Reduced parietal to frontal functional connectivity for dynamic balance in late middle-to-older adults.

In this study, we investigated the changes in functional connectivity between cortical regions for balance control during a challenging balance task with advancing age. Fourteen young and fourteen late middle-to-older adults performed a challenging balance task that manipulated somatosensory information while their brain activity was recorded using electroencephalography. Both groups showed common activation regions within the posterior cingulate cortex (PCC) and premotor cortex (PMC) during the balance task. The late middle-to-older group showed significantly weaker PCC to PMC functional connectivity than the young group. This finding indicated poor sensorimotor processes during altered reliance on somatosensory inputs for balance maintenance. The regularity of foot center of pressure fluctuations measured using sample entropy was greater in the late middle-to-older group than the young group, suggesting a shift from automatic control to cognitive control of balance. Weaker PCC to PMC connectivity in late middle-to-older adults was associated with greater regularity of foot center of pressure fluctuations. In late middle-to-older adults, an additional cortical region was activated, the prefrontal cortex, during the balance task. Our findings suggest a shift from the parietal-to-frontal sensorimotor network to the prefrontal network for dynamic control of balance with advancing age.