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ABSTRACT: We compared the responsiveness of a neural firing pacemaker in different dynamic states during the process of period-adding bifurcation to excitatory and inhibitory electrical field stimulus. In the region far from the bifurcation point, with the increase of the intensity of excitatory stimulus, the firing rate increased in an approximately linear manner and no firing pattern transition was observed. While in the region near the bifurcation point, the firing rate increased markedly higher accompanied with the transition of firing pattern when the intensity of excitatory stimulus remained the same. The stimulus-response of the region near the bifurcation point shifted upward significantly compared to that of the region far from the bifurcation point. Inhibitory stimulus with the same intensity, however, decreased the firing rate slightly without the transition of firing pattern in the region near the bifurcation point. These results suggest that the responsiveness in the region near the bifurcation point is more sensitive than that in the region far from the bifurcation point, which we named "critical sensitivity", and this has directional selectivity.
Neuroscience Letters 02/2006; 392(1-2):105-9. · 2.11 Impact Factor
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ABSTRACT: A specific bursting, parabolic bursting induced by veratridine, has been observed in rat injured sciatic nerve. With the help of Plant model, the biophysical mechanism for such a phenomenon is revealed from the viewpoint of nonlinear dynamical theory. The slow sodium influx educed by veratridine and the calcium-dependent potassium outflux are regarded as the two slow variables, which are responsible for the parabolic bursting. Furthermore, the roles that veratridine plays in the emergence of the parabolic bursting, namely inhibiting the inactivation of sodium channels and eliciting the slow sodium influx, are clarified.
Sheng wu hua xue yu sheng wu wu li xue bao Acta biochimica et biophysica Sinica 10/2003; 35(9):806-10.
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ABSTRACT: Firing patterns of injured nerve fibers were recorded using the single-fiber firing recording technique. Under the same background firing pattern, three types of bursting were induced separately by EGTA, veratridine or high [Ca(2+)](o) in the same type of nerve fibers. The results suggest that different firing patterns are related to different stimuli, which means that each firing pattern carries corresponding neural information.
Sheng li xue bao: [Acta physiologica Sinica] 09/2002; 54(4):329-32.
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ABSTRACT: Veratridine, a blocker of inactive gate of sodium channel, was used to perfuse L5 dorsal root ganglion (DRG) topically. Afferent activities of type A single fiber from these DRGs were recorded. It was found that after a 10-min bath of veratridine (1.8-3 micromol/L), some of the primary silent DRG neurons were triggered by touch or pressure on the receptive fields or by electrical stimulation of the sciatic nerve to produce high-frequency firing, which was termed triggered oscillation presenting a U-type of interspike intervals (ISI) or other types of oscillations. The longer the intervals between stimulating pulses, the more stimulating pulses were needed to trigger the oscillation. The oscillation, triggered by electric stimuli with different duration or patterns, had no significant difference in their patterns. The duration of the inhibitory period after a triggered oscillation was generally 30-90 s. It was also observed that this kind of triggered oscillation was induced by afferent pulses of the same neurons. These results suggest that triggered oscillation, which may contribute to the fit of triggered pain, can be produced in primary sensory neurons after application of veratridine.
Sheng li xue bao: [Acta physiologica Sinica] 07/2002; 54(3):208-12.
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ABSTRACT: Critical amplitude curves for different periodic stimuli and different dynamical mechanisms of excitability are investigated numerically in the Morris–Lecar model neuron. It has been considered as a universal phenomenon that critical amplitude curves exhibit U-shaped structures in the previous investigations. Nevertheless, we find that the critical amplitude relies on not only the type of a periodic stimulus but also the dynamical mechanism of excitability of a neuron. The dynamical mechanism of excitability determines whether a neuron is a resonator or integrator. There is a U-shaped structure in the critical amplitude curve for a resonator subjected to a sinusoidal stimulus or a periodic pulse stimulus. However, in high frequency range the critical amplitude increases monotonically with the stimulus frequency for a sinusoidal stimulus and decreases monotonically for a periodic pulse stimulus. In contrast, for an integrator, the critical amplitude versus the stimulus frequency is always a monotonic curve. The change in the critical amplitude curve is shown through the Morris–Lecar model.
Communications in Nonlinear Science and Numerical Simulation.
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ABSTRACT: An interesting phenomenon that aperiodic firing neurons have a higher sensitivity to drugs than periodic firing neurons have been reported for the chronically compressed dorsal root ganglion neurons in rats. In this study, the dynamical mechanisms for such a phenomenon are uncovered from the viewpoint of dynamical systems theory. We use the Rose–Hindmarsh neuron model to illustrate our opinions. Periodic orbit theory is introduced to characterize the dynamical behavior of aperiodic firing neurons. It is considered that bifurcations, crises and sensitive dependence of chaotic motions on control parameters can be the underlying mechanisms. And then, a similar analysis is applied to the modified Chay model describing the firing behavior of pancreatic beta cells. The same dynamical mechanisms can be obtained underlying that aperiodic firing cells are more sensitive to external stimulation than periodic firing ones. As a result, we conjecture that sensitive response of aperiodic firing cells to external stimulation is a universal property of excitable cells.
Chaos Solitons & Fractals 22(1):151-160. · 1.22 Impact Factor
