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  Spatial dependence of the nonlinear BOLD response at short stimulus duration

Pfeuffer, J., McCullough, J., de Moortele, P.-F., Ugurbil, K., & Hu, X. (2003). Spatial dependence of the nonlinear BOLD response at short stimulus duration. NeuroImage, 18(4), 990-1000. doi:10.1016/S1053-8119(03)00035-1.

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Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0013-DCAB-6 Version Permalink: http://hdl.handle.net/21.11116/0000-0005-6ABA-3
Genre: Journal Article

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Pfeuffer, J1, 2, Author              
McCullough , JC, Author
de Moortele , P-FV, Author
Ugurbil, K, Author
Hu, X, Author
Affiliations:
1Department Physiology of Cognitive Processes, Max Planck Institute for Biological Cybernetics, Max Planck Society, ou_1497798              
2Max Planck Institute for Biological Cybernetics, Max Planck Society, Spemannstrasse 38, 72076 Tübingen, DE, ou_1497794              

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 Abstract: Most functional magnetic resonance imaging studies use linear models to predict the measured response by convolution of an impulse response with the stimulus profile. Using very short visual presentation times (<2 s), deviation from the linear model in the measured BOLD data from the human brain was found for the response integral, amplitude, and width. In this study, high temporal and spatial resolution were used to quantify nonlinear effects and investigate the spatial dependence. Data at 4 Tesla showed at short stimulus duration a nonlinearity, i.e., deviation from a linear model, with an index up to 400, whereas data at 7 Tesla exhibited a nonlinearity index up to 40. The effect was more pronounced for response amplitude than for response area. A reduced width and sharpening of responses at shorter stimulus duration was also found. A voxel-based analysis of 7 Tesla data with 1.2 × 1.2 × 2 mm3 resolution revealed a correlation between response onset and nonlinearity index. This suggests that the nonlinearity effects are a tissue-specific phenomenon and are likely to be more localized to the site of neuronal activity. The observed magnetic field dependence and the demonstrated nonlinearity in the response width support the hypothesis that the source of the nonlinearity at short stimulus duration has a considerable hemodynamic contribution. The nonlinearity was modeled as a “switch”-type initial hemodynamic response onset. Understanding these nonlinearities in the BOLD response is important for design and the analysis of rapid event-related fMRI experiments with brief stimulus presentations.

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 Dates: 2003-04
 Publication Status: Published in print
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 Table of Contents: -
 Rev. Method: -
 Identifiers: DOI: 10.1016/S1053-8119(03)00035-1
BibTex Citekey: 2040
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Title: NeuroImage
Source Genre: Journal
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Publ. Info: Orlando, FL : Academic Press
Pages: - Volume / Issue: 18 (4) Sequence Number: - Start / End Page: 990 - 1000 Identifier: ISSN: 1053-8119
CoNE: https://pure.mpg.de/cone/journals/resource/954922650166