The vagus nerve branches are difficult to study due to their “intricate intermingling,” but researchers at the Icahn School of Medicine utilized a state-of-the-art technology known as “optogenetics” that used light to manipulate specific neurons. “This optical activation of gut-innervating vagal sensory neurons recapitulates the hallmark effects of stimulating brain reward neurons.”
What they discovered was that the right vagal branch, not the left, connects to the dopamine-containing reward neurons in the brain. Surprisingly, the researchers also discovered an asymmetric ascending pathway of the vagal branches into the central nervous system, further clarifying varied roles of specific vagal neurons.
“Transneuronal labeling identified the glutamatergic neurons of the dorsolateral parabrachial region as the obligatory relay linking the right vagal sensory ganglion to dopamine cells in Substantia nigra. Consistently, optical activation of parabrachio-nigral projections replicated the rewarding effects of right vagus excitation.”
This novel gut-to-brain neural circuit gives a concrete link between visceral organs and brain function as it relates to the reward circuitry, and may help to inform novel targets for vagal stimulation therapy, particularly for eating and emotional disorders.
Related Biotics Research Products: