Multilingualism in semantic dementia: language-dependent lexical retrieval from degraded conceptual representations

ABSTRACT

Background: Patients with the semantic variant of Primary Progressive Aphasia (svPPA) offer a unique opportunity to study the relationship between lexical retrieval and semantics, as they are characterised by progressive degradation of central semantic representations. However, there are few studies of how lexical retrieval across languages is affected in multilingual speakers.

Aims: We examine the impact of conceptual degradation in a trilingual patient (TC) with svPPA, to investigate whether the semantic memory breakdown affects her three languages similarly (English-Catalan-Spanish) in different linguistic tasks.

Methods & Procedures: We followed up her performance over one year in several tasks including: (a) naming with or without semantic interference contexts, (b) word translation, (c) word- and sentence-picture matching, (d) associative semantic priming and (e) language switching.

Outcomes & Results: There was significant response consistency between languages in the items that were relatively well-known and more semantically degraded, at least in a standard picture naming task. The patient’s sentence-to-picture matching did not show progressive deterioration in any language. However, some aspects of lexical retrieval showed language-dependency, as indexed by different patterns of performance in semantically-blocked cyclical naming task across languages.

Conclusions: These data suggest that while degradation of central semantic representations affects all languages, this deficit can be amplified or ameliorated by the strength of conceptual to lexical mappings, which varies across languages.

KEYWORDS:

• Bilingualism
• multilingualism
• semantic control
• semantic memory

Acknowledgments

We would like to dedicate this publication to the memory of Albert Costa. His scientific contributions have been of great importance to the field of bilingualism and we are infinitely grateful to him for having been part of this study as one of the authors. Marco Calabria was supported by the postdoctoral Ramón y Cajal fellowship (RYC-2013-14013) and Agencia Estatal de Investigación (AEI, National Research Agency) and Fondo Europeo de Desarrollo Regional (FEDER, European Regional Development Fund) under projects PSI2017-87784-R and RED2018-102615-T. This work was also supported by grants from the Catalan government (2017 SGR 268 and 2009 SGR 1521) and the European Union’s Seventh Framework Program for Research (no. 613465).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by European Regional Development Fund and  Agencia Estatal de Investigación (AEI, National Research Agency) (PSI2017-87784-R; RED2018-102615-T); Catalan government (2017 SGR 268; 2009 SGR 1521); FP7 Science in Society   (613465).