Presentation
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fNIRS Functional Connectivity in Chronic Post-Stroke Aphasia: A Pilot Study
Poster C58 in Poster Session C, Wednesday, October 25, 10:15 am - 12:00 pm CEST, Espace Vieux-Port
This poster is part of the Sandbox Series.
Erin Carpenter1,3, Emily Braun1, Manuel Marte1,3, Meryem Yücel2,3, David Boas2,3, Swathi Kiran1,3; 1Center for Brain Recovery, Department of Speech, Language & Hearing Sciences, Boston University, USA, 2Biomedical Engineering Department, Boston University, USA, 3Boston University Neurophotonics Center, Boston University, USA
Introduction: Functional near-infrared spectroscopy (fNIRS) provides an opportunity to investigate neural activation in more naturalistic settings, as participants wear a portable cap while engaging in real-world tasks (e.g., speaking, conversation, movie watching). fNIRS additionally provides an opportunity to investigate neural activation in clinical disorders such as aphasia, as it can be used with individuals who are either ineligible for fMRI or unable to tolerate fMRI examination due to reduced health status. fNIRS functional connectivity (FC) analyses have also recently gained popularity as a measure of neural network dynamics both at rest and during tasks. Therefore, the aim of this study is to investigate fNIRS FC during movie watching in people with aphasia (PWA) and two groups of neurotypical adults (HC). To date only two studies have investigated fNIRS FC in post-stroke aphasia, making this a relatively novel contribution to the field. Methods: 14 neurotypical young adults (YHC), 15 neurotypical older adults (OHC), and 17 PWA, completed a movie watching task in which they were first instructed to watch 68-second silent narrative videos, and then provide 15-second verbal summaries. Offline behavioral measures were administered to ascertain aphasia severity for PWA (WAB-R, BNT, and CLQT). fNIRS data were collected via a NIRx NIRSport2 continuous-wave NIRS device. The fNIRS montage consisted of 16 sources and 15 detectors forming 37 long-separation channels covering bilateral frontal, temporal and parietal regions. An ROI-based fNIRS FC analysis will be conducted to investigate intra- and inter-hemispheric connectivity in oxygenated- (HbO) and deoxygenated- (HbR) hemoglobin between regions of interest (ROIs) in the perisylvian language areas and contralateral homologues. The 68-second movie watching segments will be extracted and pre-processed via transformation of raw data to optical density, motion artifact correction, band-pass filtering, and conversion of optical density to hemoglobin concentration units via the Modified Beer-Lambert Law. For PWA, channels within lesioned areas will be manually excluded. Following pre-processing, 15 seconds will be removed from the beginning and end of each epoch to reduce potential effects of unstable signals. fNIRS signals will be averaged across channels to form broad ROIs (e.g., bilateral inferior frontal gyri (IFG), middle frontal gyri (MFG), precentral gyri, and temporal and parietal regions). FC maps will be obtained for each participant by computing the Pearson correlation coefficient r across each ROI on the time series data. Group FC maps will be computed by averaging individual FC maps. Linear mixed effects models will be conducted to compare FC values between groups across ROIs. For PWA, FC values will be correlated with assessment scores to investigate the relationship between fNIRS FC and aphasia severity. Anticipated Results: We anticipate PWA will show reduced intra-hemispheric and inter-hemispheric FC compared to HC due to damage within perisylvian language areas and neural network disruptions post-stroke. Additionally, we hypothesize that greater intra-hemispheric and inter-hemispheric connectivity will be associated with milder aphasia. Summary: These results will provide preliminary evidence on the use of fNIRS FC analyses to measure cortical network dynamics during naturalistic tasks in healthy and clinical populations.
Topic Areas: Disorders: Acquired, Methods