Maintaining Task Performance Levels Under Cognitive Load While Walking Requires Widespread Reallocation of Neural Resources.

This study elucidates the neural mechanisms underlying increasing cognitive load while walking by employing 2 versions of a response inhibition task, the '1-back' version and the more cognitively demanding '2-back' version. By using the Mobile Brain/Body Imaging (MoBI) modality, electroencephalographic (EEG) activity, three-dimensional (3D) gait kinematics and task-related behavioral responses were collected while young adults (n = 61) performed either the 1-back or 2-back response inhibition task. Interestingly, increasing inhibitory difficulty from 1-back to 2-back during walking was not associated with any detectable costs in response accuracy, response speed, or gait consistency. However, the more difficult cognitive task was associated with distinct EEG component changes during both successful inhibitions (correct rejections) and successful executions (hits) of the motor response. During correct rejections, ERP changes were found over frontal regions, during latencies related to sensory gain control, conflict monitoring and working memory storage and processing. During hits, ERP changes were found over left-parietal regions during latencies related to orienting attention and subsequent selection and execution of the motor plan. The pattern of attenuation in walking-related EEG amplitude changes, during 2-back task performance, is thought to reflect more effortful recalibration of neural processes, a mechanism which might be a key driver of performance maintenance in the face of increased cognitive demands while walking. Overall, the present findings shed light on the extent of the neurocognitive capacity of young adults and may lead to a better understanding of how factors such as aging or neurological disorders could impinge on this capacity.