Correlations between the gut microbiome and behavioural conditions, especially autism have made neuroscientists sit up and attempt to understand how gut bacteria may influence the brain. In the most recent edition of Nature, there is a short piece to highlight the upcoming 19 November 2014, symposium at the annual Society for Neuroscience meeting in Washington DC called ‘Gut Microbes and the Brain: Paradigm Shift in Neuroscience’. This meeting will highlight the impact of gut microbes and bacterial waste products on brain function. It is known, for example, that at least two types of intestinal bacterium produce the neurotransmitter y-aminobutyric acid (GABA). The meeting will discuss events in early life with brain function and how the microbiome composition soon after birth may have a profound effect on brain function development in later life.