September 30, 2021
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Brain development from conception to early adulthood
⟶ Updated 22 Nov 2018 ⟶
List of edits
25 Nov 2018
Socioemotional development in childhood and adolescence
Birth: 25% of adult brain weight, more than 100 billion neurons
Neural tube 22 days after conception
REM sleep begins at week 21
Neurogenesis: at about week 28, brain development grows in leaps and bounds
Synaptogenesis acceleration peak during the first five weeks
Visual cortex develops rapidly between 3 and 4 months of age, peaking at 12 months.
Transient exuberance and peak plasticity
Myelination proceeds most rapidly from birth to age 4 with motor and sensory brain regions myelinating first
Prefrontal 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 sounds
Infants 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 development
Lateralization begins dependent on which side the foetus lays on
Brain reaches 75% of its adult weight at age 2, signifying the start of Early childhood
90% of adult brain weight
Corpus collosum grows and myelinates rapidly during early childhood
Brain 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 pathways
After 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.
By 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 adulthood
Dual-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.
Processing speed reach adult levels at age 15.
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