Linking the Gut Microbiota to a Brain Neurotransmitter

The past decade has yielded substantial evidence that the gut microbiome modulates brain function, including for instance behaviors relevant to anxiety and depression, pointing to a need to identify the biological pathways involved. In 2013 Clarke and colleagues reported that the early-life microbiome regulates the hippocampal serotonergic system in a sex-dependent manner, findings that opened up numerous lines of inquiry on the effects of the microbiome on neurodevelopment and behavior.