GENESIS: Documentation

De Schutter: Purkinje Cell Model

Figure 1:

Activation properties of the persistent Na⁺ (NaP, - - -, no inactivation) ionic conductance in the model. Seady-state activation vs. voltage are plotted at the left and the time constant of activation (τ_m) vs. voltage on the right (Note: Semilogarithmic scale).

Persistent Sodium Current

The persistent sodium (NaP) current is assumed to cause the plateau potentials in the soma described by [4]. The basis for the equations describing NaP current were single-electrode voltage-clamp recordings of NaP current in guinea pig hippocampal neurons [1]. These recordings provided steady-state activation data and we assumed the same number of gates as for the NaF channel [2]. Time constants for activation and deactivation and the threshold of activation for NaP current were obtained from [3]. Note: The NaP current activation follows a slope similar to that of NaF current activation, but with a lower threshold of activation.

References

[1] CR French, P Sah, KJ Buckett, , and PW Gage. A voltage-dependent persistent sodium current in mammalian hippocampal neurons. The Journal of General Physiology, 95:1139–1157, 1990.

[2] A Hodgkin and A Huxley. A quantitative description of membrane current and its application to conduction and excitation in nerve. Journal of Physiology (Lond.), 117:500–544, 1952.

[3] AR Kay, M Sugimori, and RR Llinás. Voltage clamp analysis of a persistent ttx-sensitive na current in cerebellar purkinje cells. Society for Neuroscience Abstracts, 16:182, 1990.

[4] RR Llinás and M Sugimori. Electrophysiological properties of in vitro Purkinje cell somata in mammalian cerebellar slices. Journal of Physiology (Lond.), 305:171–195, 1980.