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Cerebral Cortex Advance Access published online on July 13, 2009
Cerebral Cortex, doi:10.1093/cercor/bhp107
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© 2009 The Authors
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Duration of Coherence Intervals in Electrical Brain Activity in Perceptual Organization

Andrey R. Nikolaev1,2, Sergei Gepshtein1,3, Pulin Gong1,4 and Cees van Leeuwen1

1 Laboratory for Perceptual Dynamics, RIKEN Brain Science Institute, Wako-shi 351-0198, Japan, 2 Laboratory for Human Higher Nervous Activity, Institute of Higher Nervous Activity, Moscow 117485, Russia, 3 Vision Center Laboratory, Salk Institute for Biological Studies, La Jolla, CA 92037, USA, 4 School of Physics and Faculty of Medicine, University of Sydney, Sydney, NSW 2006, Australia

Address correspondence to Andrey R. Nikolaev. Email: nikolaev{at}brain.riken.jp.

We investigated the relationship between visual experience and temporal intervals of synchronized brain activity. Using high-density scalp electroencephalography, we examined how synchronized activity depends on visual stimulus information and on individual observer sensitivity. In a perceptual grouping task, we varied the ambiguity of visual stimuli and estimated observer sensitivity to this variation. We found that durations of synchronized activity in the beta frequency band were associated with both stimulus ambiguity and sensitivity: the lower the stimulus ambiguity and the higher individual observer sensitivity the longer were the episodes of synchronized activity. Durations of synchronized activity intervals followed an extreme value distribution, indicating that they were limited by the slowest mechanism among the multiple neural mechanisms engaged in the perceptual task. Because the degree of stimulus ambiguity is (inversely) related to the amount of stimulus information, the durations of synchronous episodes reflect the amount of stimulus information processed in the task. We therefore interpreted our results as evidence that the alternating episodes of desynchronized and synchronized electrical brain activity reflect, respectively, the processing of information within local regions and the transfer of information across regions.

Key Words: EEG • extreme value distribution • perceptual ambiguity • perceptual grouping • quasi-stable synchrony pattern


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