymphocytes that recognize and combine with antigens. The receptors are non-covalently associated with a complex of several polypeptides collectively called CD3 antigens (ANTIGENS, CD3). Recognition of foreign antigen and the major histocompatibility complex is accomplished by a single heterodimeric antigen-receptor structure, composed of either alpha-beta (RECEPTORS, ANTIGEN, T-CELL, ALPHA-BETA) or gamma-delta (RECEPTORS, ANTIGEN, T-CELL, GAMMA-DELTA) chains.Animals, Genetically Modified: ANIMALS whose GENOME has been altered by GENETIC ENGINEERING, or their offspring.Synaptosomes: Pinched-off nerve endings and their contents of vesicles and cytoplasm together with the attached subsynaptic area of the membrane of the post-synaptic cell. They are largely artificial structures produced by fractionation after selective centrifugation of nervous tissue homogenates.Drosophila: A genus of small, two-winged flies containing approximately 900 described species. These organisms are the most extensively studied of all genera from the standpoint of genetics and cytology.Receptor, Cannabinoid, CB1: A subclass of cannabinoid receptor found primarily on central and peripheral NEURONS where it may play a role modulating NEUROTRANSMITTER release.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.Antigen-Presenting Cells: A heterogeneous group of immunocompetent cells that mediate the cellular immune response by processing and presenting antigens to the T-cells. Traditional antigen-presenting cells include MACROPHAGES; DENDRITIC CELLS; LANGERHANS CELLS; and B-LYMPHOCYTES. FOLLICULAR DENDRITIC CELLS are not traditional antigen-presenting cells, but because they hold antigen on their cell surface in the form of IMMUNE COMPLEXES for B-cell recognition they are considered so by some authors.Amino Acid Transport System X-AG: A family of POTASSIUM and SODIUM-dependent acidic amino acid transporters that demonstrate a high affinity for GLUTAMIC ACID and ASPARTIC ACID. Several variants of this system are found in neuronal tissue.Retinal Rod Photoreceptor Cells: Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination.Ambystoma: A genus of the Ambystomatidae family. The best known species are the axolotl AMBYSTOMA MEXICANUM and the closely related tiger salamander Ambystoma tigrinum. They may retain gills and remain aquatic without developing all of the adult characteristics. However, under proper changes in the environment they metamorphose.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.Serotonin: A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.

Trans-synaptically induced bursts in regular spiking non-pyramidal cells in deep layers of the cat motor cortex. (1/13503)

In deep layers of the cat motor cortex, we have investigated the properties of neurons displaying trans-synaptically induced bursts. In in vivo experiments, extracellularly recorded burst neurons were separated into two subtypes based on their dependence on stimulation sites, the medullary pyramid or the ventrolateral (VL) thalamic nucleus, from which bursts of 10-20 spikes were triggered. The spike amplitude attenuation and frequency adaptation during a burst were more prominent in pyramid-dependent burst neurons than in VL-dependent burst neurons. Intracellular recordings in in vivo experiments revealed that pyramid-dependent bursts emerged from a long-lasting depolarization, while each spike during a VL-dependent burst was narrow in half-width and was followed by a fast AHP, similar to fast spiking neurons. In in vitro slice experiments, intracellular recordings were obtained from neurons that displayed a burst of attenuated spikes emerging from a long-lasting depolarization, and were also obtained from fast spiking neurons. They were morphologically recovered to be multipolar cells with sparsely spiny dendrites and local axonal networks, suggesting that they are inhibitory interneurons. The multipolar neurons displaying bursts of attenuated spikes may mediate the recurrent inhibition of pyramidal tract cells.  (+info)

Developmental synaptic changes increase the range of integrative capabilities of an identified excitatory neocortical connection. (2/13503)

Excitatory synaptic transmission between pyramidal cells and fast-spiking (FS) interneurons of layer V of the motor cortex was investigated in acute slices by using paired recordings at 30 degrees C combined with morphological analysis. The presynaptic and postsynaptic properties at these identified central synapses were compared between 3- and 5-week-old rats. At these two postnatal developmental stages, unitary EPSCs were mediated by the activation of AMPA receptors with fast kinetics at a holding potential of -72 mV. The amplitude distribution analysis of the EPSCs indicates that, at both stages, pyramidal-FS connections consisted of multiple functional release sites. The apparent quantal size obtained by decreasing the external calcium ([Ca2+]e) varied from 11 to 29 pA near resting membrane potential. In young rats, pairs of presynaptic action potentials elicited unitary synaptic responses that displayed paired-pulse depression at all tested frequencies. In older animals, inputs from different pyramidal cells onto the same FS interneuron had different paired-pulse response characteristics and, at most of these connections, a switch from depression to facilitation occurred when decreasing the rate of presynaptic stimulation. The balance between facilitation and depression endows pyramidal-FS connections from 5-week-old animals with wide integrative capabilities and confers unique functional properties to each synapse.  (+info)

