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Understanding brain
development
Early brain development
• The brain develops sequentially:
• Brain stem
• state regulation: pre-birth - 8 months
• Mid-brain
• motor functioning: first year
• Limbic brain
• emotional functioning: 6 months - 30 months
• Cortex
• cognitive functioning: 12 months - 48 months
Brain Architecture
• The brain is made up of neurons, or brain cells,
which connect to one another through synapses.
• Synapses are physical gaps between neurons,
like the gaps between the electrodes in spark
plugs, through which nerve impulses travel.
• The catch phrase in neuroscience is, “Cells that
fire together, wire together”; or otherwise stated,
“Use it or lose it.”
Early Brain Development
• We are born with most of the neurons we will
ever own (around 100 billion)
• At birth the brain is 25% of its adult weight by the age of 2 this has increased to 75%
and by age 3 it is 90% of adult weight.
• This growth is largely the result of the
formation and ‘hard wiring’ of synaptic
connections
What prevents normal brain development?
• Intra-uterine problems:
– Prenatal exposure to drugs and alcohol
– Maternal stress
• Attachment difficulties in the first years of life
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Parent or child chronic illness
Parental capacity overwhelmed by practical or emotional demand
Parental attachment or trauma history
Lack of fit between parent and child
• Neglect and trauma
– Physical, emotional or stimulation needs not met
– Abuse of the child
– Witnessing violence
It is now accepted that a
baby’s emotional
environment will
influence the
neurobiology that is the
basis of mind……. the
most vital part is the
emotional connection with the care giver.
• Babies’ brains are much more active and complex
than previously believed.
• We know that newborns can see at birth, particularly
objects that are within a range of 12 inches or so. This
is about the same distance between the baby’s eyes
and a carer’s face when they are feeding them.
• We also know that they can hear and can distinguish
between a variety of sounds in the language spoken to
them.
• They are able to show preferences for the smell,
sound, taste, appearance and feel of those people
who are important to them.
The way the child is stimulated and
soothed shapes the brain’s
neurobiological structure. What
happens in the early years has a
direct impact on the child’s capacity
for living, learning and relating as a
social being
Impact of unregulated stress
• All infants experience stress
• Most infants are helped to manage this by those
adults who love and care for them
• If an infant’s experience is predominantly of
neglect or fear then they will be in a state of
unregulated stress.
• The neuronal pathways that are most used are
those associated with stress, alarm and fear.
• Pathways that are associated with trust,
soothing and pleasure remain undeveloped.
Early school years 5-10
• Synaptic pathways that are regularly used are
reinforced. This is the basis of learning.
Reinforcement leads to permanent
neurological pathways.
• Neural connections needed for abstract
reasoning are developed
• Motor skills are refined
• In sensory and motor brain areas the number
of synaptic connections has reached mature
levels by mid-childhood
Puberty –a second chance?
Jay Giedd and colleagues have identified
a second burst of proliferation of synaptic
connections in the prefrontal cortex just
before puberty. This is followed by
pruning of these throughout the teenage
years. This suggests that adolescence
may be a time of both increased risk but
also heightened opportunity, especially for
those who have had particularly adverse
experiences earlier in life.
The frontal lobe undergoes far more
change during adolescence than at any
other stage of life.
Brain regions and functions
still developing in adolescence
• Frontal lobe: self-control, judgment, emotional
regulation; restructured in teen years
• Corpus callosum: intelligence, consciousness
and self-awareness; reaches full maturity in 20’s
• Parietal lobes: integrate auditory, visual, and
tactile signals; immature until age 16
• Temporal lobes: emotional maturity; still
developing after age 16
What Happens In The Adolescent Brain?
• Brain development continues up to at least the age of 20
• There is a significant remodelling of the brain in
adolescence, particularly the frontal lobes and
connections between these and the limbic system
• Myelination – this is a process which insulates nerve
fibres and enables neural pathways in the brain to
become much more efficient at transmitting information .
• Synaptic pruning in the prefrontal cortex. This is the area
of the brain responsible for “executive functions”
• Some changes are triggered by puberty, others by
increased experience
• The frequency and intensity of experiences shapes this
remodelling as the brain adapts to the environment in
which it is functioning and becomes more efficient
Emotional Functioning in Adolescence
• Age of puberty has fallen by several years in the last
century
• Brain structures that are associated with emotional
experiences change rapidly at the onset of puberty
• The frontal brain structures that are associated with
cognitive control mature much later than this
• Some research suggests that there is a dip in children’s
ability to judge social situations during early adolescence
• Therefore there is a mismatch in development of the
emotional and cognitive regulatory modes in
adolescence
• The combination of hormonal changes which increase
risk taking and ignite passion, with a reduced capacity to
make effective social judgments can be explosive.
What do the changes affect?
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Emotions
Motivation
Self awareness
Identity
Empathy
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Risk taking
Self control
Perspective taking
Judgement
Positive implications
• Adolescent brains are still malleable and
therefore potentially susceptible to
learning new emotional, social, motor and
cognitive patterns
• Environmental factors may affect the
nature of the synaptic pruning and
therefore the development of preferred
pathways.
• It is not too late!
“teenagers are empowered with
opportunities to develop their
brains through the activities in
which they choose to participate.”
ACT for Youth Factsheet
Adolescent Brain Development 2002