Infant Lec 15a

Infant Lec 15a - Brain Development page 1 Some Notes on...

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Brain Development, page 1 Some Notes on Brain Development in Infancy and Early Childhood Postnatal brain development is a protracted process, spanning childhood and into adolescence. The brain quadruples in size from birth to adulthood [350 grams to 1400] Occurs not because of increase in number of neurons, which is established at birth; rather the increases are due to three processes of elaboration: dendritic arborisation- synaptogenesis - myelination- Dendritic arborisation :- dentrite on each neuron begin to proliferate and grow Additive process, no evidence of regression or pruning [or eliminated] of dendrites (e.g., Huttenlocher, 1996) Dendritic branching begins as early as 25-30 ga [gestational age- from conception forward] and continues until birth. Major changes occur postnatally, including increased length and branching. Most dramatic development occurs between postnatal weeks 5-21. Adult levels at 5-6 months (Becker et al., 1984). Development in the frontal areas may continue until age 7 (Huttenlocher, 1996). Environmental stimulation/deprivation can increase/hinder the process (e.g., Kolb, 1995 Synaptogenesis : Synaptic connections increase from birth, with bursts of rapid growth at various stages within different cerebral regions Area V1 is in the occipital lobe: peak in density between 4-12 months (150% of adult), Plasticity if other regions get damaged so large number of dendrites …. Prefrontal cortex: density increase is much slower, peak only after first year Begins in 2nd trimester of gestation (Molliver et al., 1973) Most development is postnatal Regressive process (initial over-production of synapses then reduction [pruning]) Synapses initially unspecified in function (Huttenlocher, 1994) As neural circuits emerge synapses become utilized in these functional systems Unspecified synapses regress, starting after 1 year- pruning; children 6-8 months have ability to discern different phonins in language
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This note was uploaded on 08/10/2011 for the course CHEM 160:161 taught by Professor Siegel during the Spring '09 term at Rutgers.

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Infant Lec 15a - Brain Development page 1 Some Notes on...

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