Random effects analyses of the contrast HRF-related images in a priori regions of interest (ROIs) used a Genotype(2) × Odor(2) × Condition(2) linear mixed-effects models in SPSS 17.0 for Windows (SPSS Inc., Chicago, IL). “Genotype” represents homo- or heterozygosity for the GABRA2 risk allele (AA and AG), “Odor” refers to activation from AO and ApCO (each contrasted against the odorless control events), and “Condition” reflects alcohol and placebo infusion. We concentrated analyses on AO and ApCO, which represent two classes of appetitive stimuli. Given alcohol's vasoactive properties and the BOLD contrast mechanism's reliance on blood flow and volume, NApO were reserved to test whether alcohol altered the sensory response in primary olfactory (piriform) cortex using functionally defined regions of activation under placebo (see Kareken, et al., 2010). Since alcohol can enhance hunger (Caton et al., 2007; Yeomans et al., 1999), the use of stimuli that should not evoke ingestive behavior/cognition (i.e., NApO) helped to avoid potential interactions between alcohol's appetitive qualities and the primary sensory response.
