Global bifurcations of multiple limit cycles in the FitzHugh-Nagumo   system
  In this paper, we complete the global qualitative analysis of the well-known FitzHugh-Nagumo neuronal model. In particular, studying global limit cycle bifurcations and applying the Wintner-Perko termination principle for multiple limit cycles, we prove that the corresponding dynamical system has at most two limit cycles. 
Valery A. Gaiko
math.DS