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EFFECT OF CONTINUOUS ELECTRICAL STIMULATION ON RETINAL
STRUCTURE AND FUNCTION
by
Aditi Ray
A Dissertation Presented to the
FACULTY OF USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOMEDICAL ENGINEERING)
August 2010
Copyright 2010 Aditi Ray
Object Description
| Title | Effect of continuous electrical stimulation on retinal structure and function |
| Author | Ray, Aditi |
| Author email | aditiray@gmail.com; aditiray@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Biomedical Engineering |
| School | Viterbi School of Engineering |
| Date defended/completed | 2010-04-14 |
| Date submitted | 2010 |
| Restricted until | Unrestricted |
| Date published | 2010-08-06 |
| Advisor (committee chair) | Weiland, James D. |
| Advisor (committee member) |
Humayun, Mark S. Loeb, Gerald E. Mansfeld, Florian Hinton, David R. Lee, Eun Jin |
| Abstract | Electrical stimulation of the central nervous system albeit an unnatural way, has been found to be an effective way of causing neuronal excitation. Retinal prosthesis is an example of such a neuroprosthesis that strives to provide vision to people suffering from Retinitis Pigmentosa and Age-related Macular Degeneration. In these diseases, the photoreceptors in the retina undergo a progressive degeneration leaving the remaining retinal neurons relatively intact. It is by electrically stimulating these retinal neurons that a retinal prosthesis aims to elicit visual percepts.; In addition to providing effective stimulation, such a device has to do so in a manner that is safe for both the device and surrounding biological environment. Numerous studies have been performed to assess the safety limits of electrical stimulation of neurons. However, majority of these studies have been performed in structures other than the retina. The few safety studies performed in the retina have looked at the effect of brief pulses of stimulation. Hence, the work presented in this thesis investigates the effect of prolonged stimulation of the retina on both the structure and function of the retina.; One-hour long epiretinal stimulation was performed in an in vivo animal model along with the recording of electrically evoked responses in the superior colliculus and retinal histology. Results presented in this thesis demonstrate that the retina is capable of tolerating continuous stimulation at charge densities higher than the safe limit of platinum even when delivered at high stimulus frequencies. However, such a stimulation regime causes a decrease in the electrically evoked responses in the superior colliculus resulting in an elevation of threshold of excitation. This temporary desensitization was found to occur within the first tens of seconds of stimulation after which the responses attained a steady state level. Observations made during this research points towards some form of adaptation by the retina in response to continuous electrical stimulation.; The work presented in this thesis is aimed towards the development of high-resolution epiretinal prosthesis. This research is one of the first to systematically investigate the effect of continuous stimulation from a safety perspective and will hopefully help in the design of safe and efficacious stimulus protocols for retinal prosthesis recipients. |
| Keyword | electrical stimulation; immunohistochemistry; impedance; retina; retinal degeneration; superior colliculus |
| 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 |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3297 |
| Rights | Ray, Aditi |
| 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-Ray-3727 |
| Archival file | uscthesesreloadpub_Volume35/etd-Ray-3727.pdf |
Description
| Title | Page 1 |
| Full text | EFFECT OF CONTINUOUS ELECTRICAL STIMULATION ON RETINAL STRUCTURE AND FUNCTION by Aditi Ray A Dissertation Presented to the FACULTY OF USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOMEDICAL ENGINEERING) August 2010 Copyright 2010 Aditi Ray |
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