2 Neurodevelopment Flashcards
How heavy is the brain at birth and during adulthood?
350g –> 1300g
What are the three stages of prenatal development?
Germinal, embryonic and fetal
What is a zygote?
The union of the egg and sperm
When the zygote divides, what does it form?
A morula
When the morula divides, what does it form?
A blastocyst
What re the three layers of the embryonic disc?
Ectoderm, mesoderm and endoderm
Which layer of the embryonic disc forms the neural tube and NS?
Ectoderm
What are the 6 stages of brain development?
Proliferation, cell migration, cell differentiation and maturation, synaptogeneis and synaptic pruning, cell death, myelination
What 3 main things happen at proliferation?
Stem cells divide to form progenitor cells / progenitor cells become a neuroblast or glioblast / they migrate out of the ventricular zone
What happens during cell migration?
The neurons and glia move to their final destination via chemical signals and physical support from radial glia extensions
What happens during cell differentiation and maturation?
Neurons express particular genes to become a particular cell / grow axons and dendrites
What are the two forms of dendritic development?
Arborisation (branching) and spines (where they synapse)
During cell differentiation and maturation, how does timing influence their characteristics?
If implanted early they acquire the characteristics of that region / mature neurons can not acquire characteristics
What happens during synaptogenesis and synaptic pruning?
Growth cone develops extensions / active synapses are strengthened and unused synapses are pruned
What does synaptogeneis and synaptic pruning demonstrate that the brain has?
Plasticity
What happens during cell death?
Axons which do not form active synapses are eliminated / apoptosis is a programmed cell death - as opposed to necrotic cell death / apoptosis is avoided by survival signals
What survival signals can cells use to avoid apoptosis?
Neurotrophins (growth factors) or active communication
What happens during myelination?
The transmission of neural impulses speeds up
Myelination in the PNS uses?
Schwann cells
Myelination in the CNS uses?
Oligodendroglia
Why is the developing brain vulnerable?
Because a mutation on a gene can lead to long-lasting effects - especially if it occurs during a critical period
What is an example of a study into critical periods?
Blakemore - cats in a tube
What did the study into Genie find?
Her window of opportunity closed / she was able to learn lots of words but couldn’t do much with them
What did Hebbs experiment into rats in a lab vs at home find?
Rats in a complex home environment had increased dendritic branching = improved ability to learn
What is the difference between expectant and dependent experience?
Expectant is common to everyone / dependent is unique to the individual
“Early life environmental influences, determine health status” - what is this an example of?
Epigenetics
What are 3 environmental risk factors during prenatal development?
Mothers immune system / prenatal malnutrition / substance abuse / delivery complications
Why is maternal immune activation a risk factor during prenatal development?
If the mothers immune system is working to help her, it was taken away from the baby
What is the name of the brains immune system?
Microglia
What was originally believed of microglia?
They were either ramified or activated
What do we now know about microglia?
Even when they are in a ramified state, they are still working hard
What are three things that microglia do?
Contact neurons / eliminate apoptopic debris / modulate synaptic transmission / shape brain circuits / influence migration
