To examine possible interactions of the factors of beverage and task conditions, and to ascertain the statistical reliability of the observed effects, region-of-interest (ROI) analysis was conducted on the event-related changes in total theta power. Unbiased ROIs comprised dipole locations along cortical surface with most notable source power and were selected based on the overall group average across all subjects, task and beverage conditions. The same ROIs were used for all subjects in a manner blind to their individual activations by applying an automatic spherical morphing procedure (Fischl et al., 1999b). For each subject, task condition and beverage, theta estimates were averaged across all cortical points comprised in that ROI and these values were entered into ANOVA. The ROIs encompassed the left-lateralized fronto-temporal network associated with language and cognitive/executive operations (Figures 2–4), as well as comparable regions on the right. ROIs included the lateral occipital area (Occ), lateral temporal (LT) cortex, anteroventral inferior prefrontal cortex (aIPF) bordering on insula, posterolateral inferior prefrontal cortex (pIPF), motor cortex centered on hand area (Mot), and the anterior cingulate cortex (ACC) bilaterally.
