TITLE K-D channel : M.Migliore jun 2006 UNITS { (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { v (mV) ek (mV) : must be explicitely def. in hoc celsius (degC) gkdbar=.0 (mho/cm2) vhalfn=-33 (mV) a0n=0.01 (/ms) zetan=3 (1) gmn=0.7 (1) nmax=2 (1) q10=1 sh = 0 } NEURON { SUFFIX kd USEION k READ ek WRITE ik RANGE gkd,gkdbar, i, sh GLOBAL ninf,taun } STATE { n } ASSIGNED { ik (mA/cm2) i (mA/cm2) ninf gkd taun } BREAKPOINT { SOLVE states METHOD cnexp gkd = gkdbar*n ik = gkd*(v-ek) i = ik } INITIAL { rates(v) n=ninf } FUNCTION alpn(v(mV)) { alpn = exp(1.e-3*zetan*(v-vhalfn-sh)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION betn(v(mV)) { betn = exp(1.e-3*zetan*gmn*(v-vhalfn-sh)*9.648e4/(8.315*(273.16+celsius))) } DERIVATIVE states { : exact when v held constant; integrates over dt step rates(v) n' = (ninf - n)/taun } PROCEDURE rates(v (mV)) { :callable from hoc LOCAL a,qt qt=q10^((celsius-24)/10) a = alpn(v) if (v < -30 ) { ninf = 1/(1+a) } else { ninf = 0 } taun = betn(v)/(qt*a0n*(1+a)) if (taun