COMMENT Model for an SODIUM cuRrent recorded in DA neurons.Nav12 style Activation and inactivation parameters DERIVED FROM MIGLIORE ENDCOMMENT NEURON { THREADSAFE SUFFIX Na12 USEION na READ ena WRITE ina RANGE gbar, g, i RANGE atau, btau RANGE ainf, binf } UNITS { (pS) =(picosiemens) (mV) = (millivolt) (mA) = (milliamp) } PARAMETER { gbar = 50 (pS/microm2) Vmid_ac = -28(mV) : actually corresponds to -20 mV because the m^3 model is rightward shifted k_ac = 7.7(mV) : corresponds to 7 k_ina = -10 (mV) Vmid_ina = -50 (mV) m=3 h=1 : gate parameters according to the HH formalism (m*m*m*h) celsius = 32 (degC) q10=1.5 } ASSIGNED { v (mV) ina (mA/cm2) i (mA/cm2) g (pS/microm2) atau (ms) btau (ms) ainf (1) binf (1) ena (mV) } STATE {a b} BREAKPOINT { SOLVE states METHOD cnexp g = (gbar*(a^m)*(b^h)) i = (0.0001)*g*(v-ena) ina = i } INITIAL { rates(v) a= ainf b=binf } DERIVATIVE states { rates(v) a' = (ainf-a)/atau b' = (binf-b)/btau } FUNCTION a_inf (V (mV)) () { a_inf = 1/(1+exp(-(V-Vmid_ac)/k_ac)) : activation system (a*a*a) } FUNCTION b_inf (V (mV)) () { b_inf = 1/(1+exp(-(V-Vmid_ina)/k_ina)) : inactivation system (b) } FUNCTION a_tau (V (mV)) (ms) { UNITSOFF a_tau= 0.01+(0.33/(1+((V+20)/30)^2)) : time constant of activation depends on V UNITSON } FUNCTION b_tau (V (mV)) (ms) { UNITSOFF b_tau = 0.7+(16/(1+((V+50)/8)^2)) : fast inactivation UNITSON } PROCEDURE rates(V (mV)) { LOCAL qt UNITSOFF qt=q10^((celsius-24)/10) UNITSON atau=a_tau(V)/qt ainf=a_inf(V) btau=b_tau(V)/qt binf=b_inf(V) }