This thesis contains four studies, the first examining methodology issues and four subsequent ones examining somatosensory cortical processing using event-related potentials (ERPs). The methodology section consists of 2 experiments. The first compared the latency variability in stimulus presentation between 3 computers. The second monitored the applied force of the vibration stimuli under experimental conditions to ensure that the chosen method for somatosensory stimulus presentation was consistent and reliable. The next study involved 3 experiments that aimed to characterize the mid to long latency somatosensory event-related potentials to different duration vibratory stimuli using both intracranial and scalp recording. The results revealed differences in the waveform morphology of the responses to and on-off responses, which had not previously been noted in the somatosensory system. The third and fourth studies each consisted of 2 experiments. These examined the discrimination between vibratory stimuli using an odd-ball paradigm to try to obtain a possible 'mismatch' response, similar to that reported in the auditory system. The aim of this study was to clarify some of the discrepancies in the literature surrounding the somatosensory mismatch response and to further characterize this response. The results from intracranial and scalp ERP recordings showed a two-component, negative-positive mismatch response over the anterior parietal region and a negative component over the superior pre-frontal region in response to changes in both frequency and duration. The negative component over the frontal region had never before been described. The last study explored possible interactions between somatosensory and auditory cortical potentials in response to spatially and temporally synchronized auditory and vibratory stimuli. The results showed clear interactions in the cortical responses to combined auditory and somatosensory stimuli in both standard and mismatch conditions.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:639518 |
| Date | January 2007 |
| Creators | Spackman, L. |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/1444956/ |
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