| The role of oscillatory brain activity in object processing and figure-ground segmentation in human vision. | |
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MedLine Citation:
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PMID: 21194550 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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The perception of an object as a single entity within a visual scene requires that its features are bound together and segregated from the background and/or other objects. Here, we used magnetoencephalography (MEG) to assess the hypothesis that coherent percepts may arise from the synchronized high frequency (gamma) activity between neurons that code features of the same object. We also assessed the role of low frequency (alpha, beta) activity in object processing. The target stimulus (i.e. object) was a small patch of a concentric grating of 3c/°, viewed eccentrically. The background stimulus was either a blank field or a concentric grating of 3c/° periodicity, viewed centrally. With patterned backgrounds, the target stimulus emerged - through rotation about its own centre - as a circular subsection of the background. Data were acquired using a 275-channel whole-head MEG system and analyzed using Synthetic Aperture Magnetometry (SAM), which allows one to generate images of task-related cortical oscillatory power changes within specific frequency bands. Significant oscillatory activity across a broad range of frequencies was evident at the V1/V2 border, and subsequent analyses were based on a virtual electrode at this location. When the target was presented in isolation, we observed that: (i) contralateral stimulation yielded a sustained power increase in gamma activity; and (ii) both contra- and ipsilateral stimulation yielded near identical transient power changes in alpha (and beta) activity. When the target was presented against a patterned background, we observed that: (i) contralateral stimulation yielded an increase in high-gamma (>55Hz) power together with a decrease in low-gamma (40-55Hz) power; and (ii) both contra- and ipsilateral stimulation yielded a transient decrease in alpha (and beta) activity, though the reduction tended to be greatest for contralateral stimulation. The opposing power changes across different regions of the gamma spectrum with 'figure/ground' stimulation suggest a possible dual role for gamma rhythms in visual object coding, and provide general support of the binding-by-synchronization hypothesis. As the power changes in alpha and beta activity were largely independent of the spatial location of the target, however, we conclude that their role in object processing may relate principally to changes in visual attention. |
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Authors:
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K Kinsey; S J Anderson; A Hadjipapas; I E Holliday |
Publication Detail:
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Type: JOURNAL ARTICLE Date: 2010-12-29 |
Journal Detail:
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Title: International journal of psychophysiology : official journal of the International Organization of Psychophysiology Volume: - ISSN: 1872-7697 ISO Abbreviation: - Publication Date: 2010 Dec |
Date Detail:
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Created Date: 2011-1-31 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8406214 Medline TA: Int J Psychophysiol Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2010 Elsevier B.V. All rights reserved. |
Affiliation:
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School of Life and Health Sciences, Aston University, The Wellcome Trust Laboratory for MEG Studies, Birmingham, B4 7ET, UK; School of Life and Health Sciences, Dept. of Psychology, University of the West of England, Bristol, BS16, 1QY, UK. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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