興奮現象の一模型

概要

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Giant transitory excitation, as is familiar in nerve impulse propagation, is derived from a simple thermokinetic model. Excitations of all-or-none type, the graded type, and also the repetitive pulsing have been derived from a single model depending on the value of control parameter. The temperature, or the concentration of enetgy is included as an independent reference variable which is affected by the reaction heat. The rate of reaction is affected in turn by the temperature through Arrhenius formula. The strong nonlinearity involved in the Arrhenius formula leads to a multiple steady state which is connected with the existence of a threshold for the excitation. The dynamic large excursion along an almost closed path in phase space is related to the existence of a nearby limit cycle, which is generated by an inverted bifurcation. Thus the interplay of the soft-and hard-mode instabilities is shown to form the background of the giant transitory excitation.<BR>The transition into repetitive pulsing is also investigated from the point of view of fluctuation which reflects the difference between normal and inverted bifurcation.
日本生物物理学会の論文