Lexical-semantic processing in aphasia: integrating behavioral data and electrophysiological findings

Abstract Introduction This study investigates lexical-semantic processing in persons with aphasia (PWA) and neurologically healthy individuals (NHI). Lexical-semantic processing is critical for language comprehension and involves retrieving and integrating words within a context. The study aims to compare the performance of PWA and NHI using behavioral tasks and event-related potentials (ERPs). Method Twenty native Kannada speakers, including 10 PWA and 10 NHI, participated in lexical decision (LDT) and semantic judgment tasks (SJT). Reaction time and accuracy were measured behaviorally, and N400 ERP components were recorded to assess lexical-semantic processing. Stimuli included words and non-words for LDT and related and unrelated word pairs for SJT. Behavioral responses were recorded using DMDX software, and ERPs were captured with a Compumedics Neuroscan system. Results PWA exhibited significantly slower reaction times and lower accuracy compared to NHI in both tasks, with SJT being more challenging. N400 latency was delayed, and amplitude was less negative in PWA, indicating impaired processing. Topographical analysis revealed widespread cortical activation in PWA, suggesting neural reorganization. Discussion The findings demonstrate compromised lexical-semantic processing in PWA, with slower, less accurate responses and altered ERP patterns. The study highlights the complexity of semantic judgment tasks and the potential for neural reorganization in aphasia. Future research should include more aphasia subtypes and employ additional electrodes for comprehensive ERP analysis, enhancing understanding of recovery mechanisms.