COMMENT ca.mod Uses fixed eca instead of GHK eqn HVA Ca current Based on Reuveni, Friedman, Amitai and Gutnick (1993) J. Neurosci. 13: 4609-4621. Author: Zach Mainen, Salk Institute, 1994, zach@salk.edu ENDCOMMENT INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} NEURON { SUFFIX ca USEION ca READ eca WRITE ica RANGE m, h, gca, gbar RANGE minf, hinf, mtau, htau GLOBAL q10, temp, tadj, vmin, vmax, vshift } PARAMETER { gbar = 0.1 (pS/um2) : 0.12 mho/cm2 vshift = 0 (mV) : voltage shift (affects all) cao = 2.5 (mM) : external ca concentration cai (mM) temp = 23 (degC) : original temp q10 = 2.3 : temperature sensitivity v (mV) dt (ms) celsius (degC) vmin = -120 (mV) vmax = 100 (mV) } UNITS { (mA) = (milliamp) (mV) = (millivolt) (pS) = (picosiemens) (um) = (micron) FARADAY = (faraday) (coulomb) R = (k-mole) (joule/degC) PI = (pi) (1) } ASSIGNED { ica (mA/cm2) gca (pS/um2) eca (mV) minf hinf mtau (ms) htau (ms) tadj } STATE { m h } INITIAL { trates(v+vshift) m = minf h = hinf } BREAKPOINT { SOLVE states gca = tadj*gbar*m*m*h ica = (1e-4) * gca * (v - eca) } LOCAL mexp, hexp PROCEDURE states() { trates(v+vshift) m = m + mexp*(minf-m) h = h + hexp*(hinf-h) VERBATIM return 0; ENDVERBATIM } PROCEDURE trates(v) { LOCAL tinc TABLE minf, mexp, hinf, hexp DEPEND dt, celsius, temp FROM vmin TO vmax WITH 199 rates(v): not consistently executed from here if usetable == 1 tadj = q10^((celsius - temp)/10) tinc = -dt * tadj mexp = 1 - myexp(tinc/mtau) hexp = 1 - myexp(tinc/htau) } PROCEDURE rates(vm) { LOCAL a, b a = 0.055*(-27 - vm)/(myexp((-27-vm)/3.8) - 1) b = 0.94*myexp((-75-vm)/17) mtau = 1/(a+b) minf = a*mtau :"h" inactivation a = 0.000457*myexp((-13-vm)/50) b = 0.0065/(myexp((-vm-15)/28) + 1) htau = 1/(a+b) hinf = a*htau } FUNCTION myexp(x) { if (x < -100) { myexp = 0 }else{ myexp = exp(x) } } FUNCTION efun(z) { if (fabs(z) < 1e-4) { efun = 1 - z/2 }else{ efun = z/(myexp(z) - 1) } }