Distinct Aspects of Phrasal Production Are Associated with Distinct Lesion Correlates in Chronic Post-Stroke Aphasia

EasyChair Preprint no. 6554

Abstract

We used the Morphosyntactic Generation Task (MorGen) to assess the lesion correlates of different aspects of phrasal production in people with chronic aphasia. The MorGen is designed to elicit two-word noun phrases involving different modifiers: numeral quantifiers (one vs. two), color adjectives (red vs. blue), size adjectives (big vs. small) and inflectional morphology (plural -s vs. null inflection, possessive -s). Here we report lesion-symptom mapping analyses in chronic post-stroke aphasia, in order to ascertain whether impaired production of features are associated with distinct lesion correlates. Twenty-six people with chronic post-stroke aphasia were assessed on the MorGen. The MorGen presents two simultaneous images in each trial, which contrast based on one feature (number, color, size, possession). Subjects are asked to describe the target image using two words. We assessed inflectional morphology by averaging across performance on plural and possessive -s and assessed color and number separately. We tested three regions of interest (ROIs): posterior temporal lobe, Broca’s area, and anterior arcuate fasciculus. Performance on the three measures of interest dissociated from each other. Color adjective deficits involved posterior temporal lobe, similar to those described previously for deficits on picture naming tasks with noun targets. Deficits in inflectional morphology were primarily associated with damage to arcuate fasciculus and, to a lesser extent, Broca’s area. This is consistent with the need to coordinate posterior temporal and inferior frontal regions with each other to select the correct inflectional form given the structural context. Finally, deficits on numeral quantifiers primarily implicated damage to Broca’s area, which is consistent with a role for this region in retrieving functional elements. In sum, production of different morphemes requires overlapping but distinct brain systems.

Keyphrases: aphasia, Lesion-symptom mapping, morphology, syntax

@Booklet{EasyChair:6554,
  author = {William Matchin and Melissa Stockbridge and Alexandra Walker and Bonnie Breining and Argye Hillis and Julius Fridriksson and Gregory Hickok},
  title = {Distinct Aspects of Phrasal Production Are Associated with Distinct Lesion Correlates in Chronic Post-Stroke Aphasia},
  howpublished = {EasyChair Preprint no. 6554},

  year = {EasyChair, 2021}}