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

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"... 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. …"
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;
Simulation Environment: GENESIS;
Model Concept(s): Oscillations; STDP; Calcium dynamics;
Implementer(s): Evans, Rebekah [Rebekah.Evans at];
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;

/***************************		MS Model, Version 9.1	**********************
**************************** 	      	globals.g 			**********************


//Careful - all of these can be overridden in the .p file
        float ELEAK = -0.06
        float PI = 3.1415926
        float RA = 1.0 //determined by .p file (6)
        float RM = 2.8  //8.69565217  not overwritten in .p file, this is the right value
        float CM = 0.01  //is determined in .p file (altered to compensate for lack of spines)
        float EREST_ACT = -0.085 //-85 mV
 	float TEMPERATURE = 35

//parameters determined by hand tuning to match spike width, AHP shape &amp, fI curve

float somaLen=16.1e-6
float prox=26.1e-6
float mid=60e-6
float dist=1000e-6

        float gNaFprox={45000}  //  only in soma   
        float gNaFmid={6000}	// in prox and mid dends
        float gNaFdist={1000}	

        float gKAfprox={385}      
        float gKAfmid={{550}}     
        float gKAfdist={{550}}	

        float gKAsprox={200}  	 
        float gKAsdist={22}  //includes mid 

        float gKIR={11} //{11}        
        float gKrp={14}  //10.008 is 14     
	float gBK={10}
	float gSK={1}

float Cafactor = 1 	//multiply by 
float Dendfactor = 1

	float gCaL13soma = {{3e-7}*{Cafactor}}  //{{6e-7}/{Cafactor}}  		
	float gCaL13dend = {{1.5e-8}*{Dendfactor}} //{{gCaL13soma}/{Dendfactor}} 
	float gCaTsoma  =  {{7e-8}*{Cafactor}} //{{10e-8}/{Cafactor}}         
	float gCaTdend  =  {{3e-8}*{Dendfactor}} //{{gCaTsoma}/{Dendfactor}} 

	float gCaRsoma  =  {{8e-7}*{Cafactor}} //{{18e-7}/{Cafactor}}		
	float gCaRdend  =  {{10e-7}*{Dendfactor}} //{{gCaRsoma}/{Dendfactor}}	

	float gCaNsoma =   {{12e-7}*{Cafactor}} //{{10e-7}/{Cafactor}}       
	float gCaNdend =   {{0}*{Dendfactor}} //{{gCaNsoma}/{Dendfactor}}       

	float gCaL12soma = {{6e-7}*{Cafactor}} //{{6e-7}/{Cafactor}}    	
	float gCaL12dend = {{1.5e-7}*{Dendfactor}} //{{gCaL12soma}/{Dendfactor}} 

float qfactorKir = 3
float qfactorKrp = 3
float qfactorNaF = 3  
float qfactorkAs=3
float qfactorkAf=1.5
float qfactCa = 3
//bk and sk qfacts are taken into account in their channel files. 

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