: Reference: Reuveni, Friedman, Amitai, and Gutnick, J.Neurosci. 1993 NEURON { SUFFIX Ca_HVA USEION ca READ eca WRITE ica RANGE gbar, g, ica } UNITS { (S) = (siemens) (mV) = (millivolt) (mA) = (milliamp) } PARAMETER { gbar = 0.00001 (S/cm2) } ASSIGNED { v (mV) eca (mV) ica (mA/cm2) g (S/cm2) mInf mTau mAlpha mBeta hInf hTau hAlpha hBeta } STATE { m h } BREAKPOINT { SOLVE states METHOD cnexp g = gbar*m*m*h ica = g*(v-eca) } DERIVATIVE states { rates() m' = (mInf-m)/mTau h' = (hInf-h)/hTau } INITIAL{ rates() m = mInf h = hInf } PROCEDURE rates(){ UNITSOFF : if((v == -27) ){ : v = v+0.0001 : } :mAlpha = (0.055*(-27-v))/(exp((-27-v)/3.8) - 1) mAlpha = 0.055 * vtrap(-27 - v, 3.8) mBeta = (0.94*exp((-75-v)/17)) mInf = mAlpha/(mAlpha + mBeta) mTau = 1/(mAlpha + mBeta) hAlpha = (0.000457*exp((-13-v)/50)) hBeta = (0.0065/(exp((-v-15)/28)+1)) hInf = hAlpha/(hAlpha + hBeta) hTau = 1/(hAlpha + hBeta) UNITSON } FUNCTION vtrap(x, y) { : Traps for 0 in denominator of rate equations UNITSOFF if (fabs(x / y) < 1e-6) { vtrap = y * (1 - x / y / 2) } else { vtrap = x / (exp(x / y) - 1) } UNITSON }