Mind Your Language, All Right? Performance-Dependent Neural Patterns of Language
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| Publicado en: | PQDT - Global (2013) |
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ProQuest Dissertations & Theses
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| Acceso en línea: | Citation/Abstract Full Text - PDF Full text outside of ProQuest |
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| Resumen: | The main aim of this dissertation was to investigate the difference in neural language patterns related to language ability in healthy adults. The focus lies on unraveling the contributions of the right-hemispheric homologues to Broca's area in the inferior frontal gyrus (IFG) and Wernicke's area in the posterior temporal and inferior parietal lobes. The functions of these regions are far from fully understood at present. Two study populations consisting of healthy adults and a small group of people with generalized epilepsy were investigated. Individual performance scores in tests of language ability were correlated with brain activation obtained with functional magnetic resonance imaging during semantic and word fluency tasks. Performance-dependent differences were expected in the left-hemispheric Broca's and Wernicke's area and in their right-hemispheric counterparts. PAPER I revealed a shift in laterality towards right-hemispheric IFG and posterior temporal lobe activation, related to high semantic performance. The whole-brain analysis results of PAPER II revealed numerous candidate regions for language ability modulation. PAPER II also confirmed the finding of PAPER I, by showing several performance-dependent regions in the right-hemispheric IFG and the posterior temporal lobe. In PAPER III, a new study population of healthy adults was tested. Again, the right posterior temporal lobe was related to high semantic performance. A decrease in left- hemispheric IFG activation could be linked to high word fluency ability. In addition, task difficulty was modulated. Increased task complexity showed to correlate positively with bilateral IFG activation. Lastly, PAPER IV investigated anti-correlated regions. These regions are commonly known as the default mode network (DMN) and are normally suppressed during cognitive tasks. It was found that people with generalized epilepsy had an inadequate suppression of regions in the DMN, and showed poorer performance in a complex language test. The results point to neural adaptability in the IFG and temporal lobe. Decreased left-lateralization of the IFG and increased right-lateralization of the posterior temporal lobe are proposed as characteristics of individuals with high language ability. |
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| ISBN: | 9798382285702 |
| Fuente: | ProQuest Dissertations & Theses Global |