The brain may be highly affected by the gut.
This year, the burgeoning idea that gut bacteria might have a significant impact on brain functioning gained steam in the scientific community.
The National Institute of Mental Health invested more than $1 million on a new research program investigating the link between the gut microbiome and the brain, and a neuroscience conference last month called the investigation of gut microbes a "paradigm shift" in brain science.
"It opens up a completely new way of looking at brain function and health and disease," UCLA medicine and psychiatry professor Dr. Emeran Mayer told NPR last year.
Previous research had investigated a link between disorders like autism, depressionand anxiety to variations in the microbes within the intestines -- and this year, neuroscientists began to develop a deeper understanding of just how the microbiome, as it is called, exerts an influence on the brain's development and activity. While the link is still being investigated, the immune system and the vagus nerve, which connects the brain to the digestive tract, both likely play a role.