Prenatal Brain Development

Question 1

define embryo

Answer 1

the developmental stage when major organ systems develop (about weeks 2-8 after conception in humans)

Question 2

define foetus

Answer 2

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))

Question 3

does the human brain finish developing in utero and when is development fastest

Answer 3

• is still developing after birth
• fastest in late gestation

Question 4

from how early on do major developmental stages of brain and spinal cord start

Answer 4

2-3 weeks post conception

Question 5

list the critical stages in brain sequential development stages:

Answer 5

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

Question 6

[1 - neural plate induction] when does neural plate induction process occur and what does it mark

Answer 6

2-3 wks post-conception
- development of the nervous system starting

Question 7

[1 - neural plate induction] from 18 days post-conception, the embryo consisting of 3 layers (list) does what

Answer 7

• endoderm (innermost), mesoderm, ectoderm (outermost)
• begins to implant into uterine wall

Question 8

[1 - neural plate induction] as embryo implants into uterine wall, what also develops

Answer 8

• neural plate develops from a thickening of superficial ectoderm later of cells

Question 9

[1 - neural plate induction] by 20 day post-conception what is present

Answer 9

• neural groove

Question 10

[1 - neural plate induction] what is the basis of the developing nervous system

Answer 10

neural groove

Question 11

[1 - neural plate induction] what does the neural groove ultimately form

Answer 11

neural tube

Question 12

[1 - neural plate induction] the neural plate forms into what before neural groove

Answer 12

neural fold

Question 13

[1 - neural plate induction] by day 22 post-conception what has formed and closed

Answer 13

• neural tube

Question 14

[1 - neural plate induction] by day 22 the developing foetal brain divides into what 4 major components

Answer 14

• telencephalon
• diencephalon
• mesencephalon
• rhombencephalon

Question 15

[1 - neural plate induction] what can collectively be called the prosencephalon

Answer 15

• telencephalon
• diencephalon

Question 16

[2 - neural cell proliferation] neural cell proliferation centres on _____and ____ which is the generation of new neural cells

Answer 16

• mitosis
• proliferation

Question 17

[2 - neural cell proliferation] predominantly occurs where

Answer 17

ventricular zone of neural tube

Question 18

[2 - neural cell proliferation] generates new cells at rates up to what

Answer 18

250,000 cells per minute

Question 19

[2 - neural cell proliferation] initially at this point in neural development what parts of neural cells are point in neurodevelopment

Answer 19

• soma
• immature axons

Question 20

[2 - neural cell proliferation] all cells are _____ at the start of ____

Answer 20

• undifferentiated
• migration

Question 21

[2 - neural cell proliferation] what happens as neurons begin to migrate to their abilities and to what state they are in

Answer 21

• develop ability to produce neurotransmitters
• change from an undifferentiated state into a differentiated neural cell

Question 22

[3 - neural cell migration and aggregation] what is central to this stage

Answer 22

radial glia

Question 23

[3 - neural cell migration and aggregation] what do radial glia do

Answer 23

• act as scaffolding for the migration of neurons

Question 24

[3 - neural cell migration and aggregation] what do apical glia do

Answer 24

• extend an apical process reaching the outer ventricular surface

Question 25

[3 - neural cell migration and aggregation] migrating cells are immature (not finished differentiating) and lack ____

Answer 25

dendrites

Question 26

[3 - neural cell migration and aggregation] describe aggregation in regards to cells

Answer 26

- cells that are done migrating - begin to align themselves with other cells and form structures - process known as aggregation

Question 27

[4 - axon growth and synapse formation] when do axons and dendrites begin to grow to their mature size and shape

Answer 27

once migration is complete and structures have been formed ie/ aggregation

Question 28

[4 - axon growth and synapse development] for maturation, dendrites do what

Answer 28

form synapse with other neurons

Question 29

[4 - axon growth and synapse development] for maturation, what do axons have on one end

Answer 29

- a growth cone comprising microtubules, actin-myosin meshwork, and actin bundles

Question 30

[4 - axon growth and synapse development] during maturation, what is critical to the processes of axons and dendrites to occur

