Neuroscience

Gut–brain axis

Enteric nervous system

Brain development

Neural system

Central nervous system

Gut flora

Biology

Psychiatry

Psychological intervention

Immunology

Gastrointestinal tract

Biochemistry

Medicine

Trends in Molecular Medicine

Microbes within and on our bodies are a thriving dynamic population forming a symbiotic superorganism. The collective comprises a myriad of bacteria, of approximately 1014 cells, containing 100 times the number of genes of the human genome [1]. Despite the evolution of this microbiome (see Glossary) for 500 million years [2,3], it is only recently that advances in sequencing technology have allowed us to appreciate the full nature of the complexities of host–microbe relationships. The largest microbial component of the human microbiome is located in the large intestine of the gastrointestinal (GI) tract.

Microbiota and neurodevelopmental windows: implications for brain disorders