Semantic Processing in Bilingual Aphasia: Evidence of Language Dependency

Area of Science:

• Neurolinguistics
• Cognitive Neuroscience
• Psycholinguistics

Background:

• Aphasia often involves lexical retrieval deficits, linked to impaired semantic control, which is partly dependent on executive control (EC).
• The impact of brain damage on semantic control in a non-dominant language is under-explored.
• Research on semantic processing overlap between languages in healthy individuals is inconclusive.

Purpose of the Study:

• To investigate the effect of brain damage on semantic processing in bilingual individuals with aphasia.
• To compare performance on semantic control tasks in both dominant and non-dominant languages.
• To explore the relationship between lexical-semantic deficits and domain-general executive control.

Main Methods:

• A semantically blocked cyclic naming task was used to assess semantic interference in Catalan-Spanish bilinguals with aphasia and controls.
• A word-picture matching task in a mixed-language condition evaluated comprehension.
• A conflict monitoring task assessed executive control (EC) deficits.

Main Results:

• Bilingual patients with aphasia performed worse than controls on both language tasks in their non-dominant language.
• A significant correlation was found between executive control (EC) task performance and semantic interference magnitude, specifically in the non-dominant language.
• Lexical retrieval deficits in bilingual aphasia appear exacerbated in the non-dominant language under high semantic competition.

Conclusions:

• Lexical retrieval is selectively impaired in bilinguals with aphasia in their non-dominant language, potentially due to increased inhibition.
• Lexico-semantic impairments are linked to conflict monitoring deficits, indicating overlap between executive control and semantic control.
• These findings highlight the intricate relationship between language dominance, executive functions, and semantic processing in aphasia.