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1.
We investigate the influence of noise on synchronization between the spiking activities of neurons with external impulsive forces. We first analyze the dependence of the synchronized firing on the amplitude and the angular frequency of the impulsive force in the noise-free system. Three cases (regular spiking, traveling wave, and chaotic spiking) with low synchronized firing are chosen to study effects due to noise. In each case we find that small noise can be a promoter of synchronization phenomena in neural activities, by choosing an appropriate noise intensity acting on some of the neurons. 相似文献
2.
We consider the dynamics of locally coupled calcium oscillation
systems, each cell is subjected to extracellular contaminated
signal, which contains common sub-threshold signal and independent
Gaussian noise. It is found that intermediate noise can enhance
synchronized oscillations of calcium ions, where the frequency
of noise-induced oscillations is matched with the one of
sub-threshold external signal. We show that synchronization is
enhanced as a result of the entrainment of external signal.
Furthermore, the effect of coupling strength is considered. We
find above-mentioned phenomenon exists only when coupling strength
is very small. Our findings may exhibit that noise can enhance the
detection of feeble external signal through the mechanism of
synchronization of intercellular calcium ions. 相似文献
3.
研究了在外界刺激电流的作用下,随机的长程关联对耦合的Hindmarsh-Rose神经元放电模式转变的影响.结果表明,当耦合强度较弱时,在神经元网络中加入一定数量的随机的长程关联,神经元的放电模式会从较少的周期态转变到较多的周期态;当耦合强度较强时,在神经元网络中加入一定数量的随机长程关联,神经元的放电模式会产生相反的转变,即从较多的周期态转变到较少的周期态.同时还简单讨论了神经系统的尺度大小和神经元之间的耦合强度,以及不同外界刺激条件下放电模式的强度与临界特性之间的关系. 相似文献
4.
We study the combined implications of connectivity and heterogeneous inputs on the synchronization features of a one-dimensional chain of diffusively coupled FitzHugh Nagumo (FHN) systems. The uncoupled systems are triggered into a regime of chaotic firing by periodic parametric forces modeling external stimuli. Due to the parameter dispersion involved in randomly distributed amplitudes and/or phases of the forces the units are nonidentical and the firing events on the chain of uncoupled units will be asynchronous leading to a distribution of the spiking times. Interest is focused on mutually synchronized spikings arising through the coupling where the connectivity of the network may range from nearest-neighbor interaction to global interactions. From our studies we conclude that increasing the interaction radius does not necessarily entail better spike synchrony and the coupling strength plays a more important role than connectivity. It is found that for driving with random amplitudes together with random phases a critical interaction radius exists beyond which firing becomes suppressed if the coupling between the units is too strong. In such cases of ‘firing death’ the units perform only small-amplitude oscillations which are mutually synchronous. The optimal coupling for spike synchrony is of intermediate strength and altering the connectivity does not really matter for the degree of spike synchrony. Distinct to that, when all the phases are equal and only the amplitudes of the forces are randomly distributed enhanced spike synchrony is achieved for sufficiently strong coupling regardless of the interaction radius. 相似文献
5.
D. Q. Wei X. S. Luo Y. L. Zou 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(2):279-282
We investigate how firing activity of complex neural
networks depends on the random long-range connections and coupling
strength. Network elements are described by excitable
space-clamped FitzHugh-Nagumo (SCFHN) neurons with the values of
parameters at which no firing activity occurs. It is found that
for a given appropriate coupling strength C, there exists a
critical fraction of random connections (or randomness) p*,
such that if p > p* the firing neurons, which are absent in the
nearest-neighbor network, occur. The firing activity becomes
more frequent as randomness p is
further increased. On the other hand, when the p is smaller,
there are no active neurons in network, no matter what the value
of C is. For a given larger p, there exist optimal coupling
strength levels, where firing activity reaches its maximum. To the
best of our knowledge, this is a novel mechanism for the emergence
of firing activity in neurons. 相似文献
6.
We study the effect of noise on the outer synchronization between two unidirectionally coupled complex networks and find analytically that outer synchronization could be achieved via white-noise-based coupling. It is also demonstrated that, if two networks have both conventional linear coupling and white-noise-based coupling, the critical deterministic coupling strength between two complex networks for synchronization transition decreases with an increase in the intensity of noise. We provide numerical results to illustrate the feasibility and effectiveness of the theoretical results. 相似文献
7.
