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  Inverse effectiveness in BOLD-response and its behavioural relevance in object categorization

Noppeney, U., & Werner, S. (2009). Inverse effectiveness in BOLD-response and its behavioural relevance in object categorization. In 10th International Multisensory Research Forum (IMRF 2009).

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0013-C443-2 Version Permalink: http://hdl.handle.net/21.11116/0000-0006-D0F5-A
Genre: Meeting Abstract

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Noppeney, U1, 2, Author              
Werner, S1, 2, Author              
Affiliations:
1Research Group Cognitive Neuroimaging, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497804              
2Max Planck Institute for Biological Cybernetics, Max Planck Society, Spemannstrasse 38, 72076 Tübingen, DE, ou_1497794              

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 Abstract: Inverse effectiveness has been invoked as a principle to describe synergistic effects of multisensory integration in neuronal and behavioural responses as a function of stimulus properties (e.g. intensity) or efficacy. We characterized ‘inverse effectiveness’ and its behavioural relevance at the macroscopic level, as provided by the fMRI BOLD-response, based on (1) stimulus-induced and (2) intrinsic response variability across voxels or subjects during object categorization. Subjects categorized audiovisual object stimuli with the relative informativeness (i.e. degradation) of the auditory and visual inputs being manipulated factorially. Controlling for low-level integration processes, higher-level audiovisual integration was observed selectively in the superior temporal sulci (STS) bilaterally. (1) Consistent with the law of inverse effectiveness, auditory and visual informativeness determined the operational modes of audiovisual integration in STS similarly to the influence of physical stimulus intensity in the superior colliculus: while multisensory interactions were primarily subadditive and even suppressive for intact stimuli, additive effects were observed for degraded, near threshold stimuli. (2) Exploiting intrinsic variability across voxels and/or subjects, we demonstrate that superadditivity for audiovisual stimuli increases with decreasing unimodal responses. This inverse relationship could be explained by inherent statistical dependencies between superadditive and unimodal responses. Nevertheless, the superadditive responses in STS (and only in this region) were related to subjects’ audiovisual behavioral benefit: only subjects that benefited from multisensory integration exhibited superadditive interactions, while those that did not benefit showed suppressive interactions. In conclusion, the (super)additive and subadditive integration modes in STS are functionally relevant and related to behavioral indices of multisensory integration with superadditive interactions mediating successful audiovisual object categorization. We argue that inverse effectiveness trends in neuronal and behavioural responses may be intimately related and mutually predictive.

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 Dates: 2009-07
 Publication Status: Published in print
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 Identifiers: BibTex Citekey: 5951
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Title: 10th International Multisensory Research Forum (IMRF 2009)
Place of Event: New York, NY, USA
Start-/End Date: 2009-06-29 - 2009-07-02

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Title: 10th International Multisensory Research Forum (IMRF 2009)
Source Genre: Proceedings
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Pages: - Volume / Issue: - Sequence Number: 897 Start / End Page: - Identifier: -