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Measuring electrophysiological connectivity by power envelope correlation: a technical review on MEG methods

O'Neill, George C.; Barratt, Eleanor L.; Hunt, Benjamin A. E.; Tewarie, Prejaas K.; Brookes, Matthew Jon

Authors

George C. O'Neill george.oneill@nottingham.ac.uk

Eleanor L. Barratt eleanor.barratt@nottingham.ac.uk

Benjamin A. E. Hunt benjamin.hunt@nottingham.ac.uk

Prejaas K. Tewarie prejaas.tewarie@nottingham.ac.uk



Abstract

The human brain can be divided into multiple areas, each responsible for different aspects of behaviour. Healthy brain function relies upon efficient connectivity between these areas and, in recent years, neuroimaging has been revolutionised by an ability to estimate this connectivity. In this paper we discuss measurement of network connectivity using magnetoencephalography (MEG), a technique capable of imaging electrophysiological brain activity with good (~5mm) spatial resolution and excellent (~1ms) temporal resolution. The rich information content of MEG facilitates many disparate measures of connectivity between spatially separate regions and in this paper we discuss a single metric known as power envelope correlation. We review in detail the methodology required to measure power envelope correlation including i) projection of MEG data into source space, ii) removing confounds introduced by the MEG inverse problem and iii) estimation of connectivity itself. In this way, we aim to provide researchers with a description of the key steps required to assess envelope based functional networks, which are thought to represent an intrinsic mode of coupling in the human brain. We highlight the principal findings of the techniques discussed, and furthermore, we show evidence that this method can probe how the brain forms and dissolves multiple transient networks on a rapid timescale in order to support current processing demand. Overall, power envelope correlation offers a unique and verifiable means to gain novel insights into network coordination and is proving to be of significant value in elucidating the neural dynamics of the human connectome in health and disease.

Journal Article Type Article
Publication Date Oct 8, 2015
Journal Physics in Medicine and Biology
Print ISSN 0031-9155
Electronic ISSN 1361-6560
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 60
Issue 21
Article Number R271-R295
APA6 Citation O'Neill, G. C., Barratt, E. L., Hunt, B. A. E., Tewarie, P. K., & Brookes, M. J. (2015). Measuring electrophysiological connectivity by power envelope correlation: a technical review on MEG methods. Physics in Medicine and Biology, 60(21), doi:10.1088/0031-9155/60/21/R271
DOI https://doi.org/10.1088/0031-9155/60/21/R271
Keywords Magnetoencephalography; MEG; functional connectivity; networks; beamformer; Hilbert envelope; leakage; electrophysiology
Publisher URL http://iopscience.iop.org/article/10.1088/0031-9155/60/21/R271/meta
Copyright Statement Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nd/4.0

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Copyright Statement
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by-nd/4.0





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