We investigate how firing activity
of globally coupled neural network depends on the coupling strength C and system size N. Network elements are described by space-clamped FitzHugh-Nagumo (SCFHN) neurons with the values
of parameters at which no firing activity occurs. It is found that for a given appropriate coupling strength, there is an intermediate range of system size where the firing activity of
globally coupled SCFHN neural network is induced and enhanced. On the other hand, for a given intermediate system size level, there exists an optimal value of coupling strength such that the intensity of firing activity reaches its maximum. These phenomena
imply that the coupling strength and system size play a vital role
in firing activity of neural network. 相似文献
8.
The dynamics of coupled excitable FitzHugh Nagumo systems under external noisy driving is studied. Different from most of previous work focusing on the noise-induced regularity in the framework of coherence resonance, here the average frequency (or firing rate) of coupled excitable elements is of much more concern. We find that (i) their frequencies first increase and then decrease with the increase of the coupling, and there is a clear crossover from a rush increase to a smooth increase with the increase of noise strength, and (ii) for nonidentical cases, all elements transit to an identical frequency simultaneously only after a certain coupling strength is achieved. These first-increase-thendecrease non-monotonic frequency behavior and isochronous frequency synchronization are believed to be two basic behaviors in coupled noisy excitable systems. 相似文献
9.
By the method of the stochastic energetics, we investigate the stochastic resonance (SR) phenomenon of an overdamped Brown particle in an asymmetric bistable potential, driven by external periodical signal and multiplicative noise. The expressions have been obtained for the
quasi-steady-state probability distribution function. It is found that the input energy (IE) pumped into the system by the external driving shows an
SR-like behavior as a function of the noise strength, whereas the IE turns
to be a monotonic function of the correlation time of the noise. The effect of potential asymmetry is also studied on SR and IE. 相似文献
10.
J M Kates 《The Journal of the Acoustical Society of America》1985,77(4):1529-1534
In this paper we describe a monaural auditory signal-processing model for the perception of coloration. The model gives a central spectrum display of a stationary input signal. The central spectrum level for a nerve fiber tuned to a given frequency is computed as a combination of the average firing rate and the firing synchronized to the center frequency of the nerve. The model incorporates a critical-band filter bank, steady-state representations of the average and synchronized firing rates, and temporal integration. The central spectrum model, when used to process simulated data, accurately predicts the perception of coloration in filtered Gaussian noise. 相似文献
11.
12.
We investigate a system of coupled phase oscillators with nearest neighbors coupling in a chain with fixed ends. We find that the system synchronizes to a common value of the time-averaged frequency, which depends on the initial phases of the oscillators at the ends of the chain. This time-averaged frequency decays as the coupling strength increases. Near the transition to the frozen state, the time-averaged frequency has a power law behavior as a function of the coupling strength, with synchronized time-averaged frequency equal to zero. Associated with this power law, there is an increase in phases of each oscillator with 2pi jumps with a scaling law of the elapsed time between jumps. During the interval between the full frequency synchronization and the transition to the frozen state, the maximum Lyapunov exponent indicates quasiperiodicity. Time series analysis of the oscillators frequency shows this quasiperiodicity, as the coupling strength increases. 相似文献
13.
The influence of a weight-dependent spike-timing dependent plasticity (STDP) rule on the temporal evolution and equilibrium
state of a certain synapse is investigated. We show that under certain conditions, a spike-induced rate-learning scheme could
be achieved. Through studying the situation when a single Hodgkin-Huxley neuron is driven by a large ensemble of input neurons,
we find that synchronized firing of a sub population of input neurons may be important to information processing in the nervous
system. Using simulations, we show that the temporal structure of the spike trains of these synchronized input neurons can
be transmitted reliably; further, synapses from these neurons will increase stably due to the STDP rule and this may provide
a mechanism for learning and information storage in biologically plausible network models.
Received 12 September 2002 / Received in final form 12 December 2002 Published online 14 February 2003
RID="a"
ID="a"e-mail: huang_yue@netease.com 相似文献
14.