Answer 30

- chemo attractants

Question 31

what is the final stage of foetal brain development

Answer 31

cell death and synapse rearrangement

Question 32

[cell death and synapse rearrangement] what is synaptogenesis

Answer 32

formation of new synapses

Question 33

[cell death and synapse rearrangement] what does synaptogenesis depend on

Answer 33

- the presence of glial cells - especially astrocytes

Question 34

[cell death and synapse rearrangement] what do astrocytes do

Answer 34

modulate synaptic function

Question 35

[cell death and synapse rearrangement] what is critical to the process of synaptogenesis

Answer 35

- exchange of chemical signals between pre and post synaptic neurons

Question 36

[cell death and synapse rearrangement] if the chemical signal between pre and post synaptic neurons is strong, what happens to synapse formation

Answer 36

is encourages and strengthened

Question 37

[cell death and synapse rearrangement] if the chemical signal between pre and post synaptic neurons is weak, what happens to synapse formation

Answer 37

synaptic relationships are lost

Question 38

[cell death and synapse rearrangement] what critical function do microglia have

Answer 38

prune less active synapses to refine neural circuit function -> correct function

Question 39

[cell death and synapse rearrangement] approx how many developing neurons die after migration

Answer 39

between 40-75%

Question 40

[cell death and synapse rearrangement] neuronal death is predominantly due to ____ to compete for _____

Answer 40

- failure - neurotrophins

Question 41

[cell death and synapse rearrangement] what are neurotrophins

Answer 41

- chemo attractants produced by targets

Question 42

[cell death and synapse rearrangement] function of neurotrophins

Answer 42

- promote growth and survival - guide axons - promote synaptogenesis

Question 43

what are the 3 major stages for milestones for neurodevelopment in utero

Answer 43

- fundamentals of neuro-development - neuronal maturation (grey matter development) - myelination (white matter development)

Question 44

[milestones for neurodevelopment in utero] what is the time of greatest importance during pregnancy for brain development

Answer 44

2nd and 3rd trimesters

Question 45

[milestones for neurodevelopment in utero] brain development during 2nd and 3rd trimesters is characterised by: (4)

Answer 45

- neurogenesis - gliogenesis - axonal ingrowth (elongation) - elaboration of synaptic connections

Question 46

[milestones for neurodevelopment in utero] myelination of axons (by oligodendrocytes) accelerates a process that....

Answer 46

is critical for the development of cognitive function later in childhood

Question 47

[milestones for neurodevelopment in utero] by 34 weeks, foetal brain weight is already __% of full-term weight

Answer 47

65%

Question 48

[milestones for neurodevelopment in utero] _______ & ________ grow dramatically during the last 6 weeks of pregnancy

Answer 48

- cortical surface area - cerebral volume

Question 49

[milestones for neurodevelopment in utero] premature birth and foetal growth restriction are both associated with

Answer 49

particular problems with normal neurodevelopment

Question 50

[milestones for neurodevelopment in utero] prematurity and FGE can lead to what structural deficits

Answer 50

- 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

Question 51

[milestones for neurodevelopment in utero] prematurity and FGR can lead to what functional deficits due to these structural deficits

Answer 51

- motor - cognition and learning - behaviour

Question 52

[milestones for neurodevelopment in utero] premature and FGR functional deficit motor list

Answer 52

- reduced gross and fine motor skills - reduced visuomotor skills - clumsiness - cerebral palsy

Question 53

[milestones for neurodevelopment in utero] premature and FGR functional deficit cognition and learning list

Answer 53

- reduced IQ / executive function - reduced verbal IQ - poor memory

Question 54

[milestones for neurodevelopment in utero] premature and FGR functional deficit behaviour list

Answer 54

- attention and interaction difficulties - hyperactivity - mood and irritability - anxiety

Question 55

[milestones for neurodevelopment in utero] what can FGR (and prematurity) neuropathology be caused by, list 4

Answer 55

- chronic hypoxia - hypoglycaemia - oxidative stress - inflammation

Question 56

[milestones for neurodevelopment in utero] depending on what is the main driver the FGR (and prematurity) neuropathology seen could be either

Answer 56

- grey matter pathology - white matter pathology

Question 57

[milestones for neurodevelopment in utero] the brain network connectivity in infant and childhood is the same for FGR versus appropriately grown - T or F

Answer 57

F

Question 58

[milestones for neurodevelopment in utero] the difference in brain network connectivity in FGR versus appropriately grown does what as child grows up

Answer 58

increases in severity