|
Association Neurons
Interneurons (also called internuncial neurons, relay neurons, association neurons, connector neurons, intermediate neurons or local circuit neurons) are neurons that connect two brain regions, i.e. not direct motor neurons or sensory neurons. Interneurons are the central nodes of neural circuits, enabling communication between sensory or motor neurons and the central nervous system (CNS). They play vital roles in reflexes, neuronal oscillations, and neurogenesis in the adult mammalian brain. Interneurons can be further broken down into two groups: local interneurons and relay interneurons. Local interneurons have short axons and form circuits with nearby neurons to analyze small pieces of information. Relay interneurons have long axons and connect circuits of neurons in one region of the brain with those in other regions. However, interneurons are generally considered to operate mainly within local brain areas. The interaction between interneurons allow the brain to perform c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Locust
Locusts (derived from the Vulgar Latin ''locusta'', meaning grasshopper) are various species of short-horned grasshoppers in the family Acrididae that have a swarming phase. These insects are usually solitary, but under certain circumstances they become more abundant and change their behaviour and habits, becoming gregarious. No taxonomic distinction is made between locust and grasshopper species; the basis for the definition is whether a species forms swarms under intermittently suitable conditions; this has evolved independently in multiple lineages, comprising at least 18 genera in 5 different acridid subfamilies. Normally, these grasshoppers are innocuous, their numbers are low, and they do not pose a major economic threat to agriculture. However, under suitable conditions of drought followed by rapid vegetation growth, serotonin in their brains triggers dramatic changes: they start to breed abundantly, becoming gregarious and nomadic (loosely described as migratory) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rexed Laminae
The Rexed laminae comprise a system of ten layers of grey matter (I–X), identified in the early 1950s by Bror Rexed to label portions of the grey columns of the spinal cord. Similar to Brodmann areas, they are defined by their cellular structure rather than by their location, but the location still remains reasonably consistent. Laminae * Posterior grey column: I–VI ** Lamina I: marginal nucleus of spinal cord or posteromarginal nucleus ** Lamina II: substantia gelatinosa of Rolando ** Laminae III and IV: nucleus proprius ** Lamina V: Neck of the dorsal horn. Neurons within lamina V are mainly involved in processing sensory afferent stimuli from cutaneous, muscle and joint mechanical nociceptors as well as visceral nociceptors. This layer is home to wide dynamic range tract neurons, interneurons and propriospinal neurons. Viscerosomatic pain signal convergence often occurs in this lamina due to the presence of wide dynamic range tract neurons resulting in pain referral. ** Lam ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inhibitory Postsynaptic Potential
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. IPSP were first investigated in motorneurons by David P. C. Lloyd, John Eccles and Rodolfo Llinás in the 1950s and 1960s. 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. Inhibitory presynaptic neurons release neurotransmitters that then bind to the postsynaptic receptors; this induces a change in the permeability of the postsynaptic neuronal membrane to particular ions. An electric current that changes the postsynaptic membrane potential to create ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrosine Hydroxylase
Tyrosine hydroxylase or tyrosine 3-monooxygenase is the enzyme responsible for catalyzing the conversion of the amino acid L-tyrosine to L-3,4-dihydroxyphenylalanine (L-DOPA). It does so using molecular oxygen (O2), as well as iron (Fe2+) and tetrahydrobiopterin as cofactors. L-DOPA is a precursor for dopamine, which, in turn, is a precursor for the important neurotransmitters norepinephrine (noradrenaline) and epinephrine (adrenaline). Tyrosine hydroxylase catalyzes the rate limiting step in this synthesis of catecholamines. In humans, tyrosine hydroxylase is encoded by the ''TH'' gene, and the enzyme is present in the central nervous system (CNS), peripheral sympathetic neurons and the adrenal medulla. Tyrosine hydroxylase, phenylalanine hydroxylase and tryptophan hydroxylase together make up the family of aromatic amino acid hydroxylases (AAAHs). Reaction Tyrosine hydroxylase catalyzes the reaction in which L-tyrosine is hydroxylated in the meta position to obtain L- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cholinergic
Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word "choline" describes the various quaternary ammonium salts containing the ''N'',''N'',''N''-trimethylethanolammonium cation. Found in most animal tissues, choline is a primary component of the neurotransmitter acetylcholine and functions with inositol as a basic constituent of lecithin. Choline also prevents fat deposits in the liver and facilitates the movement of fats into cells. The parasympathetic nervous system, which uses acetylcholine almost exclusively to send its messages, is said to be almost entirely cholinergic. Neuromuscular junctions, preganglionic neurons of the sympathetic nervous system, the basal forebrain, and brain stem complexes are also cholinergic, as are the receptor for the merocrine sweat glands. In neuroscience and related fields, the term cholinergic is used in these related contexts: * A substance (or ligand) is cholinergic if it ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unipolar Brush Cell
