TITLE I-h channel from Magee 1998 : Modified to make it slower according to SfN 2006 Poster 342.23. : The peak activation time constant of Ih is around 100ms, around : twice slower than that at CA1. And vhalf is around -89 mV, which : is similar to what one sees in CA1 dendrites UNITS { (mA) = (milliamp) (mV) = (millivolt) } PARAMETER { v (mV) ehd (mV) celsius (degC) ghdbar=.0001 (mho/cm2) vhalfl=-89 (mV) kl=-8 vhalft=-75 (mV) a0t=0.005 (/ms) :original 0.011 zetat=2.2 (1) gmt=.4 (1) q10=4.5 qtl=1 } NEURON { SUFFIX hd NONSPECIFIC_CURRENT i RANGE ghdbar, vhalfl GLOBAL linf,taul } STATE { l } ASSIGNED { i (mA/cm2) linf taul ghd } INITIAL { rate(v) l=linf } BREAKPOINT { SOLVE states METHOD cnexp ghd = ghdbar*l i = ghd*(v-ehd) } FUNCTION alpt(v(mV)) { alpt = exp(0.0378*zetat*(v-vhalft)) } FUNCTION bett(v(mV)) { bett = exp(0.0378*zetat*gmt*(v-vhalft)) } DERIVATIVE states { : exact when v held constant; integrates over dt step rate(v) l' = (linf - l)/taul } PROCEDURE rate(v (mV)) { :callable from hoc LOCAL a,qt qt=q10^((celsius-33)/10) a = alpt(v) linf = 1/(1 + exp(-(v-vhalfl)/kl)) : linf = 1/(1+ alpl(v)) taul = bett(v)/(qtl*qt*a0t*(1+a)) }