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Viewing in Ambient Illumination 66 VESTIBULO-OCULAR RESPONSES TO VERTICAL TRANSLATION by Ke Liao Submitted in partial fulfillment of the requirements For the degree of Doctor of Philosophy Thesis Adviser: Richard John Leigh M.D. Department of Biomedical Engineering CASE WESTERN RESERVE UNIVERSITY August, 2008 CASE WESTERN RESERVE UNIVERSITY SCHOOL OF GRADUATE STUDIES We hereby approve the thesis/dissertation of Ke Liao candidate for the Ph.D. degree *. (signed) Robert F. Kirsch Ph.D (chair of the committee) R. John Leigh M.D. John Stahl M.D. Ph.D Louis F. Dell'Osso Ph.D Miklos Gratzl Ph.D (date) May 20th, 2008 *We also certify that written approval has been obtained for any proprietary material contained therein. Dedication To my parents 献给我的父母 And my wife 和我的妻子 Table of Contents Table of Contents 1 List of Tables 7 List of Figures 8 Acknowledgements 10 Abstract 11 Chapter 1 Introduction to Eye Movements during Natural Behaviors 13-40 1-1. Eye movements, visual acuity and motion parallax 13 1-2. Advantages of Studying Eye Movements 15 1-3. Eye movements during locomotion 17 1-4. Binocular vision and eye movements during locomotion 20 1-5. Prior Studies of translational vestibulo-ocular reflex (tVOR) 22 1-5-1. Methodological Considerations 22 1-5-2. Summary of tVOR Properties Reported to Date 24 1-6. Reference List 35 Chapter 2 Methodology 41-57 2-1. Summary of current eye movement recording techniques 41 2-1-1. Clinical observation and ophthalmoscopy 42 2-1-2. DC Electro-oculography (EOG) 43 1 2-1-3. Ocular electromyography (EMG) 44 2-1-4. Infrared reflection (IR) technique 44 2-1-5. Purkinje image tracker 45 2-1-6. Video-based systems (tracking pupil and reflected corneal images) 45 2-1-7. Magnetic search-coil systems 46 2-2. Rationale for using the magnetic search coil technique in the present study 48 2-3. Vestibular and visual stimuli selected for this study 49 2-4. Reference List 55 Chapter 3 Performance of the translational vestibulo-ocular reflex (tVOR) in normal human subjects 58-86 3-1. Introduction 58 3-2. Methods 60 3-3. Results 66 3-3-1. tVOR Responses during binocular viewing in ambient illumination 66 3-3-2. Comparison of tVOR responses during different viewing conditions 68 3-4. Discussion 70 3-4-1. Comparison with Prior Studies of tVOR 70 3-4-2. What mechanisms determine tVOR responses? 73 3-4-3. Possible role of tVOR during natural activities 74 3-5. Reference List 82 2 Chapter 4 Factors determining tVOR performance 87-105 4-1. Introduction 87 4-2. Methods 88 4-3. Results 91 4-3-1. Comparison of cancellation of tVOR and smooth visual tracking 91 4-3-2. Effect of moving visual background on tVOR 92 4-4. Discussion 93 4-5 Reference List 104 Chapter 5 Potential application of this study to clinic disorders---First Example: Progressive Supranuclear Palsy (PSP) 106-130 5-1. Introduction 106 5-2. Methods 109 5-2-1. Vestibulo-Ocular Testing 109 5-2-2. Vestibulo-Spinal Testing 111 5-3. Results 112 5-3-1. Responses to Translating while Rotating 112 5-3-2. Responses to Click-Induced Stimulation 114 5-4. Discussion 115 5-5 Reference List 125 3 Chapter 6 Potential application of this study to clinic disorders---Second Example: Cerebellar Ataxias 131-141 6-1. Introduction 131 6-2. Methods 132 6-2-1. Stimuli 132 6-2-2. Measurement of Eye and Head Movements 133 6-3. Results 134 6-3-1. Translational VOR 134 6-3-2. Rotational VOR 135 6-4. Discussion 135 6-5. Reference List 141 Chapter 7 General Discussion and Future Research of the Translation Vestibulo-Ocular Reflex 142-167 7-1. History of a scientific journey 142 7-2. Development of a new device to test tVOR 143 7-3. Safety procedures 148 7-4. Remaining engineering considerations 148 7-5. Evolution of findings and hypotheses for tVOR 149 7-5-1. The first finding: tVOR does not maintain foveal foveation of visual targets 149 4 7-5-2. The second finding: tVOR responsivity is determined by binocular visual cues, but not vergence angle or visual tracking mechanisms 152 7-5-3. A hypothesis to account for visual influences on tvor and a test of the hypothesis 154 7-5-4. Applying present findings to interpret the effects of disease 155 7-6. Concluding Remarks 157 7-7. Reference List 165 Appendix 1 Three dimension transformation algorithm 168-174 A1-1. Head three dimension rotation 168 A1-2. Eye three dimension rotations 169 A1-3. Required three dimension eye rotations 171 A1-4. Reference List 174 