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Novitskiy et al. Neuromath 2009
Nikolay Novitskiy, Lab Exp. Psych., KU Leuven 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
Presentation plan Why to combine fMRI and ERPs? Stimuli and procedure Results fMRI alone EEG alone EEG-instructed fMRI Conclusions 14/04/2019 Novitskiy et al. Neuromath 2009
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Advantages and pitfalls of integration
+ = + = 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
Visual P1 and N1 Omnipresent in visual ERP studies Higher amplitude and/or shorter latencies in the contralateral hemisphere (Di Russo et al., 2002) Different role of P1 and N1 in the selective attention (Luck et al. 1990) -2 μV N1 -100 ms 300 ms P1 P1 2 μV (after Di Russo et al., 2002) 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
Stimuli and procedure 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
DR Visual detection task 5 types of equiprobable stimuli : 4 checkerboard segments, one per quadrant, ~5° from the center of the sceen 1 full central checkerboard, ~10° Variable randomized SOA 14/04/2019 Novitskiy et al. Neuromath 2009 DL UR DL UL
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Novitskiy et al. Neuromath 2009
Experimental procedure 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
fMRI alone 14/04/2019 Novitskiy et al. Neuromath 2009
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Tonotopic V1 activations as expected
Right side Left side Upper Left Stimulus location Upper Right Down Left Down Right 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
Strong activations near MOG FWE p<0.0001 Central LVF peripheral RVF 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
EEG alone 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
EEG preprocessing is multi-step procedure Gradient artifact cleaning with a moving template subtraction (Brain Vision Analyzer) BCG cleaning with OBS template (EEGlab) Residual BCG cleaning with ICA (EEGlab) Blink cleaning with ICA (EEGlab) Extreme values rejection (EEGlab) 14/04/2019 Novitskiy et al. Neuromath 2009
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Inside and outside ERPs a similar in waveforms …
contralateral hemisphere ipsilateral hemisphere N1 Contra P1 ipsi P1 inside the scanner outside 14/04/2019 Novitskiy et al. Neuromath 2009
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… and in scalp voltage maps
92 ms 112 ms 152 ms 180 ms Outside Contra-P1 Ipsi-P1 contra-N1 Inside 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
P1 amplitude inside the scanner is larger to contralateral stimuli 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
EEG-instructed fMRI 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
10 occipital electrodes are chosen in regressor construction, … v 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
… single trial amplitude are averaged around ERP peak latency and subtracted, … Left hemisphere Single trials . . . Right hemisphere - - - - . . . Time window of amplitude averaging , 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
… negative and positive amplitudes are separated in different vectors, … 14/04/2019 Novitskiy et al. Neuromath 2009
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… and convolved with canonical HRF function.
x 14/04/2019 Novitskiy et al. Neuromath 2009
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EEG-instructed fMRI results
Left-positive P1 Left-negative N1 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
fMRI only EEG-insructed fMRI Left-positiveP1 RVF triggers Left-negative N1 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
Conclusions The EEG data quality inside the scanner is sufficient for visual P1 and N1 measurement The sources of P1 and N1 may involve different subareas within the same brain areas Combined EEG/fMRI allows accurate localization of different stages of stimuli processing 14/04/2019 Novitskiy et al. Neuromath 2009
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Novitskiy et al. Neuromath 2009
Thanks to: Jennifer Raumatar Katrien Vanderperren Peter Stiers Stefan Sunaert Johan Wagemans Bea Van den Bergh Bart Vanrumste Lieven Lagae Sabine Van Huffel 14/04/2019 Novitskiy et al. Neuromath 2009
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