Functional Brain Imaging by EEG: A Window to the Human Mind
Publication: Research › Ph.d. thesis – Annual report year: 2011
This thesis presents electroencephalography (EEG) brain imaging by covering
topics as empirical evaluation of source confusion, probabilistic inverse methods,
and source analysis performed on infant EEG data. In terms of source confusion
we inspect how current sources within the brain may be confused with each other
as noise is present in the EEG recordings. Moreover, we examine how errors in
the forward model affect the source confusion.
The primary aim of this thesis is to provide sharper EEG brain images by
improving current inverse methods. In this relation we focus the attention on
two topics in EEG source reconstruction, namely, the forward progation model
(describing the mapping from the current sources within the brain to the sensors
at the scalp) and the temporal patterns present in the EEG.
As forward models may suffer from a number of errors including the geometrical
representation of the human head, the tissue conductivity distribution,
and electrode positions, we propose an algorithm which consider forward model
uncertainties. Bayesian graphical models provide a powerful means of incorporating
prior assumptions that narrow the solution space and lead to tractable
posterior distributions over the unknown sources given the observed data. Here,
we propose a hierarchical Bayesian model that attempts to minimize the influence
of uncertainties associated with the forward model on the source estimates.
Similarly, we develop a hierarchical spatio-temporal Bayesian model that accommodates
the principled computation of sparse spatial and smooth temporal
EEG source reconstructions consistent with neurophysiological assumptions in
a variety of event-related imaging paradigms.
| Original language | English |
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| Publication date | 2011 |
| Place of publication | Kgs. Lyngby, Denmark |
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| Publisher | Technical University of Denmark (DTU) |
| State | Submitted |
| Name | IMM-PHD-2011-254 |
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ID: 5505674