: Reference: Colbert and Pan 2002 NEURON { SUFFIX NaTs USEION na READ ena WRITE ina RANGE gbar, g, ina } UNITS { (S) = (siemens) (mV) = (millivolt) (mA) = (milliamp) } PARAMETER { gbar = 0.00001 (S/cm2) malphaF = 0.182 mbetaF = 0.124 mvhalf = -40 (mV) mk = 6 (mV) halphaF = 0.015 hbetaF = 0.015 hvhalf = -66 (mV) hk = 6 (mV) } ASSIGNED { v (mV) ena (mV) ina (mA/cm2) g (S/cm2) celsius (degC) mInf mTau mAlpha mBeta hInf hTau hAlpha hBeta } STATE { m h } BREAKPOINT { SOLVE states METHOD cnexp g = gbar*m*m*m*h ina = g*(v-ena) } DERIVATIVE states { rates() m' = (mInf-m)/mTau h' = (hInf-h)/hTau } INITIAL{ rates() m = mInf h = hInf } PROCEDURE rates(){ LOCAL qt qt = 2.3^((celsius-23)/10) UNITSOFF mAlpha = malphaF * vtrap(-(v - mvhalf), mk) mBeta = mbetaF * vtrap((v - mvhalf), mk) mInf = mAlpha/(mAlpha + mBeta) mTau = (1/(mAlpha + mBeta))/qt hAlpha = halphaF * vtrap(v - hvhalf, hk) hBeta = hbetaF * vtrap(-(v - hvhalf), hk) hInf = hAlpha/(hAlpha + hBeta) hTau = (1/(hAlpha + hBeta))/qt 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 }