Optimal intracellular calcium signaling

In many cell types, calcium is released from internal stores through calcium release channels upon external stimulation (e.g., pressure or receptor binding), These channels are clustered with a typical cluster size of about 20 channels, generating stochastic calcium puffs, We find that the clustering of the release channels in small clusters increases the sensitivity of the calcium response, allowing for coherent calcium responses at signals to which homogeneously distributed channels would not respond

Entropically enhanced excitability in small systems

We consider the dynamics of small excitable systems, ubiquitous in physics, chemistry, and biology. Spontaneous excitation rates induced by system-size fluctuations exhibit sharp maxima at multiple, small system sizes at which also the system's response to external perturbations is strongly enhanced. This novel effect is traced back to algebraic features of small integers and thus generic

Neuronal modeling with intracellular calcium signaling

【中文摘要】 细胞溶质内的游离钙离子在许多细胞活动中发挥着重要的作用。对于神经元,细胞膜上的神经电信号和胞内钙离子化学信号之间有着复杂的相互作用,每个神经元都可看作为一个含有细胞膜和内质网膜的双膜系统,而神经细胞的内质网则可视为神经元内的神经元。本综述探讨了神经元膜上神经电信号与内质网钙通道释放的胞内钙信号相耦合的动力学模型。我们认为,计算神经动力学的一个研究方向是考虑包含胞内钙动力学的神经元模拟,而且该研究前沿转向考虑胞内钙波扩散运动的空间神经元模型。包含内质网钙动力学的神经模型,尤其是考虑胞体和树突内钙扩散的空间神经元模型,将加深我们对神经动力学的认识。 【英文摘要】 Cytosolic Ca2+ ions play an important role in the regulation of numerous aspects of cellular activity in virtually all cell types. There is a complex interaction between the neuronal electrical signals on plasma membrane and the chemical signals of intracellular calcium. Each neuron can be considered as a binary membrane system with plasma membrane and endoplasmic reticulum membrane, and the neuronal endoplasmic reticulum can be regarded as a neuron-within-a-neuron. This review explores the simulation model...supported by the National Natural Science Foundation of China (No. 30970970

Simple approach to the creation of a strange nonchaotic attractor in any chaotic system

A simple approach to the creation of a strange nonchaotic attractor in any chaotic system is described. The main idea is to control the parameter of the system in such a manner that the system dynamics is expanding at some times, but converging at others. With this approach, a strange nonchaotic attractor can be found in a large region in the parameter space near the boundaries between chaotic and regular phases or within the chaotic region far from the regular one. The maximum nontrivial Lyapunov exponent of the system can pass through zero nonsmoothly and cannot be fitted by a linear function. [S1063-651X(99)13805-4]

Reply to"Comment on 'Simple approach to the creation of a strange nonchaotic attractor in any chaotic system' "

We have recently proposed a simple method to create a strange nonchaotic attractor with any chaotic system [Phys. Rev. E 59, 5338 (1999)]. Such a system is controlled to switch periodically between a chaotic and a quasiperiodic attractor, each with an appropriate time duration. A topological condition for this approach is pointed out in the preceding Comment by Neumann and Pikovsky [Phys. Rev. E 64, 058201 (2001)]. We show that this, condition is not necessary if the durations are sufficiently long. Our approach is a general method to construct a strange nonchaotic attractor in any chaotic system

Selection of intracellular calcium patterns in a model with clustered Ca2+ release channels

A two-dimensional model is proposed for intracellular Ca2+ waves, which incorporates both the discrete nature of Ca2+ release sites in the endoplasmic reticulum membrane and the stochastic dynamics of the clustered inositol 1,4,5-triphosphate (IP3) receptors. Depending on the Ca2+ diffusion coefficient and concentration of IP3, various spontaneous Ca2+ patterns, such as calcium puffs, local waves, abortive waves, global oscillation, and tide waves, can be observed. We further investigate the speed of the global waves as a function of the IP3 concentration and the Ca2+ diffusion coefficient and under what conditions the spatially averaged Ca2+ response can be described by a simple set of ordinary differential equations

Sub-threshold Ca2+ waves

In this paper we consider a model for intracellular Ca2+ waves where the ion channels ( excitability) is distributed in spatially distinct clusters. We report that channel noise in conjunction with spatial clustering can result in the onset of spatially and temporally extremely coherent Ca2+ signals at levels of stimulant well below the threshold of Ca2+ oscillations for homogeneously distributed channels. The physiological significance of this phenomenon is strongly enhanced cellular Ca2+-signalling capability with few agonist molecules binding

软物质体系动力学特性及生物体系物质与信号的传输

简要介绍理论物理研究所在软物质领域包括在聚合物刷、蛋白质扩散动力学、复杂流体的相分离方面的研究进展,以及在生物物理方面包括细胞内钙信号和艾滋病免疫系统动力学的研究进展,显示了在软物质及生物物理领域中非线性、多尺度、涨落、熵驱动的重要特征

Intercellular calcium waves in glial cells with bistable dynamics

Ministry of Education of China [108075]; National Science Foundation of China [10775114, 30970970]A two-dimensional model is proposed for intercellular calcium (Ca(2+)) waves with Ca(2+)-induced IP(3) regeneration and the diffusion of IP(3) through gap junctions. Many experimental observations in glial cells, i.e. responding to local mechanical stimulation, glutamate application, mechanical stimulation followed by ACh application, and glutamate followed by mechanical stimulation, are reproduced and classified by the model. We show that a glial cell model with bistable dynamics, i.e. a Ca(2+) oscillation state coexisting with a fixed point, can cause a prolonged plateau of Ca(2+) signals in the cells nearby the stimulated cell when the cell network responds to the local mechanical stimulation