  We report relationships between the effects of noise and applied constant
currents on the behavior of a system of excitable elements. The analytical
approach based on the nonlinear Fokker-Planck equation of a mean-field model
allows us to study the effects of noise without approximations only by dealing
with deterministic nonlinear dynamics . We find the similarity, with respect to
the occurrence of oscillations involving subcritical Hopf bifurcations, between
the systems of an excitable element with applied constant currents and
mean-field coupled excitable elements with noise.
