TITLE Potassium D-Current for Cortical Neuron Axon COMMENT Model Reference: Foust, A.J., Yu, Y., Popovic, M., Zecevic, D. and McCormick, D.A., 2011. "Somatic membrane potential and Kv1 channels control spike repolarization in cortical axon collaterals and presynaptic boutons." Journal of Neuroscience, 31(43), pp.15490-15498. Implemented by John Fleming - john.fleming@ucdconnect.ie - 06/12/18 Edits: ENDCOMMENT UNITS { (mV) = (millivolt) (mA) = (milliamp) (S) = (siemens) } NEURON { SUFFIX cortical_axon_i_kd USEION k WRITE ik : Using k ion, treat the reversal potential as a parameter and write to ik so the total k current can be tracked RANGE g_Kd, i_Kd : Potassium current, specific conductance and equilibrium potential } PARAMETER { ek = -90 (mV) i_Kd = 0.0 (mA/cm2) : Parameter to record this current separately to total sodium current g_Kd = 0.6e-3 (S/cm2) tau_m = 1 (ms) tau_h = 1500 (ms) V_half_m = -43 (mV) V_half_h = -67 (mV) q_m = 8 q_h = 7.3 Q_s = 3.209 : Temperature rescaling - Q_10 = 2.3 => Q_s = (Q_10)^((37-23)/10) = 3.209 } ASSIGNED { v (mV) ik (mA/cm2) m_inf h_inf } STATE { m h } BREAKPOINT { SOLVE states METHOD cnexp ik = g_Kd*m*h*(v - ek) i_Kd = ik : Record i_Kv (just this potassium current) to check it is working } UNITSOFF INITIAL { settables(v) m = m_inf h = h_inf } DERIVATIVE states { settables(v) m' = (m_inf-m)/tau_m h' = (h_inf-h)/tau_h } PROCEDURE settables(v) { TABLE m_inf, h_inf FROM -100 TO 100 WITH 400 m_inf = 1-(1/(1+exp((v-V_half_m)/q_m))) h_inf = 1-(1/(1+exp((v-V_half_h)/q_h))) } UNITSON