Functional Near-Infrared Spectroscopy (fNIRS) imaging of Functional Connectivity and Task-Activity in the Cerebral Cortex of patients with mTBI
Date
2020-09-04
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Abstract
Functional near-infrared spectroscopy (fNIRS) is a novel neuroimaging technology which has shown potential as a biomarker of mTBI. In this thesis, we developed novel easy-to-use software for analyzing measures of functional coherence and task-activity in the brain using fNIRS. We then applied this software to characterize fNIRS measures in healthy individuals, and to investigate whether fNIRS is sensitive to altered brain activity following mTBI. The software provides a full pipeline for preprocessing and utilizes wavelet analysis methods to estimate coherence, variability, phase, and power of fNIRS hemodynamic data. Using the software, we investigated the within-subject and between-subject variability of fNIRS coherence in healthy adults, finding poor-moderate between-subject reproducibility and high within-subject reliability, as well as task-effects of reduced interhemispheric coherence (IHC) and reduced power of low-frequency oscillations (LFOs) that were focused in the prefrontal brain regions during execution of a working memory task. In youth 30 days following mTBI, reduced IHC and IHC variability in the prefrontal cortex was observed during working memory, as well as a group effect of mTBI on power of LFO, compared to controls. In adults, fNIRS was used to study brain activity in pre, post, and two weeks following therapeutic repetitive transcranial magnetic stimulation (rTMS) as a treatment for persistent mTBI-related headache. In this case series, abnormal activation in the prefrontal cortex during working memory was observed on fNIRS in one subject prior to treatment which persisted at the post-treatment time point, but appeared to normalize by two weeks post-treatment, in comparison to controls, suggesting fNIRS as a potential method to study treatment effect in therapeutic rTMS trials in patients with mTBI. In this thesis, software was developed and published in the online repository GitHub, and utilized to characterize the variability and task effect in healthy individuals, informing future studies wanting to apply wavelet methodologies to investigate clinical populations. In subsequent observational studies, we observed alterations in fNIRS brain activity in pediatric patients with mTBI 1 month post-injury, as well as in an adult mTBI patient undergoing rTMS treatment, suggesting a potential role for fNIRS as an accessible technology to study mTBI-associated pathophysiology.
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Keywords
mTBI, Concussion, fNIRS, Functional Connectivity
Citation
Duszynski, C. (2020). Functional Near-Infrared Spectroscopy (fNIRS) imaging of Functional Connectivity and Task-Activity in the Cerebral Cortex of patients with mTBI (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.