A chaotic synchronized system of two coupled skew tent maps is discussed in this paper. The locally and globally riddled basins of the chaotic synchronized attractor are studied. It is found that there is a novel phenomenon in the local-global riddling bifurcation of the attractive basin of the chaotic synchronized attractor in some specific coupling intervals. The coupling parameter corresponding to the locally riddled basin has a single value which is embedded in the coupling parameter interval corresponding to the globally riddled basin, just like a breakpoint. Also, there is no relation between this phenomenon and the form of the chaotic synchronized attractor. This phenomenon is found analytically. We also try to explain it in a physical sense. It may be that the chaotic synchronized attractor is in the critical state, as it is infinitely close to the boundary of its attractive basin. We conjecture that this isolated critical value phenomenon will be common in a system with a chaotic attractor in the critical state, in spite of the system being discrete or differential. 相似文献
15.
We study pairs of identical coupled chaotic oscillators. In particular, we have used Roessler (in the funnel and no funnel regimes), Lorenz, and four-dimensional chaotic Lotka-Volterra models. In all four of these cases, a pair of identical oscillators is asymmetrically coupled. The main result of the numerical simulations is that in all cases, specific values of coupling strength and asymmetry exist that render the two oscillators periodic and synchronized. The values of the coupling strength for which this phenomenon occurs is well below the previously known value for complete synchronization. We have found that this behavior exists for all the chaotic oscillators that we have used in the analysis. We postulate that this behavior is presumably generic to all chaotic oscillators. In order to complete the study, we have tested the robustness of this phenomenon of chaos suppression versus the addition of some Gaussian noise. We found that chaos suppression is robust for the addition of finite noise level. Finally, we propose some extension to this research. 相似文献
16.
Taylor AF Kapetanopoulos P Whitaker BJ Toth R Bull L Tinsley MR 《Physical review letters》2008,100(21):214101
We experimentally investigate the transition to synchronization in a population of photochemical oscillators with weak global coupling. Above a critical coupling strength the oscillators join a one-phase group or two-phase clusters. The number of oscillators in each cluster depends on the initial phase distribution, and irregular switching of oscillators between clusters is observed. The fully synchronized state emerges above a second critical coupling strength. In agreement with earlier theory, the experiments demonstrate the importance of population heterogeneity in cluster multistability. 相似文献
17.
We present the phase-locking and coherence properties between two weakly coupled lasers. We show how the degree of coherence between the two lasers can be enhanced by nearly 1 order of magnitude after taking into account the effects of coupling on both their phases as well as their amplitudes. Specifically, correlations between synchronized spikes in the amplitude dynamics and the phase dynamics of the lasers allow for an interference pattern with a fringe visibility of 90%, even when the coupling strength is far below the critical value and they are not phase locked. 相似文献
18.
We study synchronization as a means of control of collective behavior of an ensemble of coupled stochastic units in which oscillations are induced merely by external noise. For a large number of one-dimensional continuous stochastic elements coupled non-homogeneously through the mean field with delay we developed an approach to find a boundary of synchronization domain and the frequency of the mean-field oscillations on it. Namely, the exact location of the synchronization threshold is shown to be a solution of the boundary value problem (BVP) which was derived from the linearized Fokker-Planck equation. Here the synchronization threshold is found by solving this BVP numerically. Approximate analytics is obtained by expanding the solution of the linearized Fokker-Planck equation into a series of eigenfunctions of the stationary Fokker-Planck operator. Bistable systems with a polynomial and piece-wise linear potential are considered as examples. Multistability and hysteresis in the mean-field behavior are observed in the stochastic network at finite noise intensities. In the limit of small noise intensities the critical coupling strength is shown to remain finite, provided that the delay in the coupling function is not infinitely small. Delay in the coupling term can be used as a control parameter that manipulates the location of the synchronization threshold. 相似文献
19.
20.
We demonstrate the effect of coherence resonance in a heterogeneous array of coupled Fitz Hugh-Nagumo neurons. It is shown that coupling of such elements leads to a significantly stronger coherence compared to that of a single element. We report nontrivial effects of parameter heterogeneity and spatial independence of noise on array-enhanced coherence resonance; especially, we find that (i) the coherence increases as spatial correlation of the noise decreases, and (ii) inhomogeneity in the parameters of the array enhances the coherence. Our results have the implication that generic heterogeneity and background noise can play a constructive role to enhance the time precision of firing in neural systems. 相似文献