Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Accompanying CD-ROM contains supporting information. Includes bibliographical references (leaves 153-156). Also available in electronic version.

A theoretical analysis of the acoustic field around a sound source suggested that fish would be able to locate a sound source by detecting the associated near field displacements with their lateral line system. Blinded goldfish and Mexican blind cave characins were able to locate both stationary objects and sound sources. The lateral line system was implicated as the directionally sensitive organs involved. Blind cave fish were able to locate both stationary objects and a sound source against a background noise. The existence of a noise suppressing mechanism to the lateral line organs was suggested. An efferent nervous supply was shown to innervate anterior lateral line organs of goldfish, and the inhibitory nature of the efferent nerves was demonstrated. The efferent nerves were found to be insensitive to the stimulation of acoustically sensitive organs on the fish, but responded to changing states of muscular activity in the fish. Swimming goldfish changed hydrodynamically during respiration from bluff bodies, when their mouths were shut, to streamlined bodies, when their mouths were open. This change in configuration lead to the proposal that the anterior lateral line organs function both as velocity detectors and near field displacement detectors. A central location was suggested for a neuro-physiological noise attenuating system to the lateral line system, and the efferent nerves innervating the lateral line organs were suggested to form part of a mechanism reflexively controlling swimming velocity. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (Ph. D.)--University of Oregon, 2002. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 127-139). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p3045096.

Principal neurons of the medial superior olive (MSO) encode low-frequency sound localization cues by comparing the relative arrival time of sound to the two ears. In mammals, MSO neurons display biophysical specializations, such as voltage-gated sodium (Na[subscript v]) and potassium (K[subscript v]) channels that enable them to detect these cues with microsecond precision. In this dissertation electrophysiological techniques were used to examine the specific channel properties and functional role these channels play in MSO neurons following hearing onset. In addition, computational models that incorporated these physiological data were used to further study how the specific properties of these channels facilitate MSO function. Experiments in this dissertation showed that Na[subscript v] channels are heavily expressed in the persisomatic region of MSO neurons, but unlike those expressed in other neurons they minimally contribute to action potential generation. This is likely due to the low percentage of channels available for activation at the resting membrane potential. Current clamp recordings determined that Na[subscript v] channels counterbalance K[subscript v] channels voltage rectification by boosting near action potential threshold excitatory post-synaptic potentials (EPSPs). Further, computational modeling revealed that synaptic inputs are larger at the soma with Na[subscript v] channels restricted to the soma than when they are evenly distributed throughout the soma and dendrites. During the first few weeks after hearing onset current clamp experiments showed EPSP duration decreased while the temporal resolution for detecting the arrival time of synaptic inputs increased. These changes in EPSP duration are due in part to both the development of faster membrane response properties and increases in the expression of low voltage-activated K[subscript v] channels (K[subscript LVA]). Further investigation determined these channels display a somatically enriched distribution and act to counterbalance the distortions that result from dendritic cable filtering. This is accomplished by K[subscript LVA] actively decreasing the duration of EPSPs in a voltage dependent manner. Computational modeling confirmed these results as well as illustrating their effects on the integration of mono- versus bilateral excitation. Together these findings indicate that the expression of specialized Na[subscript v] and K[subscript v] channels facilitate the neuron’s computational task, detecting and comparing the relative timing of synaptic inputs used in low frequency sound localization. / text

Crickets rely on binaural comparisons of intensity to locate sound. Intensity can be encoded by response magnitude as well as response latency. The effects of sound intensity and pulse repetition rate on the auditory responses of the tympanal nerve were investigated. Adaptation, a decline in the response due to repeated stimulation, is greater for higher pulse rates and higher intensities. Since sound intensity is louder at the ear closer to the sound source, adaptation is more pronounced in the ipsilateral ear. As a result, the interaural difference in response magnitude decreases. Therefore response magnitude cannot be a reliable cue for sound location. I found that response latency also adapts: it increases over time. However, this change is not intensity dependent. So interaural latency difference is stable over time. The results show that interaural latency difference is a more reliable cue than interaural magnitude difference to locate sound.

Thesis (Ph. D.)--Discipline of Physiology, Faculty of Medicine, University of Sydney, 2004. / Includes list of published articles: leaf iv. Bibliography: leaves [188]-203.

Thesis (Ph. D.)--University of Sydney, 2004. / Title from title screen (viewed 14 May 2008). Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Discipline of Physiology, Faculty of Medicine. Includes bibliographical references. Also available in print form.

Thesis (Ph. D.)--Drexel University, 2004. / Includes abstract and vita. Includes bibliographical references (leaves 39-42).

Thesis (Ph. D.)--University of Missouri-Columbia, 1996. / Typescript. Vita. Includes bibliographical references (leaves 109-115). Also available on the Internet.