Multimodal regimes in a compartmental model of the dopamine neuron

We study chains of strongly electrically coupled relaxation oscillators modeling dopamine neurons. When individual oscillators are in the regime close to an Andronov-Hopf bifurcation (AHB), the coupled system exhibits a variety of oscillatory behavior. We show that the proximity of individual oscillators to the AHB has a significant impact on the system dynamics in a wide range of parameters. It manifests itself through a family of stable multimodal periodic solutions that are composed out of large-amplitude relaxation oscillations and small-amplitude oscillations. This family of solutions has a rich bifurcation structure. The waveform and the period vary greatly across the family. The structure and bifurcations of the stable periodic solutions of the coupled system are investigated using numerical and analytic techniques. (C) 2004 Elsevier B.V. All rights reserved.