infant lec - Brain Development, page 1 Some Notes on Brain...

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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. 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 : Additive process, no evidence of regression or pruning of dendrites (e.g., Huttenlocher, 1996) Dendritic branching begins as early as 25-30 ga 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) 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 then reduction) 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
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Brain Development, page 2 Rise and fall of synaptic density for visual (open circles), auditory (filled circles) and prefrontal
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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 - Brain Development, page 1 Some Notes on Brain...

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