Semantic and lexical features of words dissimilarly affected by non-fluent, logopenic, and semantic primary progressive aphasia

Jet M J Vonk, Roel Jonkers, H Isabel Hubbard, Maria Luisa Gorno-Tempini, Adam M Brickman, Loraine K Obler

Research output: Contribution to journalArticleAcademicpeer-review


OBJECTIVE: To determine the effect of three psycholinguistic variables-lexical frequency, age of acquisition (AoA), and neighborhood density (ND)-on lexical-semantic processing in individuals with non-fluent (nfvPPA), logopenic (lvPPA), and semantic primary progressive aphasia (svPPA). Identifying the scope and independence of these features can provide valuable information about the organization of words in our mind and brain.

METHOD: We administered a lexical decision task-with words carefully selected to permit distinguishing lexical frequency, AoA, and orthographic ND effects-to 41 individuals with PPA (13 nfvPPA, 14 lvPPA, 14 svPPA) and 25 controls.

RESULTS: Of the psycholinguistic variables studied, lexical frequency had the largest influence on lexical-semantic processing, but AoA and ND also played an independent role. The results reflect a brain-language relationship with different proportional effects of frequency, AoA, and ND in the PPA variants, in a pattern that is consistent with the organization of the mental lexicon. Individuals with nfvPPA and lvPPA experienced an ND effect consistent with the role of inferior frontal and temporoparietal regions in lexical analysis and word form processing. By contrast, individuals with svPPA experienced an AoA effect consistent with the role of the anterior temporal lobe in semantic processing.

CONCLUSIONS: The findings are in line with a hierarchical mental lexicon structure with a conceptual (semantic) and a lexeme (word-form) level, such that a selective deficit at one of these levels of the mental lexicon manifests differently in lexical-semantic processing performance, consistent with the affected language-specific brain region in each PPA variant.

Original languageEnglish
Pages (from-to)1011-1022
Number of pages12
JournalJournal of the International Neuropsychological Society
Issue number10
Early online date12 Sept 2019
Publication statusPublished - Nov 2019
Externally publishedYes


  • Age of acquisition
  • Lexical frequency
  • Neighborhood density
  • Psycholinguistics
  • Word processing
  • Mental lexicon
  • Dementia


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