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Leonid L. Kontsevich, Christopher W. Tyler; Component analysis of BOLD response. Journal of Vision 2004;4(8):272. doi: https://doi.org/10.1167/4.8.272.
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© ARVO (1962-2015); The Authors (2016-present)
We studied the independent components of the Blood Oxygenation Level Dependent (BOLD) response in the visual cortex. The stimuli were discs and annuli filled with eccentricity-scaled dynamic checks. The plots of the first and the second principal component contained two clusters reflecting independent components in the BOLD responses: one that almost coincided with the first principal component had only positive amplitude and the other one had amplitudes of both signs. Similar properties were also found for the first and third components. Activation map for the unipolar independent component reflected spatial pattern of the stimulus; the other two components had no obvious spatial organization. The map for the unipolar component had more distinct borders and detail than did the map based on simple correlation with the main harmonic. The response of this component to block-design stimuli had nonlinear onset and linear offset, which may partly explain why linear methods often produce poor maps. We hypothesize that the main independent component found represents the local response whereas the others are due to less local factors.
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