The bacteria in our gut could impact our mood and general behavior. People have been talking about trusting our “gut instincts” since the beginning of time and it has always meant that humans should trust that instinctual part of them that tells them if something is right or wrong. This old adage hasn’t really been backed by science, but researchers from the University of California, Los Angeles have found new meaning for the term by finding a link between the microbes in our intestines and the way our brains are formed and how they function.
Scientists at the university looked at 40 different women and performed two tests, one involving their fecal matter and the other using a magnetic resonance imagine (MRI) scanner. When inside the MRI scanner, the women were shown various images of individuals, environments, situations or objects that were designed to evoke emotional responses.
Of the 40 women tested, 33 of them had more of the bacterium called Bacterioids, so they were grouped together in the first primary group. The remaining 7 women had more of the Prevotella bacteria. The Bacterioids group showed that they had greater thickness of the gray matter found in the frontal cortex and insula, which are regions involved in complex processing of information. This group also had larger volumes of the hippocampus, which is involved in memory processing. These women were less likely to experience negative emotions when shown negative images.
By contrast, the Prevotella group had very different results. These women displayed more connections between emotional, attentional, and sensory brain regions and lower brain volumes in several regions, like the hippocampus. This group’s hippocampus was less active than the other group’s while viewing negative images and they exhibited higher levels of negative feelings related to anxiety, distress, and irritability than the Bacterioids group did.