The development and application of advanced methods for MEG and EEG data analysis

Godfrey, Megan 2021. The development and application of advanced methods for MEG and EEG data analysis. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Magnetoencephalography (MEG), in combination with complex analysis techniques, has made large contributions to our understanding of the brain. However, MEG research often considers only oscillatory activity within the brain, whereas most brain activity appears to be more disorderly. During this thesis, rank-vector entropy (RVE), a time-resolved measure of neuronal irregularity, was found to be useful as a complement to oscillatory measures in the analysis of MEG data. The parameters of the RVE measure were first optimised to maximise temporal resolution and, separately, the temporal correlation between the RVE and oscillatory amplitude envelopes of virtual sensor timecourses. The RVE of MEG was then found to exhibit temporal correlation with the BOLD signal; this was positive in task-activated areas but negative in regions comprising the default mode network. An important development put forward in this thesis was the extension to multiscale RVE, which measures dynamic neuronal entropy over a range of temporal scales. MRVE correlation was shown to provide insight into functional connectivity across temporal scales in health and disease and gave complementary information to that given by measures based on oscillatory synchronisation. It was also found that functional connectivity measurements, as calculated using MRVE correlation and the more conventional method of oscillatory amplitude envelope correlation (AEC), depended on the data cleaning method used. The removal of eye movement artefacts using ICA was found to increase sensitivity to connectivity alterations in a cohort at genetic neurodevelopmental risk. The final chapter of this thesis attempts to address the inferior sensitivity of MEG to deeper sources by performing source localisation using simultaneous MEG and EEG (MEEG). MEEG was not shown to improve source localisation in the deep brain over MEG alone. However, MEG alone was found to be able to detect activity within the medial temporal lobe during a spatial memory task

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Cardiff University Brain Research Imaging Centre (CUBRIC) Psychology
Subjects:	B Philosophy. Psychology. Religion > BF Psychology
Funders:	EPSRC
Date of First Compliant Deposit:	8 June 2021
Date of Acceptance:	8 June 2021
Last Modified:	06 Jan 2024 04:31
URI:	https://orca.cardiff.ac.uk/id/eprint/141793

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