Cortical hemodynamic responses during action observation with and without audiovisual stimuli: a randomized...

This study investigated whether the inclusion of audiovisual cues during action observation influences cortical hemodynamic responses in healthy young adults. Cortical activation was measured using functional near-infrared spectroscopy (fNIRS) while participants observed action videos under two conditions: an action observation condition with additional audiovisual cues and a conventional action observation condition without such cues. The regions of interest included the primary motor cortex (M1), inferior frontal gyrus (IFG), and inferior parietal lobule (IPL), which are associated with action observation and sensorimotor integration processes. The results demonstrated significantly greater oxygenated hemoglobin (HbO) responses in the left M1 and bilateral IPL regions in the audiovisual action observation condition compared with the conventional condition (p < 0.05). However, no significant between-condition differences were observed in HbO responses within the IFG region, and no significant differences in deoxygenated hemoglobin (HbR) responses were identified in any region of interest. These findings suggest that audiovisual cues during action observation may modulate cortical processing of observed movements by enhancing attention to movement-related kinematic features and sensorimotor integration processes. However, further studies are required to determine whether these neurophysiological changes translate into improvements in motor performance or rehabilitation outcomes. Trial registration: Korean Clinical Research Information Service (KCT0011613), registered on 23 February 2026.