Lecture 10 - Neuroplasticity Flashcards
What are the Neuroplastic responses to NS damage?
Degeneration —> Regeneration –> Reorganization —> Recovery
What is Neural Degeneration?
Deterioration and death of neurons
What is Neural Degeneration common in?
- Neurodegenerative disease
- Normal Neurodevelopment
What is the complex onset?
- Different in different types of neurons
- Different in different pathologies
- Modulated by nearby Glia Cells
- Modulated by activity of accepted neurons
What are Axotomy models?
Cutting an axon
What always happens in Axotomy models?
Anterograde degeneration the distal segment between the cut and synaptic terminal
What do we often see in Axotomy models?
Retrograde degeneration of the proximal segment between the cut and cell body
What do sometimes see in Axotomy models?
Transneuronal degeneration of neurons connected to the damaged neurons. Can be anterograde or retrograde (neurons that are synapse on the dead neuron may degenerate)
What does anterograde mean?
Forward
What does retrograde mean?
Backward
What does trans mean?
Across/beyond
What is Neural regeneration?
The regrowth of damaged neurons
What is regeneration high in?
Invertebrates (frogs and geckos)
What does regeneration not occur in?
Mammals in the CNS
Where can regeneration be observed in mammals?
In the PNS but not common
What influences regeneration?
Glia cells
What do Schwann Cells do?
Promote regeneration
How do Schwann Cells promote regeneration?
- Clean up cellular Debris of degeneration
- Release neurotrophic factors that stimulate growth
- CAMS that provide a pathway
What do Oligodendrocytes?
Inhibit regeneration
How do olioodendrocytes inhibit regeneration?
- Do not clean up debris
- Do not release neurotrophins and CAMs
- Release factors that inhibit regeneration
What happens in the PNS, when you sever a Schwann cells sheaths ?
Often regenerate up incorrect sheaths and reach incorrect targets
When is there no functional regeneration in Schwann cells?
When a nerve is damaged and the severed ends of the Schwann cells sheaths are widely separated
What are the three patterns of Axonal Regeneration in the PNS?
- Original Schwann cell myelin can remain intact (promote regeneration)
- Severed ends separated by a few mm (may go to wrong target)
- Severed ends are widely separated (no regeneration)
What is collateral sprouting?
The neighbouring neuron of a dead neuron will spread a branch to create a connection with the post synaptic neuron
