title: A multi-layer network approach to MEG connectivity analysis.
abstract: Recent years have shown the critical importance of inter-regional neural network connectivity in supporting healthy brain function. Such connectivity is measurable using neuroimaging techniques such as MEG, however the richness of the electrophysiological signal makes gaining a complete picture challenging. Specifically, connectivity can be calculated as statistical interdependencies between neural oscillations within a large range of different frequency bands. Further, connectivity can be computed between frequency bands. This pan-spectral network hierarchy likely helps to mediate simultaneous formation of multiple brain networks, which support ongoing task demand. However, to date it has been largely overlooked, with many electrophysiological functional connectivity studies treating individual frequency bands in isolation. Here, we combine oscillatory envelope based functional connectivity metrics with a multi-layer network framework in order to derive a more complete picture of connectivity within and between frequencies. We test this methodology using MEG data recorded during a visuomotor task, highlighting simultaneous and transient formation of motor networks in the beta band, visual networks in the gamma band and a beta to gamma interaction. Having tested our method, we use it to demonstrate differences in occipital alpha band connectivity in patients with schizophrenia compared to healthy controls. We further show that these connectivity differences are predictive of the severity of persistent symptoms of the disease, highlighting their clinical relevance. Our findings demonstrate the unique potential of MEG to characterise neural network formation and dissolution. Further, we add weight to the argument that dysconnectivity is a core feature of the neuropathology underlying schizophrenia.
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom. Electronic address: matthew.brookes@nottingham.ac.uk.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Brookes
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Prejaas K
authors.initials: PK
authors.lastname: Tewarie
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Benjamin A E
authors.initials: BAE
authors.lastname: Hunt
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Sian E
authors.initials: SE
authors.lastname: Robson
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Lauren E
authors.initials: LE
authors.lastname: Gascoyne
authors.affiliation: Centre for Translational Neuroimaging in Mental Health, Institute of Mental Health, School of Medicine, University of Nottingham, Jubilee Campus, Triumph Road, Nottingham NG7 2TU, United Kingdom.
authors.forename: Elizabeth B
authors.initials: EB
authors.lastname: Liddle
authors.affiliation: Centre for Translational Neuroimaging in Mental Health, Institute of Mental Health, School of Medicine, University of Nottingham, Jubilee Campus, Triumph Road, Nottingham NG7 2TU, United Kingdom.
authors.forename: Peter F
authors.initials: PF
authors.lastname: Liddle
authors.affiliation: Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, University Park, Nottingham NG7 2RD, United Kingdom.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Morris
mesh_terms: D000328:Adult; D000513:Alpha Rhythm; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D058256:Brain Waves; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D015225:Magnetoencephalography; D008297:Male; D008959:Models, Neurological; D016571:Neural Networks, Computer; D009434:Neural Pathways / Q000502:physiology; D009778:Occipital Lobe; D012559:Schizophrenia / Q000503:physiopathology; D012815:Signal Processing, Computer-Assisted; D055815:Young Adult
keywords: Functional connectivity; MEG; Magnetoencephalography; Motor cortex; Multi-layer networks; Neural oscillations; Schizophrenia; Visual cortex