This thesis includes four studies investigating neural correlates underlying pitch perception, and effects of tonal context on this percept. Each study addressed the issue from a unique methodological perspective. The first study confirmed that tonal context can affect the way a tone's pitch is perceived. In this study, normal listeners made pitch discriminations between tones varying in pitch and/or timbre, a difficult task when presented in isolation. Increasing tonal context increased performance, with melodic context providing the most facilitation. / A similar task was presented to patients with unilateral focal excisions in the temporal lobe. Patients with right but not left temporal lobe lesions were impaired at using melodic cues to facilitate performance. Posterior extent of the lesions did not affect results, implying that right anterior temporal regions can process pitch information relative to tones heard previously. A functional magnetic resonance imaging (fMRI) study using a similar task with normal listeners found converging evidence. Melodic context produced the most activity in right anterior superior temporal gyrus (STG), as well as the most facilitation behaviorally. / A positron emission tomography study investigating neural processing of song stimuli broadened the investigation to include a comparison between musical and linguistic processing. Left frontal and temporal structures known to be involved in language processing were active when subjects attended to song lyrics, and right temporal-lobe structures were again implicated in melodic processing, suggesting that a song's lyrics and melodies are processed separately. / These studies find pitch processing in tonal contexts to involve right temporal-lobe structures. The right anterior STG in particular appears to be involved in processing pitch relative to previously heard tones. This suggests that the right anterior STG processes tones with respect to their tonal context, which entails holding contextual tones in memory while processing subsequent tones. This region has connections to right dorsolateral frontal areas previously implicated in tonal working memory, possibly providing a mechanism for holding contextual tones in memory. Supporting this theory, all contextual conditions in the fMRI study produced activity in right dorsolateral frontal cortex.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36848 |
| Date | January 2000 |
| Creators | Warrier, Catherine M. |
| Contributors | Zatorre, Robert (advisor) |
| 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: 001782105, proquestno: NQ69945, Theses scanned by UMI/ProQuest. |
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