Toward Understanding Microbiome-Neuronal Signaling.

Host-associated microbiomes are emerging as important modifiers of brain activity and behavior. Metabolic, immune, and neuronal pathways are proposed to mediate communication across the so-called microbiota-gut-brain axis. However, strong mechanistic evidence, especially for direct signaling between microbes and sensory neurons, is lacking. Here, we discuss microbial regulation of short-chain fatty acids, neurotransmitters, as-yet-uncharacterized biochemicals, and derivatives of neuromodulatory drugs as important areas for assessing microbial interactions with the nervous system.