Scientists have found that intestinal bacteria play an important role in inducing anxiety and depression. Published in Nature Communications , the new research is the first of which studies the role of intestinal microbiota in the altered behaviour that is a consequence of early life stress. Previously there has been little research on this subject. All scientists knew was that intestinal bacterium can affect behaviour, but this was all based upon research conducted on healthy mice. [Definition: Microbiota - noun – the microorganisms of a particular site, habitat, or geological period.] "We have shown for the first time in an established mouse model of anxiety and depression that bacteria play a crucial role in inducing this abnormal behaviour," said Premysl Bercik, senior author of the paper and an associate professor of medicine with McMaster's Michael G. DeGroote School of Medicine. "But it's not only bacteria, it's the altered bi-directio