Dendrites dendrons, are branched protoplasmic extensions of a nerve cell that propagate the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project. Electrical stimulation is transmitted onto dendrites by upstream neurons via synapses which are located at various points throughout the dendritic tree. Dendrites play a critical role in integrating these synaptic inputs and in determining the extent to which action potentials are produced by the neuron. Dendritic arborization known as dendritic branching, is a multi-step biological process by which neurons form new dendritic trees and branches to create new synapses; the morphology of dendrites such as branch density and grouping patterns are correlated to the function of the neuron. Malformation of dendrites is tightly correlated to impaired nervous system function; some disorders that are associated with the malformation of dendrites are autism, schizophrenia, Down syndrome and anxiety.
Certain classes of dendrites contain small projections referred to as dendritic spines that increase receptive properties of dendrites to isolate signal specificity. Increased neural activity and the establishment of long-term potentiation at dendritic spines change the sizes and conduction; this ability for dendritic growth is thought to play a role in memory formation. There can be as many as 15,000 spines per cell, each of which serves as a postsynaptic process for individual presynaptic axons. Dendritic branching can be extensive and in some cases is sufficient to receive as many as 100,000 inputs to a single neuron. Dendrites are one of two types of protoplasmic protrusions that extrude from the cell body of a neuron, the other type being an axon. Axons can be distinguished from dendrites by several features including shape and function. Dendrites taper off in shape and are shorter, while axons tend to maintain a constant radius and be long. Axons transmit electrochemical signals and dendrites receive the electrochemical signals, although some types of neurons in certain species lack axons and transmit signals via their dendrites.
Dendrites provide an enlarged surface area to receive signals from the terminal buttons of other axons, the axon commonly divides at its far end into many branches each of which ends in a nerve terminal, allowing a chemical signal to pass to many target cells. When an electrochemical signal stimulates a neuron, it occurs at a dendrite and causes changes in the electrical potential across the neuron's plasma membrane; this change in the membrane potential will passively spread across the dendrite but becomes weaker with distance without an action potential. An action potential propagates the electrical activity along the membrane of the neuron's dendrites to the cell body and afferently down the length of the axon to the axon terminal, where it triggers the release of neurotransmitters into the synaptic cleft. However, synapses involving dendrites can be axodendritic, involving an axon signaling to a dendrite, or dendrodendritic, involving signaling between dendrites. An autapse is a synapse.
There are three main types of neurons. Multipolar neurons, such as the one shown in the image, are composed of one axon and many dendritic trees. Pyramidal cells are multipolar cortical neurons with pyramid shaped cell bodies and large dendrites called apical dendrites that extend to the surface of the cortex. Bipolar neurons have one dendritic tree at opposing ends of the cell body. Unipolar neurons have a stalk that extends from the cell body that separates into two branches with one containing the dendrites and the other with the terminal buttons. Unipolar dendrites are used to detect sensory stimuli such as temperature; the term dendrites was first used in 1889 by Wilhelm His to describe the number of smaller "protoplasmic processes" that were attached to a nerve cell. German anatomist Otto Friedrich Karl Deiters is credited with the discovery of the axon by distinguishing it from the dendrites; some of the first intracellular recordings in a nervous system were made in the late 1930s by Kenneth S. Cole and Howard J. Curtis.
Swiss Rüdolf Albert von Kölliker and German Robert Remak were the first to identify and characterize the axon initial segment. Alan Hodgkin and Andrew Huxley employed the squid giant axon and by 1952 they had obtained a full quantitative description of the ionic basis of the action potential, leading the formulation of the Hodgkin–Huxley model. Hodgkin and Huxley were awarded jointly the Nobel Prize for this work in 1963; the formulas detailing axonal conductance were extended to vertebrates in the Frankenhaeuser–Huxley equations. Louis-Antoine Ranvier was the first to describe the gaps or nodes found on axons and for this contribution these axonal features are now referred to as the Nodes of Ranvier. Santiago Ramón y Cajal, a Spanish anatomist, proposed that axons were the output components of neurons, he proposed that neurons were discrete cells that communicated with each other via specialized junctions, or spaces, between cells, now known as a synapse. Ramón y Cajal improved a silver staining process known as Golgi's method, developed by his rival, Camillo Golgi.
