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| Research article summary (published 18 Aug 2002): |
Dynamic shape integration in extrastriate cortex.
Full Abstract
BACKGROUND:
In anorthoscopic viewing conditions, observers can perceive a moving object through a narrow slit even when only portions of its contour are visible at any time. We used fMRI to examine the contribution of early and later visual cortical areas to dynamic shape integration. Observers' success at integrating the shape of the slit-viewed object was manipulated by varying the degree to which the stimulus was dynamically distorted. Line drawings of common objects were either moderately distorted, strongly distorted, or shown undistorted. Phenomenologically, increasing the stimulus distortion made both object shape and motion more difficult to perceive.RESULTS:
We found that bilateral cortical activity in portions of the ventral occipital cortex, corresponding to known object areas within the lateral occipital complex (LOC), was inversely correlated with the degree of stimulus distortion. We found that activity in left MT+, the human cortical area specialized for motion, showed a similar pattern as the ventral occipital region. The LOC also showed greater activity to a fully visible moving object than to the undistorted slit-viewed object. Area MT+, however, showed more equivalent activity to both the slit-viewed and fully visible moving objects.CONCLUSIONS:
In early retinotopic cortex, the distorted and undistorted stimuli elicited the same amount of activity. Higher visual areas, however, were correlated with the percept of the coherent object, and this correlation suggests that the shape integration is mediated by later visual cortical areas. Motion information from the dorsal stream may project to the LOC to produce the shape percept.
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Author information
Author/s: Yin, Carol (C); Shimojo, Shinsuke (S); Moore, Cassandra (C); Engel, Stephen A (SA);
Affiliation: Computation and Neural Systems, Division of Biology, MC 139-74, California Institute of Technology, Pasadena, CA 91125, USA.
Journal and publication information
Publication Type: Journal Article
Journal: Current biology : CB (Curr Biol), published in England. (Language: eng)
Reference: 2002-Aug; vol 12 (issue 16) : pp 1379-85
Dates: Created 2002/08/26; Completed 2003/03/11; Revised 2004/11/17;
PMID: 12194818, status: MEDLINE (last retrieval date: 11/6/2008)
Sourced from the National Library of Medicine. Abstract text and other information may be subject to copyright.
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