Why Scientists Think This Part Of The Body Is “The First Brain”

Of all organs in the body, the gastrointestinal tract is the only organ to have developed its only fully independent nervous system.

This is why this tract, which runs from the mouth to the anus, has earned the nicknames of “mini-brain” and “second brain”. But Nick Spencer, professor at Flinders University in Australia, argues for another nickname: the first brain.

“I was fascinated 23 years ago when I started researching the enteric nervous system, and I am even more so now,” says Spencer. Reverse.

The enteric nervous system (ENS), or intrinsic nervous system, is the nervous system of the gut and is home to hundreds of thousands of individual neurons. These neurons are what provide propulsion along the intestine. They are essential for muscle contraction and relaxation and work without any interaction with the brain.

Thanks to a recent study published in the journal Communications biology, Spencer and his colleagues became the first to discover how the neurons in this bodily system “talk to each other” to induce propulsion. These findings reveal how an admittedly strange part of the body works, bringing us one step closer to treating a disease caused by loss of neurons.

“This is why we think the intestinal enteric nervous system is the first brain.”

It is also a reminder of the length of our journey towards understanding our humanity. While the brain has long taken center stage in our quest to probe the cause and effects of evolution, a growing number of studies are now highlighting the importance of the gut.

The gut, as we now know, influences our emotional state, our longevity and our immune system. Gut bacteria are even linked to certain brain conditions, which makes brain comparisons even more important. But we still have a long way to go in our understanding of its influence. Research like this Spencer’s article reinforces our underestimation of this body part and its uniqueness.

The first brain – Some invertebrate animals do not have a brain. These are creatures like sea cucumbers, sea urchins, and sea sponges.

Hydra is a genus of brainless invertebrates, and has been around for over 600 million years. They are incredible, seemingly ageless freshwater creatures that look a bit like a tube with arms sticking out.

Hydra, explains Spencer, supports his “first brain” theory.

“Hydras have an intrinsic nervous system, remarkably similar to the intrinsic nervous system (or ENS) in the gut of vertebrate animals that exist today,” he explains via email.

“Despite the lack of a formal brain, as we know it, their intrinsic nervous system allows them to swim, feed and ingest food.”

The idea that the enteric nervous system in the gut is the first brain, he explains, is “based on the fact that the brain and spinal cord evolved in vertebrate animals, such as fish and humans, well after the evolution of the enteric or nervous system. “

“That’s why we think the intestinal enteric nervous system is the first brain,” he says.

The enteric nervous system – “The enteric nervous system is essential for life,” says Spencer. “No vertebrate animal can live without it. “

It has a number of tasks: it is essential for the propulsion of things through the intestine as well as for the expulsion of those things as waste. It allows, as this study shows, the muscles to contract and relax – which is why we can digest and absorb our food. The enteric nervous system also has its own sensory neurons.

“No other organ in the body has its own intrinsic sensory neurons which are contained within the organ and function independently of the spinal or vagal afferent neurons outside the intestine,” explains Spencer.

While different neurons in the enteric nervous system have different tasks, Spencer and his colleagues have found that thousands of them synchronize and coordinate the trigger, which causes propulsion through the colon, part of the gastrointestinal system. Propulsion begins with swallowing and continues through the process of peristalsis, involuntary constriction and relaxation of muscles. You choose to swallow a bite of food and your neurons help propel that food through your system.

Sometimes, however, the digestion is not going as expected.

“It’s impossible to know how to fix an ENS problem if you don’t know how it works.

Some animals, such as horses, mice, and humans, suffer from a condition called Hirschsprung’s disease. This can prohibit bowel movements and is caused by a loss of neural development in the enteric nervous system, which may be due to genetic mutations. It is estimated that one in 5,000 human babies has some degree of Hirschsprung disease, Spencer says. Although it can be life threatening, surgery very often leads to a successful recovery.

While Spencer’s work serves a fundamental purpose – “in science it is essential to know how the organ works” – it also explains why conditions such as Hirschsprung’s disease occur.

“It’s impossible to know how to fix an ENS problem if you don’t know how it works,” he says.

“My lab focuses a lot on understanding how the organ works before trying to cure organ disease. It’s like being asked to fix the engine of a broken down car, but you have no idea how the engine works.

Fortunately, we are on the right track to understanding how the assembly works.