Correlation Between Ventromedial Prefrontal Cortex Activation to Food Aromas and Cue-Driven Eating: An fMRI Study

Food aromas are signals associated with both food's availability and pleasure. Previous research from this laboratory has shown that food aromas under fasting conditions evoke robust activation of medial prefrontal brain regions thought to reflect reward value (Bragulat et al., Obesity (Silver Spring), 18(8): 1566-1571, 2010). In the current study, 18 women (11 normal weight and 7 obese) underwent a 2-day imaging study (one after being fed and one while fasting). All were imaged on a 3T Siemens Trio-Tim scanner while sniffing two food (F; pasta and beef) odors, one non-food (NF; Douglas fir) odor, and an odorless control (CO). Prior to imaging, participants rated hunger and perceived odor qualities and completed the Dutch Eating Behavior Questionnaire (DEBQ) to assess externality (the extent to which eating is driven by external food cues). Across all participants, both food and non-food odors (compared to CO) elicited large blood oxygenation level dependent (BOLD) responses in olfactory and reward-related areas, including the medial prefrontal and anterior cingulate cortex, bilateral orbitofrontal cortex, and bilateral piriform cortex, amygdala, and hippocampus. However, food odors produced greater activation of medial prefrontal cortex, left lateral orbitofrontal cortex, and inferior insula than non-food odors. Moreover, there was a significant correlation between the (F>CO) BOLD response in ventromedial prefrontal cortex and externality sub-scale scores of the DEBQ, but only under the fed condition; no such correlation was present with the (NF>CO) response. This suggests that in those with high externality, ventromedial prefrontal cortex may inappropriately valuate external food cues in the absence of internal hunger.