The ability to combine single words to more complex meanings is the building block of the expressive power of human language. Semantic composition enables us to understand new concepts that we have not encountered before by combining the representations of the underlying individual concepts. The neural correlates of semantic composition have been at the heart of many research agendas in the past but the neural mechanisms at the most basic level still need to be explored consistently. This thesis aimed to advance our knowledge about the spatio-temporal network of brain regions involved in and necessary for basic semantic composition and presents work from three studies applying the same experimental paradigm across three different neuroscientific methodologies. Study I investigated which brain regions support basic semantic composition and how the regions interact via functional magnetic resonance imaging (fMRI). We found differential involvement of left-hemispheric brain regions for a more general combinatorial and a more specific plausibility evaluation process. We furthermore found evidence for an enhanced coupling between two key nodes of the semantic network during successful composition.
In Study II, we probed the relevance of the involved brain regions by studying a cohort of people with aphasia (PWA) and conducting voxel-based lesion-symptom mapping (VLSM). We found a functional dissociation of frontal and temporal brain regions necessary for accurate and efficient semantic decisions, respectively. Finally, in Study III we investigated the temporal dynamics of basic semantic composition in PWA and healthy age-matched controls via electroencephalography (EEG). This study revealed deviant event-related potentials in PWA, where a lack of an early semantic component might be compensated by a stronger late component. Overall, this thesis provides novel insights into the spatial, causal and temporal underpinnings of basic semantic composition making use of three complementary methodologies of neurocognitive research.
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:81990 |
| Date | 08 November 2022 |
| Creators | Graessner, Astrid |
| Contributors | Universität Leipzig |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | 10.1007/s00429-020-02196-2 |
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