Modulation of long-term synaptic depression in visual cortex by acetylcholine and norepinephrine. (3/13503)

In a slice preparation of rat visual cortex, we discovered that paired-pulse stimulation (PPS) elicits a form of homosynaptic long-term depression (LTD) in the superficial layers when carbachol (CCh) or norepinephrine (NE) is applied concurrently. PPS by itself, or CCh and NE in the absence of synaptic stimulation, produced no lasting change. The LTD induced by PPS in the presence of NE or CCh is of comparable magnitude with that obtained with prolonged low-frequency stimulation (LFS) but requires far fewer stimulation pulses (40 vs 900). The cholinergic facilitation of LTD was blocked by atropine and pirenzepine, suggesting involvement of M1 receptors. The noradrenergic facilitation of LTD was blocked by urapidil and was mimicked by methoxamine, suggesting involvement of alpha1 receptors. beta receptor agonists and antagonists were without effect. Induction of LTD by PPS was inhibited by NMDA receptor blockers (completely in the case of NE; partially in the case of CCh), suggesting that one action of the modulators is to control the gain of NMDA receptor-dependent homosynaptic LTD in visual cortex. We propose that this is a mechanism by which cholinergic and noradrenergic inputs to the neocortex modulate naturally occurring receptive field plasticity.  (+info)

Plasticity of first-order sensory synapses: interactions between homosynaptic long-term potentiation and heterosynaptically evoked dopaminergic potentiation. (4/13503)

Persistent potentiations of the chemical and electrotonic components of the eighth nerve (NVIII) EPSP recorded in vivo in the goldfish reticulospinal neuron, the Mauthner cell, can be evoked by afferent tetanization or local dendritic application of an endogenous transmitter, dopamine (3-hydroxytyramine). These modifications are attributable to the activation of distinct intracellular kinase cascades. Although dopamine-evoked potentiation (DEP) is mediated by the cAMP-dependent protein kinase (PKA), tetanization most likely activates a Ca2+-dependent protein kinase via an increased intracellular Ca2+ concentration. We present evidence that the eighth nerve tetanus that induces LTP does not act by triggering dopamine release, because it is evoked in the presence of a broad spectrum of dopamine antagonists. To test for interactions between these pathways, we applied the potentiating paradigms sequentially. When dopamine was applied first, tetanization produced additional potentiation of the mixed synaptic response, but when the sequence was reversed, DEP was occluded, indicating that the synapses potentiated by the two procedures belong to the same or overlapping populations. Experiments were conducted to determine interactions between the underlying regulatory mechanisms and the level of their convergence. Inhibiting PKA does not impede tetanus-induced LTP, and chelating postsynaptic Ca2+ with BAPTA does not block DEP, indicating that the initial steps of the induction processes are independent. Pharmacological and voltage-clamp analyses indicate that the two pathways converge on functional AMPA/kainate receptors for the chemically mediated EPSP and gap junctions for the electrotonic component or at intermediaries common to both pathways. A cellular model incorporating these interactions is proposed on the basis of differential modulation of synaptic responses via receptor-protein phosphorylation.  (+info)

Cellular sites for dynorphin activation of kappa-opioid receptors in the rat nucleus accumbens shell. (5/13503)

