Resting-state functional connectivity for determining outcomes in upper extremity function after stroke: A functional...

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Medical Imaging

Background:

• Functional near-infrared spectroscopy (fNIRS) is a non-invasive neuroimaging technique used to map brain activity.
• Stroke recovery involves complex changes in brain functional networks.
• Upper extremity motor impairment is a common and significant challenge for stroke survivors.

Purpose of the Study:

• To investigate resting-state functional connectivity (RSFC) patterns using fNIRS in subacute stroke patients with varying degrees of upper extremity motor impairment.
• To determine the association between Fugl-Meyer motor assessment of upper extremity (FMA-UE) scores and RSFC in different brain regions.

Main Methods:

• Forty-nine subacute stroke patients were classified into mild, moderate, and severe upper extremity motor impairment groups based on FMA-UE scores.
• Resting-state fNIRS data were collected over seven regions of interest (ROIs), including bilateral DLPFC, MPFC, M1, and S1.
• Functional connectivity (FC) was calculated, and group-level and ROI-level comparisons were performed. Spearman's correlation analyses examined the association between FMA-UE scores and RSFC.

Main Results:

• A significant difference in group-averaged FC was observed among the three impairment groups (p=0.04).
• The mild impairment group exhibited significantly higher FC than the severe group (p=0.013).
• The severe group showed significantly lower FC in ipsilesional DLPFC-M1 connections compared to the mild group (FDR-corrected p<0.05). Significant correlations were found between FMA-UE scores and FC in DLPFC-associated regions.

Conclusions:

• Different degrees of post-stroke upper extremity motor impairment are associated with distinct RSFC patterns, particularly involving the DLPFC and M1.
• The ipsilesional DLPFC plays a crucial role in motor-related plasticity, as indicated by its association with FMA-UE scores.
• These findings offer insights into neurophysiological mechanisms of motor impairment and recovery, suggesting the ipsilesional DLPFC-bilateral M1 network as a potential neuromodulation target.