AUTHOR=Labounek René , Wu Zhuolin , Bridwell David A. , Brázdil Milan , Jan Jiří , Nestrašil Igor 

TITLE=Blind Visualization of Task-Related Networks From Visual Oddball Simultaneous EEG-fMRI Data: Spectral or Spatiospectral Model?

JOURNAL=Frontiers in Neurology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2021.644874

DOI=10.3389/fneur.2021.644874

ISSN=1664-2295

ABSTRACT=<p>Various disease conditions can alter EEG event-related responses and fMRI-BOLD signals. We hypothesized that event-related responses and their clinical alterations are imprinted in the EEG spectral domain as event-related (spatio)spectral patterns (ERSPat). We tested four EEG-fMRI fusion models utilizing EEG power spectra fluctuations (i.e., absolute spectral model - ASM; relative spectral model - RSM; absolute spatiospectral model - ASSM; and relative spatiospectral model - RSSM) for fully automated and blind visualization of task-related neural networks. Two (spatio)spectral patterns (high <italic>δ</italic><sub>4</sub> band and low <italic>β</italic><sub>1</sub> band) demonstrated significant negative linear relationship (<italic>p</italic><sub>FWE</sub> &lt; 0.05) to the frequent stimulus and three patterns (two low <italic>δ</italic><sub>2</sub> and <italic>δ</italic><sub>3</sub> bands, and narrow <italic>θ</italic><sub>1</sub> band) demonstrated significant positive relationship (<italic>p</italic> &lt; 0.05) to the target stimulus. These patterns were identified as ERSPats. EEG-fMRI F-map of each <italic>δ</italic><sub>4</sub> model showed strong engagement of insula, cuneus, precuneus, basal ganglia, sensory-motor, motor and dorsal part of fronto-parietal control (FPCN) networks with fast HRF peak and noticeable trough. ASM and RSSM emphasized spatial statistics, and the relative power amplified the relationship to the frequent stimulus. For the <italic>δ</italic><sub>4</sub> model, we detected a reduced HRF peak amplitude and a magnified HRF trough amplitude in the frontal part of the FPCN, default mode network (DMN) and in the frontal white matter. The frequent-related <italic>β</italic><sub>1</sub> patterns visualized less significant and distinct suprathreshold spatial associations. Each <italic>θ</italic><sub>1</sub> model showed strong involvement of lateralized left-sided sensory-motor and motor networks with simultaneous basal ganglia co-activations and reduced HRF peak and amplified HRF trough in the frontal part of the FPCN and DMN. The ASM <italic>θ</italic><sub>1</sub> model preserved target-related EEG-fMRI associations in the dorsal part of the FPCN. For <italic>δ</italic><sub>4</sub>, <italic>β</italic><sub>1</sub>, and <italic>θ</italic><sub>1</sub> bands, all models provided high local F-statistics in expected regions. The most robust EEG-fMRI associations were observed for ASM and RSSM.</p>