The gut really does have a mind of its own. Along with that mushy gray thing inside our skull, we also have a “second brain” in our intestinal tract. Scientists have now documented a totally new pattern of neurons firing within this network and observed how it directly affects the gut’s behavior.
In layman's terms, they basically discovered how our second brain helps us to poop.
The "second brain" is scientifically known as the enteric nervous system (ENS). It’s essentially a mesh-like system of around 400 million neurons, with dozens of different types of neurotransmitters (chemical signals) passing between them, that loops around the gastrointestinal tract. It's the largest collection of neurons found outside of the brain and it’s able to work almost independently of your central nervous system. Although it does communicate with your "main brain", you can sever the vagus nerve and the ENS will continue to function normally.
Its influence on the body is thought to be far-reaching, although it’s not actively involved in decision-making and consciousness – it won’t help you decide what you want for lunch. Its primary job is to control and manage the messy business of digestion.
As reported in the journal JNeurosci, this new study saw Australian scientists make a considerable leap in understanding this mysterious network by observing a never-before-seen neuronal firing pattern in the colons of mice.
The researchers noted a “novel pattern of rhythmic coordinated neuronal firing" that appeared to directly generate the movement of muscles around the large intestine, causing it to pump poop-like pellets through the mouse's gut. Using new neuronal imaging techniques, they observed neurons firing simultaneously in repetitive bursts to activate the muscle cells at the same rate. The new finding is described as a “previously unknown pattern of neuronal activity.”
"This revealed that activity in the ENS can temporally coordinate [electrical] activity over significant distances along the length of [the] colon," the team wrote in their paper.
The “second brain” still holds many mysteries, and the more scientists learn about it, the more complex and intriguing it appears. There’s considerable evidence to suggest that the ENS could even play a role in influencing our emotions and state of mind. Just as one example, over 90 percent of the body's serotonin – the “feel good” neurotransmitter – is produced in the bowel, as is almost half of our dopamine. Perhaps craziest of all, evidence has suggested that the ENS actually evolved before the brain and the central nervous system.