On the role of subthreshold currents in the Huber–Braun cold receptor model

Abstract

We study the role of the strength of subthreshold currents in a four-dimensional Hodgkin-Huxley-type model of mammalian cold receptors. Since a total diminution of subthreshold activity corresponds to a decomposition of the model into a slow, subthreshold, and a fast, spiking subsystem, we first elucidate their respective dynamics separately and draw conclusions about their role for the generation of different spiking patterns. These results motivate a numerical bifurcation analysis of the effect of varying the strength of subthreshold currents, which is done by varying a suitable control parameter. We work out the key mechanisms which can be attributed to subthreshold activity and furthermore elucidate the dynamical backbone of different activity patterns generated by this model.

Temperature-dependent bursting pattern analysis by modified Plant model

“…In order to simulate various temperature-dependent spiking patterns of bursting pacemaker neuron, we set up nonlinear differential equations by modifying the Plant model [[15]] with temperature-dependent scaling factors [[25]-[27]]. The Plant model studied by Rinzel and Lee was designed to assess parabolic bursters by analyzing the fast and slow processes to show how spike activities were generated by their mutual interaction [[16]].…”

“…Different types of impulse patterns of mammalian cold receptors can be observed as a function of skin temperature: irregular and less frequent burst discharges, regular and frequent bursting patterns, and irregular single spike patterns are observed from low to high temperatures. These patterns could be simulated by Braun et al, and the Huber-Braun cold receptor model has been described in detail with 5 currents and 5 static variables (membrane potential and four voltage-dependent state-variables) [[26],[27],[31]-[36]]. This model consisted of two minimal sets of ionic conductances operating at different voltage levels with different delays and the leakage current.…”

A Computational Model of the Temperature-dependent Changes in Firing Patterns inAplysiaNeurons

“…Although the Huber-Braun cold receptor model [14,15] describes cold receptors well, proper biophysical model for warm receptors has not been searched. To set up nonlinear differential equations that could simulate all of these various spiking patterns together, it was necessary to modify the equations (Chay-Lee model) derived by Chay and Lee [6,7] with temperature-dependent scaling factors; we adapted the temperature-dependent scaling factors for the ionic currents, ρ(T), and for the ionic kinetics, φ(T), that are used in the Huber-Braun cold receptor model.…”

“…However, the effects of temperature changes on cold or warm receptors have been studied in various species, including cats [8,9], vampire bats and mice [10], snakes [11], rabbit [12], and human [13]. Although mammalian cold receptors are discussed in the Huber-Braun cold receptor model [14,15], it was not even able to find a proper biophysical model for warm receptors.…”

“…To set up nonlinear differential equations that can simulate all of these various spiking patterns together, it is necessary to modify the equations derived by Chay and Lee [6,7] with temperature-dependent scaling factors; we will adopt a temperature-dependent scaling factor for the ionic currents and ionic kinetics that are used in the Huber-Braun cold receptor model [14,15]. The cell membrane of this new model contains sodium, calcium, and potassium channels carrying a fast sodium current, I Na , fast calcium current, I Ca , and a potassium current, I K , respectively.…”