The effects of time constraints on electrocortical dynamics underlying obstacle avoidance while walking

A growing body of literature has characterized the extensive and widespread engagement of cortical resources during the execution of locomotor adaptations. However, evidence suggests that the extent of cortical regulation involved in such adaptations is modulated by the available time to respond. In this study, a treadmill-based virtual reality paradigm was used to examine the electrocortical oscillations associated with obstacle avoidance under short versus long available response times (ARTs). Electroencephalography data were recorded from healthy young adults as they stepped over virtual obstacles. These obstacles were presented in far space, allowing either a short (1.5 sec) or long (4 sec) ART between their presentation and clearance. Data were parsed with independent component analysis and clustered within the prefrontal, sensorimotor, parietal and occipital regions. Distinct spectral signatures were observed across all cortical regions, characterized by transient synchronizations shortly after obstacle presentation and immediately prior to clearance. Compared to the long ART condition, the short ART condition elicited stronger prefrontal theta, alpha, and beta synchronizations. During clearance, long ARTs were associated with a sensorimotor alpha desynchronization during obstacle clearance; however, such desynchronization was largely absent under short ART. Taken together, these findings suggest that tighter temporal constraints during obstacle avoidance enhance prefrontal involvement and decrease sensorimotor network activation. Such time-dependent cortical dynamics offer new insights into the neural mechanisms underlying locomotor adjustments that can inform our understanding of locomotor deficits in aging and neurological disorders.