We present the Fokker-Planck equation for arbitrary nonlinear noise te
rms. The white noise limit is taken as the zero correlation time limit
of the Ornstein-Uhlenbeck process. The drift and diffusion coefficien
ts of the Fokker-Planck equation are given by triple integrals of the
fluctuations. We apply the Fokker-Planck equation to the active rotato
r model with a fluctuating potential barrier which depends nonlinearly
on an additive noise. We show that the nonlinearity may be transforme
d into the correlation of linear noise terms. (C) 1997 Published by El
sevier Science B.V.