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Comparison of the hemodynamic response to different visual stimuli in single‐event and block stimulation fMRI experiments
Author(s) -
Janz Clemens,
Schmitt Christina,
Speck Oliver,
Hennig Jürgen
Publication year - 2000
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/1522-2586(200011)12:5<708::aid-jmri7>3.0.co;2-g
Subject(s) - visual cortex , stimulus (psychology) , stimulation , neuroscience , luminance , psychology , computer science , artificial intelligence , cognitive psychology
Experiments with three different types of basic visual stimulation were performed to compare cortical activation in single‐event and block trials. Independent of the stimulation paradigm, the single‐event presentation leads to highly consistent signal responses regarding both the activated cortical areas and the dynamics of the signal time course. In contrast, signal time courses during block paradigms depend on the stimulus applied and are a complex and nonlinear function of the single‐event responses. Additionally, the initial dip during the first 2 seconds after stimulus onset is consistently observed. However, the small amplitude change (−0.1% to −0.3%) requires signal averaging to establish statistical significance of the effect. Furthermore, different patterns of activation were observed within the primary visual cortex. In an anterior part of the primary visual cortex, activation was only observed at the onset and at the cessation of stimulation involving luminance changes. J. Magn. Reson. Imaging 2000;12:708–714. © 2000 Wiley‐Liss, Inc.