Overview
This lecture sets out how the brain and behaviour develop together, and what shifts that trajectory. It starts with two classical behavioural models (Piaget’s cognitive stages and Erikson’s psychosocial stages across the lifespan), then maps the biological substrate: the sequence of brain developmental processes from neurulation to myelination, grey matter maturation through adolescence, and critical periods. Perry’s Neurosequential Model of Therapeutics and the mātauranga Māori framework Te Whare o Oro are used to link brain levels (brainstem upward) to the needs a child has at each level. The final part covers the variables that alter development: sex, parenting and responsive relationships, environmental factors, infections, teratogens, adverse events and the stress-response spectrum. The organising point is that development is sequential, experience-dependent and does not stop at age 16.
Piaget’s model of cognitive development
Schemas are the units of the model. Several separate schemas combine into a single operation: gazing, reaching and grasping converge into the operation of picking up a rattle.
The four stages run in fixed order:
- Sensorimotor (birth to 2 years). The infant knows the world through their movements and sensations. Children learn through basic actions such as sucking, grasping, looking and listening. Infants learn that things continue to exist even when they cannot be seen (object permanence). They learn they are separate beings from the people and objects around them, and that their actions can cause things to happen in the world.
- Preoperational (2 to 7 years). Children begin to think symbolically and use words and pictures to represent objects. They tend to be egocentric and struggle to see things from another’s perspective. Language and thinking are improving, but thought is still very concrete.
- Concrete operational (7 to 11 years). Children begin thinking logically about concrete events. They grasp conservation, for example that the amount of liquid in a short wide cup equals that in a tall skinny glass. Thinking becomes more logical and organised but remains concrete. Inductive logic appears: reasoning from specific information to a general principle.
- Formal operational (12 and up; adolescence into adulthood). The adolescent or young adult begins to think abstractly and reason about hypothetical problems. Abstract thought emerges. Teens begin to think about moral, philosophical, ethical, social and political issues requiring theoretical and abstract reasoning. Deductive logic appears: reasoning from a general principle to specific information.
Erikson’s psychosocial stages across the lifespan
Eight stages, each a virtue set against a crisis, plotted along the lifespan:
- Infant: basic trust vs basic mistrust
- Toddler: autonomy vs shame and doubt
- Pre-schooler: initiative vs guilt
- School-ager: industry vs inferiority
- Adolescent: identity vs role confusion
- Young adult: intimacy vs isolation
- Middle age: generativity vs stagnation
- Older adult: ego-integrity vs despair
The transcript notes the figure’s caption banner (“Erik H. Erikson, Stages of Psychosocial Development”) was small and stylised, transcribed as the best legible reading.
Sequence of brain development
Six processes, in order of onset from conception onward:
- Neurulation in the first few weeks after conception (shortest window).
- Neuronal proliferation, beginning shortly after neurulation and extending further into gestation.
- Neural migration, beginning after proliferation starts and extending across most of gestation.
- Synaptogenesis, beginning mid-gestation and extending well past birth.
- Apoptosis, beginning mid to late gestation and extending past birth.
- Myelination, beginning around birth and extending furthest of all, through 4 months and into adolescence and adulthood.
Warning
The timings above come from a chart axis rather than explicit numbers on the slide. The relative order and overlap are as shown, but the precise start and end boundaries are approximate.
Grey matter maturation. Serial MRI maps (right lateral and dorsal views) across ages 5 to 20 years show a progressive shift on the grey matter volume scale from red and yellow (higher volume) toward blue and purple (lower volume). The sequence illustrates loss and refinement of grey matter volume with increasing age. No region-by-region labelling is given beyond the age progression.
Critical periods and the Neurosequential Model of Therapeutics
Critical periods are windows in a child’s life where the brain is most sensitive to experiences.
- These experiences play a crucial role in shaping the brain’s healthy development.
- During these periods the brain is highly receptive and highly adaptive.
- If certain experiences occur within these windows, neurodevelopment continues as expected.
- Critical periods include development of motor skills, social connections and language.
The Neurosequential Model of Therapeutics (NMT) is clinical problem-solving using a developmentally sensitive and neurobiologically informed approach. It is widely used to conceptualise traumatised and maltreated children and youth (Perry & Hambrick, 2008).
Brain level mapped to child need (Perry’s 2004 model, adapted by McCaleb & Mikaere-Wallis, 2005), narrowing from top to bottom:
| Brain level | Child need |
|---|---|
| Cortical | Tamariki: ako / learning |
| Limbic | Mātua: whanaungatanga / emotional engagement |
| Midbrain | Tūpuna: tino rangatiratanga / movement |
| Brainstem | Tūpuna: wairua rangimarie / safety |
The accompanying brain diagram labels, top to bottom: cerebral cortex, limbic system, cerebellum and diencephalon, brain stem. Glossary: tūpuna (ancestors), mātua (parents), tamariki (children).
