Neural connectivity and balance control in aging: Insights from directed cortical networks during sensory conflict

Balance control is crucial for stability during daily activities, relying on the integration of sensory inputs from the visual, vestibular, and somatosensory systems. Aging impairs the efficiency of these systems, leading to an increased risk of falls; however, the neural mechanisms underlying this decline, particularly under sensory conflict, are not fully understood. This study investigated the effects of aging on neural connectivity and sensory integration during balance tasks. Ninety-six participants (47 older adults and 49 young adults) were subjected to balance perturbation tasks under sensory-congruent and sensory-conflict conditions using a virtual reality headset and rotating platform. Behavioral measures, including postural sway and perceptual accuracy, were recorded. Electroencephalography (EEG) data were analyzed using generalized partial directed coherence (GPDC) to assess the directed functional connectivity and network efficiency. Older adults exhibited significantly greater postural sway, reduced perceptual accuracy, and a diminished ability to detect sensory conflicts than young adults, particularly under conflict conditions. As demonstrated by connectivity analysis, young adults showed adaptive shifts in connectivity from the visual to somatosensory regions during sensory conflict. In contrast, older adults demonstrated a less adaptable mode of connectivity. At the same time, global efficiency and clustering coefficients of young adults were higher, suggesting more effective and modular brain networks. Correlation analyses in older adults revealed that higher visual cortex efficiency was linked to lower postural sway specifically during sensory conflict, whereas higher motor cortex efficiency was associated with greater sway only under sensory-congruent conditions. In short, neural adaptability is vital in sensory integration and balance control. Due to decreased neural flexibility and network efficiency in older adults, their sensory reweighting was undermined and instability increased during the sensory conflict. These findings establish a foundation for development of targeted interventions to strengthen balance and lower the risks of falls in older adults.