The Left Posterior Parietal Cortex Contributes to the Selection Process for the Initial Swing Leg in Gait Initiation

Area of Science:

• Neuroscience
• Motor Control
• Human Locomotion

Background:

• Gait initiation is a complex motor task involving the selection of an initial swing leg.
• The neural mechanisms underlying this selection process, particularly the role of specific cortical regions, are not fully understood.

Purpose of the Study:

• To investigate the contribution of the left posterior parietal cortex to the selection of the initial swing leg during gait initiation.
• To explore the influence of transcranial magnetic stimulation (TMS) on gait initiation parameters.

Main Methods:

• Healthy participants performed gait initiation in response to an auditory cue.
• Transcranial magnetic stimulation (TMS) was applied over specific scalp locations (P3, P4, F3, F4) during gait initiation.
• A within-subject design compared on-TMS and off-TMS conditions to assess the effects of stimulation.

Main Results:

• Applying TMS over the left posterior parietal cortex (P3) significantly reduced the probability of selecting the right leg as the initial swing leg.
• TMS over F4 or P4 shortened the anticipatory postural adjustment (APA) latency for left-leg initiation.
• TMS over P3 or P4 shortened the APA latency for right-leg initiation.

Conclusions:

• The left posterior parietal cortex plays a significant role in the selection of the initial swing leg during gait initiation.
• Cortical processes influencing the motor execution of gait initiation, particularly for the right leg, may be linked to the initial swing leg selection mechanism.