Pedriatische neuropsychologie – Developmental Neuropsychology, a Clinical Approach
Ch. 2 Cerebral development
- Knowledge of the biological processes and timing of CNS maturation may lead to the
identification of parallels between specific stages of CNS development and associated
cognitive progress.
- An understanding of the sequence of events occurring within the CNS and their timing may
enhance current knowledge of the nature and possible recovery of cognitive deficits
exhibited by children sustaining pre- and postnatal CNS insult.
Brain development: general principles
The fastest rate of brain growth occurs prenatally. Although the structural morphology of the brain is
mature by birth, growth continues during the postnatal period. Between birth and adulthood the
human brain quadruples in size, increasing from around 400 g to 1500 g at maturity in early
adulthood, peaking between 18 and 30 years and then commencing a gradual decline. The postnatal
increase in brain weight is largely due to differentiation, growth and maturation of existing neurons,
including elaboration of dendrites and synapses, and ongoing myelination.
Prenatal development structural formation of the CNS, and is thought to be largely genetically
determined. Interruptions to development during this period, via genetic mechanisms or interuterine
trauma or infections, is likely to have impact on cerebral structure, the brain’s morphology appears
abnormal.
Postnatal development associated with elaboration of the CNS (in particular, dendritic
arborisation, myelination, and synaptogenesis). Brain damage sustained postnatally will have less
impact on gross brain morphology, but may interfere with ongoing CNS elaboration, and the
development of interconnections and functional systems within the CNS.
2 major developmental processes:
- Additive development there is an ongoing accumulation or growth process.
Prenatally the number of neurons generated is in excess of
what is required in the mature CNS. During the
differentiation stage of development, a number of these
redundant neurons die off. A similar elimination of
redundant elements is seen for synapses formed
postnatally and during childhood. These too have been
observed to increase rapidly in early childhood, exceeding
adult levels, then decrease to adult levels.
Critical (sensitive) period= a stage in the developmental
sequence during which an aspect of behavioural function
may experience a major progression. If this progression
does not occur appropriately then it may never occur.
Hierarchical progression within the CNS cerebellar/brain
stem areas maturing first, following by posterior areas, and
lastly anterior regions, particularly the frontal cortex. This
hierarchical development is argued to progress in spurts,
representing the ongoing elaboration of the system.
1
Ch. 2 Cerebral development
- Knowledge of the biological processes and timing of CNS maturation may lead to the
identification of parallels between specific stages of CNS development and associated
cognitive progress.
- An understanding of the sequence of events occurring within the CNS and their timing may
enhance current knowledge of the nature and possible recovery of cognitive deficits
exhibited by children sustaining pre- and postnatal CNS insult.
Brain development: general principles
The fastest rate of brain growth occurs prenatally. Although the structural morphology of the brain is
mature by birth, growth continues during the postnatal period. Between birth and adulthood the
human brain quadruples in size, increasing from around 400 g to 1500 g at maturity in early
adulthood, peaking between 18 and 30 years and then commencing a gradual decline. The postnatal
increase in brain weight is largely due to differentiation, growth and maturation of existing neurons,
including elaboration of dendrites and synapses, and ongoing myelination.
Prenatal development structural formation of the CNS, and is thought to be largely genetically
determined. Interruptions to development during this period, via genetic mechanisms or interuterine
trauma or infections, is likely to have impact on cerebral structure, the brain’s morphology appears
abnormal.
Postnatal development associated with elaboration of the CNS (in particular, dendritic
arborisation, myelination, and synaptogenesis). Brain damage sustained postnatally will have less
impact on gross brain morphology, but may interfere with ongoing CNS elaboration, and the
development of interconnections and functional systems within the CNS.
2 major developmental processes:
- Additive development there is an ongoing accumulation or growth process.
Prenatally the number of neurons generated is in excess of
what is required in the mature CNS. During the
differentiation stage of development, a number of these
redundant neurons die off. A similar elimination of
redundant elements is seen for synapses formed
postnatally and during childhood. These too have been
observed to increase rapidly in early childhood, exceeding
adult levels, then decrease to adult levels.
Critical (sensitive) period= a stage in the developmental
sequence during which an aspect of behavioural function
may experience a major progression. If this progression
does not occur appropriately then it may never occur.
Hierarchical progression within the CNS cerebellar/brain
stem areas maturing first, following by posterior areas, and
lastly anterior regions, particularly the frontal cortex. This
hierarchical development is argued to progress in spurts,
representing the ongoing elaboration of the system.
1
