Week 3-Prenatal and infant brain development Flashcards
Define morphogenesis
the process from a single cell to a complex brain
Define genetic guidance
genetically determined sequence of events that can be modulated by environment
What would be the impact of having no cortex on brain function?
no vision/audition/reasoning/memory/planning
State the three main stages of prenatal development (with time period)
1.Germinal (clump of cells) 0-2 weeks
2.Embryonic (focusing on this stage onwards) 3-8 weeks
3.Fetal 9 weeks-birth
What are the 3 main characteristics needed in an adult brain network?
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
True or false: some structures are already in place before birth which isn’t the big event
True, maturation comes post-birth but a baby’s brain needs different cells/layers/connections
Explain the gross neuroanatomy in prenatal brain development (image to learn on notes)
-early brain is a tube (neural tube)
-neural tube rapidly evolves and differentiates via a series of thickening/constrictions (4 weeks-6 months)
Explain the micro development of a prenatal brain
-embryonic brain undergoes a series of massive cellular changes
-a series of genetically programmed events create a brain pre-birth
True or false: A baby’s brain is mature at birth
false it tends to take 40 weeks of gestation for a baby to be mature
Define gestation
a process of something developing over a time period (can be in the womb)
State the 5 genetically programmed events which develop the neural structure
1.Cell proliferation
2.Cell migration
3.Cell differentiation
4.Programmed cell death
5.Synaptic rearrangement
Explain the process of neural (cell) proliferation
-cell creation
-massive production of cells occurs 2-4 months after gestation but continues until/after birth
True or false: no more neurones are produced after birth
True, but in some instances adults can produce new ones but its the glial cells (‘babysitter of neurons’) that continues being produced after birth
Explain the process of cell migration
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
Explain the process of cell migration: layer differentiation
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
What is the purpose of glial cells in cell migration?
they act as the ‘nurse of the neurons’ (neurones travel through the layers of this cell to form new layers)
Explain the process of cell differentiation
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
Explain the genesis of connections
-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)
True or false: connected neurons process the same information in the chain
True
Explain programmed cell death: apoptosis
-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
True or false: neurons are cells
True
6.Elimination of synapses: explain what synaptic re-arrangement is
-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)
True or false: a prenatal brain has 70% more synapses than the adult brain
false it’s 50% (still a crazy amount of wiring in the prenatal brain)
True or false: info from the left/right visual field are processed in different sides/parts of the brain
True (links to contralateral theory)