Page 1 |
Save page Remove page | Previous | 1 of 115 | Next |
|
small (250x250 max)
medium (500x500 max)
large ( > 500x500)
Full Resolution
All (PDF)
|
This page
All
Subset |
DYNAMIC FUNCTIONAL MAGNETIC RESONANCE IMAGING
TO LOCALIZE ACTIVATED NEURONS
by
Witaya Sungkarat
A Dissertation Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOMEDICAL ENGINEERING)
May 2007
Copyright 2007 Witaya Sungkarat
Object Description
| Title | Dynamic functional magnetic resonance imaging to localize activated neurons |
| Author | Sungkarat, Witaya |
| Author email | sungkara@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Biomedical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2006-12-06 |
| Restricted until | Unrestricted |
| Advisor (committee chair) | Singh, Manbir |
| Advisor (committee member) |
Yen, Jesse T. Wolf, Walter |
| Abstract | An important challenge in functional magnetic resonance imaging (fMRI) is to achieve the most spatially accurate results, i.e., to localize activation as close as possible to the actual site of working neurons. Because fMRI detection methods are based on the blood oxygen level dependent (BOLD) property of brain microvascular and venous systems, any model-based fMRI detection method will provide inaccurate results if the model is biased to the BOLD response of a draining venous system, e.g., a vein. Here, a novel detection method is proposed to achieve accurate localization by measuring the spatiotemporal dynamics of brain activations in fMRI to separate microvasculature from venous activations. The method utilizes precisely down-sampled multiple models (with positive and negative delays). Thus conventional 3D fMRI results are expanded into 4D (with an additional temporal dimension). Example fMRI studies underline the usefulness of the approach.; Even though early BOLD activations may be very close to the working neurons, they are not guaranteed to be at the actual site of working neurons. Because the BOLD effect is a slow process (a few seconds to its peak), one cannot use it to detect fast electrical signals produced by working neurons. The proposed method is extended to directly detect fast electrical signals of neurons by a design that converts millisecond latencies of the electric fields to relatively slow latencies through aliasing. The dephasing of the MRI magnetic field caused by the neural currents can then be detected at the relatively slow aliased frequencies by using the proposed method to measure spatiotemporal dynamics. |
| Keyword | fMRI; dfMRI; nfMRI; msMRI; drect neuromagnetic signal detection; neuroelectric signal; aliasing; magnetic source; spatiotemporal dynamics |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Type | texts |
| Legacy record ID | usctheses-m274 |
| Rights | Sungkarat, Witaya |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Sungkarat-20070215 |
| Archival file | uscthesesreloadpub_Volume40/etd-Sungkarat-20070215.pdf |
Description
| Title | Page 1 |
| Full text | DYNAMIC FUNCTIONAL MAGNETIC RESONANCE IMAGING TO LOCALIZE ACTIVATED NEURONS by Witaya Sungkarat A Dissertation Presented to the FACULTY OF THE GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOMEDICAL ENGINEERING) May 2007 Copyright 2007 Witaya Sungkarat |
Comments
Post a Comment for Page 1
