We tend to think of our internal organs as specialists, highly refined machines that work 24/7 at specific tasks. The one exception is the brain: the ultimate supercomputer that can make a multitude of decisions and manage our behavior with incredible speed and efficiency.

Now research shows that the brain doesn’t have a monopoly on intelligence. The heart and stomach, for example, are fully equipped to do some thinking of their own. And sometimes they’re giving the brain orders instead of taking them.

The Heart: Not Just Brawn But Brains, Too

Lub-dub. Lub-dub. About 100,000 times a day the heart repeats this monotonous task of survival. But what many think is a mindless pump turns out to have a mind of its own. According to the Institute of HeartMath—a nonprofit research and education organization dedicated to helping people live healthier, happier lives—there are networks of nerve cells (neurons) around the heart that function in much the same way as parts of the brain.

Back in the 1960s, research conducted by John and Beatrice Lacey—pioneers in the field of psychophysiology—showed that the heart has its own reasoning that is not determined by directives from the brain. Subsequent investigations revealed an actual pathway and mechanism allowing the heart to send messages that inhibit or facilitate electrical activity in the brain. The new field of neurocardiology evolving from this research led to the development of the concept of the “heart brain” in 1991.

The “heart brain” is equipped with some 40,000 neurons. These neurons can deliver pain signals and other sensations to the autonomic parts of the brain (which are largely unconscious), as well as messages to brain centers involved in conscious thought and emotion. Contact with the “executive” part of the brain can influence perception, decision making, and emotional responses. Studies have shown, for example, that a person is better at recognizing a scary face when observing it as the heart contracts, or pumps blood out to the body, than when observing it as the heart relaxes and takes blood in. Clearly, this type of response can play an important part in survival.

The Institute of HeartMath is exploring possible ways to harness the intelligence of the heart to deal more effectively with stress and to shift the emotional balance toward more positive behaviors. The beat goes on…

When the Stomach Talks, the Brain Listens

The stomach does a lot more than dump acid on your latest meal. It also fires off signals to the brain via its own extensive network of neurons. According to Michael Gershon, chairman of the Department of Anatomy and Cell Biology at New York–Presbyterian Hospital/Columbia University Medical Center, there are 100 million neurons in this “second brain.” This arsenal far outnumbers the neuron supply in the spinal cord or the rest of the nervous system outside of the brain.

Although not involved in conscious thought or decision making, the stomach brain enables the gut to make its own decisions regarding the behavior of the digestive system. And the stomach has plenty to tell the brain as well. Research shows that about 90% of the fibers in the vagus nerve—the main nerve for the gut—carry information from the gut to the brain.

It turns out that “butterflies” and that “sinking feeling” in the stomach have a neurological basis. Neurons lining the stomach are filled with neurotransmitters, chemicals that help nerve cells communicate with one another. One key neurotransmitter is serotonin, which plays a major role in mood regulation. While serotonin is also found in the brain, 95% of the body’s supply is in the stomach. This abundance explains why drugs like Prozac, known as selective serotonin reuptake inhibitors (SSRIs), help elevate mood by increasing serotonin levels but may also cause stomach disturbances.

Growing interest in the stomach brain has spawned a field of study known as neurogastroenterology, which will likely reveal even more exciting findings about the stomach’s IQ in the future.

---

Find Out More

• Adam Hadhazy, “How the Gut’s ‘Second Brain’ Influences Mood and Well-Being,” Scientific American.