Schematic representation of the taste and gastrointestinal (GI) input. Schematic representation of the taste and gastrointestinal (GI) input to the brain from the gustatory and vagus nerves, respectively. The gustatory system is represented by taste cells in onion-like taste buds and their gustatory nerves. Corresponding to the GI system, there are two enteroendocrine cells (EEC), one that is open to the lumen-releasing cholecystokinin (CCK) and glucagon-like peptide 1 (GLP-1) in response to luminal nutrients and one that is closed. Vagal fibers are located underneath the GI mucosa in close contact with hormone secretions. The signals from the gustatory system reach the rostral nucleus of the solitary tract whereas visceral impulses terminate at the caudal nucleus of the solitary tract. From the nucleus of the solitary tract, gustatory and visceral information projects to several brain regions including the amygdala, the hypothalamus, and the ventral posterior nucleus of the thalamus. These regions are involved with ingestive motivation, physiological reflexes, and energy homeostasis.