Please use this identifier to cite or link to this item: https://hdl.handle.net/10316/109937
Title: Stimulus dependency of object-evoked responses in human visual cortex: an inverse problem for category specificity
Authors: Graewe, Britta
De Weerd, Peter
Farivar, Reza
Castelo-Branco, Miguel 
Issue Date: 2012
Publisher: Public Library of Science
Project: SFRH/BD/37385/2007 
PTDC/SAU/NEU/68483/2006 
PIC/IC/82986/2007 
Bial Foundation 94/06 (http://www.bial.com/en/bial_foundation.11/grants.18/ grants.a38.html) 
Serial title, monograph or event: PLoS ONE
Volume: 7
Issue: 2
Abstract: Many studies have linked the processing of different object categories to specific event-related potentials (ERPs) such as the face-specific N170. Despite reports showing that object-related ERPs are influenced by visual stimulus features, there is consensus that these components primarily reflect categorical aspects of the stimuli. Here, we re-investigated this idea by systematically measuring the effects of visual feature manipulations on ERP responses elicited by both structure-from-motion (SFM)-defined and luminance-defined object stimuli. SFM objects elicited a novel component at 200-250 ms (N250) over parietal and posterior temporal sites. We found, however, that the N250 amplitude was unaffected by restructuring SFM stimuli into meaningless objects based on identical visual cues. This suggests that this N250 peak was not uniquely linked to categorical aspects of the objects, but is strongly determined by visual stimulus features. We provide strong support for this hypothesis by parametrically manipulating the depth range of both SFM- and luminance-defined object stimuli and showing that the N250 evoked by SFM stimuli as well as the well-known N170 to static faces were sensitive to this manipulation. Importantly, this effect could not be attributed to compromised object categorization in low depth stimuli, confirming a strong impact of visual stimulus features on object-related ERP signals. As ERP components linked with visual categorical object perception are likely determined by multiple stimulus features, this creates an interesting inverse problem when deriving specific perceptual processes from variations in ERP components.
URI: http://hdl.handle.net/10316/109937
ISSN: 1932-6203
DOI: 10.1371/journal.pone.0030727
Rights: openAccess
Appears in Collections:I&D IBILI - Artigos em Revistas Internacionais

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