Self-controlled Practice on Motor Learning and Motivation in Parkinson's Disease

The accuracy of the overall performance of the target waveform trajectory. The RMSE is the mean difference between the target waveform trajectory and the participant's performed waveform trajectory calculated over their actual movement time. Smaller RMSE value indicates better task performance. With a total of 144 trials practiced during the practice phase on D1 and D2, the RMSE will be averaged every 12 trials as a block for later data analysis and presentation, resulting in a total of 12 practice blocks (B1 to B12), 2 retention test blocks (imme-ret and delay-ret) and 1 transfer test block (xfer).

The participants will be required to verbally estimate their RMSE after each trial for retention and transfer test trials. The equation for calculating EE is √(CE^2+ VE^2 ), while constant error (CE) captures estimation bias (estimated-actual) and variable error (VE) is the standard deviation of these errors. A lower EE value indicates that the participants are more precise in estimating their performance and suggests better cognitive processing.

Motivation evaluation will be conducted after the practice phase during day 1 and day 2, and will be assessed with a self-reported motivational questionnaire consisting of perceived competence, task interest/enjoyment, and autonomy. This motivation questionnaire is composed of a total of 14 items scored on a 7-point Likert scale. Score ranges from 14 to 98, with a higher score indicating better perceived competence, task interest/enjoyment, and autonomy.

TMS is a non-invasive neurophysiological assessment tool used to evaluate changes in corticomotor excitability associated with self-controlled practice in motor learning. Assessments will be conducted using the Magstim® BiStim² (The Magstim Company Ltd., Whitland, UK) device with a figure-of-eight coil. TMS outcomes of interest will include resting and active motor-evoked potential (MEP), cortical silent period (CSP), short-interval intracortical inhibition (SICI), and intracortical facilitation (ICF).

It consists of 4 parts, including non-motor aspects of experiences of daily living, motor aspects of experiences of daily living, motor examination, and motor complications. Total score ranges from 0 to 200, with a higher score indicating greater disease severity.

The Chinese version of the self-rated Apathy Evaluation Scale (AES) will be used to measure apathy. Each item scores on a 4-point Likert scale, and the score ranges from 18 to 72, with a higher score indicating greater apathy.

The clinician-rated short-form Lille Apathy Rating Scale (short-form LARS) will be used to measure apathy. The scale is scored with a 5-point Likert scale in the first 3 items and a binary (yes/no) scale with an additional "not available (NA)" condition for non-classifiable or non-applicable answers or items. The total score ranges between -15 and 15, with a higher score indicating greater severity in apathy.

Cognitive function of the participants will be assessed through Montreal Cognitive Assessment (MoCA), which is a widely used screening tool for detecting cognitive impairment. The MoCA consists of memory, attention, language, abstraction, orientation to time and place, visuospatial abilities, and executive functions. The total score ranges from 0 to 30, with a higher score indicating better cognitive function.

Hospital Anxiety and Depression Scale (HADS) will be conducted for evaluating the symptoms of anxiety and depression. The HADS consists of 14 items, which 7 items are categorized into anxiety (HADS-A) and 7 items into depression (HADS-D). Each item will be scored on a 4-point Likert scale with a total score ranging from 0 to 21, and a higher score indicates greater symptoms of anxiety and depression. The cutoff score for identifying symptoms of anxiety and depression in the PD population has been established as ≥ 11 points in the anxiety or depression subscales, respectively.