The human gastrointestinal tract is colonised by a large number of microorganisms, so called the gut microbiota. These microorganisms play fundamental physiological, metabolic and immunological roles for the host. 

Recently it has been shown that even behaviour is affected by alterations in the gut microbiota. This presentation will touch upon some of these aspects on the basis of the paradigm that an aberrant microbe-gut-brain interaction is pivotal in the pathology of diverse diseases.