PSYCH 144: Gastrointestinal Disorders

Clinical Deep Dives · Oct 6, 2026 · 43m · transcript

and the extraordinary bidirectional conversation of the brain–gut–microbiome axis.

Medlock Holmes enters The Great Gut–Brain Exchange, an immense Neo-Victorian communication network in which the brain and gastrointestinal tract are joined by constantly moving signals. Messages travel downward through the autonomic nervous system, HPA axis and neuroendocrine pathways, while sensory, immune, hormonal and microbial signals travel back towards the brain.

There is no single direction of causation.

Instead:

BRAIN ↔ GUT ↔ IMMUNE SYSTEM ↔ MICROBIOME

This brain–gut–microbiome axis provides the central…