Date of Award

Fall 2005

Document Type

Dissertation - Restricted

Degree Name

Doctor of Philosophy (PhD)


Biomedical Engineering

First Advisor

Ropella, Kristina M.

Second Advisor

Liebenthal, Einat

Third Advisor

Hudetz, Anthony G.


The ultimate goal of functional neuroimaging is to provide accurate information about brain activity during a particular task. Functional neuroimaging techniques are basically of two different varieties: 1) electrophysiological methods, which provide direct measures of neural activity (i.e., electroencephalography (EEG) and magnetoencephalography (MEG)), and 2) hemodynamic/metabolic methods, which provide indirect measures of neural activity (i.e., functional magnetic resonance imaging (fMRI) and positron emission tomography (PET)). EEG and blood oxygenation level-dependent (BOLD) fMRI are two techniques that have complementary strengths. FMRI offers good spatial resolution but poor temporal resolution, whereas EEG has good temporal resolution but poor spatial resolution. In order to truly ensure that identical experimental conditions exist across "imaging" modalities, it is necessary to acquire the data simultaneously. The simultaneous use of these two techniques is a relatively new approach for monitoring brain function that has received an increased amount of attention over the past few years. Simultaneous recordings allow for perfect correspondence of the experimental conditions (i.e., scanner and background noise, vibrations during gradient switching, illumination, and the subject's position) and cognitive states (i.e., variation in the subject's arousal level, attention, and familiarity with a task) during the studies of the subjects between the two recordings. This is particularly important for cognitive studies, as well as for studies of auditory perception because of the difficulty in accurately reproducing the acoustic environment in the MRI scanner for separate EEG recordings. Ultimately, the goal of combining these two brain imaging techniques is to allow for a determination of the time course of brain activation, i.e., the sequence and dynamics of brain activity...



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