No abstract

The integration of visual and vestibular information is an example of multisensory processing commonly applied to our daily life. The undeniable role of visual inputs in compensation, restoration, and adaptation for vestibular deficiency has been addressed in several studies. However, current literature fails to objectively measure vestibular responses following a targeted visual stimulus. In the studies of this thesis, using Electrovestibulography (EVestG), we measured participants' vestibular activity from the ear canals in response to targeted visual stimuli, developed in immersive virtual reality (VR) environments, delivered through a head-mounted display (HMD), quantitatively and non-invasively. This dissertation consists of four sub-studies: 1. Quantifying the difference between physically (applied via a hydraulic chair)-and visually (replicas of the physical tilts designed in a VR environment)-induced vestibular responses; 2. Investigating vestibular responses to the combined and individual effects of intensity and hue of three monochromatic colored-light stimuli (blue, green, red); 3. Investigating changes in the vestibular activity when exposed to a horizontal pursuit and saccadic eye movements; and 4. Investigating vestibular responses to the visually-evoked sensation of body movement (Vection) utilizing a VR roller-coaster.Overall from the four sub-studies mentioned above, we conclude that different visual stimuli can produce a measurably different vestibular response (measured by EVestG) depending on the VR environments' characteristics (object motion, color, etc.). As long as the applied visual stimuli do not induce a self-motion sensation, the vestibular response is generally inhibitory (sub-studies 2 and 3). Upon feeling a self-motion sensation, the vestibular response may become an excitatory response (sub-study 4).To better understand the implications of these results, future studies should address the effect of other factors in the field of view (e.g. speed, simultaneous visual and vestibular stimuli, etc.) on the vestibular response measured by EVestG. The findings of this thesis are of significant clinical importance and can pave the way for future research in this field. This research takes us one step closer to the development of a portable EVestG technology that can become commonplace in neuro-diagnostic and clinical areas. iii Acknowledgment Although words cannot describe my deepest feeling of appreciation and gratitude towards people who supported me throughout the Ph. D. program duration, nevertheless, I would like to express my sincere thanks to individuals and entities that made it possible for this dissertation to become a reality. My special thanks go to my supervisors, Dr. Zahra Moussavi and Prof. Brian Lithgow for providing me this great opportunity for scholarly growth and development. Without your dedication, scientific advice, patience, and support I would not have been able to accomplish this research. I consider myself very lucky to have you as my supervisors and I am very muc...

No abstract

No abstract

No abstract