This thesis includes four studies designed to improve the ability to predict and assess language representation in healthy children and/or individuals with neurological disorders arising in childhood.
In the first study, the role of pathology type on interhemispheric plasticity of language was determined by comparing lateralization in children with developmental, acquired, and tumour pathologies. Findings from 105 consecutive intracarotid sodium amobarbital procedures were retrospectively analyzed, revealing no lateralization differences between pathology groups.
In the second study, a novel verb generation paradigm and magnetoencephalography (MEG) were used to determine the spatial-temporal characteristics of language expression in healthy subjects (n = 12) and children with neurological disorders (n = 4). Time-frequency and differential beamformer analyses revealed low-beta event-related desynchronization (ERD) in the left inferior frontal lobe for verb generation. The paradigm was well-tolerated by all subjects.
The third study involved assessment of expressive language lateralization in 25 healthy subjects, aged 5-18 years, using two novel MEG paradigms: covert picture naming and verb generation. Novel analyses permitted objective quantification of ERD lateralization on an individual basis. For both tasks, left lateralization of frontal lobe ERD tended to increase with advancing age. Findings suggest that adult-typical left lateralization emerges from an early bilateral language network in normal development.
In the fourth study, frontal lobe ERD lateralization for naming and verb generation was characterized in 14 children and adolescents with neurological disorders. Novel analyses permitted objective assessment of individual scans at multiple contrast time windows. In several cases, rapid hemispheric shifts in predominant frontal lobe ERD were observed through the response period. On an individual basis, the assessment protocol showed promise for future use in a presurgical context.
These studies serve to advance the understanding of normal paediatric language representation, and improve the ability to predict and assess language lateralization in individuals who have experienced early neurological insults.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/24776 |
| Date | 13 August 2010 |
| Creators | Kadis, Darren |
| Contributors | Smith, Mary Lou |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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