The nucleus accumbens (Acb) is prominently involved in the aversive behavioral aspects of kappa-opioid receptor (KOR) agonists, including its endogenous ligand dynorphin (Dyn). We examined the ultrastructural immunoperoxidase localization of KOR and immunogold labeling of Dyn to determine the major cellular sites for KOR activation in this region. Of 851 KOR-labeled structures sampled from a total area of 10,457 microm2, 63% were small axons and morphologically heterogenous axon terminals, 31% of which apposed Dyn-labeled terminals or also contained Dyn. Sixty-eight percent of the KOR-containing axon terminals formed punctate-symmetric or appositional contacts with unlabeled dendrites and spines, many of which received convergent input from terminals that formed asymmetric synapses. Excitatory-type terminals that formed asymmetric synapses with dendritic spines comprised 21% of the KOR-immunoreactive profiles. Dendritic spines within the neuropil were the major nonaxonal structures that contained KOR immunoreactivity. These spines also received excitatory-type synapses from unlabeled terminals and were apposed by Dyn-containing terminals. These results provide ultrastructural evidence that in the Acb shell (AcbSh), KOR agonists play a primary role in regulating the presynaptic release of Dyn and other neuromodulators that influence the output of spiny neurons via changes in the presynaptic release of or the postsynaptic responses to excitatory amino acids. The cellular distribution of KOR complements those described previously for the reward-associated mu- and delta-opioid receptors in the Acb shell.  (+info)

GABAergic excitatory synapses and electrical coupling sustain prolonged discharges in the prey capture neural network of Clione limacina. (6/13503)

Afterdischarges represent a prominent characteristic of the neural network that controls prey capture reactions in the carnivorous mollusc Clione limacina. Their main functional implication is transformation of a brief sensory input from a prey into a lasting prey capture response. The present study, which focuses on the neuronal mechanisms of afterdischarges, demonstrates that a single pair of interneurons [cerebral A interneuron (Cr-Aint)] is responsible for afterdischarge generation in the network. Cr-Aint neurons are electrically coupled to all other neurons in the network and produce slow excitatory synaptic inputs to them. This excitatory transmission is found to be GABAergic, which is demonstrated by the use of GABA antagonists, uptake inhibitors, and double-labeling experiments showing that Cr-Aint neurons are GABA-immunoreactive. The Cr-Aint neurons organize three different pathways in the prey capture network, which provide positive feedback necessary for sustaining prolonged spike activity. The first pathway includes electrical coupling and slow chemical transmission from the Cr-Aint neurons to all other neurons in the network. The second feedback is based on excitatory reciprocal connections between contralateral interneurons. Recurrent excitation via the contralateral cell can sustain prolonged interneuron firing, which then drives the activity of all other cells in the network. The third positive feedback is represented by prominent afterdepolarizing potentials after individual spikes in the Cr-Aint neurons. Afterdepolarizations apparently represent recurrent GABAergic excitatory inputs. It is suggested here that these afterdepolarizing potentials are produced by GABAergic excitatory autapses.  (+info)

A genetic approach to visualization of multisynaptic neural pathways using plant lectin transgene. (7/13503)

The wiring patterns among various types of neurons via specific synaptic connections are the basis of functional logic employed by the brain for information processing. This study introduces a powerful method of analyzing the neuronal connectivity patterns by delivering a tracer selectively to specific types of neurons while simultaneously transsynaptically labeling their target neurons. We developed a novel genetic approach introducing cDNA for a plant lectin, wheat germ agglutinin (WGA), as a transgene under the control of specific promoter elements. Using this method, we demonstrate three examples of visualization of specific transsynaptic neural pathways: the mouse cerebellar efferent pathways, the mouse olfactory pathways, and the Drosophila visual pathways. This strategy should greatly facilitate studies on the anatomical and functional organization of the developing and mature nervous system.  (+info)

Single synaptic events evoke NMDA receptor-mediated release of calcium from internal stores in hippocampal dendritic spines. (8/13503)

We have used confocal microscopy to monitor synaptically evoked Ca2+ transients in the dendritic spines of hippocampal pyramidal cells. Individual spines respond to single afferent stimuli (<0.1 Hz) with Ca2+ transients or failures, reflecting the probability of transmitter release at the activated synapse. Both AMPA and NMDA glutamate receptor antagonists block the synaptically evoked Ca2+ transients; the block by AMPA antagonists is relieved by low Mg2+. The Ca2+ transients are mainly due to the release of calcium from internal stores, since they are abolished by antagonists of calcium-induced calcium release (CICR); CICR antagonists, however, do not depress spine Ca2+ transients generated by backpropagating action potentials. These results have implications for synaptic plasticity, since they show that synaptic stimulation can activate NMDA receptors, evoking substantial Ca2+ release from the internal stores in spines without inducing long-term potentiation (LTP) or depression (LTD).  (+info)

