FACTOID # 4: Just 1% of the houses in Nevada were built before 1939.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
   
 
WHAT'S NEW
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Dendritic spine
Close up of the dendrite of a striatal medium spiny neuron.
Close up of the dendrite of a striatal medium spiny neuron.
Cartoon showing some common types of dendritic spines
Cartoon showing some common types of dendritic spines

A dendritic spine is a small (sub-micron) membranous extrusion that protrudes from a dendrite and forms one half of a synapse. Typically spines have a bulbous head (the spine head) which is connected to the parent dendrite through a thin spine neck. Dendritic spines are found on the dendrites of most principal neurons in the brain including cortical pyramidal neurons, medium spiny neurons of the striatum and Purkinje cells in the cerebellum. Hippocampal and cortical pyramidal neurons may receive tens of thousands of mostly excitatory inputs from other neurons onto their equally numerous spines, whereas the number of spines on Purkinje neuron dendrites is an order of magnitude larger. Image File history File links Spines on the dendrite of a medium spiny striatal neuron. ... The striatum is a subcortical part of the brain consisting of the caudate nucleus and the putamen. ... Image File history File links Cartoon soming some of the more common spine types found on the dendrites of neurons. ... In biology, a dendrite is a slender, typically branched projection of a nerve cell, or neuron, which conducts the electrical stimulation received from other cells to the body or soma of the cell from which it projects. ... Synapses allow nerve cells to communicate with one another through axons and dendrites, converting electrical signals into chemical ones. ... In biology, a dendrite is a slender, typically branched projection of a nerve cell, or neuron, which conducts the electrical stimulation received from other cells to the body or soma of the cell from which it projects. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ... In the anatomy of animals, the brain, or encephalon, is the supervisory center of the nervous system. ... The striatum is a subcortical part of the brain consisting of the caudate nucleus and the putamen. ... Cerebellum (in blue) of the human brain For assistance with anatomical location terms, see Anatomical terms of location The cerebellum (literally little brain) is a brain region important for the integration of sensory perception with motor output. ... The location of the hippocampus in the human brain. ... A pyramidal cell is a multipolar neuron located in the hippocampus and cerebral cortex. ... Neurons (also called nerve cells) are the primary cells of the nervous system. ...


Spines come in a variety of shapes and have been categorized accordingly, e.g. mushroom spines, thin spines and stubby spines. Electron microscopy studies have shown that there is a continuum of shapes between these categories. There is some evidence that differently shaped spines reflect different developmental stages of a synapse. Using two-photon laser scanning microscopy it has been shown that the volume of spines can change depending on the types of stimuli that are presented to a synapse. Also using the same technique, time-lapse studies in the brains of living animals have shown that spines come and go, with the larger mushroom spines being the most stable over time. The electron microscope is a microscope that can magnify very small details with high resolving power due to the use of electrons rather than light to scatter off material, magnifying at levels up to 500,000 times. ...


Dendritic spines as biochemical compartments

Spines are believed to restrict diffusion of ions and second messengers from the synapse to the dendrite. As such, they form biochemical compartments that can encode changes in the state of an individual synapse without necessarily affecting the state of other synapses of the same neuron. An ion is an elementary particle or system of elementary particles with a net electric charge. ... In biology, second messengers are low-weight diffusible molecules that are used in signal transduction to relay a signal within a cell. ...


Role in synaptic plasticity

Changes in dendritic spine density underlie many brain functions, including motivation, learning, and memory. In particular, long-term memory is mediated in part by the growth of new dendritic spines to reinforce a particular neural pathway. By strengthening the connection between two neurons, the ability of the presynaptic cell to activate the postsynaptic cell is enhanced. This type of synaptic regulation forms the basis of synaptic plasticity. In psychology, motivation is the driving force (desire) behind all actions of an organism. ... Learned redirects here. ... Memory is a function of the brain: the ability to retain information. ... Long-term memory (LTM) is memory that lasts from over 30 seconds to years. ... This page is a candidate to be moved to Wiktionary. ... A synapse is a connection between two neurons: presynaptic and postsynaptic. ... The term synaptic plasticity refers to the variability of the strength of a signal transmitted through a synapse. ...


References

  • Structure and function of dendritic spines
  • Structural basis of long-term potentiation in single dendritic spines
  • From form to function: calcium compartmentalization in dendritic spines.
  • The dynamics of spine density changes
  • Dendritic spine structures and functions

  Results from FactBites:
 
Development of Dendritic Spines (969 words)
Dendritic filopodia are formed from the dendrites first and then convert into spines after being innervated by synaptic fibers.
Spines are predominantly found at excitatory synapses where inputs from many areas of the brain arrive.
If each spine is able to receive and store inputs, and there are thousands of spines on each dendrite, then it is understandable that humans can learn and retain facts and ideas throughout their lives as well as synthesize original thoughts.
Dendritic Spines (1386 words)
Dendritic spines are known to change shape, to the extend of appearing and disappearing entirely.
Perhaps dendritic spines contain Arp2/3 complexes forming branching networks whose regulation may not be dependent on the process length.
As spines are stimulated with for example NMDA, calcium flows into the spine (through the NMDA receptor) and this leads to the slowing of actin cycling.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m