Almost all of us know that the brain is located in the head, but few may realize that there is a second brain, and it is located in… the butt.
This is not a brain in the literal sense, but an independent tissue consisting of millions of neurons that somehow has the ability to control the intestinal muscles without the help of the central nervous system. Moreover, these neurons are not actually located in the butt, but are distributed throughout the large intestine – a tubular organ that connects the small intestine to the rectum, responsible for excreting the leftover food during the final stages of digestion.
Using a recently developed technique that combines high-resolution video recording with electrophysiological analysis, scientists have been able to study the colon of mice and, in particular, how the intestines move.
The scientists have referred to this information-transmitting region in the large intestine as the enteric nervous system (ENS), and because it can operate without the guidance of the brain or spinal cord, it is sometimes affectionately called the “second brain.” However, no one has yet dared to assert how intelligent this independent brain is. Nonetheless, according to a publication in the Journal of Neuroscience on May 29 regarding a study conducted on mice, the answer might be “extremely intelligent.”
One of the important findings is the discovery of how thousands of neurons within the ENS communicate with each other, causing contractions in the digestive tract to aid the digestion process. So far, it remains unclear how these neurons can work together to achieve this.
Neuroscientist Nick Spencer from Flinders University (Australia) stated: “Interestingly, the same neural pathway has been activated during both propulsion contractions and non-propulsive contractions.”
Mammals are believed to have an additional ‘second brain’ (gut brain) in their intestines. (Image: Shutterstock).
“The ENS contains millions of neurons that are essential for organizing the functions of the intestines,” said the research team from Australia, who observed the diligent activity of the “second brain” using high-precision neuroimaging techniques. When they specifically stimulated the colon of mice using mild electrical shock therapy, the scientists discovered a “novel combined neural transmission pattern” directly corresponding to the muscle movements in the vicinity of the large intestine.
This synchronized, rhythmic neural activity has helped distinct segments of the intestinal muscles operate appropriately, ensuring that colonic contractions – also known as “colonic migrating motor complexes” – keep the feces moving in the right direction at a steady pace.
“This finding suggests that the enteric nervous system can coordinate activities with the muscles over time and across significant distances along the length of the large intestine.” Additionally, the researchers noted that such synchronized neural patterns are also common in the early developmental stages of the brain, raising the question: Could the neural transmission patterns in the large intestine be a “primitive trait” retained from the early days of the evolution of the enteric nervous system?
Furthermore, some scientists have even hypothesized that the enteric nervous system may have evolved before the central nervous system, and that the neural transmission patterns in the large intestine are characteristic of the first brain that operated in the human body. If this is true, then the “brain in the butt” might actually be “the first,” not “the second.” Thus, it can be said that the evolution of the brain in mammals was initially for the purpose of expelling feces, and only later took on more complex tasks.
Although this is the first time we have discovered such a neural transmission pattern in the large intestine, and so far only in mice, researchers are confident that their findings can be applied to many other mammalian species. However, to better understand the capabilities of the enteric nervous system in the human body, further in-depth studies are necessary.
