| We study the dynamics of the model for thermosensitive neurons originally developed by Huber and Braun [1] which mimics the response of a neuron to temperature changes. The mechanism of spike generation in this model is based on the introduction of slow repolarizing and depolarizing currents leading to subthreshold oscillations. Depending on several control parameters such as temperature, external current and the impact of subthreshold oscillations, the model exhibits a variety of different dynamical behaviours. The most prominent ones are tonic firing as well as regular and chaotic bursting. Variations of the control parameters lead to characteristic changes in the dynamics of the neuron, the most important one being the transition from tonic firing to bursting. We show that regardless of the control parameter considered, a homoclinic bifurcation which is related to extremely large interspike intervals appears to be connected with this transition. Our emphasis lies on the role of subthreshold oscillations leading to different dynamical characteristics of the tonic firing and bursting regimes, respectively. Moreover, the impact of the subthreshold oscillations can be measured in terms of their amplitude. In the absence of external currents, a decreasing amplitude finally yields a disappearance of spikes. Along this route, the neuron dynamics undergoes a series of systematic changes underlining that variations in the amplitude of subthreshold currents are of high physiological importance. We compare this scenario to the dynamics emerging from variations in temperature and incorporate the role of the leak current for the dynamics of the model. References: [1] C. Finke, J. Vollmer, S. Postnova and Braun, H.A. : Propagation effects of current and conductance noise in a model neuron with subthreshold oscillations, Mathematical Biosciences 214 (2008) 109-121 |
|