Two Nerve Discharge Rhythm, Generated By The Three-state Transition Mechanism

An experimental pacemaker of CCI model was widely used in researches of neural firing rhythm and bifurcation. Series of firing rhythms are found in the experimental pacemaker by now, and the dynamical mechanism of the spontaneous neural firing is discovered by nonlinear dynamics method. Researchers pay attention to the role of noise in system signal output by Application of stochastic resonance phenomenon and theory. Stochastic resonance phenomenon also exists in neuron system, so noise could participate in neuron system. Researches of neural firing rhythm and the role of noise in neural system are very important. The regulation of stochastic rhythms and the mechanism of stochastic rhythms is a significant research subject. This article shows two types of unfamiliar neural firing rhythms composed of three patterns observed in an experimental neural pacemaker model, then use nonlinear dynamics method to find the mechanism of those rhythms.Main results of this article are as follows:1. Two types of neural firing rhythms composed of three patterns were observed in an experimental neural pacemaker model. The behavior of such rhythms were dynamic transitions among quiescence, period m burst and period m+1 burst (m=1,2).2. Two types of period-adding bifurcations can be found in deterministic Chay model. The behavior of such period-adding bifurcations were the bifurcation points form quiescence to bursting and form period m bursting to period m+1 bursting are very close. When vc ranged in a very small area there are three different states.3. When adding noise (D=0.005) in above-mentioned period-adding bifurcation in stochastic Chay model we could simulate two types of firing rhythms familiar with experiment found. These firing rhythms are generated by noise-induced dynamic transition between three states separated by two bifurcation points quite nearly.4. The exists of noise is very important. The mathematic simulation results show that neural system transitions among three states in presence of noise.5. The mathematic simulation results show that different noise density has different effect on neural firing rhythms. In the same period-adding bifurcation and the same vc area, neural firing rhythms composed of three patterns while noise density is D=0.005, but neural firing rhythms composed of two patterns while noise density is D=0.001.