UC San Diego

Anomia is a ubiquitous deficit across individuals with left hemisphere stroke-induced aphasia. This deficit in lexical retrieval has varying characteristics and the underlying process that is disrupted may also vary, brain lesion location being one possible contributing factor to this variance. Left posterior temporal (pLTC) regions have been linked to lexical access and left prefrontal cortex (LPFC) regions have been linked to cognitive control processes key to resolving semantic interference and lexical selection. Semantic relationships have been associated with varying behavioral results taxonomic relationships (e.g., bee-wasp) have been shown to result in semantic interference (slower reaction times and increased errors) whereas thematic relationships (e.g., bee-honey) have been shown to lead to semantic facilitation (faster reaction times and decreased errors). Across four studies, this dissertation analyzes temporal and spatiotemporal dynamics to further characterize the brain regions underlying lexical retrieval. I will present two non-stroke studies and two studies with individuals with left hemisphere stroke-induced aphasia. The overarching goal of this research is to determine the impact of semantic relationships on individuals with aphasia based on lesion location in order to inform individualized treatment practices for individuals with lexical retrieval deficits.