Peer-Reviewed Journal Details
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Abu Bakar, A,Liu, L,Conci, M,Elliott, MA,Ioannides, AA
2008
November
Human Brain Mapping
Visual Field and Task Influence Illusory Figure Responses
Published
()
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Kanizsa magnetoencephalography magnetic field tomography (MFT) V1 V2 lateral occipital complex (LOC) fusiform gyrus LATERAL OCCIPITAL COMPLEX OBJECT-PROCESSING STAGES FUSIFORM FACE AREA SPATIOTEMPORAL DYNAMICS BRAIN ACTIVITY CORTEX CONTOURS PERCEPTION CONNECTIONS REGIONS
29
1313
1326
In normal viewing conditions, many objects are often hidden or occluded by others, therefore restricting the information that enters the eye. One ability that the human visual system has developed to compensate for this visual limitation is to relate the surrounding elements to globally interpret the whole scene. The appearance of illusory figures (IF) based on surrounding elements also relies on this similar function. In the present study, we hypothesized that different mechanisms may be used by the brain to process IF from the center and periphery of the visual field. We compared magnetoencephalographic responses to IFs presented at different parts of the visual field tinder three task loads. For central presentation, IF specific responses peaked first in V1/V2 (96-101 ms), and then in the lateral occipital complex (LOC; 132-141 ms), independent of task. For peripheral presentation, the relative modulation towards IF was markedly reduced in V1/V2 and LOC while prominent activation peaks now shifted to the Fusiform Gyros (from 200 ins onwards). Additionally, the type of task influenced processing at early stages beginning in V1/V2 (87 ms). Our results show that retinal eccentricity plays a crucial role in IF processing: figural completion at the center of the visual field is achieved in an 'automatic' and seemingly effortless fashion whereas peripheral stimulus locations necessitate higher-order object completion stages which rely more heavily on attentional demands. Hunt Brain Mapp 29:1313-1326, 2008. (C) 2007 Wiley-Liss, Inc.
DOI 10.1002/hbm.20464
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