During the development of dendrites, several factors can influence differentiation. These include modulation of sensory input, environmental pollutants, body temperature, drug use. For example, rats raised in dark environments were found to have a reduced number of spines in
Park Jung-suk known as Reach or Reach is a professional South Korean StarCraft player. Park, who goes by the usernames Six_Devil_nO.1, ChoGoSy or TechniCal, is recognized as one of the best Protoss players in the world, an accomplishment for which he has been nicknamed "Hero Toss". He is skillful at macromanagement and does successful psionic storms and dragoon dancing, but plays inconsistently against Zerg, he won the 2002 Sky Ongamenet StarLeague, beating SlayerS `BoxeR` with a 3-1 score. He uses a Logitech optical mini and Samsung DT-35 Black keyboard. Park was the first player to achieve 100 Proleague victories, an accomplishment commemorated when he and Lee Jaedong formed prints of their mouse-controlling hands in clay in a September 2009 ceremony. Park is now a coach for League of Tekken team NaJin e-mFire in Korea. 1st place, 2002 SKY Starleague 2nd place, 2002 Pepsi Twist 2nd KPGA TOUR 4th place, 2003 Mycube Starleague 2nd place, 2004 Gilette Starleague 2nd place, 2005 UZOO MSL TLPD: Player profile & game record Reach's match replays
David Soren is an American archaeologist and former vaudeville performer. Soren was born in Philadelphia, Pennsylvania on October 7, 1946, he began his career in the entertainment business at the age of eight, a year was the youngest cast member of CBS television's The Horn and Hardart Children's Hour. Subsequently, Soren performed in vaudeville and road shows with members of the Philadelphia Eagles football team, Pete Boyle and with local children's program hosts Sally Starr and Chief Halftown, he is included in the Encyclopedia of Vaudeville. Switching gears in his late teens, Soren received a B. A. in Greek and Roman Studies from Dartmouth College an M. A. in Fine Arts and a Ph. D. in Classical Archaeology from Harvard University. During this time he directed archaeological investigations for the Smithsonian Institution at Utica, Thuburbo Majus and El Djem in Tunisia, he taught at the University of Missouri in Columbia, Missouri for 10 years from 1973, becoming department head in the Art History Department and directing excavations at Miróbriga, where he co-designed a large room of the Santiago do Cacem Museum with Star Wars production designer Harry Lange.
He was Guest Curator at the American Museum of Natural History in New York City from 1980 to 1988. Soren moved to the University of Arizona in 1983, first as department head in Classical Studies being appointed Regents Professor of Classics and Anthropology. Soren is known in archaeology for three discoveries, his archaeological excavations at Kourion, Cyprus were designed to identify the epicenter of the famous Mediterranean earthquake of July 21, 365 A. D, he located the epicenter of this mega-disaster offshore 25 miles southwest of the town of Kourion. Brian Fagan described this discovery as one of the 50 most significant in world archaeology, his second discovery was the identification of Plasmodium falciparum malaria as a significant contributor to the downfall of the Roman Empire. This was done through analysis of DNA of infant bones from a cemetery he excavated at Lugnano in Teverina, Umbria between 1987 and 1991 – the first such use of DNA evidence on an archaeological site; the third discovery was the site of the famous Roman fontes Clusini or Springs of Chiusi, a healing sanctuary featuring a cold water spring said by the poet Horace in his Epistles to have cured the gravely ill emperor Augustus from his stomach pains in 23 B.
C. Soren discovered the largest cold water ancient spring and sanctuary in Italy, near Chiusi in the Tuscan town of Chianciano Terme; the ancient spring he found was still flowing and the water contained large amounts of calcium sulfate which functions as a strong laxative. He has staged museum exhibitions for the American Museum of Natural History and the Hayden Planetarium. Soren has written numerous books on film, including biographies of director Dorothy Arzner, dancer Vera-Ellen, Belgian filmmaker Harry Kumel, he has served as creative consultant for NBC's Lost Civilizations and History International's Where Did It Come From?. He directed portions of Arts and Entertainment's Human Sacrifice, hosted by Leonard Nimoy. For his cinematic work he won a Cine Golden Eagle Award along with director David McAllister, he is directing and producing two archaeological documentaries about ancient Rome for the Oxford University Press and directing the institute he founded in Orvieto, for the University of Arizona.
Soren has been the subject of television specials by the BBC, RAI-1 in Italy, National Geographic, the Discovery Channel and The Learning Channel. Soren has been married to Noelle Soren, a former archaeologist and photographer, since 1967. Arizona in Italy