Rodriguez, E. et al. Perception's shadow: long-distance synchronization of human brain activity. Nature 397, 430-433
ABSTRACT Transient periods of synchronization of oscillating neuronal discharges in the frequency range 30-80 Hz (gamma oscillations) have been proposed to act as an integrative mechanism that may bring a widely distributed set of neurons together into a coherent ensemble that underlies a cognitive act. Results of several experiments in animals provide support for this idea. In humans, gamma oscillations have been described both on the scalp (measured by electroencephalography and magnetoencephalography) and in intracortical recordings, but no direct participation of synchrony in a cognitive task has been demonstrated so far. Here we record electrical brain activity from subjects who are viewing ambiguous visual stimuli (perceived either as faces or as meaningless shapes). We show for the first time, to our knowledge, that only face perception induces a long-distance pattern of synchronization, corresponding to the moment of perception itself and to the ensuing motor response. A period of strong desynchronization marks the transition between the moment of perception and the motor response. We suggest that this desynchronization reflects a process of active uncoupling of the underlying neural ensembles that is necessary to proceed from one cognitive state to another.
Full-textDOI: · Available from: Jacques Martinerie, Dec 25, 2013
- SourceAvailable from: Simone Sarasso
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- "High-frequency gamma oscillations are critical for communication among brain areas, thus allowing integration among cortical modules (Nikolic et al., 2013; Rodriguez et al., 1999; Whittington et al., 2000b). In the last decade clinical research on oscillatory brain dynamics reported altered neuronal oscillations in neuropsychiatric disorders (Basar, 2013; Basar and Guntekin, 2008; Herrmann and Demiralp, 2005; Uhlhaas and Singer, 2010), suggesting that reduced gamma oscillations could be common to bipolar disorder (BPD), major depressive disorder (MDD) and schizophrenia (SCZ) (Maharajh et al., 2007; O'Donnell et al., 2004b). "
ABSTRACT: Recent studies have demonstrated that cortical brain areas tend to oscillate at a specific natural frequency when directly perturbed by transcranial magnetic stimulation (TMS). Fast electroencephalographic (EEG) oscillations, which typically originate from frontal regions, have been reported to be markedly reduced in schizophrenia. Here we employed TMS/EEG to assess the natural frequency of the premotor area in a sample of 48 age-matched participants (12 each in major depression disorder (MDD)), bipolar disorder (BPD), schizophrenia (SCZ) and healthy controls. Event related spectral perturbations (ERSP) were obtained for each study participant using wavelet decomposition. TMS resulted in a significant activation of the beta/gamma band response (21-50Hz) to frontal cortical perturbation in healthy control subjects. By contrast, the main frequencies of frontal EEG responses to TMS were significantly reduced in patients with BPD, MDD and SCZ (11-27Hz) relative to healthy subjects. Patients with bipolar disorder, major depression and schizophrenia showed a significantly lower natural frequency of frontal cortico-thalamocortical circuits compared to healthy controls. These results suggest a common neurobiological mechanism of corticothalamic impairment. The most likely candidates include dysfunction of GABAergic circuits. Further studies are needed to consider other biological markers, gene variants, and their interaction with clinical variables. Copyright © 2015 Elsevier B.V. All rights reserved.Journal of Affective Disorders 06/2015; 184:111-115. DOI:10.1016/j.jad.2015.05.043 · 3.71 Impact Factor
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- "Significant changes in GBA based on task difficulty are also expected during the threestimulus oddball task. Inter-regional phase synchronization likely underlies the functional integration of the widely distributed neural assemblies in task-relevant cortical regions (Rodriguez et al., 1999; Varela et al., 2001). Recent EEG and MEG studies reported large-scale neural synchronies during an oddball task (Akimoto et al., 2013; Fujimoto et al., 2013; Maurits et al., 2006). "
ABSTRACT: The major purpose of this study was to explore the changes in the local/global gamma-band neural synchronies during target/non-target processing due to task difficulty under an auditory three-stimulus oddball paradigm. Multichannel event-related potentials (ERPs) were recorded from fifteen healthy participants during the oddball task. In addition to the conventional ERP analysis, we investigated the modulations in gamma-band activity (GBA) and inter-regional gamma-band phase synchrony (GBPS) for infrequent target and non-target processing due to task difficulty. The most notable finding was that the difficulty-related changes in inter-regional GBPS (33-35Hz) at P300 epoch (350-600ms) completely differed for target and non-target processing. As task difficulty increased, the GBPS significantly reduced for target processing but increased for non-target processing. This result contrasts with the local neural synchrony in gamma-bands, which was not affected by task difficulty. Another major finding was that the spatial patterns of functional connectivity were dissociated for target and non-target processing with regard to the difficult task. The spatial pattern for target processing was compatible with the top-down attention network, whereas that for the non-target corresponded to the bottom-up attention network. Overall, we found that the inter-regional gamma-band neural synchronies during target/non-target processing change significantly with task difficulty and that this change is dissociated between target and non-target processing. Our results indicate that large-scale neural synchrony is more relevant for the difference in information processing between target and non-target stimuli. Copyright © 2015. Published by Elsevier B.V.Brain Research 04/2015; 1603:114-123. DOI:10.1016/j.brainres.2015.01.031 · 2.83 Impact Factor
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- "An emergent property of this dynamical system is that a set of neurons synchronize and fire impulses simultaneously. Neuronal synchronization plays a vital role in mechanisms of information processing within different brain area   . It is also suggested that synchronization is the origin of neurological diseases such as epilepsy  and Parkinson's disease . "
ABSTRACT: Cluster synchronization and rhythm dynamics are studied for a complex neuronal network with the small world structure connected by chemical synapses. Cluster synchronization is considered as that in-phase burst synchronization occurs inside each group of the network but diversity may take place among different groups. It is found that both one-cluster and multi-cluster synchronization may exist for chemically excitatory coupled neuronal networks, however, only multi-cluster synchronization can be achieved for chemically inhibitory coupled neuronal networks. The rhythm dynamics of bursting neurons can be described by a quantitative characteristic, the width factor. We also study the effects of coupling schemes, the intrinsic property of neurons and the network topology on the rhythm dynamics of the small world neuronal network. It is shown that the short bursting type is robust with respect to the coupling strength and the coupling scheme. As for the network topology, more links can only change the type of long bursting neurons, and short bursting neurons are also robust to the link numbers.International Journal of Non-Linear Mechanics 04/2015; 70:112-118. DOI:10.1016/j.ijnonlinmec.2014.11.030 · 1.46 Impact Factor