COMMENT kca.mod Calcium-dependent potassium channel Based on Pennefather (1990) -- sympathetic ganglion cells taken from Reuveni et al (1993) -- neocortical cells Author: Zach Mainen, Salk Institute, 1995, zach@salk.edu ENDCOMMENT INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} NEURON { SUFFIX kca USEION k READ ek WRITE ik USEION ca READ cai RANGE n, gk, gbar RANGE ninf, ntau GLOBAL Ra, Rb, caix GLOBAL q10, temp, tadj, vmin, vmax } UNITS { (mA) = (milliamp) (mV) = (millivolt) (pS) = (picosiemens) (um) = (micron) } PARAMETER { gbar = 10 (pS/um2) : 0.03 mho/cm2 v (mV) cai (mM) caix = 1 Ra = 0.01 (/ms) : max act rate Rb = 0.02 (/ms) : max deact rate dt (ms) celsius (degC) temp = 23 (degC) : original temp q10 = 2.3 : temperature sensitivity vmin = -120 (mV) vmax = 100 (mV) } ASSIGNED { a (/ms) b (/ms) ik (mA/cm2) gk (pS/um2) ek (mV) ninf ntau (ms) tadj } STATE { n } INITIAL { rates(cai) n = ninf } BREAKPOINT { SOLVE states gk = tadj*gbar*n ik = (1e-4) * gk * (v - ek) } LOCAL nexp PROCEDURE states() { :Computes state variable n rates(cai) : at the current v and dt. n = n + nexp*(ninf-n) VERBATIM //return 0; ENDVERBATIM } PROCEDURE rates(cai(mM)) { LOCAL tinc a = Ra * cai^caix b = Rb ntau = 1/(a+b) ninf = a*ntau tadj = q10^((celsius - temp)/10) tinc = -dt * tadj nexp = 1 - exp(tinc/ntau) }