Navigating complex virtual environments at a range of gait speeds differentially modulates human sensorimotor and occipitoparietal electrocortical spectral power

Visually navigating environmental terrain on foot requires the human cerebral cortex to process multisensory information. To study the effects of gait speed and visual environment on human electrocortical spectral power dynamics during visually guided treadmill locomotion, we recorded high-density mobile electroencephalography (EEG) signals from 11 healthy subjects at a range of treadmill walking speeds (0.6, 0.8, 1.0, and 1.5 m/s) in three contrasting virtual reality scenes: (1) a stationary three-dimensional (3D) grid, (2) a moving forest trail, and (3) a moving city street that matched the treadmill's gait speed. Sensorimotor and parietal cortical regions showed greater theta band spectral power (4−8 Hz) and reduced the alpha (8−13 Hz), beta (13−30 Hz), and gamma band (> 30 Hz) power at faster walking speeds, indicative of greater cortical processing. In contrast, visual and parietal cortical processing increased while walking along a virtual forest trail and city street compared with a stationary 3D grid, but sensorimotor cortical processing increased in the absence of a moving visual environment. Differential responses among cortical structures while navigating contrasting environments at different speeds provide insight into sensory reweighting that can improve our understanding of cortical processing during gait and help identify biomarkers for predicting locomotor deficits and the risk of falls due to competing sensory demands.