Appendix 2 Details of instrumentations 175-195 A2-1. Summary of system Infrastructure 175 A2-2. Control of Moog™ motion platform 176 A2-2-1. Introduction to the Moog™ motion platform 176 A2-2-2. Procedure to generate command to move the Moog™ platform 178 A2-2-3. Operation and maintenance of Moog™ 179 A2-3. Operation of Vicon™ infrared tracking system 181 5 A2-3-1. Introduction to Vicon™ infrared tracking system 181 A2-3-2. Calibration of Vicon™ 181 A2-3-3. Collecting data from Vicon™ 184 A2-4. Operation of the magnetic search coil system 184 A2-4-1. Introduction to the magnetic search coil system 184 A2-4-2. Calibration of 3-D coil system 185 A2-5. Synchronization of coil system and Vicon™ system 189 A2-6. Transformation of raw data to eye movement measurement 190 Bibliography 196-213 6 List of Tables 1-1 Fnctional classes of human eye movements 30 1-2 Summary of prior studies of tVOR 31 2-1 Methods available for measuring eye movements 54 5-1 Summary of clinical information of patients studied 123 6-1 Summary of Cerebellar Ataxia Patients Studied 140 7 List of Figures 1-1 Geometry of motion parallax 27 1-2 Geometry of the angular vestibulo-ocular reflex (aVOR) 28 1-3 Geometry of the translational vestibulo-ocular reflex (tVOR) 29 3-1 Representative eye movement records from one subject 78 3-2 Summary of tVOR responsivity and aVOR gain from all 20 subjects 79 3-3 (A) Comparison of direct and prism viewing on tVOR responsivity 80 3-3 (B) Comparison of vertical smooth-tracking and tVOR 80 3-4 Retinal image speed (RIS) as a function of target distance 81 4-1 Representative records of one subject during viewing far, near target and mirror viewing 97 4-2 Summary of tVOR responses to bob at 2.0 Hz 98 4-3 Representative records comparing direct versus prism viewing 99 4-4 Representative records of the effects of illumination on tVOR 100 4-5 Comparison of measured CanR and estimated CanR 101 4-6 Effects of tVOR with a moving background 102 4-7 Geometry of peak retinal image speed (RIS) as a function of target distance 103 5-1 Comparison of VOR for a normal subject and a PSP patient 120 5-2 Comparison of aVOR (A) and tVOR (B) responsivity ratio 121 5-3 Amplitudes of the VEMPs in PSP patients and healthy controls. 122 6-1 Representative responses to vertical translation in one normal subject and three patients 138 6-2 (A) Responsivity and vergence angle in normal subjects and patients 139 6-2 (B) Comparison of tVOR responsivity and rVOR gain in each subject 139 7-1 Temporal installation of Moog platform in office space 159 8 7-2 Close view of Moog base 160 7-3 Early photographic records of human locomotion 160 7-4 Chair and coil frame for Moog 161 7-5 tVOR during viewing targets at optical infinity 162 7-6 Moog with magnetic field coils, skate-board helmet and safety rails installed 163 7-7 Visual background on a large flat-screen monitor 164 A1-1 Vectors of coil frame and coils on the eye ball 173 A2-1 Moog motion platform 193 A2-2 Coil frame, helmet and the head rest mounted on the moog platform 193 A2-3 Magnetic search coil after inserted to human eye 194 A2-4 Front panel of the moog computer 195 9 Acknowledgements Studying in USA and getting a Ph.D degree has long been my dream. Now I am very close to it. I want to thank Dr. R. John Leigh for his years-long support. Without his help, I wouldn’t have been able to come to the United States. He kept the position and tried his best to help me after my visa was checked for one year. Without his help, my journey to pursue Ph.D degree would have also been much longer and harder. I also want to thank my committee members, Drs. Louis F. Dell’Osso, Robert F. Kirsch, Miklos Gratzl, and John Stahl for giving their insightful comments and guidance during the course of my research. Their suggestions have helped me to develop a more complete and robust research project. Many thanks to my colleagues at the Lab, from whom I got great help every time and learned a lot during our conversations and discussions. Special thanks to our secretary, Ms. Ann Rutledge, who has provided not only the office supplies but also wisdom of life with which I am able to live more comfortable in a new environment and a different culture. Finally, I want to thank my family including my parents and my wife. They have always been supportive to me in my life. My wife gave up her career in China, and came to United States to accompany me.
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