Examinando por Autor "Almendral, J.A."

Mostrando 1 - 4 de 4

Regulating synchronous states of complex networks by pinning interaction with an external node
(Physical Review E, 2009-12-14) Almendral, J.A.; Sendiña-Nadal, I.; Yu, D.; Leyva, I.; Boccaletti, S.
An initial ensemble of networking dynamical systems is regulated towards a desired synchronized behavior by means of a pinning interaction with an external node. We rigorously demonstrate that there are two classes of networks susceptible of being regulated into a synchronous motion, and practically demonstrate, for each one of them, how to design a proper minimal, optimal, and maximal pinning sequence to achieve synchrony regulation. A series of numerical examples are offered to support our analytical claims. We also discuss how the obtained sequences can be compared with a topological ranking of the network nodes, such as centrality, and the practical applications of our study in the understanding of how networking systems can adjust their architecture in order to establish (or maintain) a synchronous functioning.
Self-organization and evolution of structure and function in cultured neuronal networks
(Elsevier, 2023) Ballesteros-Esteban, L.M.; Leyva, I.; Almendral, J.A.; Sendiña-Nadal, I.
Cultured neuronal networks (CNNs) have recently achieved major relevance as an alternative to in vivo models. While many works investigate the evolution of functional connectivity alone, experimental evidence of the simultaneous change of the structural neuronal network substrate is scarce. In the present study, we monitored the coevolution of structural and functional connectivities of neuronal cultures grown on top of microelectrode arrays, in a setup that allows the simultaneous recording of electrophysiological signals and microphotography detailed to the single-link level. During the observed 3 weeks lifespan, initially isolated invertebrate neurons form an ex novo complex circuitry of neuronal aggregates characterized by a small-world topology, with abundant neuronal loops (high clustering) and short distances. At the same time, the observation of synchronization events among electrodes reaches a maximum, coinciding with the spatial percolation of the neuronal network. At this stage, the correlation between the structural and the corresponding functional network is the largest, with around 15% of the physical links relating electrodes that fire synchronously. As the culture matures, this correlation smoothly declines but becomes more significant. Finally, at the local level, we found that the electrodes supporting the most coherent activity, the functional hubs, are not hubs in the physical circuitry but nodes with an average degree. This study demonstrates that functional networks of self-organized neuronal systems are discreet proxies of the underlying structure. It paves the way for future investigations to elucidate the intricate relationship between structure and function in other scenarios mediated by external stimulation.
Synchronization waves in geometric networks
(Physical Review E, 2011-12-06) Leyva, I.; Navas, A.; Sendiña-Nadal, I.; Buldú, J.M.; Almendral, J.A.; Boccaletti, S.
We report synchronization of networked excitable nodes embedded in a metric space, where the connectivity properties are mostly determined by the distance between units. Such a high clustered structure, combined with the lack of long-range connections, prevents full synchronization, and yields, instead, the emergence of synchronization waves. We show that this regime is optimal for information transmission through the system, as it enhances the options of reconstructing the topology from the dynamics. Measurements of topological and functional centralities reveal, indeed, that the wave synchronization state allows to detect the most structurally relevant nodes from a single observation of the dynamics, without any a-priori information on the model equations ruling the evolution of the ensemble.
The dynamics of overlapping structures in modular networks
(Physical Review E, 2010-07-23) Almendral, J.A.; Lyeva, I.; Li, D.; Sendiña-Nadal, I.; Havlin, S.; Boccaletti, S.
Modularity is a fundamental feature of real networks, being intimately bounded to their function- ality, i.e. to their capability of performing parallel tasks in a coordinated way. Although the modular structure of real graphs has been intensively studied, very little is known on the interactions be- tween functional modules of a graph. Here we present a general method based on synchronization of networking oscillators, that is able to detect overlapping structures in multi-modular environments. We furthermore report the full analytical and theoretical description on the relationship between the overlapping dynamics and the underlying network topology. The method is illustrated by means of a series of applications.