Week 3-Prenatal and infant brain development

Question 1

Define morphogenesis

Answer 1

the process from a single cell to a complex brain

Question 2

Define genetic guidance

Answer 2

genetically determined sequence of events that can be modulated by environment

Question 3

What would be the impact of having no cortex on brain function?

Answer 3

no vision/audition/reasoning/memory/planning

Question 4

State the three main stages of prenatal development (with time period)

Answer 4

1.Germinal (clump of cells) 0-2 weeks
2.Embryonic (focusing on this stage onwards) 3-8 weeks
3.Fetal 9 weeks-birth

Question 5

What are the 3 main characteristics needed in an adult brain network?

Answer 5

1.laminar organisation of the cortex (neurones organised across different layers)
2.different layers=different roles in network e.g. perceiving sound,colour etc.,
3.different connections/wires of the brain=all areas communicate

Question 6

True or false: some structures are already in place before birth which isn’t the big event

Answer 6

True, maturation comes post-birth but a baby’s brain needs different cells/layers/connections

Question 7

Explain the gross neuroanatomy in prenatal brain development (image to learn on notes)

Answer 7

-early brain is a tube (neural tube)
-neural tube rapidly evolves and differentiates via a series of thickening/constrictions (4 weeks-6 months)

Question 8

Explain the micro development of a prenatal brain

Answer 8

-embryonic brain undergoes a series of massive cellular changes
-a series of genetically programmed events create a brain pre-birth

Question 9

True or false: A baby’s brain is mature at birth

Answer 9

false it tends to take 40 weeks of gestation for a baby to be mature

Question 10

Define gestation

Answer 10

a process of something developing over a time period (can be in the womb)

Question 11

State the 5 genetically programmed events which develop the neural structure

Answer 11

1.Cell proliferation
2.Cell migration
3.Cell differentiation
4.Programmed cell death
5.Synaptic rearrangement

Question 12

Explain the process of neural (cell) proliferation

Answer 12

-cell creation
-massive production of cells occurs 2-4 months after gestation but continues until/after birth

Question 13

True or false: no more neurones are produced after birth

Answer 13

True, but in some instances adults can produce new ones but its the glial cells (‘babysitter of neurons’) that continues being produced after birth

Question 14

Explain the process of cell migration

Answer 14

1.All neurones come from neural precursor cells (which can become any type of cell)
2.These undifferentiated cells become either neurones or glia cells
3.Then the immature neurons migrate to colonise all parts of the embryonic brain

Question 15

Explain the process of cell migration: layer differentiation

Answer 15

1.neurons migrating to target layers=cortex layers created
2.neurones use glial cells as a ladder and first cells arrive at own layer and are in the deepest layer (layer 6)
3.cortex assembled from inside out

Question 16

What is the purpose of glial cells in cell migration?

Answer 16

they act as the ‘nurse of the neurons’ (neurones travel through the layers of this cell to form new layers)

Question 17

Explain the process of cell differentiation

Answer 17

Cells start to differentiate when they migrate and become the neural cell they’ll be throughout our lives
-neurons come from precursor cells and there are different types of neurons

Question 18

Explain the genesis of connections

Answer 18

-neurons formed from cell body,dendrites (receiver) and axons (output)
-neurons interconnect with axons forming a network (GoC)
-as neurons differentiate, growing tip of an axon extends to travel and find appropriate target (guided by special proteins and repulsed by others until proper target found to connect with)

Question 19

True or false: connected neurons process the same information in the chain

Answer 19

True

Question 20

Explain programmed cell death: apoptosis

Answer 20

-aims to discard input neurones that didn’t connect to other target neurones as it doesn’t help to process info in the network
-survival of the connected (no role=discarded from neural network)
-brain doesn’t keep things that aren’t useful for processing

Question 21

True or false: neurons are cells

Answer 21

True

Question 22

6.Elimination of synapses: explain what synaptic re-arrangement is

Answer 22

-it’s the change of connection between the synapses/neurons (like wires and all genetically programmed/modulated by environment)
-no signal received however=eliminated (the arrangement is activity-dependent e.g. visual system)

Question 23

True or false: a prenatal brain has 70% more synapses than the adult brain

Answer 23

false it’s 50% (still a crazy amount of wiring in the prenatal brain)

Question 24

True or false: info from the left/right visual field are processed in different sides/parts of the brain

Answer 24

True (links to contralateral theory)

Question 25

How does synapse elimination occur in the visual area?

