Arm swing in healthy and Parkinsonian gait
Human bipedal gait exhibits a coherent four-limb movement pattern comparable to that observed in quadrupedal gait, with upper limbs swinging in anti-phase with both opposite upper and ipsilateral lower limbs. Although the role of these upper limb movements in bipedal gait is not as obvious as in quadrupedal gait, one proposed advantage concerns the modulation of neural control to maintain the cyclic gait pattern. This dissertation broadens the knowledge on this supporting role of arm swing in gait control in healthy participants and patients with Parkinson’s Disease (PD), a neurodegenerative disease that affects both lower-limb gait and gait-related arm swing. We used a multi-level approach including electroencephalography, electromyography and gait analyses to explore how this is organized within and between brain, muscle and movement level, respectively. We demonstrated that arm swing can drive and shape lower limb muscle activity via subcortical and cortical pathways, in which the supplementary motor area plays a central role. As a result of this neural interlimb coupling, we found that disturbed upper and lower limb movements in PD gait are correlated. These findings provide neural support for the observed facilitating effect of arm swing instructions on gait initiation and continued gait in PD patients. Overall, this dissertation supports that arm swing instructions or exercises could potentially be used as an effective non-invasive gait rehabilitation method in PD patients.