Bistability in cerebellar Purkinje cell dendrites modelled with high-threshold calcium and delayed-rectifier potassium channels |
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Authors: | G L Yuen P E Hockberger J C Houk |
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Institution: | (1) Department of Physiology, Northwestern University Medical Center, Chicago, IL 60611, USA, US |
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Abstract: | Phase-plane analysis of the ionic currents underlying dendritic plateau potentials was carried out to study the nonlinear
dynamics and steady-state transfer properties of the dendritic tree in cerebellar Purkinje cells. The results of an analysis
of the P-type calcium and delayed rectifier potassium channel system are presented in this study. These channels constitute
a simple system that can support bistability and plateau potentials. By requiring both the steady-state current-voltage curve
and nullclines to mimic basic plateau potential properties, we obtained well-defined ranges of specific conductance that can
support bistability. Hysteresis was found to be surprisingly prevalent in this simple ion-channel system. Using the steady-state
current voltage relationship, we derive concise, algebraic expressions for the voltage and current thresholds of state transitions
as functions of specific conductance. The significance of bistability in this ion-channel system is discussed with respect
to the generation of plateau potentials in Purkinje cells dendrites and the role of the cerebellum in motor control.
Received: 13 October 1993/Accepted in revised form: 21 March 1995 |
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