Examinando por Autor "Maidana, Jean Paul"

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    Ítem
    Chaos versus noise as drivers of multistability in neural networks
    (Chaos, 2018-10-18) Orio, Patricio; Gatica, Marilyn; Herzog, Rubén; Maidana, Jean Paul; Castro, Samy; Xu, Kesheng
    The multistable behavior of neural networks is actively being studied as a landmark of ongoing cerebral activity, reported in both functional Magnetic Resonance Imaging (fMRI) and electro- or magnetoencephalography recordings. This consists of a continuous jumping between different partially synchronized states in the absence of external stimuli. It is thought to be an important mechanism for dealing with sensory novelty and to allow for efficient coding of information in an ever-changing surrounding environment. Many advances have been made to understand how network topology, connection delays, and noise can contribute to building this dynamic. Little or no attention, however, has been paid to the difference between local chaotic and stochastic influences on the switching between different network states. Using a conductance-based neural model that can have chaotic dynamics, we showed that a network can show multistable dynamics in a certain range of global connectivity strength and under deterministic conditions. In the present work, we characterize the multistable dynamics when the networks are, in addition to chaotic, subject to ion channel stochasticity in the form of multiplicative (channel) or additive (current) noise. We calculate the Functional Connectivity Dynamics matrix by comparing the Functional Connectivity (FC) matrices that describe the pair-wise phase synchronization in a moving window fashion and performing clustering of FCs. Moderate noise can enhance the multistable behavior that is evoked by chaos, resulting in more heterogeneous synchronization patterns, while more intense noise abolishes multistability. In networks composed of nonchaotic nodes, some noise can induce multistability in an otherwise synchronized, nonchaotic network. Finally, we found the same results regardless of the multiplicative or additive nature of noise.
  • Miniatura
    Ítem
    Diversity of neuronal activity is provided by hybrid synapses
    (Springer, 2021) Xu, Kesheng; Maidana, Jean Paul; Orio, Patricio
    The coexistence of electrical and chemical synaptic communication among excitatory cells has been evidenced by neuroscientists. Nevertheless, theoretical understanding of hybrid synaptic connections in diverse dynamical states of neural networks for self-organization and robustness, still has not been fully studied. Here, we present a model of neural network that includes chemical excitatory coupling in a way of small-world topology and electrical synaptic coupling among adjacent excitatory cells for excitatory population. Firstly, we use this model to investigate the effect of electrical synaptic coupling among excitatory cells on global network behavior with the goal of theoretically understanding mechanisms of generating rich firing patterns. Secondly, we further study the emergence of various firing ripple events by considering the variation of chemical synaptic inhibition and other factors, such as network densities. We found that the excitatory population has a tendency to synchronization as the weights of electrical synaptic coupling among excitatory cells are increased. Moreover, the existence of these electrical synaptic connections can cause various firing patterns of interest by slightly changing the chemical synaptic weights. Our results pave a way in the study of the dynamical mechanisms and computational significance of the contribution of mixed synapse in the neural functions.