The apéritif effect: Alcohol's effects on the brain's response to food aromas in women.

OBJECTIVE: Consuming alcohol prior to a meal (an apéritif) increases food consumption. This greater food consumption may result from increased activity in brain regions that mediate reward and regulate feeding behavior. Using functional magnetic resonance imaging, we evaluated the blood oxygenation level dependent (BOLD) response to the food aromas of either roast beef or Italian meat sauce following pharmacokinetically controlled intravenous infusion of alcohol. METHODS: BOLD activation to food aromas in non-obese women (n = 35) was evaluated once during intravenous infusion of 6% v/v EtOH, clamped at a steady-state breath alcohol concentration of 50 mg%, and once during infusion of saline using matching pump rates. Ad libitum intake of roast beef with noodles or Italian meat sauce with pasta following imaging was recorded. RESULTS: BOLD activation to food relative to non-food odors in the hypothalamic area was increased during alcohol pre-load when compared to saline. Food consumption was significantly greater, and levels of ghrelin were reduced, following alcohol. CONCLUSIONS: An alcohol pre-load increased food consumption and potentiated differences between food and non-food BOLD responses in the region of the hypothalamus. The hypothalamus may mediate the interplay of alcohol and responses to food cues, thus playing a role in the apéritif phenomenon.

Ventral frontal satiation-mediated responses to food aromas in obese and normal-weight women.

BACKGROUND: Sensory properties of foods promote and guide consumption in hunger states, whereas satiation should dampen the sensory activation of ingestive behaviors. Such activation may be disordered in obese individuals. OBJECTIVE: Using functional magnetic resonance imaging (fMRI), we studied regional brain responses to food odor stimulation in the sated state in obese and normal-weight individuals targeting ventral frontal regions known to be involved in coding for stimulus reward value. DESIGN: Forty-eight women (25 normal weight; 23 obese) participated in a 2-day (fed compared with fasting) fMRI study while smelling odors of 2 foods and an inedible, nonfood object. Analyses were conducted to permit an examination of both general and sensory-specific satiation (satiation effects specific to a given food). RESULTS: Normal-weight subjects showed significant blood oxygen level-dependent responses in the ventromedial prefrontal cortex (vmPFC) to food aromas compared with responses induced by the odor of an inedible object. Normal-weight subjects also showed general (but not sensory-specific) satiation effects in both the vmPFC and orbitofrontal cortex. Obese subjects showed no differential response to the aromas of food and the inedible object when fasting. Within- and between-group differences in satiation were driven largely by changes in the response to the odor of the inedible stimulus. Responses to food aromas in the obese correlated with trait negative urgency, the tendency toward negative affect-provoked impulsivity. CONCLUSIONS: Ventral frontal signaling of reward value may be disordered in obesity, with negative urgency heightening responses to food aromas. The observed nature of responses to food and nonfood stimuli suggests that future research should independently quantify each to fully understand brain reward signaling in obesity.

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. 2010). In the current study, eighteen women (eleven normal-weight and seven obese) underwent a two-day imaging study (one after being fed, 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.