A Multivariate Behavioural and Lesion-Symptom Mapping Investigation of the Core Aspects of Fluent Speech Production

EasyChair Preprint 6671

Abstract

Fluent speech production requires coordination of multiple processes, including syntax, sentence planning, semantics, and phonology. We used Quantitative Production Analysis (QPA) to derive a comprehensive set of 13 measures of narrative speech production, which were combined 8 measures of general language impairment and semantic and phonological deficits.

Behavioural data for 69 participants with post-stroke aphasia (right-handed, native English speakers) were entered into a principal component analysis (PCA) with bifactor rotation – a latent structure model where each item loads on a general factor that reflects what is common among the items, and orthogonal factors that explain variance not accounted for by the general factor. The PCA produced a 4-factor solution that accounted for 70.6% of the variance in the data, with factors corresponding to (1) length and complexity of output, (2) lexical syntax, (3) semantics, and (4) phonology.

Lesion data were available for 58 of the participants. Each factor score was analysed with multivariate lesion-symptom mapping using SCCAN, with sparseness optimised independently for each analysis using 8-fold cross-validation (CV). Deficits on the lexical-syntax factor were associated with damage in a relatively small set of fronto-parietal regions (sparseness = 0.216, CV r = 0.517, p < 0.001). Deficits in length and complexity of speech output were associated with a somewhat larger temporo-parietal region (sparseness = 0.576, CV r = 0.603, p < 0.001). For comparison (and not surprisingly), overall aphasia severity was associated with damage to a large portion of the lesion territory (sparseness = 0.798, CV r = 0.653, p < 0.001).

These results suggest a cognitive and neural dissociation between lexical-level syntactic production and the length, complexity, and structure of narrative speech; both of which are relatively separate from lower-level phonological and semantic abilities.

Keyphrases: Lesion-symptom mapping, factor analysis, fluency, syntax

@booklet{EasyChair:6671,
  author    = {Eleni Zevgolatakou and Melissa Thye and Daniel Mirman},
  title     = {A Multivariate Behavioural and Lesion-Symptom Mapping Investigation of the Core Aspects of Fluent Speech Production},
  howpublished = {EasyChair Preprint 6671},
  year      = {EasyChair, 2021}}