Evolution: t he gut has its own independent neuron network (Introduction)

by David Turell , Friday, December 25, 2020, 15:57 (1427 days ago) @ David Turell

100 billion neurons connected to send signals to the brain by the vagus nerve while running the digestive processes:

https://mindmatters.ai/2020/12/did-you-know-you-have-a-second-brain/

"Our huge gastrointestinal tracts operate their own nervous system, using neurons that follow different principles from those of brain neurons, according to recent findings:

"Our approximately seven-meter long gastrointestinal (GI) tract has its own functionally distinct neurons. Since this enteric nervous system (ENS) operates autonomously, it is sometimes referred to as the “second” or “abdominal” brain. While the ENS controls muscle movement (peristalsis) in the gut and its fluid balance and blood flow, it also communicates with the immune system and microbiome.

"The Karolinska researchers made progress in studying the little-understood second brain by mapping the neuron types in the digestive systems of mice. The human gut is estimated to contain an independent network of over 100 billion neurons that not only control digestion but work with the immune system to fight a constant war with hostile bacteria.

"These neurons help account for the curious sensation of “butterflies in the stomach.”

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"...scientists were shocked to learn that about 90 percent of the fibers in the primary visceral nerve, the vagus, carry information from the gut to the brain and not the other way around. “Some of that info is decidedly unpleasant,” Gershon says.

"The second brain informs our state of mind in other more obscure ways, as well. “A big part of our emotions are probably influenced by the nerves in our gut,” Mayer says. Butterflies in the stomach—signaling in the gut as part of our physiological stress response, Gershon says—is but one example. Although gastrointestinal (GI) turmoil can sour one’s moods, everyday emotional well-being may rely on messages from the brain below to the brain above. For example, electrical stimulation of the vagus nerve—a useful treatment for depression—may mimic these signals, Gershon says."

Comment: The vagus nerve, the tenth cranial nerve, directly connected to the brain keeps tabs on what is going on but the system really is autonomous and runs the show. This is not new knowledge. I learned this in medical school. The details are new, especially the new findings that the gut biome can affect our emotions. The design is not by chance.