engleski

Auditory lexical – semantic processing in aphasia during semantic categorization task: ERP study

Objective: N400 has proved to be a robust ERP component and has been regarded as an electrophysiological correlate of various aspects of language processing: semantic integration, facilitated lexical access, semantic memory search etc. According to previous neuropsychological, neuroimaging and some electrophysiological studies on semantic categorization in healthy volunteers animate and inanimate categories differentially modulate N400 at fronto-central sites. Although there are controversies about these differences, some electrophysiological studies on healthy individuals have shown that N400 effect begins earlier and have smaller amplitude for animate than inanimate words due to their easier processing (Proverbio et al., 2007 ; Kiefer, 2001 ; Bermeitinger, 2010 ; Costanzo et al., 2013). As supported by available literature animate stimuli are easier for categorization than inanimate ones because they represent more homogenous category sharing more perceptual and semantic features. Some behavioral studies on brain damaged patients have shown that they selectively lost semantic knowledge on animate categories while retaining knowledge on inanimate ones, although the opposite pattern has also been observed. However, there are no ERP studies on aphasia using semantic categorization task. The aim of this study is to investigate semantic processing in patients with aphasia with different levels of auditory comprehension disorder using semantic categorization task. Methods: We will utilize event related brain potentials (ERP) to characterize subjects' responses as they made superordinate categorical decision (animate vs. inanimate) for about 200 auditory presented disyllabic words. Three groups of participants will be included in the research: 5 aphasics with predominant language comprehension disorder, 5 aphasics with predominant language expression disorder and 10 controls. Results: We will observe N400 differences between groups depending on stimulus types (animate vs. inanimate) and prototypicality of category examples.

aphasia ; comprehension disabilities ; lexical-semantic processing ; superordinate categorization ; ERP ; N400

nije evidentirano