Since Kringelbach et al. (2003) and Small et al. (2001) reported correlations between orbitofrontal activation and perceived pleasantness, the greater activation caused by AO compared to NApO could be related to differences in perceived pleasantness. Two lines of reasoning suggest otherwise. First, the differential activity between these stimulus types occurred primarily in the alcohol infusion condition, whereas pleasantness ratings (made after each infusion) did not differ between alcohol and placebo infusion days. Second, the stimuli perceived as most pleasant were the ApCO. However, the AO still caused greater orbitofrontal activation than ApCO. Secondary analyses, in fact, suggest that the odors perceived as least pleasant (NApO) induced somewhat more activation during alcohol infusion in nearby orbital areas than the odors perceived as most pleasant (NApO > ApCO; 14 voxels at p < 0.01 at [20, 36, −20]).
