engleski

Differences in auditory processing of words and pseudowords in aphasic patients: ERP study

Objective: Lexicality effect in N400 has been confirmed in numerous ERP studies suggesting differential processing of words (W) compared to pseudowords (PW). Some electrophysiological studies in healthy individuals found long latency of peak activation and larger N400 amplitude for pseudowords as opposed to words. This may indicate prolonged search in the mental lexicon and more effortful processing of pseudowords than real words (Cheng et al., 2014, Curran, 1999). This effect is found to be more pronounced in aphasic patients (for both words and pseudowords) suggesting a prolonged memory search and increase of nervous activity in the cells surrounding damaged area (Kitade, 1999.) During the years, two most prominent types of aphasia have been recognized: (i) patients with dominant difficulties in expressive language and (ii) patients with dominant difficulties in comprehension. In most aphasias, patients have difficulties in finding words. Therefore, it is reasonable to expect that patients with aphasia will have difficulties in differentiating words and pseudowords. Methods: The aim of this paper is to compare the N400 effect during auditory lexical decision task between 5 patients with dominant difficulties in expressive language and 5 patients with dominant difficulties in comprehension. A group of healthy subjects matched by age, gender, handedness and education level will serve as a control group. All patients are included in language therapy in Polyclinic SUVAG, Zagreb. The stimuli in this research will be 120 disyllabic Croatian words and pseudowords (60 of each) specially chosen regarding the imageability and frequency of a word. Pseudowords are constructed from words using programme Wuggy- 0.1.9. The subject is required to decide whether the auditory presented stimuli is a real word or a pseudoword. Results: We will observe N400 effect differences during auditory lexical decision task between aphasic and control groups and differences between two types of aphasic patients.

aphasia; N400; word; pseudoword; lexical decision task

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