Calcium influx during striatal upstates (Evans et al. 2013)

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Accession:150912
"... To investigate the mechanisms that underlie the relationship between calcium and AP timing, we have developed a realistic biophysical model of a medium spiny neuron (MSN). ... Using this model, we found that either the slow inactivation of dendritic sodium channels (NaSI) or the calcium inactivation of voltage-gated calcium channels (CDI) can cause high calcium corresponding to early APs and lower calcium corresponding to later APs. We found that only CDI can account for the experimental observation that sensitivity to AP timing is dependent on NMDA receptors. Additional simulations demonstrated a mechanism by which MSNs can dynamically modulate their sensitivity to AP timing and show that sensitivity to specifically timed pre- and postsynaptic pairings (as in spike timing-dependent plasticity protocols) is altered by the timing of the pairing within the upstate. …"
Reference:
1 . Evans RC, Maniar YM, Blackwell KT (2013) Dynamic modulation of spike timing-dependent calcium influx during corticostriatal upstates. J Neurophysiol 110:1631-45 [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: Striatum;
Cell Type(s): Neostriatum medium spiny direct pathway GABA cell;
Channel(s): I Na,t; I L high threshold; I N; I A; I K; I K,Ca; I A, slow; I Krp; I R;
Gap Junctions:
Receptor(s): AMPA; NMDA; Gaba;
Gene(s): Cav1.3 CACNA1D; Cav1.2 CACNA1C; Cav2.2 CACNA1B;
Transmitter(s):
Simulation Environment: GENESIS;
Model Concept(s): Oscillations; STDP; Calcium dynamics;
Implementer(s): Evans, Rebekah [Rebekah.Evans at nih.gov];
Search NeuronDB for information about:  Neostriatum medium spiny direct pathway GABA cell; AMPA; NMDA; Gaba; I Na,t; I L high threshold; I N; I A; I K; I K,Ca; I A, slow; I Krp; I R;
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EvansEtAl2013
MScell
channels
ampa_channel.g
BK.g *
CaL12CDI.g
CaL13CDI.g
CaN.g
CaNCDI.g
CaR.g
CaRCDI.g
CaT.g *
gaba_channel.g *
KaF.g *
KaFnew.g *
KaS.g
Kir.g *
Krp.g
NaF.g *
NaFslowinact.g *
nmda_channel.g
SK.g *
synaptic_channel.g
tabchanforms.g *
                            
//genesis

/***************************		MS Model, Version 9.1	*********************
**************************** 	  		CaN.g 			*********************
Rebekah Evans updated 3/20/12
******************************************************************************
******************************************************************************/

function create_CaN
	str chanName = "CaN_channel"
	str compPath = "/library"

	int c	
	float Ek = 0.140 //(nernst calculated for 35degrees, [Cain] 50nM [Caout]2mM)
			//Ek is overwritten the the GHK object if it is used. 
	float x = -0.1
	int xdivs = 3000
	float xmin = -0.1
	float xmax = 0.05
        float increment ={{xmax}-{xmin}}/{xdivs}
        echo "CaN increment:" {increment} "V"
  	float mPower = 2.0  // Kasai 1992 p169
  	float hPower = 1.0

	float mvHalfCaN = -3e-3
	float mkCaN = -8e-3
	float hvHalfCaN = -74.8e-3
	float hkCaN = 6.5e-3
	float mTauCaN = 0.0
	float mInfCaN = 0.0
	float hTauCaN = 70e-3
	float hInfCaN = 0.0

	float theta	= 0.0
	float theta_1 = 0.0
	float beta	= 0.0
	float beta_exp	= 0.0
	float mA	= 0.0
	float mB	= 0.0
	float surf = 0.0
 	float gMax = 0
	float qFactCaN = {qfactCa}

	pushe {compPath}

	create tabchannel {chanName}
  	setfield {chanName} Ek {Ek} Xpower {mPower} Ypower {hPower}
	call {chanName} TABCREATE X {xdivs} {xmin} {xmax}
        call {chanName} TABCREATE Y {xdivs} {xmin} {xmax}

	for(c = 0; c < {xdivs}; c = c + 1)
		/************************ Begin CaN_mTau *********************/
		// mA = 39800*(vMemb + 17.19e-3)./
		//                      (exp((vMemb + 17.19e-3)/15.22e-3)-1);
		// mB = 384.2*exp(vMemb/23.82e-3);
		// mTauCaN = (1./(mA + mB)) / qFactCaN;
		// parameters tuned to fit Kasai 1992


		theta = 39800*{ {x} + 17.19e-3}
		beta = {{x}  + 17.19e-3}/15.22e-3
		beta_exp = {exp {beta}}
		beta_exp = beta_exp - 1.0
		mA = {{theta}/{beta_exp}}

		beta = {{x}/23.82e-3}
		beta_exp = {exp {beta}} 
		mB = 384.2*{beta_exp}

		mTauCaN = {{1.0/{mA + mB}}/{qFactCaN}}		
		setfield {chanName} X_A->table[{c}] {mTauCaN}
		/************************ End CaN_mTau ***********************/
	
		/************************ Begin CaN_mInf *********************/
		// mInfCaN   = 1./(1 + exp((vMemb - mvHalfCaN)/mkCaN));
		// parameters tuned so m2 fits Bargas and Surmeier 1994 boltzmann curve
		beta = {{x} - {mvHalfCaN}}/{mkCaN}
		beta_exp = {exp {beta}} + 1.0
		mInfCaN = 1.0/{beta_exp}
		setfield {chanName} X_B->table[{c}] {mInfCaN}
		/************************ End CaN_mInf ***********************/

		/************************ Begin CaN_hTau *********************/ 
		// hTauCaN  Mcnaughton et al., 1997 table 2 tau 1 for calcium
		setfield {chanName} Y_A->table[{c}] {{hTauCaN}/{qFactCaN}}
		/************************ End CaN_hTau ***********************/

		/************************ Begin CaN_hInf *********************/
		// hInfCaN   = 1./(1 + exp((vMemb - hvHalfCaN)/hkCaN));
		// Mcnaughton et al., 1997 table 2
		beta = {{x} - {hvHalfCaN}}/{hkCaN}
		beta_exp = {exp {beta}} + 1
                //0.21 has vdep inactivation, 0.79 does not inactivate
                hInfCaN = 0.21 * {1/{beta_exp}} + 0.79
 		setfield {chanName} Y_B->table[{c}] {hInfCaN}
		/************************ End CaN_hInf ***********************/
	
   	x = x + increment
	end

	tweaktau {chanName} X
	tweaktau {chanName} Y

  	create ghk {chanName}GHK

  	setfield {chanName}GHK Cout 2 // Carter & Sabatini 2004 uses 2mM, 
  	setfield {chanName}GHK valency 2.0
  	setfield {chanName}GHK T {TEMPERATURE}
	
  	setfield {chanName} Gbar {gMax*surf}
  	addmsg {chanName} {chanName}GHK PERMEABILITY Gk	
  	pope
end


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