Warning
The transcript flags that the labels on this small inset brain diagram were low resolution and hard to fully confirm, and that the glossary text sits visually beside the following slide’s image although the PDF text stream places it here, so its slide attribution is uncertain.
Te Whare o Oro
Te Whare o Oro is a mātauranga Māori (Māori knowledge) framework for understanding the roro (brain), from McLachlan, Kingi, Waitoki, Cribb-Fox & Cribb-Fox (2023). The whare tūpuna (ancestral meeting house) is stripped back to its frame so that each pou (post or pillar) maps onto a level of the brain, from the rearmost post forward.
Pou tuarongo and the brainstem
Critical functions:
- regulation of arousal, sleep and fear
- survival functions: swallowing, breathing, blood pressure, heart rate, sleep-wake cycle regulation
- conduit functions, passing information up and down the brain and body
- cranial nerves, responsible for sensory or motor functions
- detection of threats and activation of an alarm response (fight-or-flight)
Primary developmental goals: state regulation; primary attachment; flexible stress response and resilience.
Primary needs: whanaungatanga / emotional engagement; a safe and healthy environment; rhythmic and patterned sensory input (auditory, tactile, motor); aroha (attuned) responsive caregiving.
Pou tāhū and the diencephalon and cerebellum
Critical functions:
- integration of multiple sensory inputs and fine motor control
- movement and coordination (physical messages around the body and brain), and survival responses in response to the brainstem
- visceral (automatic) responses and regulation of body temperature
- relaying information via the thalamus and hypothalamus, sub-structures of the diencephalon
- organisation of the threat response via the HPA axis, increasing heart rate, blood pressure and muscle tone
- motor function, cognition and initial emotional responses
- cerebellar roles in arousal, vestibular function, autonomic functions and sensorimotor integration
Primary developmental goals: sensory integration; motor control; relational flexibility; attunement.
Primary needs: tino rangatiratanga / movement; more complex rhythmic movement; simple narrative, emotional and physical warmth.
Pou tokomanawa and the limbic system
Critical functions:
- emotional states, social language, interpretation of nonverbal information
- attachment and emotion regulation, motivations (for example to avoid pain, approach rewards), learning, emotional responses, physiological drives (hunger, thirst) and memory
- memory and emotional responses involve the amygdala
Primary developmental goals: emotional regulation, empathy, affiliation, tolerance.
Primary needs: whanaungatanga / emotional engagement; social connections and experiences; narrative; validation; complex movement.
Pou kaiāwhā and the cerebral cortex
Critical functions:
- abstract cognitive functions and socioemotional integration
- speaking, thinking, processing information, abstract cognition and complex language
- executive functions: planning, working memory, insight, foresight and personality
Primary developmental goals: abstract reasoning, creativity, respect, moral and spiritual foundations.
Primary needs: ako / learning; complex conversation; social interactions and exploratory play.
The four taha
A further whare diagram labels four named posts: Taha Tinana, Taha Hinengaro, Taha Wairua, Taha Whānau.
Warning
The slide carries no title or body text and gives no explanation of these four taha beyond the labels themselves, so no further detail is available from the slides.
Normal influences on development
Sex
- Variation in sexual hormone levels between sexes from week eight of gestation.
- Prenatal variation in neural networks.
- Variation during adolescence in timing.
- Males more highly variable than females.
Parenting
- Rejection is damaging.
- Warmth and responsiveness is good.
Responsive relationships. Children seek interaction via babbling and similar behaviours, and adults respond.
- This back and forth interaction is essential to the wiring of the brain.
- It is expected and essential to a child’s development and well-being.
Their absence is a serious threat:
- Unreliable response or absence disrupts brain development.
- It impairs subsequent physical, mental and emotional health.
- Persistent absence is a “double whammy”: the brain does not receive the needed positive stimulation, and the stress response is activated, flooding the developing brain with potentially harmful stress hormones.
Other factors affecting development
Grouped on the slides as:
- Environmental: green space, screen time.
- Infections.
- Toxins (teratogens): alcohol, antiepileptics, environmental.
- Adverse events: loss of a parent, disaster, abuse and trauma, familial disadvantage.
Infections listed: cytomegalovirus, herpes simplex, lymphocytic choriomeningitis, parvovirus (erythema infectiosum), rubella, varicella (slide writes “mumps”), syphilis, toxoplasmosis, Venezuelan equine encephalitis.
