Plasticity And Regeneration Flashcards
Gene expression depends on what?
Inducing factors
Competence- ability to respond to factors (transduction molecules)
Neurogenesis happens between:
5th week- 5th month of gestation
Peak rate of neurogenesis?
250,000 per min
Neural progenitor cell?
Incapable of self renewing
Give rise to one class
Asymmetrical division gives rise to…
Neuroblast and progenitor cell with limited mitotic potential
Balance of numb and notch causes?
2 neural stem cells
Unequal distribution numb and notch 1 leads to?
Neuroblast with all notch 1 and progenitor cell with numb
Neuroblast Migrating neuron pends on factors?
Age of precursor cell, position in ventricular zone, environment at time of division
How do neuroblast differentiate?
Growth cone and filopodia
Differentiate conditions?
- Pathway selection e.g. retinal ganglion cell reaching the correct thalamic location.
- Target selection
e. g. selecting the appropriate thalamic nucleus, LGN. - Address selection
e. g. which LGN layer.
Chemoattractant?
Netrin
Chemorepellent?
Slit
Time window for optimal development?
Critical periods
Conditions for Successful completion of critical period?
- Availability of Appropriate influence
2. Neural capacity to respond
Peripheral regeneration?
Injury to peripheral nerve causing macrophages to remove myelin debris.
Schwann cells produce growth promoting signals, neurotrophic
Parent neuron expresses genes that restore it to a growth state, and allow it to respond to factors provided by Schwann cells
Places of neurogeneration?
Hippocampus (primarily interneurons)
,subventricular zone to olfactory bulb
Barriers to regeneration?
- Not enough neurons
- No radial glial cells for scaffolding
- No migration
- Hostile environment for repair/regeneration
- No new interneurons, no interneurons progenitors
Dividing precursor cells stages?
In G1- nucleus is near ventricular surface
During s stage, nucleus and surrounding cytoplasm migrate towards pail surface and DNA replicates
During G2- cell grows and nucleus migrates towards lumen again
In mitosis cells lose their connection to pial surface and divide.
What is a neuroblast?
Post mitotic, immature nerve cell that will differentiate into a neuron.
Where are Hsiang and neutron secreted?
Ventral midline of the spinal cord
Why do critical periods end?
Axon growth?
Synaptic transmission matures?
Constraint cortical activation
Central nerve regeneration?
Injury to nerve, causes degeneration of myelin and other elements, microglia come to clear debris, local production of inhibitory factors by astrocytes oligodendroglia and microglia and glial scar formation
