All ETDs from UAB

Advisory Committee Chair

Xin-Cheng Yao

Advisory Committee Members

Franklin Amthor

Kent Keyser

Donald Twieg

Document Type

Thesis

Date of Award

2011

Degree Name by School

Master of Science in Biomedical Engineering (MSBME) School of Engineering

Abstract

Stimulus-evoked fast intrinsic optical signals (IOSs) have time courses comparable to electrophysiological kinetics, and thus promise a sub-cellular and sub-second resolution method for functional evaluation of excitable biological tissues. The objective of my thesis research is to validate and characterize IOS imaging of stimulus-evoked activities in the retina and pancreatic islet ß-cells. In order to achieve this objective, three sets of experiments have been conducted. 1) Simultaneous measurement of retinal neurons functioning can enhance our understanding of the visual signal processing. In this stage of my study, I propose to demonstrate IOS imaging of retina slices that allows simultaneous monitoring of stimulus evoked visual signal propagation from the photoreceptor to inner retinal neurons. Our preliminary studies indicate that robust IOSs can be consistently observed at the photoreceptor, inner plexiform and ganglion cell layers. While IOSs at the photoreceptor layer are mainly confined to the area directly stimulated by the visible light; IOSs at inner retinal layers can spread into a larger area with a characteristic near to far time course. 2) Electrical stimulation of inner retinal neurons is an effective approach in designing visual prostheses which may help to restore vision from blindness due to age related macular degeneration and retinitis pigmentosa. A noninvasive imaging technology for monitoring stimulus-evoked neural responses can contribute to better design of visual prostheses. In this study, we demonstrate the feasibility of IOS imaging of the ganglion cell responses elicited by electrical stimulation. Our data revealed robust IOS activity in the stimulated ganglion cells. While single-pulse stimulation evoked robust IOS within 15 ms; pulse train stimulation indicated that fast IOS can follow frequencies up to at least 8 Hz. 3) Simultaneous monitoring of multiple ß-cells working together is essential for better understanding of ß-cell dysfunction which is an early phase in the progression to diabetes. In this study, we propose to validate the feasibility of using IOS imaging for functional examination of pancreatic islets. Our preliminary investigations with insulin secreting INS-1 cell, which is a popular model for diabetes associated ß-cell dysfunctions study, have demonstrated the potential of IOS imaging of glucose activated ß-cells.

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