The primary goal of this project is to gain a better understanding of whether and how levodopa (a common anti-Parkinson disease medication) alters postural motor learning in people with Parkinson disease. A secondary goal is to assess whether motor cortical excitability, measured via Transcranial magnetic stimulation, is related to postural motor learning. Participants with Parkinson disease will complete between 50 and 100 postural perturbations (via support surface translations), ON and OFF their dopamine replacement therapy (i.e. levodopa). Adaptation of responses to these perturbations will be tracked. Participants will also undergo transcranial magnetic stimulation to capture cortical excitability of the brain (in particular the motor cortex). Cortical excitability will be correlated to adaptation of stepping (i.e. postural motor learning) ON and OFF levodopa. Investigators will also capture postural motor learning and cortical excitability in age-matched healthy adults. Investigators hypothesize that dopamine will have a negative effect on postural motor learning, and the cortical excitability will be correlated to postural motor learning.
Study Type
OBSERVATIONAL
Enrollment
42
Participants will undergo between 50 and 100 postural perturbations (quick movements of the support surface) in multiple directions. These perturbations will be between 9 and 24cm, and between 18 and 56 cm/s depending on participant tolerance.
Oregon Health & Science University
Portland, Oregon, United States
VA Portland Health Care System, Portland, OR
Portland, Oregon, United States
VA Salt Lake City Health Care System, Salt Lake City, UT
Salt Lake City, Utah, United States
Change in Movement of Center of Mass (COM) After Postural Perturbation
Investigators will assess (via automated and custom Matlab software) the magnitude of COM movement after a postural perturbation is delivered via motion of the support surface. This will be measured throughout the intervention, as well as at follow up (24 hour later).
Time frame: Baseline and follow up (24 hours later) both ON and OFF antiparkinson medication
Change in Steps After Postural Perturbation
Investigators will assess (via automated and custom Matlab software) the number of steps taken after a postural perturbation is delivered via motion of the support surface. This will be measured throughout the intervention, as well as at follow up (24 hour later).
Time frame: Baseline and follow up (24 hours later) both ON and OFF antiparkinson medication
Change in First Step Length
Investigators will assess (via automated and custom Matlab software) the length of the first step after a postural perturbation is delivered via motion of the support surface. This will be measured throughout the intervention, as well as at follow up (24 hour later).
Time frame: Baseline and follow up (24 hours later) both ON and OFF antiparkinson medication
Cortical Excitability
Investigators will assess the cortical excitability of the primary motor cortex in a subset of participants both ON and OFF levodopa. Specifically, we used transcranial magnetic stimulation to stimulate the motor cortex, where we measure muscular activity of the arm (i.e. motor evoked potentials; MEPs). The primary outcome variable noted below is the lowest stimulation setting (measured as a percentage) which results in an MEP in 5 of 10 trials.
Time frame: TMS data was collected ON and OFF medication during one visit. This visit occurred within 3 weeks of the initial postural control assessments.
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