The impact of interactive motor-cognitive dual tasking on brain activation, functional connectivity, and behavioral performance in healthy adults: an fNIRS study.

Objective: This study aimed to explore how varying levels of interactive motor-cognitive dual task difficulty affect brain activation, functional connectivity (FC), and behavioral performance in healthy adults using functional near-infrared spectroscopy (fNIRS).

Methods: We recruited 28 healthy participants to perform interactive motor-cognitive dual task at three difficulty levels: easy task (ET), medium task (MT), and difficult task (DT). The tasks involved walking while simultaneously engaging in cognitive challenges. A continuous-wave fNIRS system was used to collect fNIRS data during the task, focusing on 10 regions of interest (ROIs): left/right prefrontal cortex (LPFC/RPFC), left/right dorsolateral prefrontal cortex (DLPFC/DRPFC), left/right premotor cortex (LPMC/RPMC), left/right sensorimotor cortex (LSC/RSC), and left/right motor cortex (LMC/RMC). Simultaneously, the subjects' gait data during walking were collected using an Inertial Measurement Unit (IMU) sensor, and their cognitive performance was recorded by the researchers.

Results: Statistical analysis revealed statistically significant differences in the mean HbO levels among the three groups for the DRPFC, LPMC/RPMC, RSC, and LMC/RMC regions. Additionally, significant differences were found in the activation of channels 3, 18, 24, 25, 28, and 29 across the three groups. The group-averaged FC in the DT (0.61 ± 0.21) was significantly higher than that in the ET (0.46 ± 0.21, = 0.023). ROI-to-ROI FC analysis showed significant differences among the three groups in the LSC∼RPMC, RPMC∼RSC, and RSC∼RMC connections. The lateralization index (LI) ranged from 0.10 to 0.35, indicating a predominant right-brain lateralization during the interactive motor-cognitive dual task. Additionally, compared to the MT, both speed and stride length, as well as cognitive performance, were lower during the DT.

Conclusion: We found that increased task difficulty heightened activation in the premotor and motor cortices, with a tendency toward right hemisphere dominance. Higher task difficulty also strengthened FC, particularly in motor-related regions, indicating greater neural coordination. Behaviorally, participants exhibited slower gait parameters and reduced cognitive performance as task complexity increased, highlighting the impact of dual-task interference.