UC San Diego

The study of human locomotion and spatial navigation in a naturalistic paradigm is vastly understudied. It has recently been shown that electrocortical activity is coupled to steady-speed human gait. Previous work has also shown a relation between delta/theta-band (2-8 Hz) activity over parietal cortex and a subject's spatial location. Our aim was to determine if the same electrocortical findings in steady-speed walking were present in unrestricted, self-initiated ambulation, and if similar spatial context related neural signals could be found in a different spatial task. We simultaneously recorded electroencephalography (EEG) and full body motion of twelve young healthy subjects walking at two self- directed speeds, slow and brisk, through a 4x4m square spiral track. The EEG data were filtered and cleaned using semi-automated means and infomax Independent Component Analysis (ICA), allowing for removal of muscular, ocular, and other artifactual signals. Gait normalized Event Related Spectral Perturbations (ERSP) were obtained, showing significant cyclical intra-stride changes in power of the delta/theta-band (3-8 Hz) in the 'slow' speed condition, and alpha/beta-band (9-25 Hz) in the 'brisk' condition only. Significant delta/theta-band decreases in power were also observed near the center point of the swing phase of each leg in the 'brisk' condition. Additionally, the data from parietal electrodes were filtered from 2-8 Hz, the analytic amplitudes were calculated and co-localized to the subject's position in space. Analysis of these data over each segment of the spiral showed significant activity in the same relative spatial location across segments. Further examination using these techniques could lead to a better understanding of diseases with motor and spatial navigation deficits, like Parkinson's and Alzheimer's disease