NP: Child Psychology Flashcards
Rasmussen’s encephalitis
chronic inflammation -> seizures -> need to remove the entire right hemisphere
when does the brain start to develop
about 21 days after conception
neural tube =
cylinder of cells that develops into the nervous system
when does the developing brain look like a human brain
100 days after conception
when do sulci and gyri form
around 28-30 weeks
where are neurons formed
near the walls of the ventricles -> from there migrate to their destinations
Brain development involves a massive overproduction of cells and connections, followed by apoptosis, or programmed cell death, to remove the excess cells
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kijken naar model brain development
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stages of brain development
- Cell birth (neurogenesis; gliogenesis)
- Cell migration to final destination
- Cell differentiation
- Cell maturation (dendrite and axon growth)
- Synaptogenesis (formation of synapses)
- Cell death and synaptic pruning (apoptosis)
- Myelogenesis (formation of myelin)
how do stem cells differentiate
stem cell -> 2 cellen, 1 stemcell en 1 progenitor cell -> neuroblast and glioblast
zie model neuron generation
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where is neurogenesis in adults
in olfactory bulb and hippocampus! dus er is wel neurogenesis in human adults
neuron generation
- Neural stem cells line the neural tube and give rise to two
daughter cells, one of which is another stem cell and one of
which is a progenitor cell - Progenitor cells divide to produce neuroblasts or glioblasts, which ultimately develop into neurons or glia
- Stem cells exist throughout life and produce new neurons in the
hippocampus and olfactory bulb - The presence of stem cells suggests that neural injuries could be
repaired, but that does not routinely happen in the adult brain - The rate of neurogenesis decreases with age, and the function of
neurons produced later in life may be different
cell migration
- Neuroblasts that form the cortex are produced by about 4.5 months gestation
- Brain is more susceptible to injury during the cell migration phase than during the
neurogenesis phase - Cell migration begins around the time the first neurons are formed, but migration will not
be complete until about 8 months after birth
differentiation, migration, maturation, myelination and glial genesis when?
differentiation - birth
migration - 8 mo after birth
maturation - adulthood
myelination - adolescence
glial - throughout life
neuroblasts are generated in the …
subventricular zone
how do neurons migrate
in columns, from the inside to the outside. dus cells that end up in the outside layers migrate first, from the inside.
development of cortical maps
- Subventricular zone contains a map of the cortex that
enables cells from a part of the zone to migrate to a specific
part of the cortex - Neurons migrate along radial glia, which extend from the
zone to the related region of the cortex - Cortex is built from the inside out, so the deepest layer, VI,
forms first, then V, and so on until layer I is formed
neural maturation
- During maturation, the cells produce dendrites to increase their surface area to form synapses
- Dendritic arborization involves branching
- Dendritic spines are the targets for the synapses
- Dendrites start to form prenatally, and this continues long after birth
- Dendrites grow slowly, only micrometers per day
- In addition, axons grow toward the appropriate targets
- Axons grow at a fairly constant rate of 1 millimeter per day
- The faster axon growth means axons reach their targets before dendrites have developed,
so can influence dendritic development
guiding the development of axons
- Axons need to synapse on specific targets in order to be functional
- Failure of the axon to reach the appropriate target results in the death of the neuron
- There are many different mechanisms to guide an axon to the target
what can interfere with the development of axons
- Growth of neurons can be blocked by scarring or disruption, lack of oxygen, or exposure to toxins
- Genetic abnormalities can result in problems with axonal migration
-> If the axonal target is damaged, the axons may degenerate or make a connection with an inappropriate target
synapses
- There are on the order of 10^14 synapses in the human brain
- Genes likely specify the broad outlines of these connections, not the specifics of each
connection - Various cues and signals specify the individual connections
5 pases of synapse formation that occur between conception and death
- Phase 1 and 2 synapses are independent of experience
- Phase 3 synapses are formed rapidly from birth through the first few years of life based on experience
- Phase 4 represents a plateau of synaptic number, followed by a rapid pruning through puberty, based on experience
- Phase 5 is a plateau in middle age through a decline later in life, based on experience
kijken naar model phases of synapse formation and pruning
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striate cortex is involved in…
visual processing
prefrontal cortex is also involved in visual processing,
maar later. dus sensory areas develop earlier than more higher order processes
glial development ~
Glial development begins after neuron formation and continues throughout life
* Myelination is not essential for neuronal function, but does make functioning more efficient
* Myelination proceeds from birth through adolescence
* Different parts of the brain are myelinated at different times in that process
* Areas that myelinate earlier are associated with simple movements or sensory analysis; areas that are myelinated later are associated with higher cognitive functions
is myelination essential for neuronal functioning
nee, maar maakt het wel meer efficient
when is myelination present
birth through adulthood
areas that mature last
prefrontal cortex, temporal and parietal cortex
kijken naar model myelination in the cortex
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adolescence =
age 10-17 in girls
age 12-18 in boys
wat gebeurt er met connections during adolescence
rapid pruning and rapid growth of new connections. increase of WM, daardoor verandert de balans tussen GM and WM. (a lot of new wm, a little bit of pruning van gm)
Throughout adolescence, there are periods of
Increased glia production, decreased cortical thickness, and changes in connectivity
Physical and hormonal changes are related to patterns of brain maturation
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kijken naar model neural development over time
- sensorimotor
- temporal and parietal
- prefrontal cortex
Which of these would appear earliest in the developmental sequence:
a. Synaptogenesis
b. Cell migration
c. Differentiation
d. Functional validation
b
plasticity =
the ability of the brain to adapt to environmental changes and compensate for injury
experience results in…
changes to the connections in the brain
what is the molecular basis of plasticity
not clear, but likely related to epigenetic changes that alter gene expression