Neural oscillations during motor imagery of complex gait: an HdEEG study

Abstract

The aim of this study was to investigate differences between usual and complex gait motor imagery (MI) task in healthy subjects using high-density electroencephalography (hdEEG) with a MI protocol. We characterized the spatial distribution of α- and β-bands oscillations extracted from hdEEG signals recorded during MI of usual walking (UW) and walking by avoiding an obstacle (Dual-Task, DT). We applied a source localization algorithm to brain regions selected from a large cortical-subcortical network, and then we analyzed α and β bands Event-Related Desynchronizations (ERDs). Nineteen healthy subjects visually imagined walking on a path with (DT) and without (UW) obstacles. Results showed in both gait MI tasks, α- and β-band ERDs in a large cortical-subcortical network encompassing mostly frontal and parietal regions. In most of the regions, we found α- and β-band ERDs in the DT compared with the UW condition. Finally, in the β band, significant correlations emerged between ERDs and scores in imagery ability tests. Overall we detected MI gait-related α- and β-band oscillations in cortical and subcortical areas and significant differences between UW and DT MI conditions. A better understanding of gait neural correlates may lead to a better knowledge of pathophysiology of gait disturbances in neurological diseases.

Figure 1

Motor imagery tasks. (A) Usual Walking (UW) condition. The picture shows a straight pathway; (B) Dual-Task (DT) condition. The picture shows a straight pathway with a hurdle positioned half-way on the right side. The black arrow indicates the task progression. The first red line (GO!) indicates the starting point of MI task; the second red line indicates the end of the MI task (STOP). The grey box (Baseline) indicates the time window selected as ERDs baseline analysis. The two grey boxes (UW and DT ERDs analysis) indicate the time window selected for ERDs analysis during UW and DT conditions.

Figure 2

Group-level analysis: significant ERDs (t-values, p_FDR < 0.05) in α and β bands in the two imagery conditions.

Figure 3

β band correlations between MI ability test scores and ds%.