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Preliminary findings from functional Near Infrared Spectroscopy-based adaptive language mapping in people with post-stroke aphasia and neurologically healthy controls
Poster Session A - Sandbox Series, Thursday, October 24, 10:00 - 11:30 am, Great Hall 3 and 4
This poster is part of the Sandbox Series.
Erin Meier1, Veronica Fletcher1, Esprit Ange Andraos1, Lauren Rauert1, Isabelle Cotenoff1, Leanna Ugent1, Gengchen Wei1; 1Northeastern University
Introduction: Longstanding questions remain unanswered about the nature of beneficial functional reorganization of language in people with post-stroke aphasia (PWA), particularly the roles of left versus right hemisphere regions and the recruitment of the multiple demand (MD) network in recovery. Previous studies in aphasia have not sufficiently controlled for task difficulty, which may have contributed to mixed findings. Reliance on fMRI as the lead imaging modality for studying aphasia recovery also creates barriers to participation for some participants (due to e.g., MR contraindications), which further limits generalizability of findings. Therefore, in this sandbox presentation, we will present preliminary results from a functional Near-Infrared Spectroscopy (fNIRS) study in which participants with aphasia and age-matched healthy controls completed the Adaptive Language Mapping (ALM) Semantic Matching (Wilson et al., 2018) and Rhyme Judgment (Yen et al., 2019) tasks. The overarching aim is to determine the extent to which PWA and controls recruit language versus MD regions when task difficulty at the subject level is controlled. Method: Twenty PWA and 20 neurologically healthy adults will participate. The ALM fNIRS tasks follow an AB design with alternating blocks of experimental trials (semantic or rhyme judgment) and control trials (letter strings matching). Data are acquired with two daisy-chained 8x8 NIRx NIRSport2 devices with 16 sources and 16 detectors. The bilaterally symmetrical 44 long- and 8 short-channel montage covers classic language regions (split into inferior frontal gyrus (IFG) and temporal regions of interest [ROIs]) and portions of the bilateral MD network (including parts of rostrolateral (RLPFC) and dorsolateral (DLPFC) prefrontal cortices) (Fedorenko & Thompson-Schill, 2014). For both tasks, data processing will be done in Homer3 (Huppert et al., 2009) and activity in MD versus language regions (broadly defined based on Fedorenko et al., 2010) will be compared between groups. Preliminary Results: Thus far, Semantic Matching behavioral and fNIRS data have been collected and analyzed for 14 PWA and eight healthy controls. As expected for an adaptive task, accuracy did not differ between groups (t= 0.679, p= 0.507) but controls were significantly faster than PWA (t=14.51,p<0.001). At a group level, PWA and controls exhibited activity across channels within bilateral frontal and temporal language ROIs. Activity in the MD regions was observed for some participants, resulting in significant activity at the group level for PWA but not controls. Counter to predictions, PWA exhibited greater activity in language ROIs (bilaterally) than controls, but these findings may reflect reduced power with the current small sample of controls. Discussion: The overarching motivation for this study is to address a central methodological limitation of previous functional imaging studies in PWA (i.e., task difficulty confounds) using a promising imaging modality, fNIRS. The preliminary findings suggest that PWA activate MD regions, even when task difficulty is controlled for at a single subject level. Next steps include analysis of the complete dataset and investigation of relationships between fNIRS activity and language task data. During the sandbox presentation, feedback from attendees about important methodological (e.g., fNIRS modeling) and theoretical issues will be elicited.
Topic Areas: Disorders: Acquired,