TITLE Hyperpolarization-activated cation current : Implemented in Rubin and Cleland (2006) J Neurophysiology : Adapted from Saraga et al (2003) J. Physiology UNITS { (mA) = (milliamp) (mV) = (millivolt) } NEURON { SUFFIX Ih USEION h READ eh WRITE ih VALENCE 1 RANGE gkhbar,ih GLOBAL rinf, rexp, tau_r } INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)} PARAMETER { v (mV) p = 5 (degC) dt (ms) gkhbar = 0.00 (mho/cm2) eh = -32.9 (mV) } STATE { r } ASSIGNED { ih (mA/cm2) rinf rexp tau_r } BREAKPOINT { SOLVE deriv METHOD derivimplicit ih = gkhbar*r*(v - eh) } INITIAL { rates(v) r = rinf } DERIVATIVE deriv { :Computes state variable h at current v and dt. rates(v) r' = (rinf - r)/tau_r } PROCEDURE rates(v) { :Computes rate and other constants at current v. :Call once from HOC to initialize inf at resting v. TABLE rinf, rexp, tau_r DEPEND dt, p FROM -200 TO 100 WITH 300 rinf = 1/(1 + exp((v+84.1)/10.2)) rexp = 1 - exp(-dt/(tau_r)) tau_r = 100 + 1/(exp(-17.9-0.116*v)+exp(-1.84+0.09*v)) } UNITSON