AUTHOR=Kelly John R. , Minuto Chiara , Cryan John F. , Clarke Gerard , Dinan Timothy G. TITLE=Cross Talk: The Microbiota and Neurodevelopmental Disorders JOURNAL=Frontiers in Neuroscience VOLUME=Volume 11 - 2017 YEAR=2017 URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2017.00490 DOI=10.3389/fnins.2017.00490 ISSN=1662-453X ABSTRACT=Humans evolved within a microbial ecosystem resulting in an interlinked physiology. The gut microbiota can signal to the brain via the immune system, the vagus nerve or other host-microbe interactions facilitated by gut hormones, regulation of tryptophan metabolism and microbial metabolites such as short chain fatty acids (SCFA), to influence brain development, function and behaviour. Emerging evidence suggests that the gut microbiota may play a role in shaping cognitive networks encompassing emotional and social domains in neurodevelopmental disorders. Drawing upon preclinical and clinical evidence, we review the potential role of the gut microbiota in the origins and development of social and emotional domains related to Autism spectrum disorders (ASD) and Schizophrenia. Small preliminary clinical studies have demonstrated gut microbiota alterations in both ASD and Schizophrenia compared to healthy controls. However, we await the further development of mechanistic insights, together with large scale longitudinal clinical trials, that encompass a systems level dimensional approach, to investigate whether promising pre-clinical and initial clinical findings lead to clinical relevance.