This doctoral work consists of several studies that investigated the relationship between language lateralization and structural asymmetries found in auditory and language-related regions of the human brain. Language lateralization was determined via the intracarotid Sodium Amytal procedure in epilepsy patients. In study 1, three groups of patients were investigated: a left speech group (LSG); a right speech group (RSG); and a bilateral speech group (BSG). Two auditory cortex regions: Heschl's gyrus (HG) and the planum temporale (PT) were labelled on the magnetic resonance imaging scan of each subject. Additionally, an automatic voxel-based morphometry (VBM) analysis was performed. The overall findings suggested that the structural asymmetries found in the auditory regions did not clearly and directly relate to language lateralization. The VBM analysis, however, revealed a grey matter concentration difference in the region of Broca's area favoring the left hemisphere (LH) in the LSG, and the right hemisphere (RH) in the RSG. That structural difference did relate to language lateralization and was further investigated in studies 2 and 3. Previously collected positron emission tomography data were examined in these two studies. Three regions of interest (ROI) analyses and one group average analysis were performed. Activation related to various speech tasks was examined. The ROI analyses revealed a significant activation difference favoring the LH for two targeted speech-task subtractions but only for the LSG. The group analysis, in contrast, revealed that the LSG showed a functional asymmetry favoring the LH, and that the RSG showed a functional asymmetry favoring the RH. Overall, the present results provided only partial evidence for a relationship existing between structural asymmetry in Broca's area and language lateralization. The structural asymmetries found in HG and the PT, in contrast, did not clearly and directly relate to language
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.85153 |
| Date | January 2005 |
| Creators | Dorsaint-Pierre, Raquel |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Psychology.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 002227231, proquestno: AAINR12833, Theses scanned by UMI/ProQuest. |
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