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IPSP
An inhibitory postsynaptic potential (IPSP) is a kind of synaptic potential that makes a postsynaptic neuron less likely to generate an action potential.Purves et al. Neuroscience. 4th ed. Sunderland (MA): Sinauer Associates, Incorporated; 2008. The opposite of an inhibitory postsynaptic potential is an excitatory postsynaptic potential (EPSP), which is a synaptic potential that makes a postsynaptic neuron ''more'' likely to generate an action potential. IPSPs can take place at all chemical synapses, which use the secretion of neurotransmitters to create cell-to-cell signalling. EPSPs and IPSPs compete with each other at numerous synapses of a neuron. This determines whether an action potential occurring at the presynaptic terminal produces an action potential at the postsynaptic membrane. Some common neurotransmitters involved in IPSPs are GABA and glycine. Inhibitory presynaptic neurons release neurotransmitters that then bind to the postsynaptic receptors; this induces a ch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Temporal Summation
Summation, which includes both spatial summation and temporal summation, is the process that determines whether or not an action potential will be generated by the combined effects of excitatory and inhibitory signals, both from multiple simultaneous inputs (spatial summation), and from repeated inputs (temporal summation). Depending on the sum total of many individual inputs, summation may or may not reach the threshold voltage to trigger an action potential. Neurotransmitters released from the terminals of a presynaptic neuron fall under one of two categories, depending on the ion channels gated or modulated by the neurotransmitter receptor. Excitatory neurotransmitters produce depolarization of the postsynaptic cell, whereas the hyperpolarization produced by an inhibitory neurotransmitter will mitigate the effects of an excitatory neurotransmitter. This depolarization is called an EPSP, or an excitatory postsynaptic potential, and the hyperpolarization is called an IPSP, or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synaptic Potential
Synaptic potential refers to the potential difference across the postsynaptic membrane that results from the action of neurotransmitters at a neuronal synapse. In other words, it is the “incoming” signal that a neuron receives. There are two forms of synaptic potential: excitatory and inhibitory. The type of potential produced depends on both the postsynaptic receptor, more specifically the changes in conductance of ion channels in the post synaptic membrane, and the nature of the released neurotransmitter. Excitatory post-synaptic potentials (EPSPs) depolarize the membrane and move the potential closer to the threshold for an action potential to be generated. Inhibitory postsynaptic potentials (IPSPs) hyperpolarize the membrane and move the potential farther away from the threshold, decreasing the likelihood of an action potential occurring. The Excitatory Post Synaptic potential is most likely going to be carried out by the neurotransmitters glutamate and acetylcholine, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Postsynaptic Potential
Postsynaptic potentials are changes in the membrane potential of the postsynaptic terminal of a chemical synapse. Postsynaptic potentials are graded potentials, and should not be confused with action potentials although their function is to initiate or inhibit action potentials. Postsynaptic potentials occur when the presynaptic neuron releases neurotransmitters into the synaptic cleft. These neurotransmitters bind to receptors on the postsynaptic terminal, which may be a neuron, or a muscle cell in the case of a neuromuscular junction. These are collectively referred to as postsynaptic receptors, since they are located on the membrane of the postsynaptic cell. Postsynaptic potentials are important mechanisms by which neurons communicate with each other allowing for information processing, learning, memory formation, and complex behavior within the nervous system. Ion Involvement Ions can create excitatory or inhibitory potentials due to their unique reversal potentials and the m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Excitatory Postsynaptic Potential
In neuroscience, an excitatory postsynaptic potential (EPSP) is a postsynaptic potential that makes the postsynaptic neuron more likely to fire an action potential. This temporary depolarization of postsynaptic membrane potential, caused by the flow of positively charged ions into the postsynaptic cell, is a result of opening ligand-gated ion channels. These are the opposite of inhibitory postsynaptic potentials (IPSPs), which usually result from the flow of ''negative'' ions into the cell or positive ions ''out'' of the cell. EPSPs can also result from a decrease in outgoing positive charges, while IPSPs are sometimes caused by an increase in positive charge outflow. The flow of ions that causes an EPSP is an excitatory postsynaptic current (EPSC). EPSPs, like IPSPs, are graded (i.e. they have an additive effect). When multiple EPSPs occur on a single patch of postsynaptic membrane, their combined effect is the sum of the individual EPSPs. Larger EPSPs result in greater membra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Synapse
Chemical synapses are biological junctions through which neurons' signals can be sent to each other and to non-neuronal cells such as those in muscles or glands. Chemical synapses allow neurons to form circuits within the central nervous system. They are crucial to the biological computations that underlie perception and thought. They allow the nervous system to connect to and control other systems of the body. At a chemical synapse, one neuron releases neurotransmitter molecules into a small space (the synaptic cleft) that is adjacent to another neuron. The neurotransmitters are contained within small sacs called synaptic vesicles, and are released into the synaptic cleft by exocytosis. These molecules then bind to neurotransmitter receptors on the postsynaptic cell. Finally, the neurotransmitters are cleared from the synapse through one of several potential mechanisms including enzymatic degradation or re-uptake by specific transporters either on the presynaptic cell or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GABAA Receptor
