NMDA subunit effects on Calcium and STDP (Evans et al. 2012)

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Accession:145917
Effect of NMDA subunit on spike timing dependent plasticity.
Reference:
1 . Evans RC, Morera-Herreras T, Cui Y, Du K, Sheehan T, Kotaleski JH, Venance L, Blackwell KT (2012) The effects of NMDA subunit composition on calcium influx and spike timing-dependent plasticity in striatal medium spiny neurons. PLoS Comput Biol 8:e1002493 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Neostriatum medium spiny direct pathway GABA cell;
Channel(s): I Na,t; I L high threshold; I T low threshold; I A; I h; I K,Ca; I Calcium; I A, slow;
Gap Junctions:
Receptor(s): GabaA; Glutamate;
Gene(s):
Transmitter(s):
Simulation Environment: GENESIS;
Model Concept(s): STDP; Calcium dynamics;
Implementer(s): Blackwell, Avrama [avrama at gmu.edu]; Evans, Rebekah [Rebekah.Evans at nih.gov];
Search NeuronDB for information about:  Neostriatum medium spiny direct pathway GABA cell; GabaA; Glutamate; I Na,t; I L high threshold; I T low threshold; I A; I h; I K,Ca; I Calcium; I A, slow;
//genesis
//  nmda_channel.g

/***************************		MS Model, Version 7.6	*********************
**************************** 	      nmda_channel.g  	*********************
	Avrama Blackwell 	kblackw1@gmu.edu
	Rebekah Evans 		rcolema2@gmu.edu	
	Tom Sheehan 		tsheeha2@gmu.edu	
******************************************************************************

*****************************************************************************/

function make_NMDA_channel (chanpath, Ek, KMg, tau2, gmax, ghk)

  str chanpath 
  float KMg, tau2, gmax  //parameters that differ between NR2A, B, C and D subunits
  
  float Ek
  int ghk 
  
  float tau1 = (4.4624e-3)/2 //  DE Chapman et al 2003, table 1 (12.13/e=5.63ms)
  float CMg = 1  // [Mg] in mM

  float eta = 1/3.57  // per mM
  float gamma = 62  // per Volt

	echo "XXXXXXXXXXXXXXX make_NMDA_channel XXXXXXXXXXXXXXXX"
	echo "chanpath = "{chanpath}
	echo "caBuffer = "{Ek}
	echo "KMg = "{KMg}
	echo "tau2 = "{tau2}
	echo "gmax = "{gmax}
	echo "XXXXXXXXXXXXXXX make_NMDA_channel XXXXXXXXXXXXXXXX"

	create synchan {chanpath}
	setfield {chanpath} \
          Ek   {Ek}   \
          tau1 {tau1} \
          tau2 {tau2} \
          gmax {gmax/2}
   
//the kinetics of the magnesium block is different for different subunits.  
// NR2A and B are about the same, but C and D are much less affected by the block.  
//these numbers were used because the made the magnesium block curve fit the figures by Moyner et al (1994 figure 7) best by eye.

  create Mg_block {chanpath}/block
  setfield {chanpath}/block CMg {CMg} 
  setfield {chanpath}/block KMg_B {1.0/{gamma}}
  setfield {chanpath}/block KMg_A {KMg}
				
  addmsg {chanpath} {chanpath}/block CHANNEL Gk Ek

  if (ghk==1)
     create ghk {chanPath}/GHK
     setfield {chanPath}/GHK Cout 2 // Carter & Sabatini 2004 uses 2mM, Wolf 5mM
     setfield {chanPath}/GHK valency 2.0
     setfield {chanPath}/GHK T {temperature}
     addmsg {compPath}/{chanpath}/block {chanPath}/GHK PERMEABILITY Gk 
  end

end


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