TITLE IKv for horizontal cell : Delayed rectifying potassium current (IKv) for horizontal cells : : Based on parameters of Aoyama et al. (2000) INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} NEURON { SUFFIX HzIKv USEION k READ ek WRITE ik RANGE gbar RANGE m_inf, h_inf RANGE tau_m, tau_h RANGE m_exp, h_exp } UNITS { (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { gbar = 4.2453e-05 (mho/cm2) : 4.5 ns total } STATE { m h } ASSIGNED { v (mV) ek (mV) ik (mA/cm2) celsius (degC) dt (ms) m_inf h_inf tau_m tau_h m_exp h_exp tadj } BREAKPOINT { SOLVE states ik = gbar * m*m*m*m*h * (v - ek) } PROCEDURE states() { : exact when v held constant evaluate_fct(v) m = m + m_exp * (m_inf - m) h = h + h_exp * (h_inf - h) } UNITSOFF INITIAL { m = 0.139 h = 0.932 tadj = 3.0 ^ ((celsius-25)/10) : correction for physio temp } PROCEDURE evaluate_fct(v(mV)) { LOCAL a, b, v2 a = ( 0.4 * (65-v) ) / ( exp( (65-v)/50 ) - 1 ) b = 4.8 * exp( (45-v) / 85 ) tau_m = 1 / (a + b) / tadj m_inf = a / (a + b) a = 1500 / ( exp( (v+92)/7 ) + 1 ) b = 0.02 + ( 80 / ( exp( (v+100)/15 ) + 1) ) tau_h = 1 / (a + b) / tadj h_inf = a / (a + b) m_exp = 1 - exp(-dt/tau_m) h_exp = 1 - exp(-dt/tau_h) } UNITSON