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Chapter 5: Brain Development and Plasticity
Terms in this set (74)
When does the human central nervous system begin to form
when the embryo is approximately two weeks old
name the three steps of the maturation of the vertebrate brain
1) the dorsal surface thickens forming a neural tube surrounding a a fluid filled cavity. 2)The forward end enlarges and differentiates into the hindbrain, midbrain, and forebrain. 3)the rest of the neural tube becomes the spinal chord
what does the fluid filled cavity become?
central canal of the spinal chord and the four ventricles of the brain
the fluid is the
compared to the size of the brain from birth, how much heavier is it after one year and adult
after one year, it is more than two times heavier. but doesn't become much heavier when adult
what are the five steps of development of neurons in the brain
proliferation, migration, differentiation, myelination, synaptogenesis
production of new cells/neurons in the brain primarily occuring early in life.
steps of proliferation
1)early in devleopment the cells lining the ventricles divide. 2)Some cells become stem cells that continue to divide. 3)others remain where they are or become neurons or glia that migrate to other locations
refers to the movement of newly formed neurons and glia to locations
During Migration some neurons or glia don't reach their destination till adulthood. true or false
migration occurs only in a specific spot in brain.
false, migration occurs in a variety of directions throughout the brain
what do immunoglobins and chemokines do?
guide neuron migration. (chemical paths)
formation of axon and dendrites that gives neurons their distinctive shape
what grows first axon or dendrite?
when does the axon grow?
during migration or until it reaches its destination
When glia produce fatty sheath covering axons in some neurons
what does mylelin due to transmition of neural impulses?
speeds it up
where does myelination first occur? then where?
spinal chord, then hindbrain, midbrain, then forbrain
myelination occurs gradually for decades. true or false
final stage of neural devleopment and refers to the formation of synapses between neurons
for how long does synaptogensis occur?
throughout life as neurons are constantly forming new connections and discarding old ones.
synaptogensis slows later in lifetime. true or false
what research showed that new neurons were formed after early development
stem cells are undifferentiated cells found in the interior of the brain that generate "daughter cells" that can transform into glia or neurons
new olfactory bulbs continually replace dying ones. true or false.
development of new neurons also occurs in other brain regions. true or false.
stem cells differentiate into new neurons in _________ __________ of mammals and _____ _________?
adult hippocampus and faciliate learning
different cells have different average life spans. true or false
what kind of cells are the newest and how old
skin cells. must under year old
what is an example of old cells and how old
heart cells. as old as person
How many neurons do mammalian cerebral cortex form after birth
few or none
how far do axons have to travel to make the right connection
What did Sperry's research on newt's show about axons
they follow a chemical trail to reach their appropriate target. they follow a gradient of chemicals in which they are attracted to some chemicals and repelled by others
what happens when axons initially reach their target?
they form synapses with several cells
what do postsynaptic cells do with some cells
strengthen with some and eliminate connections with others
what does the formation or elimination depend on
depend upon input from incoming axons
selection process of neural connections
how many synaptic connections are formed
more than we need
when the most successful axon and combinations combine, the others...
Levi Montalacini discovered that
muscles do not determine how many axons form, they determine how many survive.
Nerve Growth Factor (NGF)
type of protein (neurotopin) released by muscles that promote the survival and growth of axons.
when the brain overproduces neurons and applies apoptosis what does it enable
enables the exact matching of number of incoming axons to the number of recieving cells
if axons are not exposed to neurotropins what happens
do healthy adult nervous system contain neurons that failed to make appropriate connections?
is the visual cortex thicker or thinner for blind people? why?
thicker because of lack of visual stimuli. can't prune out ineffective neurons
can a mutation in one gene lead to many defects?
what can happen if there are chemical distortions in the brain during early development
can cause significant impairment and developmental problems
fetal alcohol syndrome caused by?. what are some characteristics?
condition children have if mother drinks heavily during pregnancy. hyperactivity and impulsivness, difficulty maintaining attention, mental retardation, motor problems heart defects, facial abnormalties.
children with fetal alcohol syndrome have different dendrites how?
they are short with few branches
what does exposure to alcohol in the fetus brain do?
suppresses glutamate and enhance the release of GABA
by supressing glutamate and enhancing the release of GABA, what happens to the neurons?
they receive less excitation and exposure to neurtophins and perform apoptosis
how do neurons in different parts of the brain differ?
in shape and chemical components
what happens when immature neurons are transplanted to a developing part of the cortex?
develop properties of new location
what about neurons that are at a later stage of development?
develop some new properties but retain old
why does brain have limited ability to reorganize itself in response to experience?
axons and dendrites continue to modify their structure and connections throughout lifetime. and dendrites continue to grow new spines
what do the gain and loss of spines indicate?
new connections which relates to learning
how are rats affected when raised in enriched enviorment?
thicker cortex and increased dendritic branching
physical activites can affect neurons how
what happens to the cerebral cortex as you age? what can prevent this from happening so intensly?
thickness declines. but much less if physically active
teaching a child a difficult concept like advanced math to enhance intelligence in other areas is an example of
Neurons become more finely tuned and responsive to experiences .....
that have been important in the past
the occipital lobe dedicated to processing visual information adapts to also process
tactile and verbal info
adults that learned to read compared to those who haven't show greater
gray matter and greater thickness in corpus collosum
MRI shows that compared to non musicians, musicians have a larger
temporal lobe in the right hemisphere and thicker gray matter for part of brain responsible for hand control and vision for key board players
phoneticans, people who specialize in analyzing details of speech, are an example of a profession that requires
skills that are known to form in brain before birth
what does practicing a skill do to the brain
reorganizes the brain to maximize performance of that skill
focal hand dystonia "musicians cramp" is an example of what
reorganization of hand goes too far.
impulsivity can be a problem when it leads to
drinking, risky driving, sex, etc
looking away from a powerful attention grabber. gradually improves throughout teenage years
when people claim that adolescents make risky decisions bc of lack of inhibition, which brain area do they point to as being responsible for inhibition
what affects how impulsive adolescents are?
peers, amount of time to make decision
adolescents prefrontal cortex may or may not be the cause of impulsivity
at old age what happens to neurons and synapses?
neurons alters synapses more slowly
what happens to brain structure at old age
what is one way in which odler adults compensate for less efficient brain functioning?
they activate additional areas
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