Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 179 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 158-179).

Thesis (Ph. D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 181-203).

Thesis (Ph.D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 181-203) Also available in print.

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).

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Thesis (Ph. D.)--West Virginia University, 2009. / Title from document title page. Document formatted into pages; contains x, 192 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

The detrimental effect of ethanol on coordinated movement and the similarity of this effect to that of pathological damage to the cerebellum or the inferior olive (10) suggests that ethanol profoundly effects the olivocerebellar system. Each cerebellar Purkinje cell (PC) displays two distinct action potential responses: the simple spike (SS), evoked intrinsicly and via the parallel fibres, and the complex spike (CS), evoked via a solitary climbing fibre (CF) which originates from the 10. Ethanol (1.5 g/kg, i.v.) was found to have no significant effect on the CS activity evoked by direct electrical activation of CFs, while it significantly reduced, in parallel, that evoked by cerebral cortex stimulation and that occurring spontaneously. In addition, ethanol, applied both systemically and locally by micropressure, reduced the spontaneous activity of inferior olive (10) neurones. These results strongly suggest an action of ethanol local to the 10 nucleus, perhaps by a direct action on the 10 neurones themselves. Elimination of spontaneous CS activity by the electrolytic lesioning of the contralateral 10 did not significantly alter spontaneous SS firing rate. However, subsequent administration of ethanol i.v. did produce a significant increase of SS rate, indicating that only part of ethanol-evoked SS rate increase is dependant upon the reduction of CS activity. Simple spike regularity was not significantly altered by either 10 lesioning or i.v. ethanol. Ethanol applied locally to PC's by micropressure was found to reduce the period of inhibition evoked by local stimulation of the cerebellar cortex in the majority of the cells tested. This result is in agreement with the previously reported effects of intravenous ethanol on this inhibition, thought to be mediated by gamma-aminobutyric acid (GABA). Both intravenously and locally applied ethanol antagonized the inhibition of PC's evoked by locally applied GABA. These results, while in agreement, are contrary to the reported effects of ethanol in other systems. Intravenously administered ethanol did not significantly alter Golgi cell spontaneous firing, while it did significantly reduce the period of inhibition of Golgi cell firing evoked by 10 stimulation. / Pharmaceutical Sciences, Faculty of / Graduate

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

The effects of auditory efferent activity on peripheral physiology may be examined by presenting broadband noise (BBN) to the contralateral ear during otoacoustic emission (OAE) recordings. The presentation of BBN typically produces a reduction of OAE amplitudes in comparison to a condition without BBN. This is termed contralateral suppression. Limited information exists regarding the effects of contralateral BBN on responses observed at higher levels in the auditory system. The present study employed this paradigm to investigate interactions of attention and laterality on the transient evoked otoacoustic emission (TEOAE), auditory brainstem response (ABR) and cortical auditory evoked potentials (CAEP) P1-N1-P2. TEOAEs were evoked by 60 dB SPL clicks; ABRs and CAEPs were evoked by 60 dB SPL 2.0 kHz tone pips in 15 normally hearing adults. Four conditions were employed for each ear: 1) quiet (no noise); 2) 60 dB SPL contralateral BBN; 3) words (at -3 dB SNR) embedded in 60 dB SPL contralateral BBN while subjects classified words as animal versus food items; 4) words from condition #3 played backwards and embedded in 60 dB SPL contralateral BBN. For TEOAEs: 1) more suppression was evident in the active attention condition than the passive listening conditions and 2) right ear OAE amplitudes for the 8-18 ms time period exhibited more suppression in the presence of BBN for all noise conditions, although this did not meet statistical significance. For the ABR experiment, amplitudes in the noise conditions decreased in all epochs for the right ear, but not for the left. For the CAEP experiment, asymmetries were evident in temporal regions and an effect of contralateral noise was evident. The outcome of this investigation suggests that efferent activation by noise and active attention has diverse modulatory effects on electroacoustic and electrophysiologic responses along the auditory pathway.

Diss. (sammanfattning) Stockholm : Karol. inst., 2004. / Härtill 5 uppsatser.