  • This information moves through our brain between neurons that are linked together by tens of trillions of tiny structures called synapses. (
  • When we learn something new, synapses can be added or strengthened, but synapses must be weakened as well - so that the brain does not become overactive. (
  • Senior author Mriganka Sur said he was excited but not surprised that his team discovered a simple, fundamental rule at the core of such a complex system as the brain, where 100 billion neurons each have thousands of ever-changing synapses. (
  • The original brain model calculated the probability of synapse formation for all pairs of neurons. (
  • The simulation of neural networks is of medical interest as our brain is not at all hardwired: After a stroke, after the amputation of limbs, but also when learning, remembering and for many other processes, new synapses form while defunct ones disappear. (
  • The functioning brain receives thousands of chemical and electrical signals at the synapse, the area of connection between neurons," Tian said. (
  • A brain is composed of cells connected to one another at synapses. (
  • Previous research has suggested that the human brain has about 100 billion neurons and approximately 1 quadrillion (1 million billion) synapses. (
  • Understanding the detailed workings of a synapse -- the junction between neurons that govern how these cells communicate with each other -- is vital for modeling brain networks and understanding how diseases as diverse as depression, Alzheimer's or schizophrenia may affect brain function, according to the researchers. (
  • Most neuroscientists will tell you that long-term memories are stored in the brain in the form of synapses , the connections between neurons. (
  • Trettenbrein acknowledges that "the idea that learning is essentially the modification of synapses in an ever-changing plastic brain has become one of the dogmas of modern neuroscience" . (
  • 081202115201.htm Why We Remember Important Things And Forget Trivia: Neuron's Synapses Remodel Themselves enlarge Only when the transmission terminals (on the red cells) and the receiver stations (on the green cells) are in the right proportion to each other can communication actually take place in the brain. (
  • Up to now, only the receiving side of a synapse was believed to play an active role in this reorganization of the brain, which is thought to underlie our ability to learn but also to forget. (
  • The brain can deal with its complicated tasks only when the nerve cells manage to exchange information at the right time and place via their synapses. (
  • Synapses are sites of cell-cell contacts that transmit electrical or chemical signals in the brain. (
  • Information can be stored in the brain by multiple synaptic mechanisms, including altered structure and chemistry of existing synapses, formation of new synapses, or elimination of old ones. (
  • This slower pruning process results in a surplus of brain synapses - the points where neurons connect and communicate with one another. (
  • It's the first time that anyone has looked for, and seen, a lack of pruning during development of children with autism," Sulzer said, "although lower numbers of synapses in some brain areas have been detected in brains from older patients and in mice with autistic-like behaviors. (
  • When neurotransmitters are secreted and absorbed at the synapse, the junction of the two neurons, the signals are transmitted and the brain functions. (
  • When the balance of the two synapses is broken, it is known that brain mental diseases such as autism, bipolar disorder and obsessive-compulsive disorder occur. (
  • A new paper, publishing in Nature Neuroscience October 19th, reveals that a second protein interacts with PSD-95 and enables adaptive changes, such as changes in sensation, to be translated into changes in the synaptic scaffold, changing the amount of PSD-95 at the synapse. (
  • We can't see or learn or talk without synapses working properly," says senior author Matthew Dalva, Ph.D., Associate Professor of Neuroscience at the Sidney Kimmel Medical College at Thomas Jefferson University and the Farber Institute of Neuroscience at Jefferson and leader of the Theme Team for Synapse Biology. (
  • If you missed the first Synapse meeting and would like to be added to the Neuroscience Journal Club mailing list, please email me at [email protected] with your name and preferred email address. (
  • Synapses ," a Taiwanese family drama directed by Chang Tso-chi, has been set as the opening film of the 2019 edition of the Golden Horse Film Festival in Taiwan. (
  • Silicon Synapse runs at the Carnegie Library, Swords until 15 December 2019 - find out more here. (
  • C ) T cell synapses are larger interfaces in which TCR microclusters that exclude CD45 are formed. (
  • The general structure of a chemical synapse is shown schematically in Figure 5.1B . The space between the pre- and postsynaptic neurons is substantially greater at chemical synapses than at electrical synapses and is called the synaptic cleft . (
