Implications of structural connections within and between brain regions for their functional counterpart are timely points of discussion. White matter microstructural organization and functional activity can be assessed in unison. At first glance, however, the corresponding findings appear variable, both in the healthy brain and in numerous neuro-pathologies. To identify consistent associations between structural and functional connectivity and possible impacts for the clinic, we reviewed the literature of combined recordings of electro-encephalography (EEG) and diffusion-based magnetic resonance imaging (MRI). It appears that the strength of event-related EEG activity increases with increased integrity of structural connectivity, while latency drops. This agrees with a simple mechanistic perspective: the nature of microstructural white matter influences the transfer of activity. The EEG, however, is often assessed for its spectral content. Spectral power shows associations with structural connectivity that can be negative or positive often dependent on the frequencies under study. Functional connectivity shows even more variations, which are difficult to rank. This might be caused by the diversity of paradigms being investigated, from sleep and resting state to cognitive and motor tasks, from healthy participants to patients. More challenging, though, is the potential dependency of findings on the kind of analysis applied. While this does not diminish the principal capacity of EEG and diffusion-based MRI co-registration, it highlights the urgency to standardize especially EEG analysis.
Bibliographical noteFunding Information:
This work was part of the Move−Age joint doctorate program, which is funded by the European Commission as part of the Erasmus Mundus programme with grant number: 2014–0691/001–001–EMJD. It also received financial support from the Research Foundation – Flanders Research Grant (G089818N) and the Excellence of Science grant (EOS, 30446199, MEMODYN), a C1 grant from the KU Leuven Research Fund (C16/15/070), a Science Foundation Ireland grant (18/IF/6272), and from the European Union’s Horizon 2020 Research and Innovation Programme under the Marie Curie-Skłodowska grant agreement No. 893823. JG received finanical support via a fellowship from the Research Foundation Flanders (#12G3919N).
© Copyright © 2021 Babaeeghazvini, Rueda-Delgado, Gooijers, Swinnen and Daffertshofer.
- diffusion-based magnetic resonance imaging (dMRI)
- electro-encephalography (EEG)
- event-related potentials (ERPs)
- functional connectivity
- resting state
- spectral analysis
- white matter (WM) microstructural organization