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 affects performance in which changing set occurs over minutes, i.e., a slow and continuous form of sensorimotor set-change. Recovery from the postural lean aftereffect following prolonged stance on an inclined surface (Experiment 1) was tested to see if the addition of light-touch tactile feedback from the fingertips during inclined stance increased the aftereffect (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 aftereffect did not dissipate; i.e., participants remained leaning forward throughout the post-incline stance period. PD does not appear to affect the ...