Optic flow modulates electrocortical activity during steady-state treadmill walking

Locomotion in real-life environments involves gathering visual information about the environment and regulating one's movements accordingly. Optic flow is a central visual cue that pedestrians use to control locomotor speed and direction. Neuroimaging studies examined cortical locomotor control primarily during treadmill walking without optic flow. In the present study, electroencephalography (EEG) data were recorded during a virtual reality treadmill walking task to obtain insights into the neural mechanisms involved in optic flow processing. Twenty-four healthy young participants performed a virtual reality task that involved periods of standing and walking with or without optic flow. Electrocortical activity data were recorded using a 64-channel EEG system and independent component analysis parsed out individual data into maximally independent components. Components from all participants were then grouped and to analyze task-relevant cortical activity, we examined theta, alpha, and beta power across the sensorimotor, parietal, and parieto-occipital regions. Results revealed significant electrocortical modulations across all regions examined. In the theta frequency band, differences between conditions occurred exclusively in the parieto-occipital region, where an increase in power was observed when walking with optic flow relative to walking without optic flow or standing. Modulations in the alpha frequency band occurred in all regions, with a decrease in sensorimotor and parietal power in both walking conditions relative to standing and a decrease in parieto-occipital power exclusively when walking with optic flow. These findings enhance our understanding of the cortical processes involved in locomotor control and provide foundational knowledge to contextualize deficits following neurological conditions.