Brain development Flashcards
What are the 7 stages of brain development from conception through to 9 months (full term)
neural induction, proliferation, migration, differentiation, synaptogenesis, cell death/stabilisation, synaptic rearrangement.
Neural induction
- forming of the neural tube takes place 18 - 24 days post conception, genetically determined, neural tube forming and ends of it close
Proliferation
-first half of pregnancy (day 24 - 125) genetically determined, HUGE proliferation of the number of cells, so by day 124 foetus has all its cells.
The ventricular zone also forms during proliferation, what is this?
single layer of cells form along inner surface of the neural tube.
Migration
cells migrate from ventricular zone out towards their final destinations
Within migration, what do radial glial cells do?
Act as scaffolding to help other cells migrate (radiate out from the centre of the neural tube towards the end)
What are the 3 layers the cells are moving through in migration?
The ventricular zone, the intermediate zone and the marginal zone
Differentiation
day 125 - postnatal - cells differentiatie into what they will become (e.g hippocampus cell or cerebellum cell) then will start to express particular genes to make exact proteins it needs thus will acquire distinctive features
Synaptogenesis
growing new synapses (connections between cells) - neurons grow more axons and dendrites to create these new synapses
Cell death / stabilisation
initial surge in synaptic growth levels off and declines after first year - process of cell death can prune some cells allowing a more efficient final arrangement
Synaptic rearrangement
Once synapses are formed, synaptic rearragment occurs meaning unnecessary or weak synapses can be lost allowing active synapses that are strenghtended to stay. Allows a more focused pattern of synaptic contact left
From birth to the first two years, what are some changes that occur in the brain?
total brain volume doubles in the first year and reaches 80% adult size by age 2 (meaning basic structual and functional framework in place by age 2).
If the brain is only 80% developed at age 2, what else is required?
After age 2 brain development is mainly characterised by reorgansising and fine tuning major circuits already established.
Childhood brain development
Rapid postnatal growth of cortical grey matter over first 2 years - but slower growpth of cortical white matter throughout CHILDHOOD and adolescence
adolescence brain development
All about developing a more streamlined brain - increasing axon myelination to speed the flow of information, decrease of synaptic connections and dendrites