Neurosequential Model, Brain Layers, 3 Rs & Neuroplasticity

Dr. Bruce Perry’s framework used to explain how brain structure relates to behaviour.
- Breaks the brain into sequential “layers.”
- Provides a bottom-up map for assessment, intervention, and teaching.
Lecturer’s rationale for using it:
- “Most coherent” and “simplified” entry point into complex neurophysiology.
- Analogous to a “driver’s manual” for the nervous system, which most people never receive.

All schematic diagrams are simplifications; real neurophysiology is fluid, overlapping, and still under investigation.
Learners should hold the tension between neat models and messy biological reality.

Lecturer learned an alternative, story-based teaching method from Ma’Du women.
- Brain presented as a developmental story rather than a static organ.
- Cultural metaphors: Lizard (brainstem), Love (limbic), Learning (cortex).

Develops first in utero; bathed in rhythmic maternal heartbeat.
At birth: most mature system, immediately confronted by sensory “assault” (light, sound, touch, movement).
Core question it asks: “Am I safe or in danger?”
Key anatomical/functional notes:
- Houses the cranial nerves.
- Vagus nerve (described as the 8^{th} cranial nerve in the talk; clinically the 10^{th}): “wandering nerve” extending into facial muscles and thoraco-abdominal organs.
- Governs the Autonomic Nervous System (ANS)—heart rate, respiration, vasodilation, digestion, salivation, facial expression, temperature, hormone (neuro-endocrine) balance.
- Generates flight–fight–freeze responses (sympathetic branch) and social-calm states (parasympathetic branch).
Example: When down-regulating a hyper-aroused vagal system you may see facial muscle spasms as tone shifts.

Develops second, contingent on safe caregiving & relationship.
Babies calm their brainstem, then attend to faces—primarily caregiver’s face, building emotional circuitry.
Outdated but serviceable label “limbic” includes amygdala, hippocampus, etc.
- Amygdala = emotion/threat detector.
- Hippocampus = episodic & contextual memory.
Cultural label “Love Brain” highlights functions:
- Social bonding, belonging, self-worth.
- Emotional regulation learned in relationship (“coregulation”).
Activation pattern: When brainstem declares safety → Social Engagement System (polyvagal concept) activates, enabling limbic attachment processes.

Comes online last in the developmental sequence.
Functions:
- Executive skills: planning, sequencing, consequence evaluation, response inhibition.
- Language, literacy, abstract reasoning, complex motor planning.
- Lecturer’s Ma’Du label: “Learning.”
Only fully functional when lower layers are both autonomically regulated and relationally safe.

Brain builds bottom-up (brainstem → limbic → cortex).
Under stress the process reverses (“hierarchical regression”):
1. Cortex goes offline → executive dysfunction.
2. Limbic dominates → catastrophic, isolating thoughts ("I’m all alone", "I’m no good").
3. Severe threat → brainstem takes over → reflexive fight/flight/freeze.
Key insight: We do not age out of this pattern; lifelong physiological rule.

Regulate → Relate → Reason (a mirror to the Ma’Du “Lizard-Love-Learning”).
1. Regulate autonomic arousal first (brainstem/ANS).
2. Relate by activating social engagement/emotional safety (limbic).
3. Reason only after lower layers are calm (cortex).
Practical implication: Common disciplinary tactic of starting with logical reasoning is often futile because the cortex is disabled during distress.

First ~6 weeks: sensory processing, cranial nerves, brainstem function.
Stress response: links brainstem + limbic (amygdala/hippocampus).
Later modules: cortical learning processes, executive function, literacy, motor planning.
Final weeks: Neuroscience of Belonging (integrates entire hierarchy; large proportion of brain is social by design).

Definition: Brain’s ability to alter structure & function across the life span.
Mechanisms:
- Neurogenesis: birth of new neurons in certain regions.
- Synaptic plasticity: strengthening/weakening of synapses via transmitter changes.
- Myelination: increased myelin → faster conduction (“highways”).
Shaping factors:
- Experiences, occupations ("doing"), stress, trauma, learning, therapy.
- Early life stress can distort wiring, but nothing is set in stone.
Occupational-therapy link:
- OT interventions = intentional occupations that harness neuroplasticity to improve participation, capability, and sense of belonging.
- Even in aged care, plasticity remains a treatment target.

Recognise physiological limits: expecting rational control from a dysregulated individual is biologically mismatched.
Trauma-informed practice: map developmental insults to brain layers, then provide corrective experiences.
Education takeaway: teach society a “nervous-system driver’s manual.”

Newborn overwhelmed by environmental stimuli → uses brainstem to decide safety.
Baby’s first visual focus on caregiver’s face when autonomically settled.
Facial spasm when vagus shifts from sympathetic to parasympathetic state.
Classroom/parent scenario: attempting to reason with a dysregulated child fails; must first co-regulate.

Intends to create interactive “Dr Karl” style Q&A for deeper dives.
Encourages students to challenge and ask for evidence; if answer unknown, she will consult literature.