  • At electrical synapses , which are relatively rare in vertebrates, the membranes of the two cells are in tight contact, producing electrical coupling, which enables a nerve impulse (or action potential ) arriving at the presynaptic nerve ending to pass swiftly and reliably to the next cell. (
  • By comparison, the other side of the synapse, the transmitter unit, also known as bouton, was believed to play only a passive role in the formation of synapses. (
  • The word "synapse" - from the Greek synapsis ( συνάψις ), meaning "conjunction", in turn from συνάπτεὶν ( συν ("together") and ἅπτειν ("to fasten")) - was introduced in 1897 by the English neurophysiologist Charles Sherrington in Michael Foster 's Textbook of Physiology . (
  • There would be some justification if the author were to make the claim that this book is the fruit of a life-time of enquiry into the physiology of synapses. (
  • Synapses are little nanoscale machines that transmit information," said senior author Vitaly A. Klyachko, PhD, an associate professor of cell biology and physiology at the School of Medicine. (
  • synapses have been detected between neurons and oligodendrocytes in CA1 of the hippocampus AND these synapses can undergo a kind of LTP. (
  • Synapses in the hippocampus are larger and stronger after sleep deprivation, according to new research in mice published in JNeurosci . (
  • Chiara Cirelli and colleagues at the University of Wisconsin-Madison examined how synapses in the hippocampus, a structure involved in learning, changed following sleep and sleep deprivation in mice. (
  • Maximize your unfair advantage with Razer Synapse 3, the unified hardware configuration tool that takes your Razer device to the next level. (
  • The diffusion memristor is helping the drift-type memristor behave similarly to a real synapse," Yang said. (
  • F ) Microgaph of a neural synapse. (
  • The student reviews information on the neural synapse. (
  • The presentation of Physiological Events at the Neural Synapse by Barbara Lang was a brief and clear presentation of material that may be useful for nursing students. (
  • The conversion of CaPARs [Ca-permeable AMPA receptors] into Ca2+-impermeable receptors at Bergmann glial cells, by transfection with the GluR2 subunit, results in the retraction of glial processes that ensheath synapses and multiple innervations of Purkinje cells by climbing fibers. (
  • Recently, using various techniques to monitor synaptic responses at single synapses, several laboratories have confirmed that mEPSC amplitudes mediated by both AMPA and NMDARs are, indeed, highly variable, even at single synapses ( 9 - 13 ). (
  • Graded signaling requires a synapse to sustain high rates of exocytosis for relatively long periods, and this capacity is the special virtue of ribbon synapses. (
  • Now researchers at Thomas Jefferson University have found a new way in which synapses organization is controlled, which could eventually lead to better treatments for neurological diseases. (
  • Researchers who study how synapses grow and are lost have long focused on a molecule called PSD-95, which helps create and maintain the scaffolding around which a synapse is built. (
  • Through high-powered microscopy and biochemical analyses, the researchers discovered that a protein called ephrin-B3, which sits at membrane of neuronal synapses near clusters of PSD-95. (
  • Consistent with previous studies in the cortex, the researchers observed that synapses were larger, and therefore stronger, after the mice were awake for six to seven hours compared to after they were asleep for the same amount of time. (
  • Additionally, the researchers found that the synapses were strongest when the mice were forced to stay awake and interact with new stimuli, compared to mice that stayed awake on their own. (
  • Synapses are known to be affected by many genes linked to autism, and some researchers have hypothesized that people with autism may have more synapses. (
  • For the first time, nanotechnology researchers in France have developed a hybrid nanoparticle-organic transistor that can mimic the main functionalities of a synapse. (
  • The researchers have identified for the first time in the world that the MDGA1 protein at the post-synapse interferes with the binding between Neuroligin-2 and Neurexin and inhibits inhibitory synapse formation. (
  • It exhibits the main behavior of a biological spiking synapse and can lead to a new generation of neuro-inspired computers, capable of responding in a manner similar to the nervous system. (
  • The output of the NOMFET is thus able to reproduce the deceasing or amplifying behavior typical of a synapse depending on the frequency of spikes," Vuillaume recently told P hysics World . (
  • Using loose-patch recording of synaptic terminals ( 10 ), local stimulation of glutamate release ( 11 ), and calcium imaging of individual dendritic spines ( 13 ), responses of AMPARs at single synapses to a single quantum of glutamate in hippocampal cultures were shown to be highly variable. (
  • Dendritic spines are protrusions on dendritic shaft where excitatory synapses are located. (
  • It is worth emphasizing that degeneration of synapses and dendritic spines is one of the earliest features in those neurodegenerative disease conditions, prior to subsequent loss of neurons. (
