Co-development of gut microbial metabolism and visual neural circuitry in human infants

Infancy is a time of rapid brain development supporting foundational sensory learning. The gut microbiome, also undergoing extensive developmental changes in early life, may influence brain development through metabolism of neuroactive compounds. Here, we show across the first 18 months of life that microbial genes encoding enzymes that produce and degrade neuroactive compounds, including neurotransmitters GABA and glutamate, the amino acid tryptophan, and short-chain fatty acids including acetate and butyrate, are associated with visual neurodevelopmental learning, measured by the visual-evoked potential (VEP). Microbial gene sets from stool collected around 4 months of age were strongly associated with VEP features measured from 9 to 14 months of age and showed more associations than concurrently measured gene sets, suggesting microbial metabolism in early life may have long term effects on neural plasticity and development.