Antiepileptics are teratogens. They cause neural tube defects and intellectual disability, and taking more than one antiepileptic increases the risk. Named agents: valproate (particularly over 1000 mg/day), lamotrigine, phenytoin, phenobarbital, carbamazepine.
Other teratogenic drugs: aminopterin, busulfan, captopril and enalapril (renal failure), iodides, lithium, tetracycline, isotretinoin, cyclosporin, penicillamine, diethylstilbestrol and other androgenic steroids, corticosteroids.
Drugs of abuse and environmental exposures: alcohol, nicotine, cocaine, methamphetamine, ionizing radiation (radio iodine), mercury, lead, toluene.
Alcohol and fetal alcohol spectrum disorders
Important
There is no safe level of alcohol use in pregnancy. Fetal alcohol spectrum is common and diagnosis is difficult.
Fetal Alcohol Spectrum Disorders (FASD) facial features: epicanthal folds, flat nasal bridge, small palpebral fissures, “railroad track” ears, upturned nose, smooth philtrum, thin upper lip.
Primary disabilities: inconsistent memory and recall; decreased mental stamina; difficulty interpreting and applying abstract concepts; impulsivity and poor judgment; resistance to change; inability to predict outcomes; inability to see another person’s perspective; inability to recognise indirect social cues.
Secondary disabilities are not present at birth and occur later in life as a result of the primary disabilities: mental health problems; poor academic achievement; inability to live independently; alcohol and/or drug problems; problems with employment; incarceration or confinement; trouble with the law; disrupted school experience.
Adverse events, resiliency and the stress response
Adverse events covered:
- Loss of a parent, through death, or divorce or separation. Many children now have multiple parental figures during their first decade of life.
- Disaster.
- Illness of parent or child, producing functional separation from parents.
- Illness or disability of a sibling.
Three tiers of stress response:
- Positive: brief increases in heart rate, mild elevations in stress hormone levels.
- Tolerable: serious but temporary stress responses, buffered by supportive relationships.
- Toxic: prolonged activation of stress response systems in the absence of protective relationships.
Takeaway points
Brain development is:
- Sequential: built from regulation, then movement, then emotion, then cognition.
- Experience-dependent: neural pathways strengthen through repeated interaction and environment.
- Relational: responsive caregiving and connection shape regulation and resilience.
- Biologically sensitive: timing matters, and prenatal exposures, stress and environment influence outcomes.
- Adaptive: behaviour reflects developmental history, not simply symptoms or diagnosis.
Clinical implication: developmental context matters. To understand behaviour, ask what this brain has experienced, and when.
Closing whakataukī: Poipoia te kākano kia puawai, nurture the seed and it will bloom.
Self-test
- List Piaget’s four stages of cognitive development with their age ranges.
- Explain what schemas are in Piaget’s model, using the rattle example from the lecture.
- Define object permanence and state the stage in which it is acquired.
- Distinguish the form of logic that emerges in the concrete operational stage from the one that emerges in the formal operational stage.
- Describe the main cognitive limitations of a child in the preoperational stage.
- List Erikson’s eight psychosocial stages in order, giving the virtue and the crisis for each.
- Place the six processes of brain development in order of onset, and state which extends latest into life.
- Describe what the serial grey matter maps from 5 to 20 years show.
- Define a critical period and give the three domains of development named as examples.
- What is the Neurosequential Model of Therapeutics, and which group is it most widely used to conceptualise?
- Match each of Perry’s four brain levels to the corresponding child need in the adapted model.
- Describe the critical functions of the brainstem level (pou tuarongo) and its primary needs.
- Distinguish the primary developmental goals of the diencephalon and cerebellum level from those of the limbic level.
- Explain which functions the cerebral cortex level (pou kaiāwhā) supports and what the child needs to develop them.
- Explain why the persistent absence of responsive relationships is described as a “double whammy” for development.
- Describe how sex acts as a normal influence on development.
- List the antiepileptics named as teratogens and state the malformations and the dose threshold given.
- Name six of the infections listed as risks to development.
- Distinguish the primary from the secondary disabilities in fetal alcohol spectrum disorders, giving examples of each.
- Distinguish positive, tolerable and toxic stress responses, and say what determines which of the last two occurs.
- A 6-year-old with a history of neglect and inconsistent caregiving cannot settle in class and reacts to minor changes with panic. Using the sequential model of brain development and the takeaway points, explain what this suggests about which level of the brain to target first and what question the clinician should be asking.
Answers
Reveal answers
- Sensorimotor, birth to 2 years; preoperational, 2 to 7 years; concrete operational, 7 to 11 years; formal operational, 12 and up (adolescence into adulthood).
- Schemas are the basic units of action or knowledge that combine into more complex operations. Gazing, reaching and grasping are three separate schemas that converge into the single operation of picking up a rattle.
