: Cone Photoreceptor h channel by using kinetics in Barnes' paper

NEURON 
{
	SUFFIX h
	
	NONSPECIFIC_CURRENT ih
	
	RANGE ghbar, gh, eh 
         

}

UNITS
{
	(mA) = (milliamp)
	(mV) = (millivolt)
	(mS) = (millimho)
}

PARAMETER
{
       
   
       : h channel
        ghbar = 3.5 (mS/cm2) <0,1e9>
        eh  = -32.5 (mV)
       
       
        

}

STATE
{
	nh
	
}

ASSIGNED
{
	v (mV)
	
	ih (mA/cm2)
	
	infh
	tauh   (ms)
	
	gh (mho/cm2)

}

INITIAL
{
	rate(v)
	nh  = infh
}




BREAKPOINT
{
	SOLVE states METHOD cnexp
	gh  = (0.001)*ghbar*(1-(1+3*nh)*(1-nh)^3)
	ih  = gh*(v - eh)
	
	: the current is in the unit of mA/cm2
	
	
}

DERIVATIVE states
{
	rate(v)
	nh'  = (infh  - nh )/tauh

}



FUNCTION alphah(v(mV)) (/ms)
{ 
	alphah = 0.001*18/( exp  (  ( v+88)/12 ) + 1 )
}


FUNCTION betah(v(mV)) (/ms)
{ 
	betah = 0.001*18/( exp  ( - ( v+18)/19 ) + 1 )
}



PROCEDURE rate(v (mV))
{
        LOCAL a, b

	
	a = alphah(v)
	b = betah(v)
	tauh = 1/(a + b)
	infh = a/(a + b)
	
}