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Monitoring Neural Activity during Motion-Force Control Task Using Functional Near-Infrared Spectroscopy

Real-time monitoring of neural activity during haptic tasks helps in enhancing scientific understanding of brain-motor relations. Considering the limitations of electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) measurements, in this paper, we address the feasibility of functional near-infrared spectroscopy (fNIRS) for monitoring neural activity during a motion-force control task. The task difficulty is modulated by changing the allowable trajectory and force tolerance. Cortical hemodynamic signals of 14 participants were recorded from the bilateral prefrontal, sensorimotor and occipital cortices. Results show that the brain activation over these brain regions and the functional connectivity between these regions increased when the motion-control became more challenging. In contrary, the activation and functional connectivity tended to decrease with the increase of the force-control difficulty. This study indicates the sensitivity of using fNIRS to differentiate difficulty levels in haptic tasks, and supports the potential of fNIRS in realistic haptic interaction.