- Object permanence is the understanding that things continue to exist even though they cannot be seen. It is acquired in the sensorimotor stage.
- Concrete operational children use inductive logic, reasoning from specific information to a general principle. Formal operational adolescents use deductive logic, reasoning from a general principle to specific information.
- They think symbolically using words and pictures to represent objects but are egocentric and struggle to see things from the perspective of others, and although language and thinking are improving they still think in very concrete terms.
- Infant, basic trust vs basic mistrust; toddler, autonomy vs shame and doubt; pre-schooler, initiative vs guilt; school-ager, industry vs inferiority; adolescent, identity vs role confusion; young adult, intimacy vs isolation; middle age, generativity vs stagnation; older adult, ego-integrity vs despair.
- Neurulation, neuronal proliferation, neural migration, synaptogenesis, apoptosis, myelination. Myelination begins around birth and extends the latest, through 4 months into adolescence and adulthood. The exact week boundaries were read off a chart axis and are approximate.
- Right lateral and dorsal views across ages 5 to 20 years show a progressive shift on the grey matter volume scale from red and yellow (higher volume) toward blue and purple (lower volume), that is a loss and refinement of grey matter volume with increasing age. The slide gives no region-by-region detail.
- A critical period is a window in a child’s life where the brain is most sensitive to experiences, being highly receptive and highly adaptive; if the relevant experiences occur within the window, neurodevelopment continues as expected. The examples given are motor skills, social connections and language development.
- It is clinical problem-solving using a developmentally sensitive and neurobiologically informed approach, widely used to conceptualise traumatised and maltreated children and youth.
- Cortical to tamariki, ako / learning; limbic to mātua, whanaungatanga / emotional engagement; midbrain to tūpuna, tino rangatiratanga / movement; brainstem to tūpuna, wairua rangimarie / safety.
- Functions: regulation of arousal, sleep and fear; survival functions such as swallowing, breathing, blood pressure, heart rate and sleep-wake cycle regulation; conduit functions passing information up and down the brain and body; cranial nerves for sensory and motor function; threat detection and activation of the fight-or-flight alarm response. Needs: whanaungatanga / emotional engagement, a safe and healthy environment, rhythmic and patterned sensory input (auditory, tactile, motor), and aroha (attuned) responsive caregiving.
- Diencephalon and cerebellum: sensory integration, motor control, relational flexibility and attunement. Limbic: emotional regulation, empathy, affiliation and tolerance.
- Abstract cognitive functions and socioemotional integration; speaking, thinking, processing information, abstract cognition and complex language; executive functions including planning, working memory, insight, foresight and personality. Needs: ako / learning, complex conversation, and social interactions and exploratory play.
- Because two harms occur at once: the brain does not receive the positive stimulation it needs, and the stress response is activated, flooding the developing brain with potentially harmful stress hormones.
- Sexual hormone levels vary between sexes from week eight of gestation, there is prenatal variation in neural networks, there is variation in timing during adolescence, and males are more highly variable than females.
- Valproate (particularly over 1000 mg/day), lamotrigine, phenytoin, phenobarbital and carbamazepine. They cause neural tube defects and intellectual disability, and using more than one antiepileptic increases the risk.
- Any six of: cytomegalovirus, herpes simplex, lymphocytic choriomeningitis, parvovirus (erythema infectiosum), rubella, varicella, syphilis, toxoplasmosis, Venezuelan equine encephalitis.
- Primary disabilities are the direct effects, for example inconsistent memory and recall, decreased mental stamina, difficulty with abstract concepts, impulsivity and poor judgment, resistance to change, inability to predict outcomes, inability to take another’s perspective, and inability to recognise indirect social cues. Secondary disabilities are not present at birth and arise later as a consequence of the primary ones, for example mental health problems, poor academic achievement, inability to live independently, alcohol or drug problems, employment problems, incarceration, trouble with the law and disrupted schooling.
- Positive is brief increases in heart rate with mild elevations in stress hormones. Tolerable is a serious but temporary stress response. Toxic is prolonged activation of stress response systems. The difference between tolerable and toxic is the presence of buffering supportive or protective relationships: tolerable stress is buffered by them, toxic stress occurs in their absence.
- Development is sequential, built from regulation, then movement, then emotion, then cognition, so the lower levels are addressed first: the brainstem level goals of state regulation, primary attachment and a flexible stress response, met through a safe environment, rhythmic and patterned sensory input and attuned responsive caregiving, rather than starting with cortical learning demands. Development is also relational and experience-dependent, and behaviour reflects developmental history rather than simply symptoms or a diagnosis, so the clinician should ask what this brain has experienced, and when.