Layer 1 — Base
Brainstem
Autonomic · Safety · Survival · Heart rate · Breathing
Layer 2 — Arousal
Diencephalon
Alertness · Rhythm · Movement · Regulation
Layer 3 — Relational
Limbic system
Affiliation · Trust · Belonging · Emotion
Layer 4 — Apex
Neocortex
Rigor · Reasoning · Language · Abstraction