Influence of directional orientations during gait initiation and stepping on movement-related cortical potentials.

The influence of directional orientation on movement-related potentials (MRPs) during gait initiation and stepping has been investigated in the present study, as well as possible effects caused by the distinction between gait initiation and stepping. Accordingly, electroencephalographic (EEG), electromyographic (EMG) and kinetic recordings were conducted while eight subjects initiated gait and were stepping in three different directions (namely, forward, backward and lateral). Five different movement-related potentials were extracted from the EEG recordings and statistically analyzed. Movement parameters were extracted from kinetic recordings and statistically analyzed as well. Results indicated that variations in directional orientation of gait and stepping were associated to changes in MRPs, but the associations between movement parameters and MRPs were conditional to the kind of task performed. Gait tasks were mainly differentiated in early MRPs while stepping tasks were more differentiated in late MRPs, indicating that differences between gait initiation and stepping might be associated with different levels of preparation and execution. Apparently the changes found in the movement-related potentials were not simply caused by changes in the sensorial input due to perception of the spatial environment, but rather because of variations in the movement kinematics and kinetics.