120 CHAPTER 6 two ROI analyses for the right extrastriate cortex and bilateral parieto-occipital sulcus where we previously found reduced imagery-related brain activity in NA patients versus healthy controls in the baseline measurement2 (see Figure 3A-B; in both NA patients and previous work in other disorders, abnormalities occurred in the hemisphere ipsilateral to the (most) affected limb2, 40). As patients may also show functional reorganization in other brain regions, 176, 177 we additionally performed an exploratory analysis at the whole brain level, including all trial types. Behavioral task performance Statistical testing was performed using IBM SPSS statistics 25 (IBM Corp, Armonk, NY USA), statistical tests were two-tailed and alpha-level was set at p=0.05. For each patient, we evaluated task performance by calculating median RTs (on correct trials) and error rates (ERs) (number of incorrect trials divided by number of valid trials) for all relevant conditions. ERs were normalized through an arcsine transformation before further analyses. 77 We performed two separate three-factor mixed ANOVAs on median RTs and normalized ERs with the same repeated factors TIME and LATERALITY, and between-subject factor GROUP, using biomechanically complex trials only as with the main fMRI hypothesis. Clinical outcomes To interpret potential group differences in cerebral adaptations in the context of clinical improvement, we compared the effects of multidisciplinary rehabilitation to usual care on the SRQ-DLV-score and persistent pain (VAS). For the SRQ-DLV, we performed a 2-factor mixed ANOVA with repeated-factor TIME and between-factor GROUP. As pain was not normally distributed, we performed a Mann-Whitney U test on the difference in pain between baseline and follow-up. Brain-behavior-symptom correlations We correlated any significant changes between brain activity, symptoms and behavioral task performance, for the affected upper extremity only. We additionally tested (onetailed) whether the significant correlations between brain activity, behavior, and symptoms that we previously reported in the full sample of patients at baseline (n=39)2 were also present at follow-up in this smaller sample (see Supplementary Materials). Confirmation of embodied processes To verify that patients employed sensorimotor representations of their own limb when performing the task, we tested the influence of factors BIOMECHANICAL COMPLEXITY and POSTURAL CONGRUENCY on behavioral task performance (RTs) and related brain activity at both baseline and follow-up across groups. Data availability The data are available through the corresponding author on reasonable request.
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