By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) – Do you ever feel sick to your stomach when you’re upset? Do stressful events, like prepping for a big presentation or traveling, trigger digestive symptoms such as diarrhea or constipation? Some have called this the mind-body connection or the gut-brain axis. It’s the line of communication between your central nervous system – your brain and your spinal cord – and the nerves and hormones in your gastrointestinal tract.

Your GI tract holds a network of 100 million nerve cells embedded in its walls. The gut also contains roughly 100 trillion bacteria, which naturally reside there – collectively known as the microbiome.

Your microbiome regulates your immune system, digestion and how your body converts food to energy. But it also has another important task – to produce neurochemicals that communicate with your brain.

Research on the connection between your gut and your brain is still in its infancy. Over the next decades we will be learning far more.