TITLE na3 : Na current : modified from Jeff Magee. M.Migliore may97 : added sh to account for higher threshold M.Migliore, Apr.2002 NEURON { SUFFIX na16 USEION na READ ena WRITE ina RANGE gbar, ar2, thegna, ina GLOBAL vhalfs,sh,tha,qa,Ra,Rb,thi1,thi2,qd,qg,mmin,hmin,q10,Rg,qq,Rd,tq,thinf,qinf,vhalfs,a0s,zetas,gms,smax,vvh,vvs } PARAMETER { sh = 8 (mV) gbar = 0.010 (mho/cm2) tha = -35 (mV) : v 1/2 for act qa = 7.2 (mV) : act slope (4.5) Ra = 0.4 (/ms) : open (v) Rb = 0.124 (/ms) : close (v) thi1 = -45 (mV) : v 1/2 for inact thi2 = -45 (mV) : v 1/2 for inact qd = 0.5 (mV) : inact tau slope qg = 1.5 (mV) mmin=0.02 hmin=0.01 q10=2 Rg = 0.01 (/ms) : inact recov (v) Rd = .03 (/ms) : inact (v) qq = 10 (mV) tq = -55 (mV) thinf = -55 (mV) : inact inf slope qinf = 7 (mV) : inact inf slope vhalfs=-60 (mV) : slow inact. a0s=0.0003 (ms) : a0s=b0s zetas=12 (1) gms=0.2 (1) smax=10 (ms) vvh=-58 (mV) vvs=2 (mV) ar2=1 (1) : 1=no inact., 0=max inact. ena (mV) Ena = 55 (mV) : must be explicitly def. in hoc celsius v (mV) } UNITS { (mA) = (milliamp) (mV) = (millivolt) (pS) = (picosiemens) (um) = (micron) } ASSIGNED { ina (mA/cm2) thegna (mho/cm2) minf hinf mtau (ms) htau (ms) sinf (ms) taus (ms) } STATE { m h s} BREAKPOINT { SOLVE states METHOD cnexp thegna = gbar*m*m*m*h*s ina = thegna * (v - Ena) } INITIAL { trates(v,ar2,sh) m=minf h=hinf s=sinf } FUNCTION alpv(v) { alpv = 1/(1+exp((v-vvh-sh)/vvs)) } FUNCTION alps(v) { alps = exp(1.e-3*zetas*(v-vhalfs-sh)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION bets(v) { bets = exp(1.e-3*zetas*gms*(v-vhalfs-sh)*9.648e4/(8.315*(273.16+celsius))) } LOCAL mexp, hexp, sexp DERIVATIVE states { trates(v,ar2,sh) m' = (minf-m)/mtau h' = (hinf-h)/htau s' = (sinf - s)/taus } PROCEDURE trates(vm,a2,sh2) { LOCAL a, b, c, qt qt=q10^((celsius-24)/10) a = trap0(vm,tha+sh2,Ra,qa) b = trap0(-vm,-tha-sh2,Rb,qa) mtau = 1/(a+b)/qt if (mtau 1e-6) { trap0 = a * (v - th) / (1 - exp(-(v - th)/q)) } else { trap0 = a * q } }