Is it at all surprising that increasing afferent input (in this case: textured insoles) to one of the areas in the brain (parasaggital sulcus in the post central gyrus) from one of the structures that has the greatest cortical representation (ie the feet) can improve gait on folks that have a disorder with their basal ganglia (which provides background positioning of joints)?

"After one week of insole wear, plantar sensation and stride length were significantly improved relative to baseline; the improvement in plantar sensation was maintained after another week of wearing conventional insoles.(1)"

 Here is a video I made a while ago about conservative management of PD. It talks about a multimodal management model that includes acupuncture.

1. Lirani-Silva E, Vitorio R, Barbieri FA, et al. Continuous use of textured insole improve plantar sensation and stride length of people with Parkinson disease: A pilot study. Gait Posture 2017;58:495-497.