GABA_BResponseODE.cpp

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#include "GABA_BResponseODE.h"


GABA_BResponseODE::GABA_BResponseODE(): ODESystem( 2 )
{
        solver = NULL;
        
    k1    = 9.0*10e4;    // [mM^-1 s^-1]
    k2    = 1.2;         // [s^-1]
    k3    = 180.0;       // [s^-1]
    k4    = 34.0;        // [s^-1]
    kd    = 100.0;       // [mM]
    n     = 4;

    dead_time = 1e-3;    // [s]
    Cdur    = 0.3e-3;    // [s]
    Cmax    = 0.5;       // [mM] 
}


GABA_BResponseODE::~GABA_BResponseODE()
{
        if( solver )
        delete solver;
}


int GABA_BResponseODE::init()
{
        setSystem( this );
    if( ! solver )
        solver = new odeiv::AdaptiveStepSolver( *this, odeiv::RungeKutta4() );
    return 0;
}


int GABA_BResponseODE::reset(double dt)
{
    if( ! solver ) 
        init();
        
    r=0.0;
    s=0.0;
    
    time_count=-dead_time-dt;
    
    psr=0.0;
    C=0.0;

        // y0[0]...r, y0[1]...s        
        double y0[2];
        y0[0]=r; y0[1]=s;
        y[0]=r; y[1]=s;
        
        solver->reset( dt, *this, y0 );

    return FiniteSpikeResponse::reset(dt);
}


void GABA_BResponseODE::derivatives(double t, const double y[], double f[])
{
    // y[0] ... r, y[1] ... s
    r = y[0];
    s = y[1];

    r = solver->y(0);
    s = solver->y(1);
    
    f[0] = k1*C*(1-r) - k2*r;
    f[1] = k3*r - k4*s;
}


int GABA_BResponseODE::advance(AdvanceInfo const &ai)
{     
        time_count -= ai.dt.in_sec();

        if(time_count <= 0.0)
            C=0.0;

    solver->advance( ai.t.in_sec(), ai.dt.in_sec(), *this );
    
    r = solver->y(0);
    s = solver->y(1);
        
    psr = g_max / ( 1.0 + kd / pow(s, n) );
        
    return advanceReturn();
}


int GABA_BResponseODE::spikeHit( spikeport_t port, SpikeEvent const& spike )
{
    if( port == 0 ) {
        if(time_count < -dead_time)     {
                C = Cmax;
                time_count = Cdur;
//                      g_max=spike.weight;
        }
        else {
                cerr << "spike missed" << endl;
        }
    }

    return spikeHitReturn( AdvanceInfo( spike.dt ) );
}


int GABA_BResponseODE::psrLength(double dt) const
{
        // TODO: replace this simple approximation
        const double tau = 0.200;   
        return (int)( (double)PSR_MULTIPLE_TAU * tau / dt + 0.5 );
}

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