Evidence for Cognitive Processes Involved in the Control of Steady State of Walking in Healthy Subjects and after Cerebral Damage

Objective. The involvement of cognitive processes in the control of walking at steady state was studied in 10 healthy subjects and 18 subjects after unilateral vascular brain damage. A dual task paradigm was used to compare the performance level of a probe reaction time (RT) in sitting (simple task) and during standing or walking on a treadmill (dual task conditions). In this latter condition, RTs were classified and analyzed in relation to the different phases of the gait cycle. Results. The results show a marked increase in RT while walking compared to sitting and standing only in stroke subjects. Specific changes in RTs related to the gait cycle phases were observed in both healthy subjects and those after brain damage. It is concluded that walking at steady state is attentionally demanding. The phase-dependent modulations of the RTs suggest that cognitive processes may play a role in the control of the step cycle. The increase of attentional demand during walking in subjects who had suffered a stroke varies, depending on severity of impairments of walking but also on a reduced general attentional capacity. The dual task paradigm provides a sensitive tool in the assessment of walking ability in stroke subjects.