Brain Wiring Flashcards
What are the five positions of cellular proliferation?
- Ist position - A cell in the ventricular zone extense a process that reaches upward toward the pia
- 2nd position - The nucleus of the cell migrates upward from the ventricular surface towards the pial surface the cell’d DNA is copies
- 3rd position - The nucleus containing two complete copies of the genetic instructions, setteles back to the ventricular surface
- 4th posiiton - the cell retracts its arm from the pial surface
- fifth position - The cell divides in two
The cell than divides vertically or horiziontally
What is the result of a cell dividing horizontally? When does this happen in development?
The daughter cell lying furthest away from the ventricular surface migrates away to take up its position in the cortex, where it never divides again. The other daughter cells stays in the ventricular zone to divide more.
Happens in later development
What is the result of a cell dividing vertically? When does this happen in development?
Both daugher cells remain in the ventricular zone to divide again and again,
Happens early in development
What happens to notch-1 and numb transcription factors during vertical or horizontal division?
Vertical - Notch-1 and numb are equally divided among daughters, allowing them to continue dividing
Horizontal - Notch-1 migrates with the cell that goes to the cortex, numb remains with the cell that will divide again.
What type of cells make the scaffolds that neuroblasts climb up during cell migration?
radial glial cells
What are young migrating neurons called?
neuroblasts
In what order does the cortex build itself through cell migration?
1.Subplate
Cortical plate becomes below
2. layer IV
3. Layer V
etc. etc.
Which protein regulates the assembly of the cortex as a transcription factor?
reeler
What order do cells of the brain differentiate?
- Neuronal differentiation
- Astrocyte differentiation
- Oligodendrocyte differentiation
What repels growing pyramidal cell axons and attracts apical dendrites? Where is it secreted?
Secreted into the marginal zone.
Semaphorin 3A
What causes cytoarchitectural differences in adult brain cortex?
The arrival of thalamic axons to the cortex
What are the three phases of axon development?
- Pathway selection
- Target selection
- Address selection
What does the glycoprotein laminin do? (hint, part of extracellular matrix)
Axon expresses special surface molecules called intergrins that bind laminins from extracellular matrix, this promotes axonal elongation. This can direct axonal growth
What is it called where axons grow and stick together?
fasciculation
What allows fasciculation of axons to happen?
Cell-adhesion molecules (CAM)
What type of molecule attracts a growing axon? What is an example?
Chemoattractant
Netrin
What is an example of a chemorepellant?
slit, chases axons away
What must axons have in order to be affected by slit?
The protein robo
What is the chemoaffinity hypothesis?
That growing axons express proteins that are matched complementary with chemical markers on their targets to establish precise connections.
What are the steps of synapse formation?
- Postsynaptic receptos begin clustering under growth cone
- Agrin is depositied in the extracellular space at point of contact
- Layer where receptors are is called basal lamina
- Muscle specific kinase binds to agrin which causes rapsyn to gather posysynaptic ACh receptors at the synapse
- Nueregulin regulates the amount of receptors expressed
- Entry of calcium into the growth cone causes it to trigger transmitter release and finally mature (through a couple weeks cytoskeleton and others change)
How do neutrophins such as nerve growth factor (NGF) save neurons from apoptosis?
Switching off the genetic program for apoptosis that all neruons have
What causes selective cell death in brain development neurons?
Competition for trophic factors
What is the condition where eyes are not perfectly aligned?
Strabismus
Cortical cells are not binochular with strabismus, ocular dominance groups are sharply segregated to left or right eye
What two diffuse modulatory systems effect plasticity?
- Cholinergic basal forebrain complex
- Epinephrinergic locus coeruleus
What three things cause critical periods to end?
- Axon growth ceases
- Synaptic transmissions mature
- Plasticity dimishes when cortical activation is constrained
