We first examined the extent of head motion as a confound to differences in regional BOLD signals between drinkers and non-drinkers. To quantify head motions, we computed the framewise displacement (FD) for each individual (0.1264 ± 0.0600 vs. 0.1090 ± 0.0922) and found no significant differences between the two groups (t = 1.1957, p = 0.2343). We also computed the percentage of FDs > 0.5mm (0.0189 + 0.0466 vs. 0.0196 + 0.0527) (Power et al., 2012; Tomasi and Volkow 2012). These were converted to z values via Fisher’s transformation and a two-sample t test again showed no differences between the two groups (t = −0.0727, p = 0.9422).
