Abstract #0596
Failure of the standard fMRI analysis in the visual cortex using a smooth visual stimulus
David Provencher 1 , Andreas Bartels 2 , Yves Brub-Lauzire 3,4 , and Kevin Whittingstall 4,5
1
Department of Nuclear Medicine and
Radiobiology, Universit de Sherbrooke, Sherbrooke, QC,
Canada,
2
Werner
Reichardt Centre for Integrative Neuroscience, Tbingen,
Germany,
3
Department
of Electrical and Computer Engineering, Universit de
Sherbrooke, Sherbrooke, QC, Canada,
4
Centre
d'imagerie molculaire de Sherbrooke (CIMS), Universit
de Sherbrooke, Sherbrooke, QC, Canada,
5
Department
of Diagnostic Radiology, Universit de Sherbrooke,
Sherbrooke, QC, Canada
Typical task-fMRI studies aim to compute brain
activation maps through voxel-wise correlation of
measured and modeled BOLD timecourses. This usually
relies on two hypotheses, namely that 1) neural activity
follows the stimulation waveform (e.g. a boxcar
function) and that 2) the hemodynamic response function
(HRF), relating neural and BOLD activity, follows a
canonical model. Here, we acquired sequential EEG-fMRI
data in 5 subjects viewing multiple repetitions of a
sinusoidally modulated visual stimulus over 8 seconds.
Through data analysis and linear deconvolution of HRFs,
we show that both hypotheses are inappropriate here, and
are therefore not generalizable to slowly changing
stimuli.
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