Brain Activity and Hormonal Changes During Food Administration

The amount and kind of food which is ingested influences the regulation of meal size. Neural signals from the gastrointestinal tract travel via the vagus nerve to the brainstem and thalamus, which projects to the rest of the brain, in particular the hypothalamus, amygdala and primary sensory cortices. In neuroimaging studies in which the stomach was distended with a gastric balloon activation was observed in the right insula, left posterior amygdala, left posterior insula, left inferior frontal gyrus and anterior cingulate cortex. So far, no study has examined the effects of the ingestion or infusion of a food on the brain. In addition to neural signals, hormonal signals are important for meal termination. Hormones like insulin, ghrelin and cholecystokinin interact with gastric as well as sensory signals in the process of satiation, which ultimately leads to meal termination. The aim of this study is to investigate the interaction between food administration, hormone responses and brain responses. To this end an oral or intra-gastric load will be administered while measuring brain activity (functional magnetic resonance imaging) and hormone concentrations. Subjects will participate in one trainings session and in three functional magnetic resonance imaging (fMRI) sessions (35-min fMRI scan). A training session will take 40-minutes and consists of placing a naso-gastric tube and ingesting 500 ml of chocolate milk orally. The fMRI sessions will consist of three conditions: in condition one (A) 500ml of chocolate milk will be administrated orally. In condition two (B) and three (C) an intra-gastric load of 500 ml is administrated.