Chunk #27 — MATERIALS AND METHODS — Neural extension II: Reward-related functional magnetic resonance imaging analyses of GWS loci in the Duke Neurogenetics Study
functional magnetic resonance imaging (fMRI) data were acquired 48. Statistical Parametric Mapping version 8 (SPM8) software was used to extract parameter estimates for the contrast of Positive Feedback > Negative Feedback from maximal voxels within left and right VS regions of interest (ROIs). Imaging acquisition protocol, task, ROIs, and preprocessing details are described in the Supplemental Text. Extracted parameter estimates from VS activity in each hemisphere were regressed on genotype (rs61826952 coded as 1 or more copies of the minor allele due to sample size; rs2418646 coded using an additive model for the number of C alleles) while co-varying for sex, and three (AA) or two (EA) ancestral principal components using Full Information Maximum Likelihood in MPlus v7.349. Trans-ancestral meta-analysis was conducted using METAL 42. To adjust for multiple comparisons, we used a Bonferroni-corrected p-value threshold (p<0.0125), to account for our hypothesized 4 tests (i.e., rs61826952 and rs2418646 in both brain hemispheres in a trans-ancestral meta-analysis).
