Tessone C J, Scirè A, Toral R, Colet P
Institut Mediterrani d'Estudis Avançats, IMEDEA (CSIC-UIB), Campus Universitat Illes Balears, E-07122 Palma de Mallorca, Spain.
Phys Rev E Stat Nonlin Soft Matter Phys. 2007 Jan;75(1 Pt 2):016203. doi: 10.1103/PhysRevE.75.016203. Epub 2007 Jan 9.
Large variety of physical, chemical, and biological systems show excitable behavior, characterized by a nonlinear response under external perturbations: only perturbations exceeding a threshold induce a full system response (firing). It has been reported that in coupled excitable identical systems noise may induce the simultaneous firing of a macroscopic fraction of units. However, a comprehensive understanding of the role of noise and that of natural diversity present in realistic systems is still lacking. Here we develop a theory for the emergence of collective firings in nonidentical excitable systems subject to noise. Three different dynamical regimes arise: subthreshold motion, where all elements remain confined near the fixed point; coherent pulsations, where a macroscopic fraction fire simultaneously; and incoherent pulsations, where units fire in a disordered fashion. We also show that the mechanism for collective firing is generic: it arises from degradation of entrainment originated either by noise or by diversity.
各种各样的物理、化学和生物系统都表现出可激发行为，其特征是在外部扰动下呈现非线性响应：只有超过阈值的扰动才会引发整个系统的响应（激发）。据报道，在耦合的相同可激发系统中，噪声可能会导致宏观比例的单元同时激发。然而，对于噪声的作用以及现实系统中存在的自然多样性的作用，仍缺乏全面的理解。在此，我们针对受噪声影响的非相同可激发系统中集体激发的出现发展了一种理论。出现了三种不同的动力学状态：亚阈值运动，此时所有元素都保持在固定点附近；相干脉动，此时宏观比例的元素同时激发；以及非相干脉动，此时单元以无序方式激发。我们还表明，集体激发的机制是普遍存在的：它源于由噪声或多样性引起的同步性的退化。
