Resting-State Functional Magnetic Resonance Imaging Connectivity Between Semantic and Phonological Regions of Interest May Inform Language Targets in Aphasia

J Speech Lang Hear Res. 2020 Sep 15;63(9):3051-3067. doi: 10.1044/2020_JSLHR-19-00117. Epub 2020 Aug 5.

Abstract

Purpose Brain imaging has provided puzzle pieces in the understanding of language. In neurologically healthy populations, the structure of certain brain regions is associated with particular language functions (e.g., semantics, phonology). In studies on focal brain damage, certain brain regions or connections are considered sufficient or necessary for a given language function. However, few of these account for the effects of lesioned tissue on the "functional" dynamics of the brain for language processing. Here, functional connectivity (FC) among semantic-phonological regions of interest (ROIs) is assessed to fill a gap in our understanding about the neural substrates of impaired language and whether connectivity strength can predict language performance on a clinical tool in individuals with aphasia. Method Clinical assessment of language, using the Western Aphasia Battery-Revised, and resting-state functional magnetic resonance imaging data were obtained for 30 individuals with chronic aphasia secondary to left-hemisphere stroke and 18 age-matched healthy controls. FC between bilateral ROIs was contrasted by group and used to predict Western Aphasia Battery-Revised scores. Results Network coherence was observed in healthy controls and participants with stroke. The left-right premotor cortex connection was stronger in healthy controls, as reported by New et al. (2015) in the same data set. FC of (a) connections between temporal regions, in the left hemisphere and bilaterally, predicted lexical-semantic processing for auditory comprehension and (b) ipsilateral connections between temporal and frontal regions in both hemispheres predicted access to semantic-phonological representations and processing for verbal production. Conclusions Network connectivity of brain regions associated with semantic-phonological processing is predictive of language performance in poststroke aphasia. The most predictive connections involved right-hemisphere ROIs-particularly those for which structural adaptions are known to associate with recovered word retrieval performance. Predictions may be made, based on these findings, about which connections have potential as targets for neuroplastic functional changes with intervention in aphasia. Supplemental Material https://doi.org/10.23641/asha.12735785.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aphasia* / diagnostic imaging
  • Aphasia* / etiology
  • Brain / diagnostic imaging
  • Brain Mapping
  • Humans
  • Language
  • Magnetic Resonance Imaging
  • Semantics
  • Stroke* / complications
  • Stroke* / diagnostic imaging

Grant support

This work was supported by National Health and Medical Research Council Project Grant 632763 and Australian Research Council Future Fellowship FT120100355 (Principal Investigator: Kirrie J. Ballard). The authors acknowledge the contributions of the members of the University of New Hampshire Cognition, Brain and Language Team (Hannah Franz, Gwyneth Horne, Mara Callahan, Jessica Lee, and Elizabeth Kinney) and their help in organizing and analyzing the data. They also thank Cathy Price and the Predicting Language Outcomes and Recovery After Stroke laboratory for conducting the automated lesion identification for this project.