During the Blastocyst stage the inner cells separate into layers while the outer cells of the Blastocyst forms the placenta. The outer layer (ectoderm) becomes the skin and nervous system and the inner layers(endoderm- becomes the lungs and digestive system). The cephalo-caudal develop (latin words for head and tail) and from the center (spine) toward the extremeties (proximo-destal) develops. This is during the period of the embryo stage.

During the first three months of fetal development, the brain cells of the fetus mature and multiply. It is possible that a fetus can live at this stage outside the womb although most do not live. The brain cells continue to multiply rapidly during the last trimester.

How much does a baby's brain weigh? Adult's?

The head develops more rapidly at the bottom than at the top. One reason a baby's skull is so large is to accomodate the brain (weighing 25% of its adult's weight ). By age two, the brain is 75% of the adult's brain weight; however, the toddler's weight is 20% of an adult's weight.

What areas of the brain control the senses and motor skills?

The primary motor areas of the cortex and primary sensory areas of the cortex increase most rapidly during the 1st months (controlling simple motor abilities and senses). Rapid development is evident by 6 months in parts of the cortex that aid cooridination between the senses (matching faces with voices) and controlling more complex motor skills (picking up an object or later kicking a ball).

How fast does the brain develop?

Changes in size, shape, and skills are most visible signs and maturation from ages 2 through 6. A six year old is able to sit in 1st grade for hours at a time,something the brightest two year old cannot do.

The brain develops faster than any part of the body. A two year old brain weighs 75% of its weight at adulthood. At age five it weighs 90% of its full weight; whereas an average five year old's body weighs less than a third of an average adult's.

Important changes of the cortex occur during early childhood that enables a six year old to concentrate and learn more like an adult. James Tanner (child psychologist-1970) infers that the emerges of the stages of mental functioning, as explained by Piaget, "is very likely dependent on progessive maturation and organization of the cortex."

The development of the brain is organized in left and right hemisphere. The left hemisphere controls the right of the body and the right side of the brain controls the left side of the body.

Brain specialization for language skills begins early in development according to recent studies; but, is not complete until adolescence as demonstrated by right-handed accident victims who suffer damage to the language area of the brain. As an adult, the victim may be mute forever. A child may lose the entire speech area of the left-half of the brain and regain speech quickly by using the right-hemisphere.


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