Individual behavioural patterns and neural underpinnings of verb processing in aphasia

In this dissertation, we investigated aspects of verb and sentence processing in aphasia – a language impairment that occurs after brain damage in adults (a stroke is one of the common causes). We worked with Russian-speaking population, so we first created and made available a database of research materials for the Russian language – verbs, corresponding action pictures, and various parameters that affect processing (e.g. word frequency, subjective picture complexity etc.). Using these materials, we conducted an experiment which aimed to reveal brain regions responsible for verb processing. A large group of stroke survivors participated in an action naming experiment, in which we investigated how their results corresponded to the lesion location in their brain. We found that various left-hemisphere cortical regions, subcortical grey matter structures, and white-matter pathways are involved in action naming, and placed our results in the context of contemporary picture naming, action semantics processing, and semantic control models. Finally, we moved beyond the single verb to the sentence level. We adapted a linguistic diagnostic battery from Dutch to Russian that was designed to assess deficits in verb and sentence processing in production and comprehension. We then tested a large group of individuals with aphasia to see if there were repeatable patterns of linguistic impairment, and if yes, how they corresponded to the type of aphasia. In our study, we did not find clear repeatable individual patterns, although verb and sentence impairments were prevalent irrespective of the aphasia type