Brain development from conception to early adulthood
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Updated: 22 Nov 2018
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Created byJon
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Birth: 25% of adult brain weight,
more than 100 billion neuronsConceptionNeural tube 22 days after conceptionREM sleep begins at week 21Neurogenesis: at about week 28, brain development
grows in leaps and boundsSynaptogenesis acceleration peak
during the first five weeksVisual cortex develops rapidly
between 3 and 4 months of age,
peaking at 12 months.Transient exuberance and
peak plasticityMyelination proceeds most
rapidly from birth to age 4
with motor and sensory brain
regions myelinating firstPrefrontal cortex development: 5- to 12- month-old
babies require fewer habituation trials than younger babies.Temporal and left frontal cortex response
indicate that newborns can discriminate
language speech from other soundsInfants show more localized frontal cortex activity
during attention tasks when they're 7.5 month old.Toddlers display improved self-control between
18 and 36 months, indicative of PFC developmentLateralization begins dependent on
which side the foetus lays onBrain reaches 75% of its
adult weight at age 2,
signifying the start of
Early childhood90% of adult brain weightCorpus collosum grows and myelinates
rapidly during early childhoodBrain development of mirror neuron system and PFC.
Metacognition and theory of mind begins to develop
at 3, resulting in false belief task success at ages 4 to 5.From ages 2 to 9 children's morality
regarding rules move from absolute
to relative, and prosocial behaviour
gets motivated by empathy rather
than egocentric motivations. Brain
regions involved in moral development
includes: VMPFC, DLPFC, MNS,
Amygdala, and the Mesocortical-
and Mesolimbic pathwaysAfter week 8, the embryo gets flushed with
testosterone if its genome has a Y-chromosome.
The testosterone has organizational effects in
the brain of the foetus (INAH, VMH, MPA)11-year-old children respond twice as quickly
as 5-year-old children. Synaptic pruning, growth
of the cerebellum and myelination of its
connections to the cortex contribute to advances
in gross and fine motor skills and speed.9-year-old children show more activity in parts of
the temporal and prefrontal cortex, as well as
other parts associated with working memory,
inhibitory control, and executive control, than 5
year-old-children.Cognitive improvements during early childhood is
mediated by myelination and pruning of the
visuospatial- and auditory working memory, and
response inhibition, differentiating them to
enable better information processing. All these
functions are differentiating primarily in the PFC.AdolescenceBy age 8 or 9, the HPG axis initiates hormonal
change. Hypopthalamus signals the pituitary
gland to release GnRH, which causes the gonads
to enlarge and produce their own hormones.
Testosterone and oestrogen flushing reorganizes
the brain. A second burst of synaptogenesis
commmences.Cerebral cortex volume peaks at age 10.5 in girls.At age 14.5, cereberal cortex volume peaks in boys.Synaptic pruning occurs at an accelerated rate
during adolescence, decreasing the volume of
grey matter and moulding the prefrontal cortex,
streamlining cognition and neural functioning.Myelination, especially in the prefrontal cortex
and corpus callosum, which increase up to 20%
in size, continues in adolescence. White matter
development is linked to improved working
memory, executive functioning, and learning.The frontal cortex is fully developed in the mid 20s.Brain senescence starts in early adulthoodDual-process model (brain asymmetry) can
explain adolescent behaviour and cognition.
Sensitivity to reward peaks at the same time
adolescents experience difficulty with responses
inhibition and behavioural control.Frontal cortex activation responses to faces
decreases in early adolescence relative to middle
childhood, while amygdala activation increases.Frontal cortex activation
responses to faces
increase in late
adolescence and
early adulthood.At age 9 to 10, serotonin
and dopamine levels shift
in the PFC and limbic system,
altering boys' reward salience.Working memory reaches adultlike levels by age
19, while the neurological changes that underlies
response inhibition continue to develop into the
20s.Early adulhoodMiddle childhoodProcessing speed reach adult levels at age 15.
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