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;
BK.g *
CaT.g *
gaba_channel.g *
KaF.g *
KaFnew.g *
Kir.g *
NaF.g *
NaFslowinact.g *
SK.g *
tabchanforms.g *

/***************************		MS Model, Version 9.1 *********************
**************************** 	    	KaF.g 			*********************
						Rebekah Evans updated 3/21/12 

function make_KAf_channel

  //initial parameters for making tab channel
	float Erev = -0.09
	int m_power = 2   //used in Wolf 2005
    int h_power = 1
//Activation constants for alphas and betas (obtained by matching m2 to Tkatch et al., 2000 Figs 2c, and mtau to fig 2b)
//units are mV, ms
	float mA_rate = 1.8  
	float mA_vhalf = -18    
	float mA_slope = -13   
	float mB_rate = 0.45  
	float mB_vhalf = 2   
	float mB_slope = 11  
//Inactivation constants for alphas and betas obtained by matching Tkatch et al., 2000 Fig 3b, and creating a tau voltage dependence 
//which is consistent with their value for V=0 in figure 3c.  
//units are mV, ms
	float hA_rate = 0.105
	float hA_vhalf = -121
	float hA_slope = 22
	float hB_rate = 0.065
	float hB_vhalf = -55
	float hB_slope = -11
	//table filling parameters	
    float xmin  = -0.1  
    float xmax  = 0.05  
    int  xdivsFiner = 3000
    int c = 0
    float increment =1000*{{xmax}-{xmin}}/{xdivsFiner}

    float x = -100

    str path = "KAf_channel" 
    create tabchannel {path} 
    call {path} TABCREATE X {xdivsFiner} {xmin} {xmax} 
    call {path} TABCREATE Y {xdivsFiner} {xmin} {xmax} 
    /*fills the tabchannel with values for minf, mtau, hinf and htau,
     *from the files.

    for (c = 0; c < {xdivsFiner} + 1; c = c + 1)
		float m_alpha = {sig_form {mA_rate} {mA_vhalf} {mA_slope} {x}}
		float m_beta = {sig_form {mB_rate} {mB_vhalf} {mB_slope} {x}}
		float h_alpha = {sig_form {hA_rate} {hA_vhalf} {hA_slope} {x}}
		float h_beta = {sig_form {hB_rate} {hB_vhalf} {hB_slope} {x}}
   /* 1e-3 converts from ms to sec. Tkactch does not specify recording temperature so room temperature is assumed*/		
		setfield {path} X_A->table[{c}] {{{1e-3/(m_alpha+m_beta)}}/{{qfactorkAf}}}
		setfield {path} X_B->table[{c}] {m_alpha/(m_alpha+m_beta)}
		setfield {path} Y_A->table[{c}] {{{1e-3/(h_alpha+h_beta)}}/{{qfactorkAf}}}
        	setfield {path} Y_B->table[{c}] {h_alpha/(h_alpha+h_beta)}
		x = x + increment
    /* Defines the powers of m and h in the Hodgkin-Huxley equation*/
    setfield {path} Ek {Erev} Xpower {m_power} Ypower {h_power} 
    tweaktau {path} X 
    tweaktau {path} Y 


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