  • In this study, Bear's team also used the phosphorylation of hippocampal glutamate receptors to show that LTP had occurred, but not its counterpart, long-term depression - another learning-induced process that involves the weakening, rather than strengthening of synapses. (
  • Thus, glutamate receptors at hippocampal synapses are not generally saturated by quantal release. (
  • We find that this variability must arise presynaptically and conclude that glutamate receptors at hippocampal synapses are, therefore, not saturated. (
  • This article is about synapses of the nervous system. (
  • Acetylcholine is the excitatory transmitter at nerve-muscle synapses, and glutamate is the main excitatory transmitter in the central nervous system . (
  • Cell-cell communication systems in the immune and nervous systems share several features, which has led to the adoption of the common term "synapse" to describe the close cell-cell contacts in each. (
  • One way to define this term is that it refers to changes in synapses and/or other parts of neurons that affect how information is processed and transmitted in the nervous system. (
  • Synapses are essential to neuronal function: neurons are cells that are specialized to pass signals to individual target cells, and synapses are the means by which they do so. (
  • The main advantage of an electrical synapse is the rapid transfer of signals from one cell to the next. (
  • The upshot of this memory effect is that the NOMFET behaves in a similar way to the manner of an organic synapse as it transmits a signal between neurons-it can modify its reaction to incoming signals based on events that happened before, or on the nature of the signal it's dealing with at that moment. (
  • The exciting thing is that the signals that a cell receives from, say, ten simultaneously active synapses can be greater than the sum of the signals from the ten individual synapses," says Volker Scheuss, summarizing the basis of his recently published study. (
  • This is the first anatomical explanation for the disproportionate strength of clustered synapse signals in comparison to the individual signals - a finding known from activity measurements. (
  • For instance, if the synapse receives very closely packed pulses of incoming signals, it will transmit a more intense action potential. (
  • Estimates for adults vary from 10 15 to 5 × 10 15 (1-5 quadrillion) synapses. (
  • SyNAPSE is a DARPA program that aims to develop electronic neuromorphic machine technology that scales to biological levels. (
  • The initial phase of the SyNAPSE program developed nanometer scale electronic synaptic components capable of adapting the connection strength between two neurons in a manner analogous to that seen in biological systems (Hebbian learning), and simulated the utility of these synaptic components in core microcircuits that support the overall system architecture. (
  • In biological systems, when a nerve impulse reaches a synapse , it causes channels to open, allowing calcium ions to flood into the synapse. (
  • But these memristors are based on physical processes very different from those in biological synapses, which limits their fidelity and the variety of possible synaptic functions, Yang said. (
  • Further updates about this project will occur only with the IBM synapse effort and the TrueNorth cognitive computer chip, since this effort continued with them. (
  • As we age, the problem is that C1q accumulates on synapses and removes ones we need for normal neuronal function, says Annexon CEO Doug Love . (
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Travel Information Paris Travel Information Eurotunnel | How Does Information Travel Across the Synapse The Travel... (
Synapse - Achieving optimal outcomes after radical prostatectomy
Synapse - Achieving optimal outcomes after radical prostatectomy (
Carver Mead - Wikipedia
Carver Mead - Wikipedia (
Impact of sub and supra-threshold adaptation currents in networks of spiking neurons | SpringerLink
Impact of sub and supra-threshold adaptation currents in networks of spiking neurons | SpringerLink (
SUM - Global Synapses
SUM - Global Synapses (
Synapse - Intensity-modulated radiotherapy for lymphoma involving the mediastinum
Synapse - Intensity-modulated radiotherapy for lymphoma involving the mediastinum (
The 10 most intriguing inventions of 2018 - MIT Technology Review
The 10 most intriguing inventions of 2018 - MIT Technology Review (
Synapse - Wikipedia
Synapse - Wikipedia (
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Alzheimer's Genome Project - YouTube
Alzheimer's Genome Project - YouTube (
OZone | Synapse
OZone | Synapse (
Synapse - Works
Synapse - Works (
Synapse Global
Synapse Global (
Synapse - Surgery
Synapse - Surgery (
Synapse - Predictors of inactive lifestyle among adult survivors of childhood cancer
Synapse - Predictors of inactive lifestyle among adult survivors of childhood cancer (
Hebbian synapses in hippocampus | PNAS
Hebbian synapses in hippocampus | PNAS (
Neural Development | SpringerLink
Neural Development | SpringerLink (
May 1987 - Scientific American
May 1987 - Scientific American (