What is the timeline for brain development?
<p>Jan 30, 2011 09:58 PM
 
myelination begins in the brain at 6 months gestation;  proceeds head to toe direction
 
myelination is the major cause of the increase in a child's brain size.
 
At birth,  the infant brain weighs  300 to  350 grams  say  2/3 of a pound = .66 pounds;  if baby weighs
6.6 pounds then brain is 10% of body weight at birth.  (As an adult, it's 2% of body weight)
 
At age 4, the brain increase to 80% of adult weight of 1200 to 1500 grams (2.6 to 3.3 pounds)
 
fMRI shows dramatic changes in brain structure in kids from age 3 to 15.
 
Few nerve centers are myelinated at birth. In the beginning, only reflexes needed for survival are completely myelinated; however, after birth the primary visual and auditory cortex neurons rapidly receive their myelination.
ferret research shows that experience matters in structuring visual vs auditory pathways (can switch them).
 
<b>Final myelination of the frontal lobes occurs in early adolescence. </b>An adolescent's brain reaches the weight of an adult brain by about <b>age fourteen due to myelin accumulation and dendritic branching</b>. At this time the potential for contribution to <b>insight, judgment, inhibition, reasoning, and social conscience are possible</b>. The adolescent's frontal lobes are increasingly active, and this ability enables the adolescent to consider several things in the mind while comparing or interrelating them.
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