The GABAA receptor (GABAAR) is an ionotropic receptor and ligand-gated ion channel. Its endogenous Ligand (biochemistry), ligand is γ-aminobutyric acid (GABA), the major inhibitory neurotransmitter in the central nervous system. Accurate regulation of GABAergic transmission through appropriate developmental processes, specificity to neural cell types, and responsiveness to activity is crucial for the proper functioning of nearly all aspects of the central nervous system (CNS). Upon opening, the GABAA receptor on the Chemical synapse, postsynaptic cell is selectively permeable to Chloride, chloride ions () and, to a lesser extent, Bicarbonate, bicarbonate ions (). GABAAR are members of the ligand-gated ion channel receptor superfamily, which is a chloride channel family with a dozen or more heterotetrametric subtypes and 19 distinct subunits. These subtypes have distinct brain regional and subcellular localization, age-dependent expression, and the ability to undergo plastic alt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hyperpolarization (biology)
Hyperpolarization is a change in a cell's membrane potential that makes it more negative. Cells typically have a negative resting potential, with neuronal action potentials depolarizing the membrane. When the resting membrane potential is made more negative, it increases the minimum stimulus needed to surpass the needed threshold. Neurons naturally become hyperpolarized at the end of an action potential, which is often referred to as the relative refractory period. Relative refractory periods typically last 2 milliseconds, during which a stronger stimulus is needed to trigger another action potential. Cells can also become hyperpolarized depending on channels and receptors present on the membrane, which can have an inhibitory effect. Hyperpolarization is often caused by efflux of K+ (a cation) through K+ channels, or influx of Cl– (an anion) through Cl– channels. On the other hand, influx of cations, e.g. Na+ through Na+ channels or Ca2+ through Ca2+ cha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Eccles (neurophysiologist)
Sir John Carew Eccles (27 January 1903 – 2 May 1997) was an Australian neurophysiologist and philosopher who won the 1963 Nobel Prize in Physiology or Medicine for his work on the synapse. He shared the prize with Andrew Huxley and Alan Lloyd Hodgkin. Life and work Early life Eccles was born in Melbourne, Australia. He grew up there with his two sisters and his parents: William and Mary Carew Eccles (both teachers, who home schooled him until he was 12). He initially attended Warrnambool High School originally published in ''Historical Records of Australian Science'', vol.13, no.4, 2001. (now Warrnambool College) (where a science wing is named in his honour), then completed his final year of schooling at Melbourne High School. Aged 17, he was awarded a senior scholarship to study medicine at the University of Melbourne. As a medical undergraduate, he was never able to find a satisfactory explanation for the interaction of mind and body; he started to think about becoming ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GABAB Receptor
GABAB receptors (GABABR) are G protein-coupled receptor, G-protein coupled receptors for gamma-aminobutyric acid (GABA), therefore making them metabotropic receptors, that are linked via G-proteins to potassium channels. The changing potassium concentrations hyperpolarize the cell at the end of an action potential. The reversal potential of the GABAB-mediated IPSP (inhibitory postsynaptic potential) is −100 mV, which is much more hyperpolarized than the GABAA receptor, GABAA IPSP. GABAB receptors are found in the central nervous system and the autonomic nervous system, autonomic division of the peripheral nervous system. The receptors were first named in 1981 when their distribution in the CNS was determined, which was determined by Norman Bowery and his team using radioactively labelled baclofen. Functions GABABRs stimulate the opening of Potassium channel, K+ channels, specifically G protein-coupled inwardly-rectifying potassium channel, GIRKs, which brings the neuro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (GGU, GGC, GGA, GGG). Glycine disrupts the formation of alpha-helices in secondary protein structure. Its small side chain causes it to favor random coils instead. Glycine is also an inhibitory neurotransmitter – interference with its release within the spinal cord (such as during a '' Clostridium tetani'' infection) can cause spastic paralysis due to uninhibited muscle contraction. It is the only achiral proteinogenic amino acid. It can fit into both hydrophilic and hydrophobic environments, due to its minimal side chain of only one hydrogen atom. History and etymology Glycine was discovered in 1820 by French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid. He originally called it "sugar of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GABA
GABA (gamma-aminobutyric acid, γ-aminobutyric acid) is the chief inhibitory neurotransmitter in the developmentally mature mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system. GABA is sold as a dietary supplement in many countries. It has been traditionally thought that exogenous GABA (i.e., taken as a supplement) does not cross the blood–brain barrier, but data obtained from more recent research (2010s) in rats describes the notion as being unclear. The carboxylate form of GABA is γ-aminobutyrate. Function Neurotransmitter Two general classes of GABA receptor are known: * GABAA in which the receptor is part of a ligand-gated ion channel complex * GABAB metabotropic receptors, which are G protein-coupled receptors that open or close ion channels via intermediaries (G proteins) Neurons that produce GABA as their output are called GABAergic neurons, and have chiefly inhibitory action at receptors in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
