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

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Accession:156260
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.
Reference:
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 neuron; Neostriatum medium spiny indirect pathway neuron; Neostriatum fast spiking interneuron;
Channel(s):
Gap Junctions: Gap junctions;
Receptor(s): NMDA; Gaba;
Gene(s):
Transmitter(s):
Simulation Environment: GENESIS;
Model Concept(s): Detailed Neuronal Models; Parkinson's;
Implementer(s): Blackwell, Avrama [avrama at gmu.edu]; Damodaran, Sriraman [dsriraman at gmail.com];
Search NeuronDB for information about:  Neostriatum medium spiny direct pathway neuron; Neostriatum medium spiny indirect pathway neuron; NMDA; Gaba;
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striatalnetwork
Conditions
No_Gaps
FScell
channels
a_channel.g *
ampa_channel.g *
ampa_channel.g~ *
gaba_channel.g *
gaba_channel.g~ *
k13_channel.g *
k3132_channel.g *
na_channel.g *
synaptic_channel.g *
                            
/* K3132 channel
 *      fills tables with values for alpha and beta and then
 *      uses tweakalpha to alter the values to A and B
 *      values for alpha and beta are taken from:
 *      J. Neurophysiology 82: 2476-2389, 1999 
 *      on page 2478
 * 
 *      the functions below convert to physiological units to do the 
 *      calulations and convert back to SI units for the output
 */

/* alpha for the type X gate (activation) */
function K13ChanAlphaX(voltage)

    float voltage = {{voltage} * 1e3  - 0} /* convert to mV, add offset */
    
    float num = {-{0.616 + {0.014 * {voltage}}}}
    float denom = {{exp {{44 + {voltage}} / {-2.3}}} - 1}

    /* convert sec to msec */
    float act = {{num} / {denom}} * 1e3
    
    return act
end

/* beta for the type X gate (activation) */
function K13ChanBetaX(voltage) 

    float voltage = {{voltage} * 1e3 - 0} /* convert to mV */

    float num = 0.0043
    float denom = {exp {{44 + {voltage}} / 34}}

    /* convert sec to msec */
    float act = {{num} / {denom}} * 1e3

    return act
end

function make_K13_channel 

    float Erev = -0.090   /* reversal potential of potassium */

    str path = "K13_channel"  

    float xmin = -0.1   /* minimum voltage we will see in the simulation */
    float xmax = 0.05   /* maximum voltage we will see in the simulation */
    float step = 0.005  /* use a 5mV step size */
    int xdivs = 30      /* the number of divisions between -0.1 and 0.05 */
    int c = 0

    create tabchannel {path}

    /* make the table for the activation with a range of -100mV - +50mV
     * with an entry for ever 5mV
     */
    call {path} TABCREATE X {xdivs} {xmin} {xmax}

    /* set the tau and m_inf for the activation and inactivation */
    for(c = 0; c < {xdivs} + 1; c = c + 1)
        setfield {path} X_A->table[{c}] {K13ChanAlphaX {{c * {step}} + xmin}}
        setfield {path} X_B->table[{c}] {K13ChanBetaX {{c * {step}} + xmin}}
    end

  /* for testing */
//  for(c = 0; c < 30; c = c + 1)  
//        showfield {path} X_A->table[{c}] 
//        showfield {path} X_B->table[{c}] 
//    end


    setfield {path} Ek {Erev} Xpower 4

    /* fill the tables with the values of alpha and beta
     * calculated from tau and m_inf
     */
    tweakalpha {path} X

    call {path} TABFILL X 3000 0 

    //setfield {path} X_A->calc_mode 0 X_B->calc_mode 0
end





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