PCA of force tracking traces across subjects.

<p><b>A</b>. Average force trace over all conditions and subjects (N = 38). <b>B–D</b>. PC loading as a function of time for PC1, PC2 and PC3, respectively. <b>B</b>. Loading profile similar to force profile for PC1, positive and increasing scores during ramp, more stable and strongest positive scores during hold. <b>C</b>. Inverse loading profile compared to force for PC2. <b>D</b>. Strongest loading during force transitions (ramp and release) for PC3. <b>E</b>. Average factor score (±SD) for PC1, PC2 and PC3 for control subjects vs medicated patients, and non-medicated patients (NMP). Significant difference between controls and both groups of patients only found for PC2 (more negative scores for controls: asterisk). <b>F</b>. Positive correlation between PC2 factor score and release duration for control subjects and patients. Correlation remained significant with exclusion of outlier subject (p = 0.003). No correlation was found between PC2 factor score and relative error or CV (p>0.5). <b>G</b>. Positive rank correlation between PC2 factor scores and PANSS scores in patients.