Plasticity and Regeneration Flashcards
What 2 factors influence gene expression in a cell?
- Inducing factors
- Competence of the cell
What can neural precursor cells also be called?
Neural stem cells
What are neural precursor cells?
Infinitely self-renewing stem cells that are able to give rise to any class of cells in the nervous system (e.g. inhibitory/excitatory neurons, oligodendrocytes, astrocytes)
What does self-renewing in regards to self-renewing stem cells?
Means that they are able to divide to give rise to more stem cells
What are neural progenitor cells, and give an example of one?
Cells that are unable to divide and only able to give rise to one class of cell.
An example is oligodendroglial progenitor cells, which can become an oligodendrocyte
What do neural progenitor cells arise from?
Neural precursor cells
What are the two proteins found on opposite poles of a neural precursor cell?
Numb and Notch-1
What is symmetrical division of neural precursor cells, and what does it give rise to?
When the division is across the poles with Notch-1 and Numb so both daughter cells contain both of proteins
Gives rise to 2 neural precursor cells
What is asymmetrical division of neural precursor cells, and what does it give rise to?
When the division leads to one daughter cell only containing Notch-1, and the other only containing Numb.
Gives rise to a neural progenitor cell and a neuroblast
What is a neuroblast, and what can it develop into?
A post-mitotic immature nerve unable to further divide but can develop into a neuron.
What factors determine the fate of neuroblasts?
- Its location on the ventricular zone
- Age of the neural precursor cell it was derived from
- The environment at the time of the division
What are the stages of neuroblast differentiation?
- Pathway selection
- Target selection
- Address selection
What are chemoattractants and give an example of one?
Chemicals secreted from the ventral midline of the spinal cord that attract axons with the correct receptor to grow towards the highest concentration of them.
An example is netrin
What are chemorepellants and give an example of one?
Chemicals secreted from the ventral midline of the spinal cord. Axons with the receptor for it grow away from the region with the highest concentration of them.
An example is slit
How can axons ensure that they continue to grow away from chemorepellants?
By upregulating receptors for the chemorepellant
What do neurotrophic factors do, and what is an example of one?
Support the survival, growth and differentiation of developing and mature neurons.
An example is neural growth factor (NGF).
What could happen to neurons that are out-competed for neurotrophic factors?
They could apoptose
What is an example of synaptic elimination?
With muscle fibres, they are initially innervated by multiple alpha motor neurons. As we develop, all but one of these alpha motor neurons are lost.
First, ACh receptors are lost and then the axon branch gets withdrawn.
What are critical periods?
Time windows where the developing brain can be influenced the most by activity-mediated events.
This allows for the learning of skills/behaviours (e.g. language)
What are the stages of peripheral nerve regeneration?
1) First, macrophages clear any debris.
2) Then, Schwann cells proliferate and express adhesion molecules on their surface. They also release neutrotrophins.
3) The regenerating axon (which acts as a parent axon), then grows to replace the damaged axon and develops the appropriate receptors.
What are the two requirements for critical periods to be successful?
- Availability of the influences (e.g. being exposed to language)
- Neural capacity to be able to respond to them
What happens in central nerve regeneration?
1) Local cellular changes occur at the site of injury and myelin (plus other cellular components) get degenerated.
2) Microglia clear the debris
3) Glial scar formation then occurs
Where are the only places that adult neurogenesis can take place?
- Sub ventricular zone (SVZ)
- Hippocampus (mainly interneurons)
What role does neurogenesis in the hippocampus play in memory?
Helps to categorise events in the memory space into different time periods, allowing different events to be separated.
