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Title: Study of the relationship between the EEG and BOLD signals using intracranial EEG-fMRI data simultaneously acquired in humans
Author: Gonçalves Murta, T. I.
ISNI:       0000 0004 7230 4265
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2016
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The principal aim of this work was to further characterise the relationship between the electrophysiological and BOLD fMRI signals at the local level, exploiting the unique opportunity to analyse intracranial EEG (icEEG) and fMRI data recorded simultaneously in humans, during a finger tapping task and at rest. The MR-environment (gradient switch and mechanical vibration) related artefacts corrupting the icEEG data were the first problem tackled; they were characterised and removed using techniques developed by me. The two parts that followed aimed to shed further light on the neurophysiological basis of the BOLD effect. Firstly, the influence of the phase of the low frequency EEG activities (< 30 Hz) on capability of an EEG power - based model to predict the amplitude of finger tapping related BOLD changes was investigated; the strength of the coupling between the phase of  and the amplitude of  (>70 Hz) (phase-amplitude coupling: PAC) was found to explain variance in addition to a combination of , , and  band powers, suggesting that PAC strength and power fluctuations result from complementary neuronal processes. Secondly, five interictal epileptiform discharge (IED) morphology and field extent related features were tested in their individual capability to predict the amplitude of the co-localised BOLD signal; these were the amplitude and rising phase slope, thought to reflect the degree of neuronal activity synchrony; width and energy, thought to reflect the duration of the excitatory post-synaptic potentials; and spatial field extent, thought to reflect the spatial extent of the surrounding, synchronised sources of neuronal activity. Among these features, the IED width was the only one found to explain BOLD signal variance in addition to the IED onsets, suggesting that the amplitude of the BOLD signal is comparatively better predicted by the duration of the underlying field potential, than by the degree of neuronal activity synchrony.
Supervisor: Lemieux, L. ; Figueiredo, P. ; Carmichael, D. W. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available