  Influence of mesoscopic channel noise on excitable dynamics of living cells
became a hot subject within the last decade, and the traditional biophysical
models of neuronal dynamics such as Hodgkin-Huxley model have been generalized
to incorporate such effects. There still exists but a controversy on how to do
it in a proper and computationally efficient way. Here we introduce an improved
Langevin description of stochastic Hodgkin-Huxley dynamics with natural
boundary conditions for gating variables. It consistently describes the channel
noise variance in a good agreement with discrete state model. Moreover, we show
by comparison with our improved Langevin model that two earlier Langevin models
by Fox and Lu also work excellently starting from several hundreds of ion
channels upon imposing numerically reflecting boundary conditions for gating
variables.
