Multimodal brain-body analysis of prefrontal cortex activity and postural sway with sensory manipulation

The involvement of different brain areas in postural balance control under various sensory inputs remains unknown. This study aims to investigate the effects of different sensory manipulations on prefrontal cortex (PFC) activity and postural sway as well as the associations between PFC activity and postural sway in different sensory conditions. To this end, younger participants underwent eight standing tests with single (visual, vestibular, and somatosensory) and double sensory manipulations. Functional near-infrared spectroscopy was employed to capture their cortical activation in the dorsolateral (DL), ventrolateral (VL), and dorsomedial (DM) PFC. An inertial measurement unit was also used to assess their postural sway. Results showed greater DMPFC and DLPFC activation with vestibular, somatosensory, and double sensory manipulations, and increased DMPFC activation with visual manipulation. These results indicate that the DMPFC and DLPFC are more involved in sensory integration during standing. Postural sway measures increased in response to double and some single sensory manipulations, implying greater regulatory activity and reduced postural stability and sway smoothness. Some meaningful correlations were also found between PFC activity and postural sway measures. Increased DMPFC activation during somatosensory and vestibular manipulation was correlated with better postural stability, highlighting its role in these sensory conditions. A negative correlation was found between DMPFC activity and postural sway in the anteroposterior direction, but not the mediolateral, indicating that DMPFC activity modulation depends on sway direction. The findings of this study lead to a better understanding of the functional architecture of the PFC and are useful for designing better clinical assessments, rehabilitation programs, and assistive devices.