Co-development of gut microbial metabolism and visual neural circuitry over human infancy

Infancy is a time of elevated neuroplasticity supporting rapid brain and
sensory development. The gut microbiome, also undergoing extensive
developmental changes in early life, may influence brain development
through metabolism of neuroactive compounds. Here, we leverage
longitudinal data from 194 infants across the first 18 months of life to
show that microbial genes encoding enzymes that metabolize molecules
playing a key role in modulating early neuroplasticity are associated with
visual cortical neurodevelopment, measured by the Visual-Evoked Potential
(VEP). Neuroactive compounds included neurotransmitters GABA and
glutamate, the amino acid tryptophan, and short-chain fatty acids involved
in myelination, including acetate and butyrate. Microbial gene sets around
4 months of age were strongly associated with the VEP from around 9 to 14
months of age and showed more associations than concurrently measured gene
sets, suggesting microbial metabolism in early life may affect subsequent
neural plasticity and development.