Known for its enteric nervous system (ENS), scientists have found that the digestive tract is connected to a vast network of neurons distributed from the esophagus to the last parts of the intestine. It works like an extension of the brain, which, beyond the skull, coordinates the entire process of nutrient absorption. Actually, the neurons below are independent of those above: some bridge the two, but they act autonomously. However, studies estimate that the ENS contains more neurons than the whole of the spinal cord. 

According to the director of the Johns Hopkins Center for Neurogastroenterology, “Its main role is controlling digestion, from swallowing to the release of enzymes that break down food to the control of blood flow that helps with nutrient absorption to elimination”, explains Jay Pasricha, M.D. 

A recent paper published by Australia’s Flinders University professor Nick Spencer offers new insights into how the connection works and the extent to which the ENS is similar to other neural networks throughout the human body, including those found in the brain and spinal cord.

The study describes how the ENS is “far more complex than expected and considerably different from the mechanisms that underlie the propulsion of fluid along with other muscle organs that have evolved without an intrinsic nervous system”.

The main finding is how the thousands of neurons inside the ENS communicate with each other to help the digestive process by causing contractions in the gastrointestinal tract. The paper suggests that far from being the second brain, the ENS is probably much older in evolutionary terms and could even be regarded as the body’s first brain.

There is still a wide field to be explored, as other studies suggest that digestive-system activity may also affect cognition (thinking skills and memory). Hidden in the walls of the digestive system, the “brain in your gut” findings are revolutionizing medicine’s understanding of the links between digestion, mood, health and the way we think.

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Source: Communications Biology journal |  Johns Hopkins