Abstract
Understanding the central nervous system responses to different threats of balance loss is instrumental for developments in behavioral neurophysiology and rehabilitation. Motor imagery (MI) and virtual reality (VR) are used to model postural threats. Cognitive–perceptual style, specifically field independence and field dependence, is known to modulate the postural response. However, data comparing responses to MI (internally generated threat) and VR (externally induced multisensory conflict) while accounting for cognitive–perceptual style remain insufficient. The degree of visual dependence, assessed using the Rod-and-Frame Test (RFT), was evaluated in 55 healthy young adults. Stabilographic parameters and surface electromyography were recorded during four stances (open eyes, closed eyes, MI of free fall, and VR simulation of free fall). At the systemic level, VR induced the most pronounced destabilization (q < 0.001). Greater RFT error (indicative of field dependence) was associated with the greatest instability (q < 0.01). At the neuromuscular level, VR was accompanied by increased gastrocnemius medialis activity (q < 0.0001). Micro-level analysis revealed significant changes in EMG signal complexity during VR and in association with RFT (q < 0.05 and q < 0.0001), suggesting differences in neuromuscular signal complexity. MI and VR differentially modulated postural control, with VR inducing stronger effects. Adaptations were detectable at multiple levels of adaptation, ranging from systemic destabilization to changes in neuromuscular coordination and micro-level muscle activity. Visual dependence was associated with greater instability. These data point to the potential value of accounting for individual variations in visual information use and highlight the need to further investigate these effects in clinical populations.