Answer 25

-before birth we experience little to no visual stimuli so our primary visual cortex isn't specialised -once born we gain visual experience causing synaptic rearrangement/specialisation to occur and the synapses connect to a specific eye becoming more specialised (PVC matures)

Question 26

Is vision innate?

Answer 26

no, argued our visual systems learns by adapting to visual input (can't separate genetics/environment which is a key theory in this lecture)

Question 27

Influence of stimulation on perception: what was learnt adding prism goggles on chicks?

Answer 27

-ability to localise food solely visual/auditory not as good as combined but 42 days after displacement they realign -shows good localisation achieved with both 2 senses

Question 28

Define plasticity

Answer 28

the brains ability to modify/reorganise i.e., learns and adapts through experience

Question 29

What factors can affect plasticity?

Answer 29

forgetting, aging, injury, illness, drugs

Question 30

Give 2 studies supporting plasticity

Answer 30

1.Juggler group compared to the control group (no juggling) MRI scans showed modified brain structure after 6 months of practise 2. Maguire's taxi study: experienced taxi drivers had a larger hippocampus

Question 31

Explain a brain plasticity limitation: ODC modification

Answer 31

-the visual neural system acquires eye specialisation (if one eye occluded a different pattern is seen) -occluding for a whole period causes the occluded eye to take up less cortical space (not seen as useful i.e. survival of the most efficient) and for too long a period causes the ODC to never change (showing plasticity can be damaging)

Question 32

Define the critical period

Answer 32

a time window for plasticity where development of brain mechanism/organ can be influenced

Question 33

Give an example of the critical period in relation to the visual system

Answer 33

-no occluded eye=no ocular dominance initially, synaptic re-arrangement=normal ODC distribution both eyes have equal brain resources -occluded eye=no ocular dominance initially, synaptic re-arrangement=abnormal ODC distribution one eye took all of the brain resources

Question 34

What is one of the key ideas in this lecture?

Answer 34

no stimulation=no function=elimination

Question 35

True or false: adult brain plasticity is higher than in infancy

Answer 35

false things such as sensory, motor, language are easier learned at a younger age

Question 36

Staudt 2010: what was found when children younger than 5 had a lesion in the left hemisphere?

Answer 36

reorganisation of language processing in the right hemisphere

Question 37

Why are infants' brains so plastic?

Answer 37

-the brain is not yet finished as grey maturation still needs to happen over time (seen in brain scans) -the brain network put in place during infancy will be 'crystallised for life'

Question 38

Explain the link between sociopathy, infancy, plasticity and the critical period

Answer 38

-MAOA gene aka the 'aggression' gene (more likely to occur with low MAOA genotype) -found MAOA genotype structurally affects the brain (scans show difference in size between left/right amygdala) -however only activated with environmental factors e.g. severe maltreatment so the risk of becoming violent as a result is nature THROUGH nuture (not vs)

Question 39

What aspects of brain structure crystallise during infancy?

Answer 39

vision and ODC

Question 40

True or false: the network is hard wired

Answer 40

False it's pre-wired (nature) and then influenced by the environment (nurture)

Question 41

What's vision like for infants?

Answer 41

-immature vision with blurry perception at 6 months of age -have 2D perception at birth not 3D but develops over time

Question 42

What is face perception like in infants?

Answer 42

-infants display same electrical pattern as adults (processing stimuli records electrical component P1) BUT response time slower -face perception and discrimination gradually improves with age

Question 43

What is sound perception like in infants?

Answer 43

-external sounds processed via auditory system 30 weeks GA -newborns discriminate mother's voice at birth or recognise songs -auditory perception follows some maturation and sounds are filtered

Question 44

Explain language in infants

Answer 44

-same language network activated in infants even though they can't process speech -newborns extract words from continuous