Help


[permalink] [id link]
+
Page "Long-term depression" ¶ 9
from Wikipedia
Edit
Promote Demote Fragment Fix

Some Related Sentences

LTD and is
The specific mechanisms of LTP are unknown at the moment, but NMDA receptors crucial for the burst firing required, and dopamine plays a very important role in medating basal ganglic, thus hippocampal and memory activity ( which is much more complex, involving neurogenesis and LTD as well ).
The group 1 metabotropic glutamate receptor ( mGluR ) pathway, which includes mGluR1 and mGluR5, is involved in mGluR-dependent long term depression ( LTD ) and long term potentiation ( LTP ), both of which are important mechanisms in learning.
The lack of FMRP, which represses mRNA production and thereby protein synthesis, leads to exaggerated LTD. FMRP also appears to affect dopamine pathways in the prefrontal cortex which is believed to result in the attention deficit, hyperactivity and impulse control problems associated with FXS.
The mechanism of these effects is not clear although it is widely believed to reflect changes in synaptic efficacy akin to long-term potentiation ( LTP ) and long-term depression ( LTD ).
Logan is served by a local sales-tax-funded zero-fare bus system called the Cache Valley Transit District ( CVTD ), which incorporated the Logan Transit District ( LTD ) in 2007.
Many small ' toy ' Stirling engines, particularly low-temperature difference ( LTD ) types, do not have a distinct regenerator component and might be considered hot air engines, however a small amount of regeneration is provided by the surface of displacer itself and the nearby cylinder wall, or similarly the passage connecting the hot and cold cylinders of an alpha configuration engine.
CMPDI ( Central Mine Planning and Design Institute ) the design wing of Mahartna Company COAL INDIA LTD is located in Kanke road, Ranchi.
Although the LTD II was not produced for many model years, this body style with stacked rectangular headlamps is among the most popular among collectors.
The neuronal circuitry affected by LTP / LTD and modified by scaling and metaplasticity leads to reverberatory neural circuit development and regulation in a Hebbian manner which is manifested as memory, whereas the changes in neural circuitry, which begin at the level of the synapse, are an integral part in the ability of an organism to learn.
Brief activation of an excitatory pathway can produce what is known as long-term depression ( LTD ) of synaptic transmission in many areas of the brain.
LTD is induced by a minimum level of postsynaptic depolarization and simultaneous increase in the intracellular calcium concentration at the postsynaptic neuron.
LTD can be initiated at inactive synapses if the calcium concentration is raised to the minimum required level by heterosynaptic activation, or if the extracellular concentration is raised.
Long-term depression ( LTD ), in neurophysiology, is an activity-dependent reduction in the efficacy of neuronal synapses lasting hours or longer.
Long-term potentiation ( LTP ) is the opposing process to LTD. LTD is thought to result mainly from a decrease in postsynaptic receptor density, although a decrease in presynaptic neurotransmitter release may also play a role.
LTD is one of several processes that serves to selectively weaken specific synapses in order to make constructive use of synaptic strengthening caused by LTP.
Metaplasticity is expressed as a change in the capacity to provoke subsequent synaptic plasticity, including LTD and LTP.
Homosynaptic LTD is restricted to the individual synapse that is activated by a low frequency stimulus.
In other words, this form of LTD is activity-dependent, because the events causing the synaptic weakening occur at the same synapse that is being activated.

LTD and induced
LTP is induced when neurotransmitter release occurs 5-15 ms before a back-propagating action potential, whereas LTD is induced when the stimulus occurs 5-15 ms after the back-propagating action potential.

