TITLE HH-type Ca++ channel : Mel-modified Hodgkin - Huxley conductances (after Ojvind et al.) NEURON { SUFFIX myca USEION ca READ eca WRITE ica RANGE gbar RANGE ar2, vhalfs RANGE inf, fac, tau RANGE taus RANGE W GLOBAL taumin } UNITS { (mA) = (milliamp) (mV) = (millivolt) } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { a0r=0.0003 (ms) b0r=0.0003 (ms) zetar=12 (1) zetas=12 (1) gms=0.2 (1) gmr=0.2 (1) a0s=0.0003 (ms) vvs = 2 (mV) vhalfr=-60 (mV) v (mV) W = 0.016 (/mV) : this 1/61.5 mV. see the paper celsius = 34 (degC) dt (ms) gbar=.12 (mho/cm2) eca = 140.0 (mV) ar2 = 1.0 b=0 taumin=3 } STATE { m h n s } ASSIGNED { ica (mA/cm2) inf[4] fac[4] tau[4] } BREAKPOINT { SOLVE states ica = gbar*m*m*h*s*(v - eca) } INITIAL { states() s=1 ica = gbar*m*m*h*s*(v - eca) } PROCEDURE calcg() { mhn(v*1(/mV)) m = m + fac[0]*(inf[0] - m) h = h + fac[1]*(inf[1] - h) n = n + fac[2]*(inf[2] - n) s = s + fac[3]*(inf[3] - s) } PROCEDURE states() { : exact when v held constant calcg() VERBATIM return 0; ENDVERBATIM } FUNCTION varss(v, i) { LOCAL max, min,vhalf,smooth if (i==0) { varss = 1 / (1 + exp((v + 40)/(-3))) :Ca activation } else if (i==1) { varss = 1 / (1 + exp((v + 45)/(3))) :Ca inactivation } else { :"s" activation system - Migliore 96 model max=1 min=0 smooth=2 vhalf=-60 varss = alpv(v,vhalfr) } } FUNCTION alpr(v(mV)) { alpr = exp(1.e-3*zetar*(v-vhalfr)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION alpv(v(mV),vh) { alpv = (1+ar2*exp((v-vh)/vvs))/(1+exp((v-vh)/vvs)) } FUNCTION betr(v(mV)) { betr = exp(1.e-3*zetar*gmr*(v-vhalfr)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION vartau(v, i) { LOCAL alpha, beta, sum,tmp if (i==0) { vartau = 0.05 :Ca activation tau } else if (i==1) { vartau = 0.5 :Ca inactivation tau } else { tmp = betr(v)/(a0r+b0r*alpr(v)) if (tmp