Synchronicity of fast-spiking interneurons balances medium-spiny neurons (Damodaran et al. 2014)

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This study investigates the role of feedforward and feedback inhibition in maintaining the balance between D1 and D2 MSNs of the striatum. The synchronized firing of FSIs are found to be critical in this mechanism and specifically the gap junction connections between FSIs.
1 . Damodaran S, Evans RC, Blackwell KT (2014) Synchronized firing of fast-spiking interneurons is critical to maintain balanced firing between direct and indirect pathway neurons of the striatum. J Neurophysiol 111:836-48 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism:
Cell Type(s): Neostriatum medium spiny direct pathway GABA cell; Neostriatum medium spiny indirect pathway GABA cell; Neostriatum fast spiking interneuron;
Gap Junctions: Gap junctions;
Receptor(s): NMDA; Gaba;
Simulation Environment: GENESIS;
Model Concept(s): Detailed Neuronal Models; Parkinson's;
Implementer(s): Blackwell, Avrama [avrama at]; Damodaran, Sriraman [dsriraman at];
Search NeuronDB for information about:  Neostriatum medium spiny direct pathway GABA cell; Neostriatum medium spiny indirect pathway GABA cell; NMDA; Gaba;
ampa_channel.g *
BKKchannel.g *
CaL12inact_channel.g *
CaL13_channel.g *
CaNinact_channel.g *
CaR_channel.g *
CaT_channel.g *
gaba_channel.g *
K_DR_channel.g *
kAf_chanRE.g *
kAs_chanRE.g *
kIR_chanKD.g *
naF_chanOg.g *
nmda_channel.g *
SKchannelCaDep.g *
synaptic_channel.g *
tabchanforms.g *

/***************************		MS Model, Version 6	*********************
**************************** 	    	KaS_channel.g 			*********************
						Rebekah Evans	
		Tom Sheehan	703-538-8361

/* K A-type Slow channel
 * This is a tab channel created from Kv1.2 channel data in Shen 2004.
 * They are using dissociated medium spiny neurons, and did not specify recording temperature, so I am assuming room temp.
 * Our data matching process showed that the original model from Johanes Hjorth via Kai Du and Tom Sheehan matched closely with the
 * activation (minf) curve, but the activation tau curve was almost the opposite of the data.  The KaS channel does not completely
 * inactivate according to the Shen data and the model they have made to match their data.  Johannes accounted for this by making two
 * KaS channels one that inactivated and one that didn't and adjusted their conductances accordingly.  However, it will be faster to 
 * have just one channel that partially inactivates.  This new tab channel uses Alphas and Betas obtained by matching the model curves in Shen 2004 
 * figure 6.   m is to the power of 2 in the previous code, I have not re-checked wolf yet to see if that's what it is there.
 * Note that to distinguish these updated channels from the old, the file is now called KaS_chan.g (instead of KaS_channel.g) and the
 * function is called make_KaS_chan.  
 * *************** Rebekah Evans 02/15/10 ********************************/
/* AB: qfactor of 2 used instead of 3 in previous channel */

function make_KAs_channel
   //include tabchanforms
  //initial parameters for making tab channel
	float Erev = -0.09
	int m_power = 2
        int h_power = 1
//Activation constants for alphas and betas (obtained by matching Tkatch 2000)
	float mA_rate = 0.25 //units msec
	float mA_vhalf = 50
	float mA_slope = -20
	float mB_rate = 0.05 //units msec
	float mB_vhalf = -90
	float mB_slope = 35
//Inactivation constants for alphas and betas
	float hA_rate = 2.5 //units sec
	float hA_vhalf = -95
	float hA_slope = 16
	float hB_rate = 2 //units sec
	float hB_vhalf = 50
	float hB_slope = -70
	//table filling parameters	
    float xmin  = -0.1  /* minimum voltage we will see in the simulation */ 
    float xmax  = 0.05  /* maximum voltage we will see in the simulation */ 
    int  xdivsFiner = 3000 /* the number of divisions between -0.1 and 0.05 */
    int c = 0
    float increment = 1000*{{xmax}-{xmin}}/{xdivsFiner}
    echo "kAs: inc="{increment}"mV"
    float x = -100
	float m_alpha, m_beta, h_alpha, h_beta
    /* make the table for the activation with a range of -100mV - +50mV
     * with an entry for every 10mV
    str path = "KAs_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.

    float qfactor=2	 
    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}}
		float xa = {1/{{m_alpha}+{m_beta}}}
		float xb = {{m_alpha}/{{m_alpha}+{m_beta}}}
		float ya = {1/{{h_alpha}+{h_beta}}}
		float yb = {{{{h_alpha}/{{h_alpha}+{h_beta}}}*0.8}+0.2}
		//the *0.8+0.2 in yb is to make the channel partially inactivate.  
		// Tables are filled with inf and taus in order to make this channel partially inactivate.
		setfield {path} X_A->table[{c}] {(xa*1e-3)/qfactor}
		setfield {path} X_B->table[{c}] {xb}
		setfield {path} Y_A->table[{c}] {ya/qfactor}
                setfield {path} Y_B->table[{c}] {yb}
		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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