| Transient process of cortical activity during Necker cube perception: from local clusters to global synchrony. | |
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MedLine Citation:
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PMID: 20522268 Owner: NLM Status: PubMed-not-MEDLINE |
Abstract/OtherAbstract:
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BACKGROUND: It has been discussed that neural phase-synchrony across distant cortical areas (or global phase-synchrony) was correlated with various aspects of consciousness. The generating process of the synchrony, however, remains largely unknown. As a first step, we investigate transient process of global phase-synchrony, focusing on phase-synchronized clusters. We hypothesize that the phase-synchronized clusters are dynamically organized before global synchrony and clustering patterns depend on perceptual conditions. METHODS: In an EEG study, Kitajo reported that phase-synchrony across distant cortical areas was selectively enhanced by top-down attention around 4 Hz in Necker cube perception. Here, we further analyzed the phase-synchronized clusters using hierarchical clustering which sequentially binds up the nearest electrodes based on similarity of phase locking between the cortical signals. First, we classified dominant components of the phase-synchronized clusters over time. We then investigated how the phase-synchronized clusters change with time, focusing on their size and spatial structure. RESULTS: Phase-locked clusters organized a stable spatial pattern common to the perceptual conditions. In addition, the phase-locked clusters were modulated transiently depending on the perceptual conditions and the time from the perceptual switch. When top-down attention succeeded in switching perception as subjects intended, independent clusters at frontal and occipital areas grew to connect with each other around the time of the perceptual switch. However, the clusters in the occipital and left parietal areas remained divided when top-down attention failed in switching perception. When no primary biases exist, the cluster in the occipital area grew to its maximum at the time of the perceptual switch within the occipital area. CONCLUSIONS: Our study confirmed the existence of stable phase-synchronized clusters. Furthermore, these clusters were transiently connected with each other. The connecting pattern depended on subjects' internal states. These results suggest that subjects' attentional states are associated with distinct spatio-temporal patterns of the phase-locked clusters. |
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Authors:
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Daisuke Shimaoka; Keiichi Kitajo; Kunihiko Kaneko; Yoko Yamaguchi |
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Publication Detail:
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Type: Journal Article Date: 2010-06-03 |
Journal Detail:
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Title: Nonlinear biomedical physics Volume: 4 Suppl 1 ISSN: 1753-4631 ISO Abbreviation: Nonlinear Biomed Phys Publication Date: 2010 |
Date Detail:
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Created Date: 2010-06-04 Completed Date: 2011-07-14 Revised Date: 2011-10-24 |
Medline Journal Info:
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Nlm Unique ID: 101303143 Medline TA: Nonlinear Biomed Phys Country: United States |
Other Details:
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Languages: eng Pagination: S7 Citation Subset: - |
Affiliation:
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Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan. shimaoka@complex.c.u-tokyo.ac.jp. |
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