Influence of posture and eye condition on resting-state cortical activity in healthy young adults

Background and Aims Postural control is a core component of human motor behavior and relies on the continuous integration of vestibular, visual, and somatosensory information to stabilize the body in space. Although previous EEG studies have shown that body position and eye condition modulate cortical rhythms, most investigations focused on a limited set of postures or frequency bands, providing only a partial view of posture-related electrocortical dynamics. This study aimed to provide a comprehensive characterization of how different static postures (standing, seated, prone, and supine) and visual conditions (eyes-open vs. eyes-closed) jointly modulate cortical activity across multiple EEG frequency bands. Materials and Methods Electrocortical activity was recorded from 20 healthy adults (10 males, 10 females; 21-28 years) using a 16-channel EEG system in four postures (standing, seated, prone, supine) under both eyes-open and eyes-closed conditions. Power spectral density (3–35 Hz) was computed for delta, theta, slow alpha, mu (over central areas), fast alpha, beta, and low gamma bands on artifact-free 30-second epochs and normalized to total power. Scalp map analysis and Independent Component Analysis were applied to quantify topographical patterns and component-specific changes, and a two-way ANOVA with FDR correction was used to test the effects of posture and visual condition; K-means clustering (± 3 SD) was employed to identify and remove outlier components. Results Single-channel analyses revealed statistically significant differences between the eyes-open and eyes-closed conditions and between the four postures in different frequency bands examined and across spatial locations. Standing posture was associated with greater overall cortical activation than sitting, prone, and supine positions, in both the eyes-open and eyes-closed conditions. Comparing postures, eyes-closed trials showed consistently greater alpha power than eyes-open trials in the prone, sitting, and supine positions, while no significant alpha differences emerged between the visual conditions in standing posture. Conclusions Different static postures and eye conditions induce distinct and frequency-specific patterns of cortical activation, indicating that the electrocortical organization of postural control is both posture- and vision-dependent. The integrated use of qEEG, topographical scalp maps, and ICA-based analysis provides a detailed electrocortical signature of standing, seated, prone, and supine positions, offering mechanistic insight into motor control and potential diagnostic markers for postural and balance disorders. Public Significance Statements Posture and eye condition significantly modulate cortical activity across multiple frequency bands, revealing distinct spatial and spectral patterns. These results highlight the dynamic adaptability of the human brain to sensory and postural demands and provide a foundation for future applications in neurorehabilitation, movement analysis, and brain-computer interface development.