Investigating fNIRS Reliability for Uncovering Fatigue and Stress Related Topological Properties of Cortical Areas (Extended Abstract)

This study investigates functional connectivity between and within the prefrontal cortex (PFC) and motor regions (M1) during a fatiguing elbow flexion task under stress using data collected from functional nearinfrared spectroscopy (fNIRS) device. Thirty healthy adults performed the task under two conditions: control (exercise only) and stress (exercise with cognitive stressors). Graph properties of real brain network, including functional integration (global efficiency), and functional specialization (clustering coefficient, and modularity) were calculated and compared against randomized networks. Results showed that while functional integration remained stable under stress, functional specialization increased due to weakened PFC-to-M1 connectivity. This disrupted connectivity impaired PFC’s influence on M1, contributing to delayed fatigue under stress. Furthermore, the study also evaluates the reliability of fNIRS for connectivity assessment. Our findings suggest that while fNIRS effectively captures higher-level functional organization between the prefrontal and motor regions, it lacks the spatial resolution needed to detect finer specializations within these regions.