Postural adaptation to a slow sensorimotor set-changing task in Parkinson's disease¹

Abstract

A general characteristic of Parkinson's disease (PD) is the inability to adapt and change set quickly. The goal of this study was to assess whether PD aff ects performance in which changing set occurs over minutes, i.e., a slow and continuous form of sensorimotor set-change. Recovery from the postural lean aftereff ect following prolonged stance on an inclined surface (Experiment 1) was tested to see if the addition of light-touch tactile feedback from the fi ngertips during inclined stance increased the aftereff ect (Experiment 2). The percentage of responders in healthy Young, Older, and PD groups was similar, as were characteristics of the recovery towards vertical stance, namely the initial forward lean, range, time constant, and half-life. Tactile feedback increased the responder rate in all groups. A novel response was also observed in which the aftereff ect did not dissipate; i.e., participants remained leaning forward throughout the post-incline stance period. PD does not appear to aff ect the ability to change sensorimotor set if the change is slow.

Individuals with a vestibular-related disorder use a somatosensory-dominant strategy for postural orientation after inclined stance

“…The 58% responder rate in the control group is similar to the responder rates of 56.5% for younger subjects (mean age= 25) and 57% for older subjects (mean age= 65) reported in previous studies. 12,13 The amplitude of postural lean was the same between the control and vestibular groups during the post-incline stance: first 5 sec-…”

“…12,13 Subjects were first familiarized to the testing protocol in order to give them assurance of safety. 12,13 Subjects were first familiarized to the testing protocol in order to give them assurance of safety.…”

“…12,13 The SOT data were analyzed with a 2 (Group) × 6 (Conditions) mixed model ANOVA with Holm-Sidak simple effects test for significant outcomes. A response was considered positive if an aftereffect was present, inferred by a difference in the subject's postural sway between the beginning and the end of the trial.…”

“…12,32 More evidence is needed to confirm the efficacy of this rehabilitative method. For example, if a patient has increased symptoms when bending over to tie their shoe, it would be logical to teach somatosensory-dominant strategies to avoid exacerbating the symptoms.…”

“…The inclined stance protocol used in this study was patterned after previous studies. 12,13 Subjects were first familiarized to the testing protocol in order to give them assurance of safety. They wore a safety harness which was strapped from a fixed overhead frame to catch them in the case of loss of balance.…”