Thesis (Ph. D.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 181 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 161-179).

published_or_final_version / Speech and Hearing Sciences / Master / Master of Science in Audiology

published_or_final_version / abstract / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

No description available.

Thesis (M. Phil.)--University of Hong Kong, 2006. / Title proper from title frame. Also available in printed format.

Functional magnetic resonance imaging (fMRI) is a noninvasive technique that can measure blood oxygenation level dependent (BOLD) signal changes in a large field of view with high spatial resolution. The objective of this dissertation is to explore and integrate novel and noninvasive fMRI methods at 7 Tesla to investigate the auditory and visual functions. First, different fMRI methods and stimulation paradigms were employed to explore some basic auditory functions such as sound pressure level (SPL) dependence in different brain structures, and periodotopy and tonotopy in the inferior colliculus (IC). BOLD signal changes increased significantly with SPL and the dependence was monotonic in the IC and lateral lemniscus (LL). The external cortex of IC (ECIC) had higher BOLD signal change than the central nucleus of IC and LL at high SPLs. This study indicates that sparse temporal sampling that is used to reduce the adverse effects of scanner noise may not be a prerequisite in auditory fMRI studies of the IC. Periodotopy and tonotopy in the IC was investigated using continuous imaging with passband balanced steady state free precession (bSSFP) sequence instead of sparse temporal sampling and echo planner imaging (EPI). The spatial gradients of best amplitude modulation frequency (referred to as periodotopy) and characteristic frequency (referred to as tonotopy) varied across the IC, but were approximately perpendicular at different locations. These findings enhance our understanding of how auditory information is preserved in the midbrain. Second, higher order function of behaviorally relevant sounds response selectivity in subcortical structures was investigated. The IC was found to exhibit a stronger response to forward vocalization than to the temporally inverted one. Moreover, blocking cholinergic projections to the IC by atropine injection was observed to significantly reduce the IC response selectivity to the 22 kHz vocalizations. These findings demonstrate the IC response selectivity to vocalizations and suggest that the cholinergic projection contributes to IC responses selectivity to the 22 kHz vocalization. This study provides further understanding about the higher order auditory processing and may have implications for the neural mechanisms underlying human speech perception Third, BOLD fMRI was applied to measure the brain response to stationary and apparent motion visual stimulation. The response of superior colliculus (SC) was weaker under dim light and saturates at higher intensities. Further, the BOLD signal changes and number of activated voxels were both significantly lower during 164 ˚/s apparent motion stimulation compared to stimuli at slower speeds. The results suggest that the SC was more sensitive to slow moving visual stimuli. This is the first fMRI study to investigate motion responsiveness and stimulus speed dependence in the rat SC. Results from these studies complement current knowledge and demonstrate the sophisticated role of subcortical structures such as IC and SC, which may have strong clinical significance to the field of auditory and visual research. Findings from the animal studies should open up new avenues of research and lay the ground work for future human studies. / published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

Thesis (Ph. D.)--University of Washington, 1988. / Vita. Bibliography: leaves [88]-96.

Thesis (M.Sc.)--University of Melbourne, Dept. of Otolaryngology, 2000. / Typescript (photocopy). Includes bibliographical references (leaves 99-109).

Thesis (Ph. D.)--Carleton University, 2004. / Includes bibliographical references (p. 199-212). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 134-144). Available also in a digital version from Dissertation Abstracts.