Prenatal Brain Development Flashcards
define embryo
the developmental stage when major organ systems develop (about weeks 2-8 after conception in humans)
define foetus
organ systems grow and mature (from about weeks 9-38 after conception, or weeks 10-40 of pregnancy (counted from date of last menstrual period))
does the human brain finish developing in utero and when is development fastest
- is still developing after birth
- fastest in late gestation
from how early on do major developmental stages of brain and spinal cord start
2-3 weeks post conception
list the critical stages in brain sequential development stages:
1 - neural plate induction
2 - neural cell proliferation
3 - neural cell migration and aggregation
4 - axon growth and synapse formation
5 - cell death and synapse rearrangement
[1 - neural plate induction] when does neural plate induction process occur and what does it mark
2-3 wks post-conception
- development of the nervous system starting
[1 - neural plate induction] from 18 days post-conception, the embryo consisting of 3 layers (list) does what
- endoderm (innermost), mesoderm, ectoderm (outermost)
- begins to implant into uterine wall
[1 - neural plate induction] as embryo implants into uterine wall, what also develops
- neural plate develops from a thickening of superficial ectoderm later of cells
[1 - neural plate induction] by 20 day post-conception what is present
- neural groove
[1 - neural plate induction] what is the basis of the developing nervous system
neural groove
[1 - neural plate induction] what does the neural groove ultimately form
neural tube
[1 - neural plate induction] the neural plate forms into what before neural groove
neural fold
[1 - neural plate induction] by day 22 post-conception what has formed and closed
- neural tube
[1 - neural plate induction] by day 22 the developing foetal brain divides into what 4 major components
- telencephalon
- diencephalon
- mesencephalon
- rhombencephalon
[1 - neural plate induction] what can collectively be called the prosencephalon
- telencephalon
- diencephalon
[2 - neural cell proliferation] neural cell proliferation centres on _____and ____ which is the generation of new neural cells
- mitosis
- proliferation
[2 - neural cell proliferation] predominantly occurs where
ventricular zone of neural tube
[2 - neural cell proliferation] generates new cells at rates up to what
250,000 cells per minute
[2 - neural cell proliferation] initially at this point in neural development what parts of neural cells are point in neurodevelopment
- soma
- immature axons
[2 - neural cell proliferation] all cells are _____ at the start of ____
- undifferentiated
- migration
[2 - neural cell proliferation] what happens as neurons begin to migrate to their abilities and to what state they are in
- develop ability to produce neurotransmitters
- change from an undifferentiated state into a differentiated neural cell
[3 - neural cell migration and aggregation] what is central to this stage
radial glia
[3 - neural cell migration and aggregation] what do radial glia do
- act as scaffolding for the migration of neurons
[3 - neural cell migration and aggregation] what do apical glia do
- extend an apical process reaching the outer ventricular surface
[3 - neural cell migration and aggregation] migrating cells are immature (not finished differentiating) and lack ____
dendrites
[3 - neural cell migration and aggregation] describe aggregation in regards to cells
- cells that are done migrating
- begin to align themselves with other cells and form structures
- process known as aggregation
[4 - axon growth and synapse formation] when do axons and dendrites begin to grow to their mature size and shape
once migration is complete and structures have been formed ie/ aggregation
[4 - axon growth and synapse development] for maturation, dendrites do what
form synapse with other neurons
[4 - axon growth and synapse development] for maturation, what do axons have on one end
- a growth cone comprising microtubules, actin-myosin meshwork, and actin bundles
[4 - axon growth and synapse development] during maturation, what is critical to the processes of axons and dendrites to occur
- chemo attractants
what is the final stage of foetal brain development
cell death and synapse rearrangement
[cell death and synapse rearrangement] what is synaptogenesis
formation of new synapses
[cell death and synapse rearrangement] what does synaptogenesis depend on
- the presence of glial cells - especially astrocytes
[cell death and synapse rearrangement] what do astrocytes do
modulate synaptic function
[cell death and synapse rearrangement] what is critical to the process of synaptogenesis
- exchange of chemical signals between pre and post synaptic neurons
[cell death and synapse rearrangement] if the chemical signal between pre and post synaptic neurons is strong, what happens to synapse formation
is encourages and strengthened
[cell death and synapse rearrangement] if the chemical signal between pre and post synaptic neurons is weak, what happens to synapse formation
synaptic relationships are lost
[cell death and synapse rearrangement] what critical function do microglia have
prune less active synapses to refine neural circuit function -> correct function
[cell death and synapse rearrangement] approx how many developing neurons die after migration
between 40-75%
[cell death and synapse rearrangement] neuronal death is predominantly due to ____ to compete for _____
- failure
- neurotrophins
[cell death and synapse rearrangement] what are neurotrophins
- chemo attractants produced by targets
[cell death and synapse rearrangement] function of neurotrophins
- promote growth and survival
- guide axons
- promote synaptogenesis
what are the 3 major stages for milestones for neurodevelopment in utero
- fundamentals of neuro-development
- neuronal maturation (grey matter development)
- myelination (white matter development)
[milestones for neurodevelopment in utero] what is the time of greatest importance during pregnancy for brain development
2nd and 3rd trimesters
[milestones for neurodevelopment in utero] brain development during 2nd and 3rd trimesters is characterised by: (4)
- neurogenesis
- gliogenesis
- axonal ingrowth (elongation)
- elaboration of synaptic connections
[milestones for neurodevelopment in utero] myelination of axons (by oligodendrocytes) accelerates a process that….
is critical for the development of cognitive function later in childhood
[milestones for neurodevelopment in utero] by 34 weeks, foetal brain weight is already __% of full-term weight
65%
[milestones for neurodevelopment in utero] _______ & ________ grow dramatically during the last 6 weeks of pregnancy
- cortical surface area
- cerebral volume
[milestones for neurodevelopment in utero] premature birth and foetal growth restriction are both associated with
particular problems with normal neurodevelopment
[milestones for neurodevelopment in utero] prematurity and FGE can lead to what structural deficits
- reduced head circumference
- reduced total and grey matter volume
- reduced hippocampal and cerebellar volume
- reduced total number of cells
- reduced myelin content
- thinning cortex with altered gyrification
- delayed myelination
- reduced connectivity
[milestones for neurodevelopment in utero] prematurity and FGR can lead to what functional deficits due to these structural deficits
- motor
- cognition and learning
- behaviour
[milestones for neurodevelopment in utero] premature and FGR functional deficit motor list
- reduced gross and fine motor skills
- reduced visuomotor skills
- clumsiness
- cerebral palsy
[milestones for neurodevelopment in utero] premature and FGR functional deficit cognition and learning list
- reduced IQ / executive function
- reduced verbal IQ
- poor memory
[milestones for neurodevelopment in utero] premature and FGR functional deficit behaviour list
- attention and interaction difficulties
- hyperactivity
- mood and irritability
- anxiety
[milestones for neurodevelopment in utero] what can FGR (and prematurity) neuropathology be caused by, list 4
- chronic hypoxia
- hypoglycaemia
- oxidative stress
- inflammation
[milestones for neurodevelopment in utero] depending on what is the main driver the FGR (and prematurity) neuropathology seen could be either
- grey matter pathology
- white matter pathology
[milestones for neurodevelopment in utero] the brain network connectivity in infant and childhood is the same for FGR versus appropriately grown - T or F
F
[milestones for neurodevelopment in utero] the difference in brain network connectivity in FGR versus appropriately grown does what as child grows up
increases in severity
