27
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: found
      Is Open Access

      On the temporal organization of neuronal avalanches

      research-article

      Read this article at

      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Spontaneous activity of cortex in vitro and in vivo has been shown to organize as neuronal avalanches. Avalanches are cascades of neuronal activity that exhibit a power law in their size and duration distribution, typical features of balanced systems in a critical state. Recently it has been shown that the distribution of quiet times between consecutive avalanches in rat cortex slice cultures displays a non-monotonic behavior with a power law decay at short time scales. This behavior has been attributed to the slow alternation between up and down-states. Here we further characterize the avalanche process and investigate how the functional behavior of the quiet time distribution depends on the fine structure of avalanche sequences. By systematically removing smaller avalanches from the experimental time series we show that size and quiet times are correlated and highlight that avalanche occurrence exhibits the characteristic periodicity of θ and β/γ oscillations, which jointly emerge in most of the analyzed samples. Furthermore, our analysis indicates that smaller avalanches tend to be associated with faster β/γ oscillations, whereas larger ones are associated with slower θ and 1–2 Hz oscillations. In particular, large avalanches corresponding to θ cycles trigger cascades of smaller ones, which occur at β/γ frequency. This temporal structure follows closely the one of nested θ − β/γ oscillations. Finally we demonstrate that, because of the multiple time scales characterizing avalanche dynamics, the distributions of quiet times between avalanches larger than a certain size do not collapse onto a unique function when rescaled by the average occurrence rate. However, when considered separately in the up-state and in the down-state, these distributions are solely controlled by the respective average rate and two different unique function can be identified.

          Related collections

          Most cited references43

          • Record: found
          • Abstract: found
          • Article: not found

          The temporal structures and functional significance of scale-free brain activity.

          Scale-free dynamics, with a power spectrum following P proportional to f(-beta), are an intrinsic feature of many complex processes in nature. In neural systems, scale-free activity is often neglected in electrophysiological research. Here, we investigate scale-free dynamics in human brain and show that it contains extensive nested frequencies, with the phase of lower frequencies modulating the amplitude of higher frequencies in an upward progression across the frequency spectrum. The functional significance of scale-free brain activity is indicated by task performance modulation and regional variation, with beta being larger in default network and visual cortex and smaller in hippocampus and cerebellum. The precise patterns of nested frequencies in the brain differ from other scale-free dynamics in nature, such as earth seismic waves and stock market fluctuations, suggesting system-specific generative mechanisms. Our findings reveal robust temporal structures and behavioral significance of scale-free brain activity and should motivate future study on its physiological mechanisms and cognitive implications. Copyright 2010 Elsevier Inc. All rights reserved.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Scale-free brain functional networks.

            Functional magnetic resonance imaging is used to extract functional networks connecting correlated human brain sites. Analysis of the resulting networks in different tasks shows that (a) the distribution of functional connections, and the probability of finding a link versus distance are both scale-free, (b) the characteristic path length is small and comparable with those of equivalent random networks, and (c) the clustering coefficient is orders of magnitude larger than those of equivalent random networks. All these properties, typical of scale-free small-world networks, reflect important functional information about brain states.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Spontaneous cortical activity in awake monkeys composed of neuronal avalanches.

              Spontaneous neuronal activity is an important property of the cerebral cortex but its spatiotemporal organization and dynamical framework remain poorly understood. Studies in reduced systems--tissue cultures, acute slices, and anesthetized rats--show that spontaneous activity forms characteristic clusters in space and time, called neuronal avalanches. Modeling studies suggest that networks with this property are poised at a critical state that optimizes input processing, information storage, and transfer, but the relevance of avalanches for fully functional cerebral systems has been controversial. Here we show that ongoing cortical synchronization in awake rhesus monkeys carries the signature of neuronal avalanches. Negative LFP deflections (nLFPs) correlate with neuronal spiking and increase in amplitude with increases in local population spike rate and synchrony. These nLFPs form neuronal avalanches that are scale-invariant in space and time and with respect to the threshold of nLFP detection. This dimension, threshold invariance, describes a fractal organization: smaller nLFPs are embedded in clusters of larger ones without destroying the spatial and temporal scale-invariance of the dynamics. These findings suggest an organization of ongoing cortical synchronization that is scale-invariant in its three fundamental dimensions--time, space, and local neuronal group size. Such scale-invariance has ontogenetic and phylogenetic implications because it allows large increases in network capacity without a fundamental reorganization of the system.
                Bookmark

                Author and article information

                Contributors
                Journal
                Front Syst Neurosci
                Front Syst Neurosci
                Front. Syst. Neurosci.
                Frontiers in Systems Neuroscience
                Frontiers Media S.A.
                1662-5137
                28 October 2014
                2014
                : 8
                : 204
                Affiliations
                [1] 1Institute of Computational Physics for Engineering Materials, ETH Zurich, Switzerland
                [2] 2Departamento de Física, Universitade Federal do Ceará Fortaleza, Brazil
                [3] 3Section on Critical Brain Dynamics, National Institute of Mental Health, National Institute of Health Bethesda, MD, USA
                [4] 4Department of Industrial and Information Engineering, Second University of Naples, National Institute for Nuclear Physics Gr. Coll. Salerno Aversa, Italy
                Author notes

                Edited by: Paolo Massobrio, University of Genova, Italy

                Reviewed by: James A. Roberts, Queensland Institute of Medical Research Berghofer Medical Research Institute, Australia; Leonardo Paulo Maia, Universidade de São Paulo, Brazil

                *Correspondence: Fabrizio Lombardi, Institute of Computational Physics for Engineering Materials, ETH, Schafmattstr. 6, Zürich, 8093, Switzerland e-mail: fabrizio.lombardi@ 123456ifb.baug.ethz.ch

                This article was submitted to the journal Frontiers in Systems Neuroscience.

                Article
                10.3389/fnsys.2014.00204
                4211381
                25389393
                da5fa581-9c46-4928-83b2-8106668812d0
                Copyright © 2014 Lombardi, Herrmann, Plenz and De Arcangelis.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

                History
                : 26 June 2014
                : 01 October 2014
                Page count
                Figures: 8, Tables: 0, Equations: 6, References: 49, Pages: 15, Words: 10481
                Categories
                Neuroscience
                Original Research Article

                Neurosciences
                neuronal avalanches,oscillations,rat cortex,waiting times,neuronal networks,criticality
                Neurosciences
                neuronal avalanches, oscillations, rat cortex, waiting times, neuronal networks, criticality

                Comments

                Comment on this article