The collection of nerves in the gut called the enteric nervous system (ENS) has been shown to act similarly to other neural networks in the central nervous system (CNS). Considering the many diverse functions of the digestive system and its accessory organs, the ENS is the most complex peripheral nervous system – and the most obscure.
In an attempt to understand the working mechanism behind this intricate system, Flinders University professor Nick Spencer conducted an investigation revealing the collaborative nature of the of the ENS. Discoveries made by these researchers offer insight on how the ENS’ several neuronal layers interact to drive muscular contractions that push substances through the digestive system.
The study results show a much more intricate nervous system than expected, according to Spencer. The ENS functions significantly different from other physiological components that propel fluids through the body, such as ureters, lymph vessels, and the portal vein which spans from the spleen to the liver. These parts of the body lack an underlying nervous system.
The ENS, which was formed long before the CNS, contains thousands of neurons that work together to carry out specific functions. This unique ‘first brain’ synchronizes electrical activity to stimulate muscle contraction in the abdomen. “Synchronization of neuronal activity across large populations of neurons is common in the nervous system of many vertebrate animals,” says Spencer.
Because of recent technological advancements in their lab, the researchers were able to simultaneously capture smooth muscle nerve impulses as well as any slight changes in the width of the walls of the colon during contraction and relaxation.
As a result of this procedure, a critical new mechanism was discovered, which ultimately explains the way in which all of the diverse neurons in the ENS work together and synchronize their activity to move substances through the colon. “Interestingly, the same neural circuit was activated during both propulsive and non-propulsive contractions,” he adds.
This suggests that the built-in nervous system in the gut carries out complex metabolic functions in a rhythmic pattern that enables smooth muscle contraction and relaxation via the same pathway. The research shows that there are vast functional circuits of neurons in the ENS that can organize themselves to create regulated impulses throughout the colon, establishing the foundation of an essential colon motor pattern.
This study is published in Communications Biology.