TITLE K-A channel from Klee Ficker and Heinemann : modified to account for Dax A Current ---------- : M.Migliore Jun 1997 UNITS { (mA) = (milliamp) (mV) = (millivolt) } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { dt (ms) v (mV) ek = -90 (mV) : must be explicitely def. in hoc celsius = 24 (degC) gbar=.008 (mho/cm2) vhalfn=11 (mV) vhalfl=-56 (mV) a0l=0.05 (/ms) a0n=0.05 (/ms) zetan=-1.5 (1) zetal=3 (1) gmn=0.55 (1) gml=1 (1) lmin=2 (ms) nmin=0.1 (ms) pw=-1 (1) tq=-40 (mV) qq=5 (mV) q10=5 qtl=1 nscale=1 lscale=1 } NEURON { SUFFIX kap USEION k READ ek WRITE ik RANGE gbar,gka,ik RANGE ninf,linf,taul,taun GLOBAL lmin,nscale,lscale } STATE { n l } ASSIGNED { ik (mA/cm2) ninf linf taul (ms) taun (ms) gka (mho/cm2) qt } INITIAL { rates(v) n=ninf l=linf gka = gbar*n*l ik = gka*(v-ek) } BREAKPOINT { SOLVE states METHOD cnexp gka = gbar*n*l ik = gka*(v-ek) } DERIVATIVE states { rates(v) n' = (ninf-n)/taun l' = (linf-l)/taul } FUNCTION alpn(v(mV)) { LOCAL zeta zeta=zetan+pw/(1+exp((v-tq)/qq)) alpn = exp(1.e-3*zeta*(v-vhalfn)*9.648e4(degC/mV)/(8.315*(273.16+celsius))) } FUNCTION betn(v(mV)) { LOCAL zeta zeta=zetan+pw/(1+exp((v-tq)/qq)) betn = exp(1.e-3*zeta*gmn*(v-vhalfn)*9.648e4(degC/mV)/(8.315*(273.16+celsius))) } FUNCTION alpl(v(mV)) { alpl = exp(1.e-3*zetal*(v-vhalfl)*9.648e4(degC/mV)/(8.315*(273.16+celsius))) } FUNCTION betl(v(mV)) { betl = exp(1.e-3*zetal*gml*(v-vhalfl)*9.648e4(degC/mV)/(8.315*(273.16+celsius))) } LOCAL facn,facl :if state_borgka is called from hoc, garbage or segmentation violation will :result because range variables won't have correct pointer. This is because : only BREAKPOINT sets up the correct pointers to range variables. :PROCEDURE states() { : exact when v held constant; integrates over dt step : rates(v) : n = n + facn*(ninf - n) : l = l + facl*(linf - l) : VERBATIM : return 0; : ENDVERBATIM :} PROCEDURE rates(v (mV)) { :callable from hoc LOCAL a,qt qt=q10^((celsius-24)/10(degC)) a = alpn(v) ninf = 1/(1 + a) taun = betn(v)/(qt*a0n*(1+a)) if (taun