Statistics
Power calculations were based on cross-sectional data, not within-subject repeated measurements of D2BP change and fMRI response in response to dietary manipulation, which had not previously been measured. To detect a meaningful difference of effect size in D2BP (ratio of the expected mean and the standard deviation of the paired differences), with 20 subjects measured, we estimated that the study would achieve a power of 98% via the paired samples fMRI images were included in AFNI’s 3dttest++ to identify clusters of significant effects of the diet condition (RF > Baseline for Individual participants’ anatomical MRI images (see above) were coregistered to the aligned PET images by minimizing a mutual information cost function for each individual participant. For the analyses described in the main text, each individual’s anatomical MRI was linearly transformed into the Talairach space, and the transformation matrix was applied to the PET images, which were then smoothed with a 5 mm full-width, half-max Gaussian kernel. Data were exported to MATLAB where time-activity curves for [18F]fallypride concentration in each voxel were fit to a kinetic model (with the cerebellum used as the reference tissue) to determine D2BP (Participants’ D2BP maps were included in AFNI’s 3dttest++ identify clusters with significant effects of diet (RF>Baseline for To test the robustness of our results with respect to alterations in processing and analysis pipeline, we also analyzed the data Individual participants’ anatomical MRI images were coregistered to the aligned PET images by minimizing a mutual information cost function for each individual participant. The aligned PET images were smoothed with a 5-mm full-width, half-max Gaussian kernel. Data were exported to MATLAB, where time-activity curves for [18F]fallypride concentration in each voxel were fit to a kinetic model with the cerebellum used as the reference tissue to determine D2BP (