Prenatal Development and the Newborn

developmental themes of the germinal period

starts out as a zygote, travels from fallopian tube to uterus, ends with implantation in uterus

developmental themes of the embryonic period

organs begin to form - brain, heart, eyes, ears, digestive system, thousands of nerve cells (sensitive period: time of rapid cell division and susceptible to teratogens)

developmental themes of the fetal period

grows 10x bigger, organs differentiated and refined, fetal movement, maximum # of nerve cells, age of viability

what is a teratogen?

a substance or factor that negatively affects the dev of the fetus (ex: mercury, caffeine, stress)

why do infants spend so much time in REM sleep?

Autostimulation theory: to make up for an absence of visual input

what is the Boisemeyer study?

supports Autostimulation theory - newborns who are provided w/lots of visual stimulation while awake show a decrease in REM sleep

do infants cry more when they are carried or fed on demand?

carried = cried more, strict schedule feeding = cried more

advantages of breastfeeding for babies

passes on mom's immunities, associated with higher IQ, relaxing

advantages of breastfeeding for moms

helps recovery, protects against breast cancer, cheaper

what is myelin and what does it do?

a fatty layer of cells that insulates axons; speed transmissions of impulses - myelinated axons transmit signals 10-100x faster than unmyelinated

what is a synapse? when does synaptogenesis occur?

a tiny, fluid-filled fap between a dendrite and an axon that connects neurons; occurs in early life and probably again in adolescence

what is synaptic pruning?

elimination of synapses that are not needed - if synapses are fired based on experiences, they will be maintained

why are synaptogenesis and pruning important?

allow the brain to organize itself based on experience

Rosenweig et al (1984)

methods: 3 groups of rats - raised alone vs. raised in group vs. enriched

results: enriched rats showed faster learning, increased weight of cerebral cortex, more synaptic connections

what is the stepping reflex?

when a baby moves its legs in such a way that it appears to be trying to walks (when held upright over an even surface)

why does the stepping reflex disappear?

legs got bigger, muscles not strong enough to move their legs appropraitely

how did Esther Thelen make the stepping reflex reappear?

submerging the babies in water - elimination of weight

preformationism

belief that prenatal life starts w/a tiny, fully-formed individual

epigenesis

new structures and functions emerge during development

germinal period

0-2 weeks; zygote -> blastocyst -> implantation

embryonic period

2-8 wks; organogenesis, sensitive period

fetal period

9 wks-birth; massive growth, refined organs, fetal movement

age of viability

22-26 wks; age a fetus can first survive outside womb