LTD and at
The " regular " Galaxie 500 continued below the LTD as Ford's mid-level full-size model from 1965 until its demise at the end of the 1974 model year.
Metaplasticity varies the threshold level at which plasticity occurs, allowing integrated responses to synaptic activity spaced over time and preventing saturated states of LTP and LTD.
Heterosynaptic LTD, in contrast, occurs at synapses that are not potentiated or are inactive.
LTD at the Schaffer collateral-CA1 synapses depends on the timing and frequency of calcium influx.
LTD occurs at these synapses when Schaffer collaterals are stimulated repetitively for extended time periods ( 10 – 15 minutes ) at a low frequency ( approximately 1 Hz ).
LTD occurs at synapses in cerebellar Purkinje neurons, which receive two forms of excitatory input, one from climbing fibers and one from parallel fibers.
A different mechanism is at work in the LTD that occurs in layer V. In layer V, LTD requires low frequency stimulation, endocannabinoid signaling, and activation of presynaptic NR2B-containing NMDA receptors.
The other LTD mechanism involves acetylcholine receptors and kainate receptors at a much earlier time, about 20 to 30 minutes after stimulus.
Endocannabinoid retrograde signaling has been shown to effect LTD at corticostriatal synapses and glutamatergic synapses in the prelimbic cortex of the nucleus accumbens ( NAc ), and it is also involved in spike-timing-dependent LTD in the visual cortex.
They are involved in inhibition of LTD at parallel fiber Purkinje neuron synapses in the cerebellum and NMDA receptor-dependent LTD in the hippocampus.
While Aβ's role in LTD regulation has not been clearly understood, it has been found that soluble Aβ facilitates hippocampal LTD and is mediated by a decrease in glutamate recycling at hippocampal synapses.
Evidence that soluble Aβ enhances LTD through a mechanism involving altered glutamate uptake at hippocampal synapses has important implications for the initiation of synaptic failure in AD and in types of age-related Aβ accumulation.
Long term depression ( LTD ) at the PF-PC synapse is hypothesized to have significant functional consequences for learning the behavioral CR in EBC ( Ito, 1984 ).
Production was therefore invested in Fairey Engineering Ltd but by 1962 this had been transformed into a 50 / 50 joint venture with the British Aircraft Corporation ( Holdings ) Ltd known as BAC ( AT ) LTD, with offices at 100 Pall Mall, London SWI.

LTD and neuron
Opening of NMDA channels ( which relates to the level of cellular depolarization ) leads to a rise in post-synaptic Ca < sup > 2 +</ sup > concentration and this has been linked to long term potentiation, LTP ( as well as to protein kinase activation ); strong depolarization of the post-synaptic cell completely displaces the magnesium ions that block NMDA ion channels and allows calcium ions to enter a cell – probably causing LTP, while weaker depolarization only partially displaces the Mg < sup > 2 +</ sup > ions, resulting in less Ca < sup > 2 +</ sup > entering the post-synaptic neuron and lower intracellular Ca < sup > 2 +</ sup > concentrations ( which activate protein phosphatases and induce long-term depression, LTD ).
Homosynaptic LTD is also associative in that it correlates the activation of the postsynaptic neuron with the firing of the presynaptic neuron.
Associative LTP has been demonstrated at layer 4 to layer 2 / 3 synapses when the layer 4 neuron fires 0-15 ms before the layer 2 / 3 neuron, and LTD is observed when this timing order is reversed.
found in cultured hippocampal neurons that the induction of LTD is also accompanied by back propagation of depression in the dendrite tree of the presynaptic neuron.

LTD and synapses
A LTD was evidenced in 2011 for the electrical synapses ( modification of Gap Junctions efficacy through their activity ).< Ref > J.
Thus, this form of LTD impacts synapses nearby those receiving action potentials.
LTD affects hippocampal synapses between the Schaffer collaterals and the CA1 pyramidal cells.
Some models of cerebellar-dependent motor learning, in particular the Marr-Albus model, propose a single plasticity mechanism involving the cerebellar long-term depression ( LTD ) of the parallel fiber synapses onto Purkinje cells.
These electrical synapses account for the speed of the escape mechanism and display some features of chemical synapses such as LTP and LTD. Variations in escape response characteristic depend on the location where the crayfish body is prodded or attacked and also depend on which of the giant neurons is stimulated.

0.291 seconds.