Figure 4. Vagal gut-brain circuits regulate cognitive aspects of feeding behavior.

Distinct populations of vagal afferent neurons innervating the gut and liver respond to post-ingestive fat (blue) and sugar (pink). Neurons of the NTS receive these signals from vagal inputs and relay them to reward (A) and memory (B) pathways, with fats and sugars recruiting separate but parallel populations of neurons at each node within each circuit.

A) In the reward pathway, glutamatergic neurons of the PBN are engaged downstream of the NTS. These neurons project to the SNc, where they activate dopaminergic neurons. Release of dopamine from SNc neurons onto the dorsal striatum underlies reward behaviors in animals and preference for fats and sugars. B) Within the polysynaptic gut-memory circuit, the medial septum is a likely intermediary node between the NTS and HPC. NTS = nucleus of the solitary tract ; PBN = parabrachial nucleus ; SNc = substantia nigra pars compacta ; MS = medial septum ; HPC = hippocampus. Created in https://BioRender.com