HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) All Versions of this Article: 91/4/1716    most recent 00380.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (16) Citing Articles via Google Scholar Google Scholar Articles by Schira, M. M. Articles by Brandt, S. A. Search for Related Content PubMed PubMed Citation Articles by Schira, M. M. Articles by Brandt, S. A.

Differential Contribution of Early Visual Areas to the Perceptual Process of Contour Processing

¹ Department of Neurology, Charité Humboldt University of Berlin, 10117 Berlin, Germany; ² Department of Human Neurobiology, University of Bremen, 28359 Bremen, Germany

Submitted 16 April 2003; accepted in final form 20 November 2003

We investigated contour processing and figure–ground detection within human retinotopic areas using event-related functional magnetic resonance imaging (fMRI) in 6 healthy and naïve subjects. A figure (6° side length) was created by a 2nd-order texture contour. An independent and demanding foveal letter-discrimination task prevented subjects from noticing this more peripheral contour stimulus. The contour subdivided our stimulus into a figure and a ground. Using localizers and retinotopic mapping stimuli we were able to subdivide each early visual area into 3 eccentricity regions corresponding to 1) the central figure, 2) the area along the contour, and 3) the background. In these subregions we investigated the hemodynamic responses to our stimuli and compared responses with or without the contour defining the figure. No contour-related blood oxygenation level–dependent modulation in early visual areas V1, V3, VP, and MT+ was found. Significant signal modulation in the contour subregions of V2v, V2d, V3a, and LO occurred. This activation pattern was different from comparable studies, which might be attributable to the letter-discrimination task reducing confounding attentional modulation. In V3a, but not in any other retinotopic area, signal modulation corresponding to the central figure could be detected. Such contextual modulation will be discussed in light of the recurrent processing hypothesis and the role of visual awareness.

This article has been cited by other articles:

				J. Haushofer, C. I. Baker, M. S. Livingstone, and N. Kanwisher Privileged Coding of Convex Shapes in Human Object-Selective Cortex J Neurophysiol, August 1, 2008; 100(2): 753 - 762. [Abstract] [Full Text] [PDF]

				J. Vinberg and K. Grill-Spector Representation of Shapes, Edges, and Surfaces Across Multiple Cues in the Human Visual Cortex J Neurophysiol, March 1, 2008; 99(3): 1380 - 1393. [Abstract] [Full Text] [PDF]

				G. P. Caplovitz and P. U. Tse V3A Processes Contour Curvature as a Trackable Feature for the Perception of Rotational Motion Cereb Cortex, May 1, 2007; 17(5): 1179 - 1189. [Abstract] [Full Text] [PDF]

				L. G. Appelbaum, A. R. Wade, V. Y. Vildavski, M. W. Pettet, and A. M. Norcia Cue-invariant networks for figure and background processing in human visual cortex. J. Neurosci., November 8, 2006; 26(45): 11695 - 11708. [Abstract] [Full Text] [PDF]

				F. W. Cornelissen, A. R. Wade, T. Vladusich, R. F. Dougherty, and B. A. Wandell No functional magnetic resonance imaging evidence for brightness and color filling-in in early human visual cortex. J. Neurosci., April 5, 2006; 26(14): 3634 - 3641. [Abstract] [Full Text] [PDF]