TITLE K-DR channel : from Klee Ficker and Heinemann : modified to account for Dax et al. : M.Migliore 1997 UNITS { (mA) = (milliamp) (mV) = (millivolt) } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { dt (ms) v (mV) ek (mV) : must be explicitely def. in hoc celsius = 24 (degC) gkdrbar=.003 (mho/cm2) vhalfn=13 (mV) a0n=0.02 (/ms) zetan=-3 (1) gmn=0.7 (1) nmax=2 (1) q10=1 } NEURON { SUFFIX kdr USEION k READ ek WRITE ik RANGE gkdr,gkdrbar GLOBAL ninf,taun } STATE { n } ASSIGNED { ik (mA/cm2) ninf gkdr taun } INITIAL { rates(v) n=ninf gkdr = gkdrbar*n ik = gkdr*(v-ek) } BREAKPOINT { SOLVE states gkdr = gkdrbar*n ik = gkdr*(v-ek) } FUNCTION alpn(v(mV)) { alpn = exp(1.e-3*zetan*(v-vhalfn)*9.648e4/(8.315*(273.16+celsius))) } FUNCTION betn(v(mV)) { betn = exp(1.e-3*zetan*gmn*(v-vhalfn)*9.648e4/(8.315*(273.16+celsius))) } LOCAL facn :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) VERBATIM return 0; ENDVERBATIM } PROCEDURE rates(v (mV)) { :callable from hoc LOCAL a,qt qt=q10^((celsius-24)/10) a = alpn(v) ninf = 1/(1+a) taun = betn(v)/(qt*a0n*(1+a)) if (taun