Fig. 2.
The Langevin model for the phase dynamics, Eqs. 3 and 4, reveals discrete attractors and noise-induced transitions between them. (A) The deterministic component of the force F(ω,ϕ), in units cycles/s2. The black lines are attracting limit cycles corresponding to forward and backward crawling, and the white dashed lines mark boundaries for our analysis of trajectories that start within the forward attractor. (B) The noise strength σ(ω,ϕ), in units cycles/s3/2. (C) A sample of the trajectories resulting from Eqs. 3 and 4, illustrating transitions between attractors at positive and negative ω, corresponding to forward and backward crawling.