Unipolar brush cells (UBCs) are a class of excitatory glutamatergic interneuron found in the granular layer of the cerebellar cortex and also in the granule cell domain of the cochlear nucleus. Structure The UBC has a round or oval cell body with usually a single short dendrite that ends in a brush-like tuft of short dendrioles (dendrites unique to UBCs). These brush dendrioles form very large synaptic junctions. The dendritic brush and the large endings of the axonal branches are involved in the formation of cerebellar glomeruli. The UBC has one short dendrite where the granule cell has four or five. The brush dendrioles emit numerous, thin evaginations called filopodia, unique to UBCs. The filopodia emanate from all over the neuron, even including the dendritic stem and the cell body in some cells. Although UBC filopodia do not bear synaptic junctions, they are nevertheless involved in cell signaling. Function UBCs are intrinsically firing neurons and considered as a cla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lugaro Cell
Lugaro cells are primary sensory interneurons of the cerebellum, that have an inhibitory function. They are fusiform, having a spindle shape that tapers at each end. They were first described by Ernesto Lugaro in the early 20th century. Lugaro cells are found just beneath the layer of Purkinje cells between the molecular layer and the granular layer. They have thick principal dendrites coming from opposite poles of their bodies. These dendrites are very long and travel along the boundary between the Purkinje layer and the granular layer. They seem to contact from 5 to 15 Purkinje cells in a horizontal direction. They can also sense stimuli close to the Purkinje cells and their dendrites form a large receptive area that monitors the environment near to the Purkinje cells. Whilst their dendrites make contact with the Purkinje cells they also receive inputs from branches of the Purkinje axons by which they seem to have a sampling and integration role.Lainé J, Axelrad H. Lugaro cells t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granule Cell
A granule is a large particle or grain. It can refer to: * Granule (cell biology), any of several submicroscopic structures, some with explicable origins, others noted only as cell type-specific features of unknown function ** Azurophilic granule, a structure characteristic of the azurophil eukaryotic cell type ** Chromaffin granule, a structure characteristic of the chromophil eukaryotic cell type. * Astrophysics and geology: ** Granule (solar physics), a visible structure in the photosphere of the Sun arising from activity in the Sun's convective zone ** Martian spherules, spherical granules of material found on the surface of the planet Mars ** Granule (geology), a specified particle size of 2–4 millimetres (-1 to -2 on the φ scale) * Granule, in pharmaceutical terms, small particles gathered into a larger, permanent aggregate in which the original particles can still be identified * Granule (Oracle DBMS), a unit of contiguously allocated virtual memory * Granular synthesis ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Golgi Cell
In neuroscience, Golgi cells are inhibitory interneurons found within the granular layer of the cerebellum. They were first identified as inhibitory in 1964. It was also the first example of an inhibitory feedback network, where the inhibitory interneuron was identified anatomically. These cells synapse onto the dendrite of granule cells and unipolar brush cells. They receive excitatory input from mossy fibres, also synapsing on granule cells, and parallel fibers, which are long granule cell axons. Thereby this circuitry allows for feed-forward and feed-back inhibition of granule cells. The main synapse made by these cells is a synapse onto the mossy fibre - granule cell excitatory synapse in a glomerulus. The glomerulus is made up of the mossy fibre terminal, granule cell dendrites, the Golgi terminal and is enclosed by a glial coat. The Golgi cell acts by altering the mossy fibre - granule cell synapse. The Golgi cells use GABA as their neurotransmitter. The basal level of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellate Cell
Stellate cells are neurons in the central nervous system, named for their star-like shape formed by dendritic processes radiating from the cell body. Many stellate cells are GABAergic and are located in the molecular layer of the cerebellum. Stellate cells are derived from dividing progenitor cells in the white matter of postnatal cerebellum. Dendritic trees can vary between neurons. There are two types of dendritic trees in the cerebral cortex, which include pyramidal cells, which are pyramid shaped and stellate cells which are star shaped. Dendrites can also aid neuron classification. Dendrites with spines are classified as spiny, those without spines are classified as aspinous. Stellate cells can be spiny or aspinous, while pyramidal cells are always spiny. Most common stellate cells are the inhibitory interneurons found within the upper half of the molecular layer in the cerebellum. Cerebellar stellate cells synapse onto the dendritic trees of Purkinje cells and send inhibit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basket Cell
Basket cells are inhibitory GABAergic interneurons of the brain, found throughout different regions of the cortex and cerebellum. Anatomy and physiology Basket cells are multipolar GABAergic interneurons that function to make inhibitory synapses and control the overall potentials of target cells. In general, dendrites of basket cells are free branching, contain smooth spines, and extend from 3 to 9 mm. Axons are highly branched, ranging in total from 20 to 50mm in total length. The branched axonal arborizations give rise to the name as they appear as baskets surrounding the soma of the target cell. Basket cells form axo-somatic synapses, meaning their synapses target somas of other cells. By controlling the somas of other neurons, basket cells can directly control the action potential discharge rate of target cells. Basket cells can be found throughout the brain, in among other the cortex, hippocampus, amygdala, basal ganglia, and the cerebellum. Cortex In the cortex, basket cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
