Halfway Check

So far, the gut and brain are in nonstop conversation:

• The vagus is the highway: most of its traffic runs upward, gut to brain.
• A second brain lives in your gut: about 500 million neurons that run digestion on their own.
• It uses brain chemicals: dopamine, serotonin, GABA, and more.
• Gut feelings are real data: interoceptive signals sway your choices below awareness.