TITLE Delayer rectifier COMMENT ----------------------------------------------------------------------------- "delayer-rectifier" K current for action potentials --------------------------------------------------- - potassium current, voltage-dependent - iterative equations Model of IKd for hippocampal pyramidal cells, from Traub & Miles, Neuronal Networks of the Hippocampus, Cambridge, 1991 Added instantaneous conductance Written by Alain Destexhe, Laval University, 1996 ----------------------------------------------------------------------------- ENDCOMMENT INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} NEURON { SUFFIX ikdT USEION k READ ek WRITE ik RANGE gkbar, g, vtraub RANGE n_inf RANGE tau_n RANGE n_exp } UNITS { (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { gkbar = .005 (mho/cm2) vtraub = -55 (mV) : adjusts threshold ek = -90 (mV) celsius = 36 (degC) dt (ms) v (mV) } STATE { n } ASSIGNED { ik (mA/cm2) n_inf tau_n n_exp tadj g (mho/cm2) : instantaneous conductance } BREAKPOINT { SOLVE states g = gkbar * n*n*n*n ik = g * (v - ek) } :DERIVATIVE states { : evaluate_fct(v) : n' = (n_inf - n) / tau_n :} PROCEDURE states() { : exact when v held constant evaluate_fct(v) n = n + n_exp * (n_inf - n) } UNITSOFF INITIAL { : : Q10 was assumed to be 2.3 for both currents : : original measurements at room temperature tadj = 3.0 ^ ((celsius-36)/ 10 ) evaluate_fct(v) n = n_inf } PROCEDURE evaluate_fct(v(mV)) { LOCAL a,b,v2 v2 = v - vtraub : convert to traub convention a = 0.032 * (15-v2) / ( exp((15-v2)/5) - 1) b = 0.5 * exp((10-v2)/40) tau_n = 1 / (a + b) / tadj n_inf = a / (a + b) n_exp = 1 - exp(-dt/tau_n) } UNITSON