The Gut-Brain Axis as Displacement Circuit: Enteric Ground State, Vagal Return Signaling, and the Microbiome as Neural Co-Regulator

We apply the Displacement Framework to the gut-brain axis, formalizing the enteric nervous system (ENS) as a semi-autonomous displacement-sensing system coupled to the CNS through four channels: vagal signaling (80% afferent), enteroendocrine hormones, HPA axis, and immune signaling. The gut microbiome is formally identified as a constitutive component of the neural ground state S0_gut-brain, not a downstream effector — microbiome displacement propagates upstream as neural displacement.

We derive the leaky gut as a displacement transfer mechanism (LPS translocation through disrupted tight junctions driving neuroinflammation), formalize depression and anxiety as joint gut-brain displacement events, and show that single-target interventions underperform relative to multi-component return strategies. The vegan/plant-based diet is shown to maximize microbiome diversity and thus basin depth of S0_gut-brain.