The Second Brain - Neurons in our "gut"

Fantastic report euphemistically stating that we don't know much about the purpose of neurons in our bellies:

"Technically known as the enteric nervous system, the second brain consists of sheaths of neurons embedded in the walls of the long tube of our gut, or alimentary canal, which measures about nine meters end to end from the esophagus to the anus. The second brain contains some 100 million neurons, more than in either the spinal cord or the peripheral nervous system, Gershon says.

This multitude of neurons in the enteric nervous system enables us to "feel" the inner world of our gut and its contents. Much of this neural firepower comes to bear in the elaborate daily grindof digestion. Breaking down food, absorbing nutrients, and expelling of waste requires chemical processing, mechanical mixing and rhythmic muscle contractions that move everything on down the line.

Thus equipped with its own reflexes and senses, the second brain can control gut behavior independently of the brain, Gershon says. We likely evolved this intricate web of nerves to perform digestion and excretion "on site," rather than remotely from our brains through the middleman of the spinal cord. "The brain in the head doesn't need to get its hands dirty with the messy business of digestion, which is delegated to the brain in the gut," Gershon says. He and other researchers explain, however, that the second brain's complexity likely cannot be interpreted through this process alone.

"The system is way too complicated to have evolved only to make sure things move out of your colon," says Emeran Mayer, professor of physiology, psychiatry and biobehavioral sciences at the David Geffen School of Medicine at the University of California, Los Angeles (U.C.L.A.). For example, 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."

Without reasoning, we innately "feel" multitudes of emotions right from our gut. There are people who thrive on gut feelings and considered it more important than reason. And there are Aristotelians who only reason, ridiculing the flags from the gut. It's safe to presume both are wrong. This becomes another version Antonio Damasio's somatic marker hypothesis. Reason should co-exist with multitudes of other feelings. I cannot find better way to fine tune this co-existance than what Damasio quoted in Descrates Error.

""In order to decide, judge; in order to judge, reason; in order to reason, decide (what to reason about)."